Use, Assessment, and Improvement of the Loci-CHEM CFD Code for Simulation of Combustion in a Single Element GO2/GH2 Injector and Chamber

NASA Technical Reports Server (NTRS)

Westra, Douglas G.; Lin, Jeff; West, Jeff; Tucker, Kevin

2006-01-01

This document is a viewgraph presentation of a paper that documents a continuing effort at Marshall Space Flight Center (MSFC) to use, assess, and continually improve CFD codes to the point of material utility in the design of rocket engine combustion devices. This paper describes how the code is presently being used to simulate combustion in a single element combustion chamber with shear coaxial injectors using gaseous oxygen and gaseous hydrogen propellants. The ultimate purpose of the efforts documented is to assess and further improve the Loci-CHEM code and the implementation of it. Single element shear coaxial injectors were tested as part of the Staged Combustion Injector Technology (SCIT) program, where detailed chamber wall heat fluxes were measured. Data was taken over a range of chamber pressures for propellants injected at both ambient and elevated temperatures. Several test cases are simulated as part of the effort to demonstrate use of the Loci-CHEM CFD code and to enable us to make improvements in the code as needed. The simulations presented also include a grid independence study on hybrid grids. Several two-equation eddy viscosity low Reynolds number turbulence models are also evaluated as part of the study. All calculations are presented with a comparison to the experimental data. Weaknesses of the code relative to test data are discussed and continuing efforts to improve the code are presented.

Swirl Coaxial Injector Testing with LOX/RP-J

NASA Technical Reports Server (NTRS)

Greene, Sandra Elam; Casiano, Matt

2013-01-01

Testing was conducted at NASA fs Marshall Space Flight Center (MSFC) in the fall of 2012 to evaluate the operation and performance of liquid oxygen (LOX) and kerosene (RP ]1) in an existing swirl coaxial injector. While selected Russian engines use variations of swirl coaxial injectors, component level performance data has not been readily available, and all previously documented component testing at MSFC with LOX/RP ]1 had been performed using a variety of impinging injector designs. Impinging injectors have been adequate for specific LOX/RP ]1 engine applications, yet swirl coaxial injectors offer easier fabrication efforts, providing cost and schedule savings for hardware development. Swirl coaxial elements also offer more flexibility for design changes. Furthermore, testing with LOX and liquid methane propellants at MSFC showed that a swirl coaxial injector offered improved performance compared to an impinging injector. So, technical interest was generated to see if similar performance gains could be achieved with LOX/RP ]1 using a swirl coaxial injector. Results would allow such injectors to be considered for future engine concepts that require LOX/RP ]1 propellants. Existing injector and chamber hardware was used in the test assemblies. The injector had been tested in previous programs at MSFC using LOX/methane and LOX/hydrogen propellants. Minor modifications were made to the injector to accommodate the required LOX/RP ]1 flows. Mainstage tests were performed over a range of chamber pressures and mixture ratios. Additional testing included detonated gbombs h for stability data. Test results suggested characteristic velocity, C*, efficiencies for the injector were 95 ]97%. The injector also appeared dynamically stable with quick recovery from the pressure perturbations generated in the bomb tests.

Measurements of admittances and characteristic combustion times of reactive gaseous propellant coaxial injectors

NASA Technical Reports Server (NTRS)

Janardan, B. A.; Daniel, B. R.; Zinn, B. T.

1979-01-01

The results of an experimental investigation that was concerned with the quantitative determination of the capabilities of combustion processes associated with coaxial injectors to amplify and sustain combustor oscillations was described. The driving provided by the combustion process was determined by employing the modified standing-wave method utilizing coaxial injectors and air-acetylene mixtures. Analyses of the measured data indicate that the investigated injectors are capable of initiating and amplifying combustion instabilities under favorable conditions of injector-combustion coupling and over certain frequency ranges. These frequency ranges and the frequency at which an injector's driving capacity is maximum are observed to depend upon the equivalence ratio, the pressure drop across the injector orifices and the number of injector elements. The characteristic combustion times of coaxial injectors were determined from steady state temperature measurements.

An experimental investigation of reacting and nonreacting coaxial jet mixing in a laboratory rocket engine

NASA Astrophysics Data System (ADS)

Schumaker, Stephen Alexander

Coaxial jets are commonly used as injectors in propulsion and combustion devices due to both the simplicity of their geometry and the rapid mixing they provide. In liquid rocket engines it is common to use coaxial jets in the context of airblast atomization. However, interest exists in developing rocket engines using a full flow staged combustion cycle. In such a configuration both propellants are injected in the gaseous phase. In addition, gaseous coaxial jets have been identified as an ideal test case for the validation of the next generation of injector modeling tools. For these reasons an understanding of the fundamental phenomena which govern mixing in gaseous coaxial jets and the effect of combustion on these phenomena in coaxial jet diffusion flames is needed. A study was performed to better understand the scaling of the stoichiometric mixing length in reacting and nonreacting coaxial jets with velocity ratios greater than one and density ratios less than one. A facility was developed that incorporates a single shear coaxial injector in a laboratory rocket engine capable of ten atmospheres. Optical access allows the use of flame luminosity and laser diagnostic techniques such as Planar Laser Induced Fluorescence (PLIF). Stoichiometric mixing lengths (LS), which are defined as the distance along the centerline where the stoichiometric condition occurs, were measured using PLIF. Acetone was seeded into the center jet to provide direct PLIF measurement of the average and instantaneous mixture fraction fields for a range of momentum flux ratios for the nonreacting cases. For the coaxial jet diffusion flames, LS was measured from OH radical contours. For nonreacting cases the use of a nondimensional momentum flux ratio was found to collapse the mixing length data. The flame lengths of coaxial jet diffusion flames were also found to scale with the momentum flux ratio but different scaling constants are required which depended on the chemistry of the reaction. The effective density ratio was measured which allowed the flame lengths to be collapsed to the nonreacting scaling relation. The equivalence principle of Tacina and Dahm was utilized to compare the theoretical and measured effective density ratios.

Benchmark Wall Heat Flux Data for a GO2/GH2 Single Element Combustor

NASA Technical Reports Server (NTRS)

Marshall, William M.; Pal, Sibtosh; Woodward, Roger d.; Santoro, Robert J.

2005-01-01

Wall heat flux measurements in a 1.5 in. diameter circular cross-section rocket chamber for a uni-element shear coaxial injector element operating on gaseous oxygen (GOz)/gaseous hydrogen (GH,) propellants are presented. The wall heat flux measurements were made using arrays of Gardon type heat flux gauges and coaxial thermocouple instrumentation. Wall heat flux measurements were made for two cases. For the first case, GOZ/GHz oxidizer-rich (O/F=l65) and fuel-rich preburners (O/F=1.09) integrated with the main chamber were utilized to provide vitiated hot fuel and oxidizer to the study shear coaxial injector element. For the second case, the preburners were removed and ambient temperature gaseous oxygen/gaseous hydrogen propellants were supplied to the study injector. Experiments were conducted at four chamber pressures of 750, 600, 450 and 300psia for each case. The overall mixture ratio for the preburner case was 6.6, whereas for the ambient propellant case, the mixture ratio was 6.0. Total propellant flow was nominally 0.27-0.29 Ibm/s for the 750 psia case with flowrates scaled down linearly for lower chamber pressures. The axial heat flux profile results for both the preburner and ambient propellant cases show peak heat flux levels a t axial locations between 2.0 and 3.0 in. from the injector face. The maximum heat flux level was about two times greater for the preburner case. This is attributed to the higher injector fuel-to-oxidizer momentum flux ratio that promotes mixing and higher initial propellant temperature for the preburner case which results in a shorter reaction zone. The axial heat flux profiles were also scaled with respect to the chamber pressure to the power 0.8. The results at the four chamber pressures for both cases collapsed to a single profile indicating that at least to first approximation, the basic fluid dynamic structures in the flow field are pressure independent as long as the chamber/njector/nozzle geometry and injection velocities remain the same.

Engine-Level Simulation of Liquid Rocket Combustion Instabilities: Transcritical Combustion Simulations in Single Injector Configurations

DTIC Science & Technology

2012-03-01

simple 1-step mechanism taking into account 4 species: CH4, O2, CO2 and H2O. Figure 2. Multiblock grid for the CVRC experiment. Left: Overall view, Right... Supercritical (and subcritical) fluid behavior and modeling: drops, streams, shear and mixing layers, jets and sprays. Progress in Energy and...hydrogen shear-coaxial jet flames at supercritical pressure. Com- bustion science and technology, 178(1-3):229–252, 2006. 12 B. E. Poling, J. M. Prausnitz

Experimental spray atomization studies of uni-element shear coaxial injector plate geometry for LOX/CH4 combustion and propulsion research

NASA Astrophysics Data System (ADS)

Dorado, Vanessa

The Center for Space Exploration Technology Research (cSETR) has developed a set of shear coaxial injectors as part of a system-level approach to study LOX/CH4 combustion. This thesis describes the experimental studies involved in the characterization of the effects produced by two design injection face plate variables: post thickness and recession length. A testing program was developed to study the injectors' atomization process using LN2 as a substitute for LOX in cold flow and the flame anchoring mechanisms in hot firings. The cold flow testing stage was conducted to obtain liquid core measurements and compare its behavior between the different geometric configurations. Shadowgraph technique was used during this testing stage to obtain these measurements and compare them to previously published data and core length mathematical models. The inlet conditions were selected to obtain mixture ratios in the 2-4 range and a wide range of high momentum flux ratios (30-150). Particle Image Velocimetry (PIV) was also used in the testing of the three injectors to assess their atomization performance and their fragmentation behaviors. Results show that changes in central post thickness and co-annular orifice recession length with respect to the injection plate have quantifiable effects in the generated spray flow field, despite not being accounted for in traditional break up calculations. The observations and results of this investigation lead to a proof of concept demonstration in a combustion setting to support the study of flame anchoring mechanisms, also discussed in this work.

Injector Design Tool Improvements: User's manual for FDNS V.4.5

NASA Technical Reports Server (NTRS)

Chen, Yen-Sen; Shang, Huan-Min; Wei, Hong; Liu, Jiwen

1998-01-01

The major emphasis of the current effort is in the development and validation of an efficient parallel machine computational model, based on the FDNS code, to analyze the fluid dynamics of a wide variety of liquid jet configurations for general liquid rocket engine injection system applications. This model includes physical models for droplet atomization, breakup/coalescence, evaporation, turbulence mixing and gas-phase combustion. Benchmark validation cases for liquid rocket engine chamber combustion conditions will be performed for model validation purpose. Test cases may include shear coaxial, swirl coaxial and impinging injection systems with combinations LOXIH2 or LOXISP-1 propellant injector elements used in rocket engine designs. As a final goal of this project, a well tested parallel CFD performance methodology together with a user's operation description in a final technical report will be reported at the end of the proposed research effort.

Combustion and Performance Analyses of Coaxial Element Injectors with Liquid Oxygen/Liquid Methane Propellants

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Jones, G. W.

2010-01-01

Liquid rocket engines using oxygen and methane propellants are being considered by the National Aeronautics and Space Administration (NASA) for in-space vehicles. This propellant combination has not been previously used in a flight-qualified engine system, so limited test data and analysis results are available at this stage of early development. NASA has funded several hardware-oriented activities with oxygen and methane propellants over the past several years with the Propulsion and Cryogenic Advanced Development (PCAD) project, under the Exploration Technology Development Program. As part of this effort, the NASA Marshall Space Flight Center has conducted combustion, performance, and combustion stability analyses of several of the configurations. This paper summarizes the analyses of combustion and performance as a follow-up to a paper published in the 2008 JANNAF/LPS meeting. Combustion stability analyses are presented in a separate paper. The current paper includes test and analysis results of coaxial element injectors using liquid oxygen and liquid methane or gaseous methane propellants. Several thrust chamber configurations have been modeled, including thrust chambers with multi-element swirl coax element injectors tested at the NASA MSFC, and a uni-element chamber with shear and swirl coax injectors tested at The Pennsylvania State University. Configurations were modeled with two one-dimensional liquid rocket combustion analysis codes, the Rocket Combustor Interaction Design and Analysis (ROCCID), and the Coaxial Injector Combustion Model (CICM). Significant effort was applied to show how these codes can be used to model combustion and performance with oxygen/methane propellants a priori, and what anchoring or calibrating features need to be applied or developed in the future. This paper describes the test hardware configurations, presents the results of all the analyses, and compares the results from the two analytical methods

A Computational and Experimental Investigation of Shear Coaxial Jet Atomization

NASA Technical Reports Server (NTRS)

Ibrahim, Essam A.; Kenny, R. Jeremy; Walker, Nathan B.

2006-01-01

The instability and subsequent atomization of a viscous liquid jet emanated into a high-pressure gaseous surrounding is studied both computationally and experimentally. Liquid water issued into nitrogen gas at elevated pressures is used to simulate the flow conditions in a coaxial shear injector element relevant to liquid propellant rocket engines. The theoretical analysis is based on a simplified mathematical formulation of the continuity and momentum equations in their conservative form. Numerical solutions of the governing equations subject to appropriate initial and boundary conditions are obtained via a robust finite difference scheme. The computations yield real-time evolution and subsequent breakup characteristics of the liquid jet. The experimental investigation utilizes a digital imaging technique to measure resultant drop sizes. Data were collected for liquid Reynolds number between 2,500 and 25,000, aerodynamic Weber number range of 50-500 and ambient gas pressures from 150 to 1200 psia. Comparison of the model predictions and experimental data for drop sizes at gas pressures of 150 and 300 psia reveal satisfactory agreement particularly for lower values of investigated Weber number. The present model is intended as a component of a practical tool to facilitate design and optimization of coaxial shear atomizers.

CFD simulation of coaxial injectors

NASA Technical Reports Server (NTRS)

Landrum, D. Brian

1993-01-01

The development of improved performance models for the Space Shuttle Main Engine (SSME) is an important, ongoing program at NASA MSFC. These models allow prediction of overall system performance, as well as analysis of run-time anomalies which might adversely affect engine performance or safety. Due to the complexity of the flow fields associated with the SSME, NASA has increasingly turned to Computational Fluid Dynamics (CFD) techniques as modeling tools. An important component of the SSME system is the fuel preburner, which consists of a cylindrical chamber with a plate containing 264 coaxial injector elements at one end. A fuel rich mixture of gaseous hydrogen and liquid oxygen is injected and combusted in the chamber. This process preheats the hydrogen fuel before it enters the main combustion chamber, powers the hydrogen turbo-pump, and provides a heat dump for nozzle cooling. Issues of interest include the temperature and pressure fields at the turbine inlet and the thermal compatibility between the preburner chamber and injector plate. Performance anomalies can occur due to incomplete combustion, blocked injector ports, etc. The performance model should include the capability to simulate the effects of these anomalies. The current approach to the numerical simulation of the SSME fuel preburner flow field is to use a global model based on the MSFC sponsored FNDS code. This code does not have the capabilities of modeling several aspects of the problem such as detailed modeling of the coaxial injectors. Therefore, an effort has been initiated to develop a detailed simulation of the preburner coaxial injectors and provide gas phase boundary conditions just downstream of the injector face as input to the FDNS code. This simulation should include three-dimensional geometric effects such as proximity of injectors to baffles and chamber walls and interaction between injectors. This report describes an investigation into the numerical simulation of GH2/LOX coaxial injectors. The following sections will discuss the physical aspects of injectors, the CFD code employed, and preliminary results of a simulation of a single coaxial injector for which experimental data is available. It is hoped that this work will lay the foundation for the development of a unique and useful tool to support the SSME program.

Supercritical Mixing in a Shear Coaxial Injector

DTIC Science & Technology

2016-07-27

in the core of the injected fluid emphasizes this observation. Two acoustically excited cases: pressure node and pressure anti-node at the center... acoustically excited cases: pressure node and pressure anti-node at the center plane of the jet are also studied in the same manner. The pressure anti-node...shortens the core flow of the injected jet. I. Introduction OCKET engines present a unique environment for injection of the propellants due to

LOX/Hydrogen Coaxial Injector Atomization Test Program

NASA Technical Reports Server (NTRS)

Zaller, M.

1990-01-01

Quantitative information about the atomization of injector sprays is needed to improve the accuracy of computational models that predict the performance and stability margin of liquid propellant rocket engines. To obtain this data, a facility for the study of spray atomization is being established at NASA-Lewis to determine the drop size and velocity distributions occurring in vaporizing liquid sprays at supercritical pressures. Hardware configuration and test conditions are selected to make the cold flow simulant testing correspond as closely as possible to conditions in liquid oxygen (LOX)/gaseous H2 rocket engines. Drop size correlations from the literature, developed for liquid/gas coaxial injector geometries, are used to make drop size predictions for LOX/H2 coaxial injectors. The mean drop size predictions for a single element coaxial injector range from 0.1 to 2000 microns, emphasizing the need for additional studies of the atomization process in LOX/H2 engines. Selection of cold flow simulants, measured techniques, and hardware for LOX/H2 atomization simulations are discussed.

Space storable propellant performance program coaxial injector characterization

NASA Technical Reports Server (NTRS)

Burick, R. J.

1972-01-01

An experimental program was conducted to characterize the circular coaxial injector concept for application with the space-storable gas/liquid propellant combination FLOX(82.6% F2)/CH4(g) at high pressure. The primary goal of the program was to obtain high characteristic velocity efficiency in conjunction with acceptable injector/chamber compatibility. A series of subscale (single element) cold flow and hot fire experiments was employed to establish design criteria for a 3000-lbf (sea level) engine operating at 500 psia. The subscale experiments characterized both high performance core elements and peripheral elements with enhanced injector/chamber compatibility. The full-scale injector which evolved from the study demonstrated a performance level of 99 percent of the theoretical shifting characteristic exhaust velocity with low chamber heat flux levels. A 44-second-duration firing demonstrated the durability of the injector. Parametric data are presented that are applicable for the design of circular, coaxial injectors that operate with injection dynamics (fuel and oxidizer velocity, etc.) similar to those employed in the work reported.

X-ray Fluorescence Measurements of Turbulent Methane-Oxygen Shear Coaxial Flames (Briefing Charts)

DTIC Science & Technology

2015-03-01

Radiography- Radial EPL Profiles • Near-injector EPL profiles have elliptical shape expected from a solid liquid jet • Closest measurements were...turbulent flames relevant to liquid rocket engines – Explore the use of two different tracers, Argon & Krypton – Identify a path forward to apply these...made 0.02 mm downstream • EPL decreases axially as liquid core is atomized and droplets are accelerated – EPL is a function of local mass flux

Flame structure of methane/oxygen shear coaxial jet with velocity ratio using high-speed imaging and OH*, CH* chemiluminescence

NASA Astrophysics Data System (ADS)

Shim, Myungbo; Noh, Kwanyoung; Yoon, Woongsup

2018-06-01

In this study, the effects of gaseous methane/oxygen injection velocity ratio on the shear coaxial jet flame structure are analyzed using high-speed imaging along with OH* and CH* chemiluminescence. The images show that, as the velocity ratio is increased, the visual flame length increases and wrinkles of the flame front are developed further downstream. The region near the equivalence ratio 1 condition in the flame could be identified by the maximum OH* position, and this region is located further downstream as the velocity ratio is increased. The dominant CH* chemiluminescence is found in the near-injector region. As the velocity ratio is decreased, the signal intensity is higher at the same downstream distance in each flame. From the results, as the velocity ratio is decreased, there is increased entrainment of the external jet, the mixing of the two jets is enhanced, the region near the stoichiometric mixture condition is located further upstream, and consequently, the flame length decreases.

Detailed Measurement of ORSC Main Chamber Injector Dynamics

NASA Astrophysics Data System (ADS)

Bedard, Michael J.

Improving fidelity in simulation of combustion dynamics in rocket combustors requires an increase in experimental measurement fidelity for validation. In a model rocket combustor, a chemiluminescence based spectroscopy technique was used to capture flame light emissions for direct comparison to a computational simulation of the production of chemiluminescent species. The comparison indicated that high fidelity models of rocket combustors can predict spatio-temporal distribution of chemiluminescent species with trend-wise accuracy. The comparison also indicated the limited ability of OH* and CH* emission to indicate flame heat release. Based on initial spectroscopy experiments, a photomultiplier based chemiluminescence sensor was designed to increase the temporal resolution of flame emission measurements. To apply developed methodologies, an experiment was designed to investigate the flow and combustion dynamics associated with main chamber injector elements typical of the RD-170 rocket engine. A unique feature of the RD-170 injector element is the beveled expansion between the injector recess and combustion chamber. To investigate effects of this geometry, a scaling methodology was applied to increase the physical scale of a single injector element while maintaining traceability to the RD-170 design. Two injector configurations were tested, one including a beveled injector face and the other a flat injector face. This design enabled improved spatial resolution of pressure and light emission measurements densely arranged in the injector recess and near-injector region of the chamber. Experimental boundary conditions were designed to closely replicate boundary conditions in simulations. Experimental results showed that the beveled injector face had a damping effect on pressure fluctuations occurring near the longitudinal resonant acoustic modes of the chamber, implying a mechanism for improved overall combustion stability. Near the injector, the beveled geometry resulted in more acoustic energy into higher frequency modes, while the flat-face geometry excited modes closer to the fundamental longitudinal mode frequency and its harmonics. Multi-scale analysis techniques were used to investigate intermittency and the range of physical scales present in measured signals. Flame light emission measurements confirmed the presence of flame holding in the injector recess in both configurations. Analysis of dynamics in light emission signals showed flame response at the chamber acoustic resonance frequency in addition to non-acoustic modes associated with mixing shear layer dynamics in the injector recess. The first known benchmark quality data sets of such injector dynamics were recorded in each configuration to enable pressure-based validation of high fidelity models of gas-centered swirl coaxial injectors. This work presents a critical contribution to development of validated combustion dynamics predictive tools and to the understanding of gas-centered swirl coaxial injector elements.

Investigation of the burning configuration of a coaxial injector in a combustion chamber

NASA Technical Reports Server (NTRS)

Ohara, J.

1978-01-01

An analytical investigation was made into the stability of the burning configuration of a single coaxial injector surrounded by similar injectors. The stability criteria was based on an average pressure difference along the boundaries of the adjacent stream tubes as calculated using Spaulding's numerical method. The results indicate qualitatively that there is a tendency for the injectors to have different burning configurations. It is believed that the configuration achieved is random, however once the burning configuration is established, it is believed to persist.

Optimum design of space storable gas/liquid coaxial injectors.

NASA Technical Reports Server (NTRS)

Burick, R. J.

1972-01-01

Review of the results of a program of single-element, cold-flow/hot-fire experiments performed for the purpose of establishing design criteria for a high-performance gas/liquid (FLOX/CH4) coaxial injector. The approach and the techniques employed resulted in the direct design of an injector that met or exceeded the performance and chamber compatibility goals of the program without any need for the traditional 'cut-and-try' development methods.

Investigation of non-premixed flame combustion characters in GO2/GH2 shear coaxial injectors using non-intrusive optical diagnostics

NASA Astrophysics Data System (ADS)

Dai, Jian; Yu, NanJia; Cai, GuoBiao

2015-12-01

Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen (GO2/GH2) as propellants. During the combustion process, several spatially and timeresolved non-intrusive optical techniques, such as OH planar laser induced fluorescence (PLIF), high speed imaging, and infrared imaging, are simultaneously employed to observe the OH radical concentration distribution, flame fluctuations, and temperature fields. The results demonstrate that the turbulent flow phenomenon of non-premixed flame exhibits a remarkable periodicity, and the mixing ratio becomes a crucial factor to influence the combustion flame length. The high speed and infrared images have a consistent temperature field trend. As for the OH-PLIF images, an intuitionistic local flame structure is revealed by single-shot instantaneous images. Furthermore, the means and standard deviations of OH radical intensity are acquired to provide statistical information regarding the flame, which may be helpful for validation of numerical simulations in future. Parameters of structure configurations, such as impinging angle and oxygen post thickness, play an important role in the reaction zone distribution. Based on a successful flame contour extraction method assembled with non-linear anisotropic diffusive filtering and variational level-set, it is possible to implement a fractal analysis to describe the fractal characteristics of the non-premixed flame contour. As a result, the flame front cannot be regarded as a fractal object. However, this turbulent process presents a self-similarity characteristic.

Cold Flow Testing for Liquid Propellant Rocket Injector Scaling and Throttling

NASA Technical Reports Server (NTRS)

Kenny, Jeremy R.; Moser, Marlow D.; Hulka, James; Jones, Gregg

2006-01-01

Scaling and throttling of combustion devices are important capabilities to demonstrate in development of liquid rocket engines for NASA's Space Exploration Mission. Scaling provides the ability to design new injectors and injection elements with predictable performance on the basis of test experience with existing injectors and elements, and could be a key aspect of future development programs. Throttling is the reduction of thrust with fixed designs and is a critical requirement in lunar and other planetary landing missions. A task in the Constellation University Institutes Program (CUIP) has been designed to evaluate spray characteristics when liquid propellant rocket engine injectors are scaled and throttled. The specific objectives of the present study are to characterize injection and primary atomization using cold flow simulations of the reacting sprays. These simulations can provide relevant information because the injection and primary atomization are believed to be the spray processes least affected by the propellant reaction. Cold flow studies also provide acceptable test conditions for a university environment. Three geometric scales - 1/4- scale, 1/2-scale, and full-scale - of two different injector element types - swirl coaxial and shear coaxial - will be designed, fabricated, and tested. A literature review is currently being conducted to revisit and compile the previous scaling documentation. Because it is simple to perform, throttling will also be examined in the present work by measuring primary atomization characteristics as the mass flow rate and pressure drop of the six injector element concepts are reduced, with corresponding changes in chamber backpressure. Simulants will include water and gaseous nitrogen, and an optically accessible chamber will be used for visual and laser-based diagnostics. The chamber will include curtain flow capability to repress recirculation, and additional gas injection to provide independent control of the backpressure. This paper provides a short review of the appropriate literature, as well as descriptions of plans for experimental hardware, test chamber instrumentation, diagnostics, and testing.

ALS LOX/H2 subscale coaxial injector testing

NASA Technical Reports Server (NTRS)

Dexter, Carol E.

1991-01-01

Tests of a 40K subscale LOX/H2 coaxial LOX swirl injector conducted without injector or chamber degradation are reported. Chamber pressures ranged from 1572 to 2355 psia with overall mixture ratios from 5.04 to 6.39. The highest characteristic velocities were measured when the mixture ratio across the injector face was uniform. Scarfing of the outer row LOX posts had the largest effect on chamber heating rates. As a result of the tests, the LSI design was modified to arrange the outer row LOX posts in a circular pattern, eliminate O/F biasing and fuel film cooling, and modify the interpropellant plate to allow for larger pressure differentials during the start and cutoff transients. Testing of a 100 K LOX/H2 coaxial LOX swirl injector involved chamber pressure ranging from 700 to 2500 psia with overall mixture ratios from 3.2 to 8.8. Stable combustion was observed to a fuel temperature of 90R and characteristic velocity efficiencies were good.

Propellant injection strategy for suppressing acoustic combustion instability

NASA Astrophysics Data System (ADS)

Diao, Qina

Shear-coaxial injector elements are often used in liquid-propellant-rocket thrust chambers, where combustion instabilities remain a significant problem. A conventional solution to the combustion instability problem relies on passive control techniques that use empirically-developed hardware such as acoustic baffles and tuned cavities. In addition to adding weight and decreasing engine performance, these devices are designed using trial-and-error methods, which do not provide the capability to predict the overall system stability characteristics in advance. In this thesis, two novel control strategies that are based on propellant fluid dynamics were investigated for mitigating acoustic instability involving shear-coaxial injector elements. The new control strategies would use a set of controlled injectors allowing local adjustment of propellant flow patterns for each operating condition, particularly when instability could become a problem. One strategy relies on reducing the oxidizer-fuel density gradient by blending heavier methane with the main fuel, hydrogen. Another strategy utilizes modifying the equivalence ratio to affect the acoustic impedance through mixing and reaction rate changes. The potential effectiveness of these strategies was assessed by conducting unit-physics experiments. Two different model combustors, one simulating a single-element injector test and the other a double-element injector test, were designed and tested for flame-acoustic interaction. For these experiments, the Reynolds number of the central oxygen jet was kept between 4700 and 5500 making the injector flames sufficiently turbulent. A compression driver, mounted on one side of the combustor wall, provided controlled acoustic excitation to the injector flames, simulating the initial phase of flame-acoustic interaction. Acoustic excitation was applied either as band-limited white noise forcing between 100 Hz and 5000 Hz or as single-frequency, fixed-amplitude forcing at 1150 Hz which represented a frequency least amplified by any resonance. Effects of each control strategy on flame-acoustic interaction were assessed in terms of modifying the acoustic resonance characteristics subject to white-noise excitation and changes in flame brush thickness under single-frequency excitation. In the methane blending experiments, the methane mole fraction was varied between 0% and 63%. Under white noise excitation, up to 16% shift in a resonant frequency was observed but the acoustic pressure spectra remained qualitatively similar. For the fixed frequency forcing, the spatial extent of flame-acoustic interaction was substantially reduced. In the other experiments, the equivalence ratio of the control injector was varied between zero and infinity, causing up to 40% shift in a resonant frequency as well as changes in the acoustic pressure spectrum. These results open up the possibility of employing flow-based control to prevent combustion instabilities in liquid-fueled rockets.

Atomization characteristics of swirl injector sprays

NASA Technical Reports Server (NTRS)

Feikema, Douglas A.

1996-01-01

Stable combustion within rocket engines is a continuing concern for designers of rocket engine systems. The swirl-coaxial injector has demonstrated effectiveness in achieving atomization and mixing, and therefore stable combustion. Swirl-coaxial injector technology is being deployed in the American RL1OA rocket design and Russian engine systems already make wide spread use of this technology. The present requirement for swirl injector research is derived from NASA's current Reusable Launch Vehicle (RLV) technology program. This report describes some of the background and literature on this topic including drop size measurements, comparison with theoretical predictions, the effect of surface tension on the atomization process, and surface wave characteristics of liquid film at the exit of the injector.

Shear coaxial injector atomization phenomena for combusting and non-combusting conditions

NASA Technical Reports Server (NTRS)

Pal, S.; Moser, M. D.; Ryan, H. M.; Foust, M. J.; Santoro, R. J.

1992-01-01

Measurements of LOX drop size and velocity in a uni-element liquid propellant rocket chamber are presented. The use of the Phase Doppler Particle Analyzer in obtaining temporally-averaged probability density functions of drop size in a harsh rocket environment has been demonstrated. Complementary measurements of drop size/velocity for simulants under cold flow conditions are also presented. The drop size/velocity measurements made for combusting and cold flow conditions are compared, and the results indicate that there are significant differences in the two flowfields.

Effect of Chamber Backpressure on Swirl Injector Fluid Mechanics

NASA Technical Reports Server (NTRS)

Kenny, R. Jeremy; Hulka, James R.; Moser, Marlow D.; Rhys, Noah O.

2008-01-01

A common propellant combination used for high thrust generation is GH2/LOX. Historical GH2/LOX injection elements have been of the shear-coaxial type. Element type has a large heritage of research work to aid in element design. The swirl-coaxial element, despite its many performance benefits, has a relatively small amount of historical, LRE-oriented work to draw from. Design features of interest are grounded in the fluid mechanics of the liquid swirl process itself, are based on data from low-pressure, low mass flow rate experiments. There is a need to investigate how high ambient pressures and mass flow rates influence internal and external swirl features. The objective of this research is to determine influence of varying liquid mass flow rate and ambient chamber pressure on the intact-length fluid mechanics of a liquid swirl element.

Primary atomization of liquid jets issuing from rocket engine coaxial injectors

NASA Astrophysics Data System (ADS)

Woodward, Roger D.

1993-01-01

The investigation of liquid jet breakup and spray development is critical to the understanding of combustion phenomena in liquid-propellant rocket engines. Much work has been done to characterize low-speed liquid jet breakup and dilute sprays, but atomizing jets and dense sprays have yielded few quantitative measurements due to their optical opacity. This work focuses on a characteristic of the primary breakup process of round liquid jets, namely the length of the intact liquid core. The specific application considered is that of shear-coaxial type rocket engine injectors. Real-time x-ray radiography, capable of imaging through the dense two-phase region surrounding the liquid core, has been used to make the measurements. Nitrogen and helium were employed as the fuel simulants while an x-ray absorbing potassium iodide aqueous solution was used as the liquid oxygen (LOX) simulant. The intact-liquid-core length data have been obtained and interpreted to illustrate the effects of chamber pressure (gas density), injected-gas and liquid velocities, and cavitation. The results clearly show that the effect of cavitation must be considered at low chamber pressures since it can be the dominant breakup mechanism. A correlation of intact core length in terms of gas-to-liquid density ratio, liquid jet Reynolds number, and Weber number is suggested. The gas-to-liquid density ratio appears to be the key parameter for aerodynamic shear breakup in this study. A small number of hot-fire, LOX/hydrogen tests were also conducted to attempt intact-LOX-core measurements under realistic conditions in a single-coaxial-element rocket engine. The tests were not successful in terms of measuring the intact core, but instantaneous imaging of LOX jets suggests that LOX jet breakup is qualitatively similar to that of cold-flow, propellant-simulant jets. The liquid oxygen jets survived in the hot-fire environment much longer than expected, and LOX was even visualized exiting the chamber nozzle under some conditions. This may be an effect of the single element configuration.

Performance and Stability Analyses of Rocket Combustion Devices Using Liquid Oxygen/Liquid Methane Propellants

NASA Technical Reports Server (NTRS)

Hulka, James R.; Jones, G. W.

2010-01-01

Liquid rocket engines using oxygen and methane propellants are being considered by the National Aeronautics and Space Administration (NASA) for in-space vehicles. This propellant combination has not been previously used in flight-qualified engine systems, so limited test data and analysis results are available at this stage of early development. NASA has funded several hardware-oriented programs with oxygen and methane propellants over the past several years with the Propulsion and Cryogenic Advanced Development (PCAD) project, under the Exploration Technology Development Program. As part of this effort, NASA Marshall Space Flight Center has conducted combustion, performance, and combustion stability analyses of several of the configurations on these programs. This paper summarizes these analyses. Test and analysis results of impinging and coaxial element injectors using liquid oxygen and liquid methane propellants are included. Several cases with gaseous methane are included for reference. Several different thrust chamber configurations have been modeled, including thrust chambers with multi-element like-on-like and swirl coax element injectors tested at NASA MSFC, and a unielement chamber with shear and swirl coax injectors tested at The Pennsylvania State University. Configurations were modeled with two one-dimensional liquid rocket combustion analysis codes, the Rocket Combustor Interaction Design and Analysis (ROCCID), and the Coaxial Injector Combustion Model (CICM). Significant effort was applied to show how these codes can be used to model combustion and performance with oxygen/methane propellants a priori, and what anchoring or calibrating features need to be applied or developed in the future. This paper describes the test hardware configurations, presents the results of all the analyses, and compares the results from the two analytical methods.

Experimental Evaluation of a Subscale Gaseous Hydrogen/gaseous Oxygen Coaxial Rocket Injector

NASA Technical Reports Server (NTRS)

Smith, Timothy D.; Klem, Mark D.; Breisacher, Kevin J.; Farhangi, Shahram; Sutton, Robert

2002-01-01

The next generation reusable launch vehicle may utilize a Full-Flow Stage Combustion (FFSC) rocket engine cycle. One of the key technologies required is the development of an injector that uses gaseous oxygen and gaseous hydrogen as propellants. Gas-gas propellant injection provides an engine with increased stability margin over a range of throttle set points. This paper summarizes an injector design and testing effort that evaluated a coaxial rocket injector for use with gaseous oxygen and gaseous hydrogen propellants. A total of 19 hot-fire tests were conducted up to a chamber pressure of 1030 psia, over a range of 3.3 to 6.7 for injector element mixture ratio. Post-test condition of the hardware was also used to assess injector face cooling. Results show that high combustion performance levels could be achieved with gas-gas propellants and there were no problems with excessive face heating for the conditions tested.

Numerical Modelling of Staged Combustion Aft-Injected Hybrid Rocket Motors

NASA Astrophysics Data System (ADS)

Nijsse, Jeff

The staged combustion aft-injected hybrid (SCAIH) rocket motor is a promising design for the future of hybrid rocket propulsion. Advances in computational fluid dynamics and scientific computing have made computational modelling an effective tool in hybrid rocket motor design and development. The focus of this thesis is the numerical modelling of the SCAIH rocket motor in a turbulent combustion, high-speed, reactive flow framework accounting for solid soot transport and radiative heat transfer. The SCAIH motor is modelled with a shear coaxial injector with liquid oxygen injected in the center at sub-critical conditions: 150 K and 150 m/s (Mach ≈ 0.9), and a gas-generator gas-solid mixture of one-third carbon soot by mass injected in the annual opening at 1175 K and 460 m/s (Mach ≈ 0.6). Flow conditions in the near injector region and the flame anchoring mechanism are of particular interest. Overall, the flow is shown to exhibit instabilities and the flame is shown to anchor directly on the injector faceplate with temperatures in excess of 2700 K.

CFD Code Validation of Wall Heat Fluxes for a G02/GH2 Single Element Combustor

NASA Technical Reports Server (NTRS)

Lin, Jeff; West, Jeff S.; Williams, Robert W.; Tucker, P. Kevin

2005-01-01

This paper puts forth the case for the need for improved injector design tools to meet NASA s Vision for Space Exploration goals. Requirements for this improved tool are outlined and discussed. The potential for Computational Fluid Dynamics (CFD) to meet these requirements is noted along with its current shortcomings, especially relative to demonstrated solution accuracy. The concept of verification and validation is introduced as the primary process for building and quantifying the confidence necessary for CFD to be useful as an injector design tool. The verification and validation process is considered in the context of the Marshall Space Flight Center (MSFC) Combustion Devices CFD Simulation Capability Roadmap via the Simulation Readiness Level (SRL) concept. The portion of the validation process which demonstrates the ability of a CFD code to simulate heat fluxes to a rocket engine combustor wall is the focus of the current effort. The FDNS and Loci-CHEM codes are used to simulate a shear coaxial single element G02/GH2 injector experiment. The experiment was conducted a t a chamber pressure of 750 psia using hot propellants from preburners. A measured wall temperature profile is used as a boundary condition to facilitate the calculations. Converged solutions, obtained from both codes by using wall functions with the K-E turbulence model and integrating to the wall using Mentor s baseline turbulence model, are compared to the experimental data. The initial solutions from both codes revealed significant issues with the wall function implementation associated with the recirculation zone between the shear coaxial jet and the chamber wall. The FDNS solution with a corrected implementation shows marked improvement in overall character and level of comparison to the data. With the FDNS code, integrating to the wall with Mentor s baseline turbulence model actually produce a degraded solution when compared to the wall function solution with the K--E model. The Loci-CHEM solution, produced by integrating to the wall with Mentor s baseline turbulence model, matches both the heat flux rise rate in the near injector region and the peak heat flux level very well. However, it moderately over predicts the heat fluxes downstream of the reattachment point. The Loci-CHEM solution achieved by integrating to the wall with Mentor s baseline turbulence model was clearly superior to the other solutions produced in this effort.

Identification of Coherent Structure Dynamics in Wall-Bounded Sprays using Proper Orthogonal Decomposition

DTIC Science & Technology

2010-08-31

Wall interaction of sprays emanating from Gas Centered Swirl Coaxial (GCSC) injectors were experimentally studied as a part of this ten-week project. A...American Society of Engineering Education (ASEE) Dated August 31st 2010 Abstract Wall interaction of sprays emanating from Gas Centered...Edwards Air Force Base (AFRL/EAFB) have documented atomization characteristics of a Gas -Centered Swirl Coaxial (GCSC) injector [1-2], in which the

User's manual for rocket combustor interactive design (ROCCID) and analysis computer program. Volume 1: User's manual

NASA Technical Reports Server (NTRS)

Muss, J. A.; Nguyen, T. V.; Johnson, C. W.

1991-01-01

The user's manual for the rocket combustor interactive design (ROCCID) computer program is presented. The program, written in Fortran 77, provides a standardized methodology using state of the art codes and procedures for the analysis of a liquid rocket engine combustor's steady state combustion performance and combustion stability. The ROCCID is currently capable of analyzing mixed element injector patterns containing impinging like doublet or unlike triplet, showerhead, shear coaxial, and swirl coaxial elements as long as only one element type exists in each injector core, baffle, or barrier zone. Real propellant properties of oxygen, hydrogen, methane, propane, and RP-1 are included in ROCCID. The properties of other propellants can easily be added. The analysis model in ROCCID can account for the influence of acoustic cavities, helmholtz resonators, and radial thrust chamber baffles on combustion stability. ROCCID also contains the logic to interactively create a combustor design which meets input performance and stability goals. A preliminary design results from the application of historical correlations to the input design requirements. The steady state performance and combustion stability of this design is evaluated using the analysis models, and ROCCID guides the user as to the design changes required to satisfy the user's performance and stability goals, including the design of stability aids. Output from ROCCID includes a formatted input file for the standardized JANNAF engine performance prediction procedure.

Performance characteristics of LOX-H2, tangential-entry, swirl-coaxial, rocket injectors

NASA Technical Reports Server (NTRS)

Howell, Doug; Petersen, Eric; Clark, Jim

1993-01-01

Development of a high performing swirl-coaxial injector requires an understanding of fundamental performance characteristics. This paper addresses the findings of studies on cold flow atomic characterizations which provided information on the influence of fluid properties and element operating conditions on the produced droplet sprays. These findings are applied to actual rocket conditions. The performance characteristics of swirl-coaxial injection elements under multi-element hot-fire conditions were obtained by analysis of combustion performance data from three separate test series. The injection elements are described and test results are analyzed using multi-variable linear regression. A direct comparison of test results indicated that reduced fuel injection velocity improved injection element performance through improved propellant mixing.

Effect of Injector Geometry on Atomization of a Liquid-Liquid Double Swirl Coaxial Injector Using Non-invasive Laser, Optical and X-ray Techniques

NASA Technical Reports Server (NTRS)

Radke, C. R.; Meyer, T. R.

2014-01-01

The spray characteristics of a liquid-liquid double swirl coaxial injector were studied using non-invasive optical, laser, and X-ray diagnostics. A parametric study of injector exit geometry demonstrated that spray breakup time, breakup type and sheet stability could be controlled with exit geometry. Phase Doppler interferometry was used to characterize droplet statistics and non-dimensional droplet parameters over a range of inlet conditions and for various fluids allowing for a study on the role of specific fluid properties in atomization. Further, X-ray radiography allowed for investigation of sheet thickness and breakup length to be quantified for different recess exit diameters and inlet pressures. Finally, computed tomography scans revealed that the spray cone was distinctively non-uniform and comprised of several pockets of increased mass flux.

Effect of Injector Geometry on Atomization of a Liquid-Liquid Double Swirl Coaxial Injector using Non-Invasive Laser, Optical and X-ray Techniques

NASA Technical Reports Server (NTRS)

Radke, C. R.; Meyer, T. R.

2014-01-01

The spray characteristics of a Liquid-Liquid Double Swirl Coaxial Injector were studied using noninvasive Optical, Laser, and X-ray diagnostics. A parametric study of injector exit geometry demonstrated that spray breakup time, breakup type and sheet stability could be controlled with exit geometry. Phase Doppler Particle Analysis characterized droplet statistics and non-dimensional droplet parameters over a range of inlet conditions and for various fluids allowing for a study on the role of specific fluid properties in atomization. Further, x-ray radiographs allowed for investigations of sheet thickness and breakup length to be quantified for different recess exits and inlet pressures. Finally Computed Tomography scans revealed that the spray cone was distinctively non-uniform and comprised of several pockets of increased mass flux.

Modeling Liquid Rocket Engine Atomization and Swirl/Coaxial Injectors

DTIC Science & Technology

2008-02-27

47-61, 2004. 2. Yoon, S . S ., and Heister, S . D., "A Fully Nonlinear Model for Atomization of High - Speed Jets," Engineering Analysis with... Power , V20, pp 468-479, 2004. 5. Yoon, S . S ., and Heister, S . D., "Analytic Solutions for Computing Velocities Induced from Potential Vortex Ring...Heister, S . D., "Three Dimensional Flow Simulations in Recessed Region of a Coaxial Injector," J. Propulsion and Power , V21, No.4, pp. 728-742

High-pressure LOX/CH4 injector program

NASA Technical Reports Server (NTRS)

Wheeler, D. B.; Kirby, F. M.

1979-01-01

Two injector types, either coaxial or impinging elements, for high pressure LOX/CH4 operation with an existing 40K chamber are examined. A comparison is presented. The detailed fabrication drawings and supporting analysis are presented.

Effect of Cup Length on Film Profiles in Gas-Centered Swirl-Coaxial Injectors

DTIC Science & Technology

2009-12-01

as the working fluid , film lengths and were determined in six unique injector geometries and over a number of flow conditions. Each injector...with water and nitrogen as the working fluid , film lengths and were determined in six unique injector geometries and over a number of flow...vary the cup length across the face of the injector to act as acoustic dampers . For these reasons and because of the need for simple design criteria

Coaxial atomization of a round liquid jet in a high speed gas stream: A phenomenological study

NASA Astrophysics Data System (ADS)

Mayer, W. O. H.

1994-05-01

Coaxial injectors have proven to be advantageous for the injection, atomization and mixing of propellants in cryogenic H2/O2 rocket engines. Thereby, a round liquid oxygen jet is atomized by a fast, coaxial gaseous hydrogen jet. This article summarizes phenomenological studies of coaxial spray generation under a broad variation of influencing parameters including injector design, inflow, and fluid conditions. The experimental investigations, performed using spark light photography and high speed cinematography in a shadow graph setup as main diagnostic means, illuminate the most important processes leading to atomization. These are identified as turbulence in the liquid jet, surface instability, surface wave growth and droplet detachment. Numerical simulations including free surface flow phenomena are a further diagnostic tool to elucidate some atomization particulars. The results of the study are of general importance in the field of liquid atomization.

An Approach to Improved Credibility of CFD Simulations for Rocket Injector Design

NASA Technical Reports Server (NTRS)

Tucker, Paul K.; Menon, Suresh; Merkle, Charles L.; Oefelein, Joseph C.; Yang, Vigor

2007-01-01

Computational fluid dynamics (CFD) has the potential to improve the historical rocket injector design process by simulating the sensitivity of performance and injector-driven thermal environments to. the details of the injector geometry and key operational parameters. Methodical verification and validation efforts on a range of coaxial injector elements have shown the current production CFD capability must be improved in order to quantitatively impact the injector design process.. This paper documents the status of an effort to understand and compare the predictive capabilities and resource requirements of a range of CFD methodologies on a set of model problem injectors. Preliminary results from a steady Reynolds-Average Navier-Stokes (RANS), an unsteady Reynolds-Average Navier Stokes (URANS) and three different Large Eddy Simulation (LES) techniques used to model a single element coaxial injector using gaseous oxygen and gaseous hydrogen propellants are presented. Initial observations are made comparing instantaneous results, corresponding time-averaged and steady-state solutions in the near -injector flow field. Significant differences in the flow fields exist, as expected, and are discussed. An important preliminary result is the identification of a fundamental mixing mechanism, accounted for by URANS and LES, but missing in the steady BANS methodology. Since propellant mixing is the core injector function, this mixing process may prove to have a profound effect on the ability to more correctly simulate injector performance and resulting thermal environments. Issues important to unifying the basis for future comparison such as solution initialization, required run time and grid resolution are addressed.

Analysis of rocket engine injection combustion processes

NASA Technical Reports Server (NTRS)

Salmon, J. W.

1976-01-01

A critique is given of the JANNAF sub-critical propellant injection/combustion process analysis computer models and application of the models to correlation of well documented hot fire engine data bases. These programs are the distributed energy release (DER) model for conventional liquid propellants injectors and the coaxial injection combustion model (CICM) for gaseous annulus/liquid core coaxial injectors. The critique identifies model inconsistencies while the computer analyses provide quantitative data on predictive accuracy. The program is comprised of three tasks: (1) computer program review and operations; (2) analysis and data correlations; and (3) documentation.

Development of Efficient Real-Fluid Model in Simulating Liquid Rocket Injector Flows

NASA Technical Reports Server (NTRS)

Cheng, Gary; Farmer, Richard

2003-01-01

The characteristics of propellant mixing near the injector have a profound effect on the liquid rocket engine performance. However, the flow features near the injector of liquid rocket engines are extremely complicated, for example supercritical-pressure spray, turbulent mixing, and chemical reactions are present. Previously, a homogeneous spray approach with a real-fluid property model was developed to account for the compressibility and evaporation effects such that thermodynamics properties of a mixture at a wide range of pressures and temperatures can be properly calculated, including liquid-phase, gas- phase, two-phase, and dense fluid regions. The developed homogeneous spray model demonstrated a good success in simulating uni- element shear coaxial injector spray combustion flows. However, the real-fluid model suffered a computational deficiency when applied to a pressure-based computational fluid dynamics (CFD) code. The deficiency is caused by the pressure and enthalpy being the independent variables in the solution procedure of a pressure-based code, whereas the real-fluid model utilizes density and temperature as independent variables. The objective of the present research work is to improve the computational efficiency of the real-fluid property model in computing thermal properties. The proposed approach is called an efficient real-fluid model, and the improvement of computational efficiency is achieved by using a combination of a liquid species and a gaseous species to represent a real-fluid species.

Magnetic reconnection process in transient coaxial helicity injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebrahimi, F.; Hooper, E. B.; Sovinec, C. R.

The physics of magnetic reconnection and fast flux closure in transient coaxial helicity injection experiments in NSTX is examined using resistive MHD simulations. These simulations have been performed using the NIMROD code with fixed boundary flux (including NSTX poloidal coil currents) in the NSTX experimental geometry. Simulations show that an X point is formed in the injector region, followed by formation of closed flux surfaces within 0.5 ms after the driven injector voltage and injector current begin to rapidly decrease. As the injector voltage is turned off, the field lines tend to untwist in the toroidal direction and magnetic fieldmore » compression exerts a radial J × B force and generates a bi-directional radial E{sub toroidal}×B{sub poloidal} pinch flow to bring oppositely directed field lines closer together to reconnect. At sufficiently low magnetic diffusivity (high Lundquist number), and with a sufficiently narrow injector flux footprint width, the oppositely directed field lines have sufficient time to reconnect (before dissipating), leading to the formation of closed flux surfaces. The reconnection process is shown to have transient Sweet-Parker characteristics.« less

User's manual for rocket combustor interactive design (ROCCID) and analysis computer program. Volume 2: Appendixes A-K

NASA Technical Reports Server (NTRS)

Muss, J. A.; Nguyen, T. V.; Johnson, C. W.

1991-01-01

The appendices A-K to the user's manual for the rocket combustor interactive design (ROCCID) computer program are presented. This includes installation instructions, flow charts, subroutine model documentation, and sample output files. The ROCCID program, written in Fortran 77, provides a standardized methodology using state of the art codes and procedures for the analysis of a liquid rocket engine combustor's steady state combustion performance and combustion stability. The ROCCID is currently capable of analyzing mixed element injector patterns containing impinging like doublet or unlike triplet, showerhead, shear coaxial and swirl coaxial elements as long as only one element type exists in each injector core, baffle, or barrier zone. Real propellant properties of oxygen, hydrogen, methane, propane, and RP-1 are included in ROCCID. The properties of other propellants can be easily added. The analysis models in ROCCID can account for the influences of acoustic cavities, helmholtz resonators, and radial thrust chamber baffles on combustion stability. ROCCID also contains the logic to interactively create a combustor design which meets input performance and stability goals. A preliminary design results from the application of historical correlations to the input design requirements. The steady state performance and combustion stability of this design is evaluated using the analysis models, and ROCCID guides the user as to the design changes required to satisfy the user's performance and stability goals, including the design of stability aids. Output from ROCCID includes a formatted input file for the standardized JANNAF engine performance prediction procedure.

Droplet Combustion and Non-Reactive Shear-Coaxial Jets with Transverse Acoustic Excitation

DTIC Science & Technology

2012-06-01

Shear-Coaxial Jets Experimental Facility: Piping and Instrumentation Diagram . . . . . . . . . . . . . . . . . . . . . . 196 B Shear-Coaxial Jets...facility piping and instrumentation diagram. . . . . . . . . 197 A.2 Expanded view of section A in Figure A.1. . . . . . . . . . . . . . . . . . 198 A.3...certified to be used in flexible fuel vehicles (FFVs) with engines specifically designed for this fuel. As for possible aviation fuel replacements

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

DOE Data Explorer

Ebrahimi, Fatima [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000331095367); Raman, Roger [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)] (ORCID:0000000220273271)

2016-01-01

A large-volume flux closure during transient coaxial helicity injection (CHI) in NSTX-U is demonstrated through resistive magnetohydrodynamics (MHD) simulations. Several major improvements, including the improved positioning of the divertor poloidal field coils, are projected to improve the CHI start-up phase in NSTX-U. Simulations in the NSTX-U configuration with constant in time coil currents show that with strong flux shaping the injected open field lines (injector flux) rapidly reconnect and form large volume of closed flux surfaces. This is achieved by driving parallel current in the injector flux coil and oppositely directed currents in the flux shaping coils to form a narrow injector flux footprint and push the injector flux into the vessel. As the helicity and plasma are injected into the device, the oppositely directed field lines in the injector region are forced to reconnect through a local Sweet–Parker type reconnection, or to spontaneously reconnect when the elongated current sheet becomes MHD unstable to form plasmoids. In these simulations for the first time, it is found that the closed flux is over 70% of the initial injector flux used to initiate the discharge. These results could work well for the application of transient CHI in devices that employ super conducting coils to generate and sustain the plasma equilibrium.

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

DOE Data Explorer

Ebrahimi, F. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Raman, R. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

2016-04-01

A large-volume flux closure during transient coaxial helicity injection (CHI) in NSTX-U is demonstrated through resistive magnetohydrodynamics (MHD) simulations. Several major improvements, including the improved positioning of the divertor poloidal field coils, are projected to improve the CHI start-up phase in NSTX-U. Simulations in the NSTX-U configuration with constant in time coil currents show that with strong flux shaping the injected open field lines (injector flux) rapidly reconnect and form large volume of closed flux surfaces. This is achieved by driving parallel current in the injector flux coil and oppositely directed currents in the flux shaping coils to form a narrow injector flux footprint and push the injector flux into the vessel. As the helicity and plasma are injected into the device, the oppositely directed field lines in the injector region are forced to reconnect through a local Sweet–Parker type reconnection, or to spontaneously reconnect when the elongated current sheet becomes MHD unstable to form plasmoids. In these simulations for the first time, it is found that the closed flux is over 70% of the initial injector flux used to initiate the discharge. These results could work well for the application of transient CHI in devices that employ super conducting coils to generate and sustain the plasma equilibrium.

Accuracy Quantification of the Loci-CHEM Code for Chamber Wall Heat Transfer in a GO2/GH2 Single Element Injector Model Problem

NASA Technical Reports Server (NTRS)

West, Jeff; Westra, Doug; Lin, Jeff; Tucker, Kevin

2006-01-01

A robust rocket engine combustor design and development process must include tools which can accurately predict the multi-dimensional thermal environments imposed on solid surfaces by the hot combustion products. Currently, empirical methods used in the design process are typically one dimensional and do not adequately account for the heat flux rise rate in the near-injector region of the chamber. Computational Fluid Dynamics holds promise to meet the design tool requirement, but requires accuracy quantification, or validation, before it can be confidently applied in the design process. This effort presents the beginning of such a validation process for the Loci-CHEM CFD code. The model problem examined here is a gaseous oxygen (GO2)/gaseous hydrogen (GH2) shear coaxial single element injector operating at a chamber pressure of 5.42 MPa. The GO2/GH2 propellant combination in this geometry represents one the simplest rocket model problems and is thus foundational to subsequent validation efforts for more complex injectors. Multiple steady state solutions have been produced with Loci-CHEM employing different hybrid grids and two-equation turbulence models. Iterative convergence for each solution is demonstrated via mass conservation, flow variable monitoring at discrete flow field locations as a function of solution iteration and overall residual performance. A baseline hybrid was used and then locally refined to demonstrate grid convergence. Solutions were obtained with three variations of the k-omega turbulence model.

Accuracy Quantification of the Loci-CHEM Code for Chamber Wall Heat Fluxes in a G02/GH2 Single Element Injector Model Problem

NASA Technical Reports Server (NTRS)

West, Jeff; Westra, Doug; Lin, Jeff; Tucker, Kevin

2006-01-01

A robust rocket engine combustor design and development process must include tools which can accurately predict the multi-dimensional thermal environments imposed on solid surfaces by the hot combustion products. Currently, empirical methods used in the design process are typically one dimensional and do not adequately account for the heat flux rise rate in the near-injector region of the chamber. Computational Fluid Dynamics holds promise to meet the design tool requirement, but requires accuracy quantification, or validation, before it can be confidently applied in the design process. This effort presents the beginning of such a validation process for the Loci- CHEM CPD code. The model problem examined here is a gaseous oxygen (GO2)/gaseous hydrogen (GH2) shear coaxial single element injector operating at a chamber pressure of 5.42 MPa. The GO2/GH2 propellant combination in this geometry represents one the simplest rocket model problems and is thus foundational to subsequent validation efforts for more complex injectors. Multiple steady state solutions have been produced with Loci-CHEM employing different hybrid grids and two-equation turbulence models. Iterative convergence for each solution is demonstrated via mass conservation, flow variable monitoring at discrete flow field locations as a function of solution iteration and overall residual performance. A baseline hybrid grid was used and then locally refined to demonstrate grid convergence. Solutions were also obtained with three variations of the k-omega turbulence model.

Single element injector cold flow testing for STME swirl coaxial injector element design

NASA Technical Reports Server (NTRS)

Hulka, J.; Schneider, J. A.

1993-01-01

An oxidizer-swirled coaxial element injector is being investigated for application in the Space Transportation Main Engine (STME). Single element cold flow experiments were conducted to provide characterization of the STME injector element for future analysis, design, and optimization. All tests were conducted to quiescent, ambient backpressure conditions. Spray angle, circumferential spray uniformity, dropsize, and dropsize distribution were measured in water-only and water/nitrogen flows. Rupe mixing efficiency was measured using water/sucrose solution flows with a large grid patternator for simple comparative evaluation of mixing. Factorial designs of experiment were used for statistical evaluation of injector geometrical design features and propellant flow conditions on mixing and atomization. Increasing the free swirl angle of the liquid oxidizer had the greatest influence on increasing the mixing efficiency. The addition of gas assistance had the most significant effect on reducing oxidizer droplet size parameters and increasing droplet size distribution. Increasing the oxidizer injection velocity had the greatest influence for reducing oxidizer droplet size parameters and increasing size distribution for non-gas assisted flows. Single element and multi-element subscale hot fire testing are recommended to verify optimized designs before committing to the STME design.

Flow visualization of a rocket injector spray using gelled propellant simulants

NASA Technical Reports Server (NTRS)

Green, James M.; Rapp, Douglas C.; Roncace, James

1991-01-01

A study was conducted at NASA-Lewis to compare the atomization characteristics of gelled and nongelled propellant simulants. A gelled propellant simulant composed of water, sodium hydroxide, and an acrylic acid polymer resin (as the gelling agent) was used to simulate the viscosity of an aluminum/PR-1 metallized fuel gel. Water was used as a comparison fluid to isolate the rheological effects of the water-gel and to simulate nongelled RP-1. The water-gel was injected through the central orifice of a triplet injector element and the central post of a coaxial injector element. Nitrogen gas flowed through the outer orifices of the triplet injector element and through the annulus of the coaxial injector element and atomized the gelled and nongelled liquids. Photographs of the water-gel spray patterns at different operating conditions were compared with images obtained using water and nitrogen. A laser light was used for illumination of the sprays. The results of the testing showed that the water sprays produced a finer and more uniform atomization than the water-gel sprays. Rheological analysis of the water-gel showed poor atomization caused by high viscosity of water-gel delaying the transition to turbulence.

Droplet Combustion and Non-Reactive Shear-Coaxial Jets with and without Transverse Acoustic Excitation

DTIC Science & Technology

2012-01-01

186 6.2 Non-Reactive Shear-Coaxial Jets . . . . . . . . . . . . . . . . . . . . . . 188 A Shear-Coaxial Jets Experimental Facility: Piping and...185 A.1 Experimental facility piping and instrumentation diagram. . . . . . . . . 194 A.2 Expanded view of section A in Figure...modification, whereas a blend of gasoline and 85% ethanol (E85) is only certified to be used in flexible fuel vehicles (FFVs) with engines specifically

A non-coaxial critical state soil model and its application to simple shear simulations

NASA Astrophysics Data System (ADS)

Yang, Yunming; Yu, H. S.

2006-11-01

The yield vertex non-coaxial theory is implemented into a critical state soil model, CASM (Int. J. Numer. Anal. Meth. Geomech. 1998; 22:621-653) to investigate the non-coaxial influences on the stress-strain simulations of real soil behaviour in the presence of principal stress rotations. The CASM is a unified clay and sand model, developed based on the soil critical state concept and the state parameter concept. Without loss of simplicity, it is capable of simulating the behaviour of sands and clays within a wide range of densities. The non-coaxial CASM is employed to simulate the simple shear responses of Erksak sand and Weald clay under different densities and initial stress states. Dependence of the soil behaviour on the Lode angle and different plastic flow rules in the deviatoric plane are also considered in the study of non-coaxial influences. All the predictions indicate that the use of the non-coaxial model makes the orientations of the principal stress and the principal strain rate different during the early stage of shearing, and they approach the same ultimate values with an increase in loading. These ultimate orientations are dependent on the density of soils, and independent of their initial stress states. The use of the non-coaxial model also softens the shear stress evolutions, compared with the coaxial model. It is also found that the ultimate shear strengths by using the coaxial and non-coaxial models are dependent on the plastic flow rules in the deviatoric plane. Copyright

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

DOE PAGES

Ebrahimi, F.; Raman, R.

2016-03-23

A large-volume flux closure during transient coaxial helicity injection (CHI) in NSTX-U is demonstrated through resistive magnetohydrodynamics (MHD) simulations. Several major improvements, including the improved positioning of the divertor poloidal field coils, are projected to improve the CHI start-up phase in NSTX-U. Simulations in the NSTX-U configuration with constant in time coil currents show that with strong flux shaping the injected open field lines (injector flux) rapidly reconnect and form large volume of closed flux surfaces. This is achieved by driving parallel current in the injector flux coil and oppositely directed currents in the flux shaping coils to form amore » narrow injector flux footprint and push the injector flux into the vessel. As the helicity and plasma are injected into the device, the oppositely directed field lines in the injector region are forced to reconnect through a local Sweet-Parker type reconnection, or to spontaneously reconnect when the elongated current sheet becomes MHD unstable to form plasmoids. In these simulations for the first time, it is found that the closed flux is over 70% of the initial injector flux used to initiate the discharge. Furthermore, these results could work well for the application of transient CHI in devices that employ super conducting coils to generate and sustain the plasma equilibrium.« less

New Fusion Concept Using Coaxial Passing Through Each Other Self-focusing Colliding Beams (Invention)

NASA Astrophysics Data System (ADS)

Chikvashvili, Ioseb

2011-10-01

In proposed Concept it is offered to use two ion beams directed coaxially at the same direction but with different velocities (center-of-mass collision energy should be sufficient for fusion), to direct oppositely the relativistic electron beam for only partial compensation of positive space charge and for allowing the combined beam's pinch capability, to apply the longitudinal electric field for compensation of alignment of velocities of reacting particles and also for compensation of energy losses of electrons via Bremsstrahlung. On base of Concept different types of reactor designs can be realized: Linear and Cyclic designs. In the simplest embodiment the Cyclic Reactor (design) may include: betatron type device (circular store of externally injected particles - induction accelerator), pulse high-current relativistic electron injector, pulse high-current slower ion injector, pulse high-current faster ion injector and reaction products extractor. Using present day technologies and materials (or a reasonable extrapolation of those) it is possible to reach: for induction linear injectors (ions&electrons) - currents of thousands A, repeatability - up to 10Hz, the same for high-current betatrons (FFAG, Stellatron, etc.). And it is possible to build the fusion reactor using the proposed Method just today.

3-D CFD Simulation and Validation of Oxygen-Rich Hydrocarbon Combustion in a Gas-Centered Swirl Coaxial Injector using a Flamelet-Based Approach

NASA Technical Reports Server (NTRS)

Richardson, Brian; Kenny, Jeremy

2015-01-01

Injector design is a critical part of the development of a rocket Thrust Chamber Assembly (TCA). Proper detailed injector design can maximize propulsion efficiency while minimizing the potential for failures in the combustion chamber. Traditional design and analysis methods for hydrocarbon-fuel injector elements are based heavily on empirical data and models developed from heritage hardware tests. Using this limited set of data produces challenges when trying to design a new propulsion system where the operating conditions may greatly differ from heritage applications. Time-accurate, Three-Dimensional (3-D) Computational Fluid Dynamics (CFD) modeling of combusting flows inside of injectors has long been a goal of the fluid analysis group at Marshall Space Flight Center (MSFC) and the larger CFD modeling community. CFD simulation can provide insight into the design and function of an injector that cannot be obtained easily through testing or empirical comparisons to existing hardware. However, the traditional finite-rate chemistry modeling approach utilized to simulate combusting flows for complex fuels, such as Rocket Propellant-2 (RP-2), is prohibitively expensive and time consuming even with a large amount of computational resources. MSFC has been working, in partnership with Streamline Numerics, Inc., to develop a computationally efficient, flamelet-based approach for modeling complex combusting flow applications. In this work, a flamelet modeling approach is used to simulate time-accurate, 3-D, combusting flow inside a single Gas Centered Swirl Coaxial (GCSC) injector using the flow solver, Loci-STREAM. CFD simulations were performed for several different injector geometries. Results of the CFD analysis helped guide the design of the injector from an initial concept to a tested prototype. The results of the CFD analysis are compared to data gathered from several hot-fire, single element injector tests performed in the Air Force Research Lab EC-1 test facility located at Edwards Air Force Base.

Measurement of intact-core length of atomizing liquid jets by image deconvolution

NASA Technical Reports Server (NTRS)

Woodward, Roger; Burch, Robert; Kuo, Kenneth; Cheung, Fan-Bill

1993-01-01

The investigation of liquid jet breakup and spray development is critical to the understanding of combustion phenomena in liquid propellant rocket engines. Much work has been done to characterize low-speed liquid jet breakup and dilute sprays, but atomizing jets and dense sprays have yielded few quantitative measurements due to their high liquid load fractions and hence their optical opacity. Focus was on a characteristic of the primary breakup process of round liquid jets, namely the length of the intact-liquid core. The specific application considered is that of shear-coaxial-type rocket engine injectors in which liquid oxygen is injected through the center post while high velocity gaseous hydrogen is injected through a concentric annulus, providing a shear force to the liquid jet surface. Real-time x ray radiography, capable of imaging through the dense two-phase region surrounding the liquid core, is used to make the measurements. The intact-liquid-core length data were obtained and interpreted using two conceptually different methods to illustrate the effects of chamber pressure, gas-to-liquid momentum ratio, and cavitation.

Passive MHD Spectroscopy for Enabling Magnetic Reconstructions on Spherical Tokamak Plasmas at General Fusion Inc

NASA Astrophysics Data System (ADS)

O'Shea, Peter; Laberge, Michel; Mossman, Alex; Reynolds, Meritt

2017-10-01

Magnetic reconstructions on lab based plasma injectors at General Fusion relies heavily on edge magnetic (``Bdot'') probes. On plasma experiments built for field compression (PCS) tests, the number and locations of Bdot probes is limited by mechanical constraints. Additional information about the q profiles near the core in our Spector plasmas is obtained using passive MHD spectroscopy. The coaxial helicity injection (CHI) formation process naturally generates hollow current profiles and reversed shear early in each discharge. Central Ohmic heating naturally peaks the current profiles as our plasmas evolve in time, simultaneously reducing the core safety factor, q(0), and reverse shear. As the central, non-monotonic q-profile crosses rational flux surfaces, we observe transient magnetic reconnection events (MRE's) due to the double tearing mode. Modal analysis allows us to infer the q surfaces involved in each burst. The parametric dependence of the timing of MRE's allows us to estimate the continuous time evolution of the core q profile. Combining core MHD spectroscopy with edge magnetic probe measurements greatly enhances our certainty of the overall q profile.

Measurement of intact-core length of atomizing liquid jets by image deconvolution

NASA Astrophysics Data System (ADS)

Woodward, Roger; Burch, Robert; Kuo, Kenneth; Cheung, Fan-Bill

1993-11-01

The investigation of liquid jet breakup and spray development is critical to the understanding of combustion phenomena in liquid propellant rocket engines. Much work has been done to characterize low-speed liquid jet breakup and dilute sprays, but atomizing jets and dense sprays have yielded few quantitative measurements due to their high liquid load fractions and hence their optical opacity. Focus was on a characteristic of the primary breakup process of round liquid jets, namely the length of the intact-liquid core. The specific application considered is that of shear-coaxial-type rocket engine injectors in which liquid oxygen is injected through the center post while high velocity gaseous hydrogen is injected through a concentric annulus, providing a shear force to the liquid jet surface. Real-time x ray radiography, capable of imaging through the dense two-phase region surrounding the liquid core, is used to make the measurements. The intact-liquid-core length data were obtained and interpreted using two conceptually different methods to illustrate the effects of chamber pressure, gas-to-liquid momentum ratio, and cavitation.

Combustion Stability Analyses of Coaxial Element Injectors with Liquid Oxygen/Liquid Methane Propellants

NASA Technical Reports Server (NTRS)

Hulka, J. R.

2010-01-01

Liquid rocket engines using oxygen and methane propellants are being considered by the National Aeronautics and Space Administration (NASA) for in-space vehicles. This propellant combination has not been previously used in a flight-qualified engine system, so limited test data and analysis results are available at this stage of early development. NASA has funded several hardware-oriented activities with oxygen and methane propellants over the past several years with the Propulsion and Cryogenic Advanced Development (PCAD) project, under the Exploration Technology Development Program. As part of this effort, the NASA Marshall Space Flight Center has conducted combustion stability analyses of several of the configurations. This paper presents test data and analyses of combustion stability from the recent PCAD-funded test programs at the NASA MSFC. These test programs used swirl coaxial element injectors with liquid oxygen and liquid methane propellants. Oxygen was injected conventionally in the center of the coaxial element, and swirl was provided by tangential entry slots. Injectors with 28-element and 40-element patterns were tested with several configurations of combustion chambers, including ablative and calorimeter spool sections, and several configurations of fuel injection design. Low frequency combustion instability (chug) occurred with both injectors, and high-frequency combustion instability occurred at the first tangential (1T) transverse mode with the 40-element injector. In most tests, a transition between high-amplitude chug with gaseous methane flow and low-amplitude chug with liquid methane flow was readily observed. Chug analyses of both conditions were conducted using techniques from Wenzel and Szuch and from the Rocket Combustor Interactive Design and Analysis (ROCCID) code. The 1T mode instability occurred in several tests and was apparent by high-frequency pressure measurements as well as dramatic increases in calorimeter-measured heat flux throughout the chamber. Analyses of the transverse mode were conducted with ROCCID and empirical methods such as Hewitt d/V. This paper describes the test hardware configurations, test data, analysis methods, and presents results of the various analyses.

Predictive Evaluations of Oxygen-Rich Hydrocarbon Combustion Gas-Centered Swirl Coaxial Injectors using a Flamelet-Based 3-D CFD Simulation Approach

NASA Technical Reports Server (NTRS)

Richardson, Brian R.; Braman, Kalem; West, Jeff

2016-01-01

NASA Marshall Space Flight Center (MSFC) has embarked upon a joint project with the Air Force to improve the state-of-the-art of space application combustion device design and operational understanding. One goal of the project is to design, build and hot-fire test a 40,000 pound-thrust Oxygen/Rocket Propellant-2 (RP-2) Oxygen-Rich staged engine at MSFC. The overall project goals afford the opportunity to test multiple different injector designs and experimentally evaluate the any effect on the engine performance and combustion dynamics. To maximize the available test resources and benefits, pre-test, combusting flow, Computational Fluid Dynamics (CFD) analysis was performed on the individual injectors to guide the design. The results of the CFD analysis were used to design the injectors for specific, targeted fluid dynamic features and the analysis results also provided some predictive input for acoustic and thermal analysis of the main Thrust Chamber Assembly (TCA). MSFC has developed and demonstrated the ability to utilize a computationally efficient, flamelet-based combustion model to guide the pre-test design of single-element Gas Centered Swirl Coaxial (GCSC) injectors. Previous, Oxygen/RP-2 simulation models utilizing the Loci-STREAM flow solver, were validated using single injector test data from the EC-1 Air Force test facility. The simulation effort herein is an extension of the validated, CFD driven, single-injector design approach applied to single injectors which will be part of a larger engine array. Time-accurate, Three-Dimensional, CFD simulations were performed for five different classes of injector geometries. Simulations were performed to guide the design of the injector to achieve a variety of intended performance goals. For example, two GCSC injectors were designed to achieve stable hydrodynamic behavior of the propellant circuits while providing the largest thermal margin possible within the design envelope. While another injector was designed to purposefully create a hydrodynamic instability in the fuel supply circuit as predicted by the CFD analysis. Future multi-injector analysis and testing will indicate what if any changes occur in the predicted behavior for the single-element injector when the same injector geometry is placed in a multi-element array.

Combustion Dynamics and Stability Modeling of a Liquid Oxygen/RP-2 Oxygen-Rich Staged Combustion Preburner and Thrust Chamber Assembly with Gas-Centered Swirl Coaxial Injector Elements

NASA Technical Reports Server (NTRS)

Casiano, M. J.; Kenny, R. J.; Protz, C. S.; Garcia, C. P.; Simpson, S. P.; Elmore, J. L.; Fischbach, S. R.; Giacomoni, C. B.; Hulka, J. R.

2016-01-01

The Combustion Stability Tool Development (CSTD) project, funded by the Air Force Space and Missile Systems Center, began in March 2015 supporting a renewed interest in the development of a liquid oxygen/hydrocarbon, oxygen-rich combustion engine. The project encompasses the design, assembly, and hot-fire testing of the NASA Marshall Space Flight Center 40-klbf Integrated Test Rig (MITR). The test rig models a staged-combustion configuration by combining an oxygen-rich preburner (ORPB), to generate hot gas, with a thrust chamber assembly (TCA) using gas-centered swirl coaxial injector elements. There are five separately designed interchangeable injectors in the TCA that each contain 19- or 27- injector elements. A companion paper in this JANNAF conference describes the design characteristics, rationale, and fabrication issues for all the injectors. The data acquired from a heavily instrumented rig encompasses several injectors, several operating points, and stability bomb tests. Another companion paper in this JANNAF conference describes this test program in detail. In this paper, dynamic data from the hot-fire testing is characterized and used to identify the responses in the ORPB and TCA. A brief review of damping metrics are discussed and applied as a measure of stability margin for damped acoustic modes. Chug and longitudinal combustion stability models and predictions are described which includes new dynamic models for compressible flow through an orifice and a modification to incorporate a third feed line for inclusion of the fuel-film coolant. Flow-acoustics finite element modeling is used to investigate the anticipated TCA acoustics, the effects of injector element length on stability margin, and the potential use of an ORPB orifice trip ring for improving longitudinal stability margin.

Injector design guidelines for gas/liquid propellant systems

NASA Technical Reports Server (NTRS)

Falk, A. Y.; Burick, R. J.

1973-01-01

Injector design guidelines are provided for gas/liquid propellant systems. Information was obtained from a 30-month applied research program encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space storable propellants. The gas/liquid propellant combination studied was FLOX (82.6% F2)/ ambient temperature gaseous methane. Design criteria that provide for simultaneous attainment of high performance and chamber compatibility are presented for both injector types. Parametric data are presented that are applicable for the design of circular coaxial and like-doublet injectors that operate with design parameters similar to those employed. However, caution should be exercised when applying these data to propellant combinations whose elements operate in ranges considerably different from those employed in this study.

Acoustically Forced Coaxial Hydrogen / Liquid Oxygen Jet Flames

DTIC Science & Technology

2016-05-15

serious problems in the development of liquid rocket engines. In order to understand and predict them, it is necessary to understand how representative...liquid rocket injector flames react to acoustic waves. In this study, a representative coaxial gaseous hydrogen / liquid oxygen (LOX) jet flame is...Combustion instabilities can pose serious problems in the development of liquid rocket engines. In order to under- stand and predict them, it is

Simulation of multi-pulse coaxial helicity injection in the Sustained Spheromak Physics Experiment

NASA Astrophysics Data System (ADS)

O'Bryan, J. B.; Romero-Talamás, C. A.; Woodruff, S.

2018-03-01

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization during multi-pulse coaxial helicity injection in the Sustained Spheromak Physics eXperiment. We describe multiple distinct phases of spheromak evolution, starting from vacuum magnetic fields and the formation of the initial magnetic flux bubble through multiple refluxing pulses and the eventual onset of the column mode instability. Experimental and computational magnetic diagnostics agree on the onset of the column mode instability, which first occurs during the second refluxing pulse of the simulated discharge. Our computations also reproduce the injector voltage traces, despite only specifying the injector current and not explicitly modeling the external capacitor bank circuit. The computations demonstrate that global magnetic evolution is fairly robust to different transport models and, therefore, that a single fluid-temperature model is sufficient for a broader, qualitative assessment of spheromak performance. Although discharges with similar traces of normalized injector current produce similar global spheromak evolution, details of the current distribution during the column mode instability impact the relative degree of poloidal flux amplification and magnetic helicity content.

Design of a low emittance and high repetition rate S-band photoinjector

NASA Astrophysics Data System (ADS)

Han, Jang-Hui

2014-09-01

As an electron beam injector of X-ray free-electron lasers (FELs), photoinjectors have been developed for the past few decades. Such an injector starting with a photocathode RF gun provides high brightness beams and therefore it is being adopted as an injector of X-ray FELs. In this paper we show how to improve photoinjector performance in terms of emittance and repetition rates by means of injector components optimization, especially with the gun. Transverse emittance at the end of an injector is reduced by optimizing the gun design, gun solenoid position, and accelerating section position. The repetition rate of an injector mainly depends on the gun. It is discussed that a repetition rate of 1 kHz at a normal-conducting S-band photoinjector is feasible by adopting a coaxial RF coupler and improving cooling-water channels surrounding the gun.

Validation of High-Fidelity CFD Simulations for Rocket Injector Design

NASA Technical Reports Server (NTRS)

Tucker, P. Kevin; Menon, Suresh; Merkle, Charles L.; Oefelein, Joseph C.; Yang, Vigor

2008-01-01

Computational fluid dynamics (CFD) has the potential to improve the historical rocket injector design process by evaluating the sensitivity of performance and injector-driven thermal environments to the details of the injector geometry and key operational parameters. Methodical verification and validation efforts on a range of coaxial injector elements have shown the current production CFD capability must be improved in order to quantitatively impact the injector design process. This paper documents the status of a focused effort to compare and understand the predictive capabilities and computational requirements of a range of CFD methodologies on a set of single element injector model problems. The steady Reynolds-Average Navier-Stokes (RANS), unsteady Reynolds-Average Navier-Stokes (URANS) and three different approaches using the Large Eddy Simulation (LES) technique were used to simulate the initial model problem, a single element coaxial injector using gaseous oxygen and gaseous hydrogen propellants. While one high-fidelity LES result matches the experimental combustion chamber wall heat flux very well, there is no monotonic convergence to the data with increasing computational tool fidelity. Systematic evaluation of key flow field regions such as the flame zone, the head end recirculation zone and the downstream near wall zone has shed significant, though as of yet incomplete, light on the complex, underlying causes for the performance level of each technique. 1 Aerospace Engineer and Combustion CFD Team Leader, MS ER42, NASA MSFC, AL 35812, Senior Member, AIAA. 2 Professor and Director, Computational Combustion Laboratory, School of Aerospace Engineering, 270 Ferst Dr., Atlanta, GA 30332, Associate Fellow, AIAA. 3 Reilly Professor of Engineering, School of Mechanical Engineering, 585 Purdue Mall, West Lafayette, IN 47907, Fellow, AIAA. 4 Principal Member of Technical Staff, Combustion Research Facility, 7011 East Avenue, MS9051, Livermore, CA 94550, Associate Fellow, AIAA. 5 J. L. and G. H. McCain Endowed Chair, Mechanical Engineering, 104 Research Building East, University Park, PA 16802, Fellow, AIAA. American Institute of Aeronautics and Astronautics 1

Simulations of S-band RF gun with RF beam control

NASA Astrophysics Data System (ADS)

Barnyakov, A. M.; Levichev, A. E.; Maltseva, M. V.; Nikiforov, D. A.

2017-08-01

The RF gun with RF control is discussed. It is based on the RF triode and two kinds of the cavities. The first cavity is a coaxial cavity with cathode-grid assembly where beam bunches are formed, the second one is an accelerating cavity. The features of such a gun are the following: bunched and relativistic beams in the output of the injector, absence of the back bombarding electrons, low energy spread and short length of the bunches. The scheme of the injector is shown. The electromagnetic field simulation and longitudinal beam dynamics are presented. The possible using of the injector is discussed.

Twisted Vanes Would Enhance Fuel/Air Mixing In Turbines

NASA Technical Reports Server (NTRS)

Nguyen, H. Lee; Micklow, Gerald J.; Dogra, Anju S.

1994-01-01

Computations of flow show performance of high-shear airblast fuel injector in gas-turbine engine enhanced by use of appropriately proportioned twisted (instead of flat) dome swirl vanes. Resultant more nearly uniform fuel/air mixture burns more efficiently, emitting smaller amounts of nitrogen oxides. Twisted-vane high-shear airblast injectors also incorporated into paint sprayers, providing advantages of low pressure drop characteristic of airblast injectors in general and finer atomization of advanced twisted-blade design.

On double shearing in frictional materials

NASA Astrophysics Data System (ADS)

Teunissen, J. A. M.

2007-01-01

This paper evaluates the mechanical behaviour of yielding frictional geomaterials. The general Double Shearing model describes this behaviour. Non-coaxiality of stress and plastic strain increments for plane strain conditions forms an important part of this model. The model is based on a micro-mechanical and macro-mechanical formulation. The stress-dilatancy theory in the model combines the mechanical behaviour on both scales.It is shown that the general Double Shearing formulation comprises other Double Shearing models. These models differ in the relation between the mobilized friction and dilatancy and in non-coaxiality. In order to describe reversible and irreversible deformations the general Double Shearing model is extended with elasticity.The failure of soil masses is controlled by shear mechanisms. These shear mechanisms are determined by the conditions along the shear band. The shear stress ratio of a shear band depends on the orientation of the stress in the shear band. There is a difference between the peak strength and the residual strength in the shear band. While peak stress depends on strength properties only, the residual strength depends upon the yield conditions and the plastic deformation mechanisms and is generally considerably lower than the maximum strength. It is shown that non-coaxial models give non-unique solutions for the shear stress ratio on the shear band. The Double Shearing model is applied to various failure problems of soils such as the direct simple shear test, the biaxial test, infinite slopes, interfaces and for the calculation of the undrained shear strength. Copyright

Development of Compact Toroid Injector for C-2 FRCs

NASA Astrophysics Data System (ADS)

Matsumoto, Tadafumi; Sekiguchi, Junichi; Asai, Tomohiko; Gota, Hiroshi; Garate, Eusebio; Allfrey, Ian; Valentine, Travis; Smith, Brett; Morehouse, Mark; TAE Team

2014-10-01

Collaborative research project with Tri Alpha Energy has been started and we have developed a new compact toroid (CT) injector for the C-2 device, mainly for fueling field-reversed configurations (FRCs). The CT is formed by a magnetized coaxial plasma-gun (MCPG), which consists of coaxial cylinder electrodes; a spheromak-like plasma is generated by discharge and pushed out from the gun by Lorentz force. The inner diameter of outer electrode is 83.1 mm and the outer diameter of inner electrode is 54.0 mm. The surface of the inner electrode is coated with tungsten in order to reduce impurities coming out from the electrode. The bias coil is mounted inside of the inner electrode. We have recently conducted test experiments and achieved a supersonic CT translation speed of up to ~100 km/s. Other typical plasma parameters are as follows: electron density ~ 5 × 1021 m-3, electron temperature ~ 40 eV, and the number of particles ~0.5-1.0 × 1019. The CT injector is now planned to be installed on C-2 and the first CT injection experiment will be conducted in the near future. The detailed MCPG design as well as the test experimental results will be presented.

Pure shear and simple shear calcite textures. Comparison of experimental, theoretical and natural data

USGS Publications Warehouse

Wenk, H.-R.; Takeshita, T.; Bechler, E.; Erskine, B.G.; Matthies, S.

1987-01-01

The pattern of lattice preferred orientation (texture) in deformed rocks is an expression of the strain path and the acting deformation mechanisms. A first indication about the strain path is given by the symmetry of pole figures: coaxial deformation produces orthorhombic pole figures, while non-coaxial deformation yields monoclinic or triclinic pole figures. More quantitative information about the strain history can be obtained by comparing natural textures with experimental ones and with theoretical models. For this comparison, a representation in the sensitive three-dimensional orientation distribution space is extremely important and efforts are made to explain this concept. We have been investigating differences between pure shear and simple shear deformation incarbonate rocks and have found considerable agreement between textures produced in plane strain experiments and predictions based on the Taylor model. We were able to simulate the observed changes with strain history (coaxial vs non-coaxial) and the profound texture transition which occurs with increasing temperature. Two natural calcite textures were then selected which we interpreted by comparing them with the experimental and theoretical results. A marble from the Santa Rosa mylonite zone in southern California displays orthorhombic pole figures with patterns consistent with low temperature deformation in pure shear. A limestone from the Tanque Verde detachment fault in Arizona has a monoclinic fabric from which we can interpret that 60% of the deformation occurred by simple shear. ?? 1987.

Single element injector testing for STME injector technology

NASA Technical Reports Server (NTRS)

Hulka, J.; Schneider, J. A.; Davis, J.

1992-01-01

An oxidizer-swirled coaxial element injector is being developed for application in the liquid oxygen/gaseous hydrogen Space Transportation Main Engine (STME) for the National Launch System (NLS) vehicle. This paper reports on the first two parts of a four part single injector element study for optimization of the STME injector design. Measurements of Rupe mixing efficiency and atomization characteristics are reported for single element versions of injection elements from two multielement injectors that have been recently hot fire tested. Rather than attempting to measure a definitive mixing efficiency or droplet size parameters of these injector elements, the purpose of these experiments was to provide a baseline comparison for evaluating future injector element design modifications. Hence, all the experiments reported here were conducted with cold flow simulants to nonflowing, ambient conditions. Mixing experiments were conducted with liquid/liquid simulants to provide economical trend data. Atomization experiments were conducted with liquid/gas simulants without backpressure. The results, despite significant differences from hot fire conditions, were found to relate to mixing and atomization parameters deduced from the hot fire testing, suggesting that these experiments are valid for trend analyses. Single element and subscale multielement hot fire testing will verify optimized designs before committing to fullscale fabrication.

Effects of gas liquid ratio on the atomization characteristics of gas-liquid swirl coaxial injectors

NASA Astrophysics Data System (ADS)

Kang, Zhongtao; Li, Qinglian; Zhang, Jiaqi; Cheng, Peng

2018-05-01

To understand the atomization characteristics and atomization mechanism of the gas-liquid swirl coaxial (GLSC) injector, a back-lighting photography technique has been employed to capture the instantaneous spray images with a high speed camera. The diameter and velocity of the droplets in the spray have been characterized with a Dantec Phase Doppler Anemometry (PDA) system. The effects of gas liquid ratio (GLR) on the spray pattern, Sauter mean diameter (SMD), diameter-velocity distribution and mass flow rate distribution were analyzed and discussed. The results show that the atomization of the GLSC injector is dominated by the film breakup when the GLR is small, and violent gas-liquid interaction when the GLR is large enough. The film breakup dominated spray can be divided into gas acceleration region and film breakup region while the violent gas-liquid interaction dominated spray can be divided into the gas acceleration region, violent gas-liquid interaction region and big droplets breakup region. The atomization characteristics of the GLSC injector is significantly influenced by the GLR. From the point of atomization performance, the increase of GLR has positive effects. It decreases the global Sauter mean diameter (GSMD) and varies the SMD distribution from a hollow cone shape (GLR = 0) to an inverted V shape, and finally slanted N shape. However, from the point of spatial distribution, the increase of GLR has negative effects, because the mass flow rate distribution becomes more nonuniform.

Optimization of a GO2/GH2 Swirl Coaxial Injector Element

NASA Technical Reports Server (NTRS)

Tucker, P. Kevin; Shyy, Wei; Vaidyanathan, Rajkumar

1999-01-01

An injector optimization methodology, method i, is used to investigate optimal design points for a gaseous oxygen/gaseous hydrogen (GO2/GH2) swirl coaxial injector element. The element is optimized in terms of design variables such as fuel pressure drop, DELTA P(sub f), oxidizer pressure drop, DELTA P(sub 0) combustor length, L(sub comb), and full cone swirl angle, theta, for a given mixture ratio and chamber pressure. Dependent variables such as energy release efficiency, ERE, wall heat flux, Q(sub w) injector heat flux, Q(sub inj), relative combustor weight, W(sub rel), and relative injector cost, C(sub rel), are calculated and then correlated with the design variables. An empirical design methodology is used to generate these responses for 180 combinations of input variables. Method i is then used to generate response surfaces for each dependent variable. Desirability functions based on dependent variable constraints are created and used to facilitate development of composite response surfaces representing some, or all, of the five dependent variables in terms of the input variables. Two examples illustrating the utility and flexibility of method i are discussed in detail. First, joint response surfaces are constructed by sequentially adding dependent variables. Optimum designs are identified after addition of each variable and the effect each variable has on the design is shown. This stepwise demonstration also highlights the importance of including variables such as weight and cost early in the design process. Secondly, using the composite response surface that includes all five dependent variables, unequal weights are assigned to emphasize certain variables relative to others. Here, method i is used to enable objective trade studies on design issues such as component life and thrust to weight ratio.

Investigation of air-assisted sprays submitted to high frequency transverse acoustic fields: Droplet clustering

NASA Astrophysics Data System (ADS)

Ficuciello, A.; Blaisot, J. B.; Richard, C.; Baillot, F.

2017-06-01

An experimental investigation of the effects of a high amplitude transverse acoustic field on coaxial jets is presented in this paper. Water and air are used as working fluids at ambient pressure. The coaxial injectors are placed on the top of a semi-open resonant cavity where the acoustic pressure fluctuations of the standing wave can reach a maximum peak-to-peak amplitude of 12 kPa at the forcing frequency of 1 kHz. Several test conditions are considered in order to quantify the influence of injection conditions, acoustic field amplitude, and injector position with respect to the standing wave acoustic field. A high speed back-light visualization technique is used to characterize the jet response. Image processing is used to obtain valuable information about the jet behavior. It is shown that the acoustic field drastically affects the atomization process for all atomization regimes. The position of the injector in the acoustic field determines the jet response, and a droplet-clustering phenomenon is highlighted in multi-point injection conditions and quantified by determining discrete droplet location distributions. A theoretical model based on nonlinear acoustics related to the spatial distribution of the radiation pressure exerted on an object explains the behavior observed.

Gas-Centered Swirl Coaxial Liquid Injector Evaluations

NASA Technical Reports Server (NTRS)

Cohn, A. K.; Strakey, P. A.; Talley, D. G.

2005-01-01

Development of Liquid Rocket Engines is expensive. Extensive testing at large scales usually required. In order to verify engine lifetime, large number of tests required. Limited Resources available for development. Sub-scale cold-flow and hot-fire testing is extremely cost effective. Could be a necessary (but not sufficient) condition for long engine lifetime. Reduces overall costs and risk of large scale testing. Goal: Determine knowledge that can be gained from sub-scale cold-flow and hot-fire evaluations of LRE injectors. Determine relationships between cold-flow and hot-fire data.

Injector design for liner-on-target gas-puff experiments

NASA Astrophysics Data System (ADS)

Valenzuela, J. C.; Krasheninnikov, I.; Conti, F.; Wessel, F.; Fadeev, V.; Narkis, J.; Ross, M. P.; Rahman, H. U.; Ruskov, E.; Beg, F. N.

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ˜1 cm radius gas profile that satisfies the theoretical requirement for best performance on ˜1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Injector design for liner-on-target gas-puff experiments.

PubMed

Valenzuela, J C; Krasheninnikov, I; Conti, F; Wessel, F; Fadeev, V; Narkis, J; Ross, M P; Rahman, H U; Ruskov, E; Beg, F N

2017-11-01

We present the design of a gas-puff injector for liner-on-target experiments. The injector is composed of an annular high atomic number (e.g., Ar and Kr) gas and an on-axis plasma gun that delivers an ionized deuterium target. The annular supersonic nozzle injector has been studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated (M > 5), ∼1 cm radius gas profile that satisfies the theoretical requirement for best performance on ∼1-MA current generators. The CFD simulations allowed us to study output density profiles as a function of the nozzle shape, gas pressure, and gas composition. We have performed line-integrated density measurements using a continuous wave (CW) He-Ne laser to characterize the liner gas density. The measurements agree well with the CFD values. We have used a simple snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector.

Performance and Stability Analyses of Rocket Thrust Chambers with Oxygen/Methane Propellants

NASA Technical Reports Server (NTRS)

Hulka, James R.; Jones, Gregg W.

2010-01-01

Liquid rocket engines using oxygen and methane propellants are being considered by the National Aeronautics and Space Administration (NASA) for future in-space vehicles. This propellant combination has not been previously used in flight-qualified engine systems developed by NASA, so limited test data and analysis results are available at this stage of early development. As part of activities for the Propulsion and Cryogenic Advanced Development (PCAD) project funded under the Exploration Technology Development Program, the NASA Marshall Space Flight Center (MSFC) has been evaluating capability to model combustion performance and stability for oxygen and methane propellants. This activity has been proceeding for about two years and this paper is a summary of results to date. Hot-fire test results of oxygen/methane propellant rocket engine combustion devices for the modeling investigations have come from several sources, including multi-element injector tests with gaseous methane from the 1980s, single element tests with gaseous methane funded through the Constellation University Institutes Program, and multi-element injector tests with both gaseous and liquid methane conducted at the NASA MSFC funded by PCAD. For the latter, test results of both impinging and coaxial element injectors using liquid oxygen and liquid methane propellants are included. Configurations were modeled with two one-dimensional liquid rocket combustion analysis codes, the Rocket Combustor Interactive Design and Analysis code and the Coaxial Injector Combustion Model. Special effort was focused on how these codes can be used to model combustion and performance with oxygen/methane propellants a priori, and what anchoring or calibrating features need to be applied, improved or developed in the future. Low frequency combustion instability (chug) occurred, with frequencies ranging from 150 to 250 Hz, with several multi-element injectors with liquid/liquid propellants, and was modeled using techniques from Wenzel and Szuch. High-frequency combustion instability also occurred at the first tangential (1T) mode, at about 4500 Hz, with several multi-element injectors with liquid/liquid propellants. Analyses of the transverse mode instability were conducted by evaluating injector resonances and empirical methods developed by Hewitt.

Earth storable bimodal engine, phase 1

NASA Technical Reports Server (NTRS)

1973-01-01

An in-depth study of an Earth Storable Bimodal (ESB) Engine using earth storable propellants N2O/N2H4 and operating in either a monopropellant or bipropellant mode was conducted. Detailed studies were completed for both a hot-gas, regeneratively cooled thrust chamber and a ducted hot-gas, film cooled thrust chamber. Hydrazine decomposition products were used for cooling in either configuration. The various arrangements and configurations of hydrazine reactors, secondary injectors, chambers and gimbal methods were considered. The two basic materials selected for the major components were columbium alloys and L-605. The secondary injector types considered were previously demonstrated by JPL and consisted of a liquid-on-gas triplet, a liquid-on-gas doublet, and a liquid-on-gas coaxial injector. Various design tradeoffs were made with different reactor types located at: the secondary injector station, the thrust chamber throat, and the nozzle/extension interface. Associated thermal, structural, and mass analyses were completed.

Development of Tripropellant CFD Design Code

NASA Technical Reports Server (NTRS)

Farmer, Richard C.; Cheng, Gary C.; Anderson, Peter G.

1998-01-01

A tripropellant, such as GO2/H2/RP-1, CFD design code has been developed to predict the local mixing of multiple propellant streams as they are injected into a rocket motor. The code utilizes real fluid properties to account for the mixing and finite-rate combustion processes which occur near an injector faceplate, thus the analysis serves as a multi-phase homogeneous spray combustion model. Proper accounting of the combustion allows accurate gas-side temperature predictions which are essential for accurate wall heating analyses. The complex secondary flows which are predicted to occur near a faceplate cannot be quantitatively predicted by less accurate methodology. Test cases have been simulated to describe an axisymmetric tripropellant coaxial injector and a 3-dimensional RP-1/LO2 impinger injector system. The analysis has been shown to realistically describe such injector combustion flowfields. The code is also valuable to design meaningful future experiments by determining the critical location and type of measurements needed.

Evolution of a calcite marble shear zone complex on Thassos Island, Greece: microstructural and textural fabrics and their kinematic significance

NASA Astrophysics Data System (ADS)

Bestmann, Michel; Kunze, Karsten; Matthews, Alan

2000-11-01

The deformation history of a monophase calcite marble shear zone complex on Thassos Island, Northern Greece, is reconstructed by detailed geometric studies of the textural and microstructural patterns relative to a fixed reference system (shear zone boundary, SZB). Strain localization within the massive marble complex is linked to decreasing P- T conditions during the exhumation process of the metamorphic core complex. Solvus thermometry indicates that temperatures of 300-350°C prevailed during part of the shear zone deformation history. The coarse-grained marble protolith outside the shear zone is characterized by symmetrically oriented twin sets due to early coaxial deformation. A component of heterogeneous non-coaxial deformation is first recorded within the adjacent protomylonite. Enhanced strain weakening by dynamic recrystallization promoted strong localization of plastic deformation in the ultramylonite of the calcite shear zone, where high strain was accommodated by non-coaxial flow. This study demonstrates that both a pure shear and a simple shear strain path can result in similar crystallographic preferred orientations (single c-axis maximum perpendicular to the SZB) by different dominant deformation mechanisms. Separated a-axis pole figures (+ a- and - a-axis) show different density distributions with orthorhombic texture symmetry in the protolith marble and monoclinic symmetry in the ultramylonite marble consistently with the observed grain fabric symmetry.

Noise from Supersonic Coaxial Jets. Part 2; Normal Velocity Profile

NASA Technical Reports Server (NTRS)

Dahl, M. D.; Morris, P. J.

1997-01-01

Instability waves have been established as noise generators in supersonic jets. Recent analysis of these slowly diverging jets has shown that these instability waves radiate noise to the far field when the waves have components with phase velocities that are supersonic relative to the ambient speed of sound. This instability wave noise generation model has been applied to supersonic jets with a single shear layer and is now applied to supersonic coaxial jets with two initial shear layers. In this paper the case of coaxial jets with normal velocity profiles is considered, where the inner jet stream velocity is higher than the outer jet stream velocity. To provide mean flow profiles at all axial locations, a numerical scheme is used to calculate the mean flow properties. Calculations are made for the stability characteristics in the coaxial jet shear layers and the noise radiated from the instability waves for different operating conditions with the same total thrust, mass flow and exit area as a single reference jet. The effects of changes in the velocity ratio, the density ratio and the area ratio are each considered independently.

Use of Proper Orthogonal Decomposition Towards Time-resolved Image Analysis of Sprays

DTIC Science & Technology

2011-03-15

High-speed movies of optically dense sprays exiting a Gas-Centered Swirl Coaxial (GCSC) injector are subjected to image analysis to determine spray...sequence prior to image analysis . Results of spray morphology including spray boundary, widths, angles and boundary oscillation frequencies, are

STE thrust chamber technology: Main injector technology program and nozzle Advanced Development Program (ADP)

NASA Technical Reports Server (NTRS)

1993-01-01

The purpose of the STME Main Injector Program was to enhance the technology base for the large-scale main injector-combustor system of oxygen-hydrogen booster engines in the areas of combustion efficiency, chamber heating rates, and combustion stability. The initial task of the Main Injector Program, focused on analysis and theoretical predictions using existing models, was complemented by the design, fabrication, and test at MSFC of a subscale calorimetric, 40,000-pound thrust class, axisymmetric thrust chamber operating at approximately 2,250 psi and a 7:1 expansion ratio. Test results were used to further define combustion stability bounds, combustion efficiency, and heating rates using a large injector scale similar to the Pratt & Whitney (P&W) STME main injector design configuration including the tangential entry swirl coaxial injection elements. The subscale combustion data was used to verify and refine analytical modeling simulation and extend the database range to guide the design of the large-scale system main injector. The subscale injector design incorporated fuel and oxidizer flow area control features which could be varied; this allowed testing of several design points so that the STME conditions could be bracketed. The subscale injector design also incorporated high-reliability and low-cost fabrication techniques such as a one-piece electrical discharged machined (EDMed) interpropellant plate. Both subscale and large-scale injectors incorporated outer row injector elements with scarfed tip features to allow evaluation of reduced heating rates to the combustion chamber.

Coaxial airblast atomizers

NASA Technical Reports Server (NTRS)

Hardalupas, Y.; Whitelaw, J. H.

1993-01-01

An experimental investigation was performed to quantify the characteristics of the sprays of coaxial injectors with particular emphasis on those aspects relevant to the performance of rocket engines. Measurements for coaxial air blast atomizers were obtained using air to represent the gaseous stream and water to represent the liquid stream. A wide range of flow conditions were examined for sprays with and without swirl for gaseous streams. The parameters varied include Weber number, gas flow rate, liquid flow rate, swirl, and nozzle geometry. Measurements were made with a phase Doppler velocimeter. Major conclusions of the study focused upon droplet size as a function of Weber number, effect of gas flow rate on atomization and spray spread, effect of nozzle geometry on atomization and spread, effect of swirl on atomization, spread, jet recirculation and breakup, and secondary atomization.

Analysis of Coaxial Injectors Using CFD++

DTIC Science & Technology

2011-09-12

turpentine droplets d = 1-90 um Uc = 2.4 m/s Low turbulence intensity of 1.4% Model Validation Case 9/12/2011 28Distribution A: Approved for Public...Approved for Public Release (Pending) Case Conditions: •Two species (Air, Turpentine ) •Base Equation Type: Compressible Real Gas Navier-Stokes/Euler

The effect of prior sandblasting of the wire on the shear bond strength of two different types of lingual retainers.

PubMed

Kilinç, Delal Dara; Sayar, Gülşilay

2018-04-07

The aim of this study was to evaluate the effect of total surface sandblasting on the shear bond strength of two different retainer wires. The null hypothesis was that there is no difference in the bond strength of the two types of lingual retainer wires when they are sandblasted. One hundred and sixty human premolar teeth were equally divided into four groups (n=40). A pair of teeth was embedded in self-curing acrylic resin and polished. Retainer wires were applied on the etched and rinsed surfaces of the teeth. Four retainers were used: group 1: braided retainer (0.010×0.028″, Ortho Technology); group 2: sandblasted braided retainer (0.010×0.028″, Ortho Technology); group 3: coaxial retainer (0.0215″ Coaxial, 3M) and group 4: sandblasted coaxial retainer (0.0215″ Coaxial, 3M). The specimens were tested using a universal test machine in shear mode with a crosshead speed of one mm/min. One-way analysis of variance (Anova) was used to determine the significant differences among the groups. There was no significant difference (P=0.117) among the groups according to this test. The null hypothesis was accepted. There was no statistically significant difference among the shear bond strength values of the four groups. Copyright © 2018 CEO. Published by Elsevier Masson SAS. All rights reserved.

Analyses of Injection-Coupled Combustion Instability from J-2X Gas Generator Development

NASA Technical Reports Server (NTRS)

Hulka, James R.; Kenny, R. Jeremy; Protz, Chris; Casiano, Matthew

2011-01-01

During development of the gas generator for the liquid oxygen/liquid hydrogen propellant J-2X rocket engine, combustion instabilities were observed near the frequency of the first longitudinal acoustic mode of the hot gas combustion chamber duct. These instabilities were similar to intermediate-frequency or buzz-type instabilities as described in historical programs, except for several aspects: 1) the frequencies were low, in the realm of chug; 2) at times the instability oscillation amplitudes were quite large, with peak-to-peak amplitudes exceeding 50% of the mean chamber pressure along with the appearance of harmonics; 3) the chamber excitation was related to but not exactly at the first longitudinal combustion chamber acoustic mode; and 4) the injector provided mass flow rate oscillations induced by capacitance and inertance effects in the injector rather than by organ pipe resonances of the coaxial oxidizer posts. This type of combustion instability is referred to as "injection coupling" because one critical driving source of the instability is mass flow rate oscillations from the injector. However, the type of injection coupling observed here is different than observed in previous instances of buzz instability with coaxial injectors, because of the lower frequencies and lack of influence from the oxidizer post organ pipe resonances. Test data and preliminary analyses of the initial combustion instabilities were presented in several papers at the 5th Liquid Propulsion Subcommittee meeting. Since that time, additional hot-fire tests with several new hardware configurations have been conducted, and additional analyses have been completed. The analytical models described in previous papers have been updated to include the influences of new geometrical configurations, including a different oxidizer injector manifold configuration and a branch pipe in the hot gas duct that supplies gaseous helium during the start transient to pre-spin the turbine. In addition, the analysis methodology has been revisited to evaluate the potential influence of a combustion response as well as an injection response.

Breakup phenomena of a coaxial jet in the non-dilute region using real-time X-ray radiography

NASA Astrophysics Data System (ADS)

Cheung, F. B.; Kuo, K. K.; Woodward, R. D.; Garner, K. N.

1990-07-01

An innovative approach to the investigation of liquid jet breakup processes in the near-injector region has been developed to overcome the experimental difficulties associated with optically opaque, dense sprays. Real-time X-ray radiography (RTR) has been employed to observe the inner structure and breakup phenomena of coaxial jets. In the atomizing regime, droplets much smaller than the exit diameter are formed beginning essentially at the injector exit. Through the use of RTR, the instantaneous contour of the liquid core was visualized. Experimental results consist of controlled-exposure digital video images of the liquid jet breakup process. Time-averaged video images have also been recorded for comparison. A digital image processing system is used to analyze the recorded images by creating radiance level distributions of the jet. A rudimentary method for deducing intact-liquid-core length has been suggested. The technique of real-time X-ray radiography has been shown to be a viable approach to the study of the breakup processes of high-speed liquid jets.

Summary of Liquid Oxygen/Hydrogen, Direct Metal Laser Sintering Injector Testing and Evaluation Effort at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Barnett, Gregory; Bullard, David B.

2015-01-01

The last several years have witnessed a significant advancement in the area of additive manufacturing technology. One area that has seen substantial expansion in application has been laser sintering (or melting) in a powder bed. This technology is often termed 3D printing or various acronyms that may be industry, process, or company specific. Components manufactured via 3D printing have the potential to significantly reduce development and fabrication time and cost. The usefulness of 3D printed components is influenced by several factors such as material properties and surface roughness. This paper details three injectors that were designed, fabricated, and tested in order to evaluate the utility of 3D printed components for rocket engine applications. The three injectors were tested in a hot-fire environment with chamber pressures of approximately 1400 psia. One injector was a 28 element design printed by Directed Manufacturing. The other two injectors were identical 40 element designs printed by Directed Manufacturing and Solid Concepts. All the injectors were swirl-coaxial designs and were subscale versions of a full-scale injector currently in fabrication. The test and evaluation programs for the 28 element and 40 element injectors provided a substantial amount of data that confirms the feasibility of 3D printed parts for future applications. The operating conditions of previously tested, conventionally manufactured injectors were reproduced in the 28 and 40 element programs in order to contrast the performance of each. Overall, the 3D printed injectors demonstrated comparable performance to the conventionally manufactured units. The design features of the aforementioned injectors can readily be implemented in future applications with a high degree of confidence.

Developing a compact toroid injector in the ThermoElectric driven Liquid metal plasma facing Structures device

NASA Astrophysics Data System (ADS)

Christenson, Michael; Szott, Matthew; Kalathiparambil, Kishor; Sovinec, Carl; Ruzic, David

2016-10-01

The ThermoElectric-driven Liquid-metal plasma-facing Structures (TELS) device at the University of Illinois is a theta-pinched, plasma-material interaction test stand used to simulate extreme events in the edge and divertor regions of a tokamak plasma. Previous measurements of the electron and ion temperatures have shown that the isotropic heat load on target ranges between 0.1 and 0.2 MJ m-2 over a pulse lasting 0.2 ms. While this compares well to the heat loads from Type 1 ELMs in larger toroidal devices, it is still much less than the energy deposition from Type 1 ELMs expected in ITER, which are in excess of 1 MJ m-2. To this end, a compact toroid (CT) injector has been proposed as a modification to the existing TELS device. By using an externally applied bias field to force reconnection at the muzzle of the coaxial plasma accelerator source that drives ionization, NIMROD MHD simulations have shown a peak magnetic flux of 3.5 mWb is reached 0.025 ms into the pulse - more than sufficient to form a CT. Early calorimetry and magnetic field measurements indicate that a new plasma structure has been formed in the magnetized coaxial plasma source. This work presents the current results of CT generation with respect to the bias field strength as well as the coaxial source geometry. DOE OFES DE-SC0008587, DE-SC0008658, DE-FG02-99ER54515.

Feasibility study of a pressure-fed engine for a water recoverable space shuttle booster. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1972-01-01

An overview is presented of the results of the analyses conducted in support of the selected engine system for the pressure-fed booster stage. During initial phases of the project, a gimbaled, regeneratively cooled, fixed thrust engine having a coaxial pintle injector was selected as optimum for this configuration.

Development And Characterization Of A Liner-On-Target Injector For Staged Z-Pinch Experiments

NASA Astrophysics Data System (ADS)

Valenzuela, J. C.; Conti, F.; Krasheninnikov, I.; Narkis, J.; Beg, F.; Wessel, F. J.; Rahman, H. U.

2016-10-01

We present the design and optimization of a liner-on-target injector for Staged Z-pinch experiments. The injector is composed of an annular high atomic number (e.g. Ar, Kr) gas-puff and an on-axis plasma gun that delivers the ionized deuterium target. The liner nozzle injector has been carefully studied using Computational Fluid Dynamics (CFD) simulations to produce a highly collimated 1 cm radius gas profile that satisfies the theoretical requirement for best performance on the 1 MA Zebra current driver. The CFD simulations produce density profiles as a function of the nozzle shape and gas. These profiles are initialized in the MHD MACH2 code to find the optimal liner density for a stable, uniform implosion. We use a simple Snowplow model to study the plasma sheath acceleration in a coaxial plasma gun to help us properly design the target injector. We have performed line-integrated density measurements using a CW He-Ne laser to characterize the liner gas and the plasma gun density as a function of time. The measurements are compared with models and calculations and benchmarked accordingly. Advanced Research Projects Agency - Energy, DE-AR0000569.

Supersonic Coaxial Jets: Noise Predictions and Measurements

NASA Technical Reports Server (NTRS)

Dahl, Milo D.; Papamoschou, Dimitri; Hixon, Ray

1998-01-01

The noise from perfectly expanded coaxial jets was measured in an anechoic chamber for different operating conditions with the same total thrust, mass flow, and exit area. The shape of the measured noise spectrum at different angles to the jet axis was found to agree with spectral shapes for single, axisymmetric jets. Based on these spectra, the sound was characterized as being generated by large turbulent structures or fine-scale turbulence. Modeling the large scale structures as instability waves, a stability analysis was conducted for the coaxial jets to identify the growing and decaying instability waves in each shear layer and predict their noise radiation pattern outside the jet. When compared to measured directivity, the analysis identified the region downstream of the outer potential core, where the two shear layers were merging, as the source of the peak radiated noise where instability waves, with their origin in the inner shear layer, reach their maximum amplitude. Numerical computations were also performed using a linearized Euler equation solver. Those results were compared to both the results from the instability wave analysis and to measured data.

Recent Developments in X-Ray Diagnostics for Cryogenic and Optically Dense Coaxial Rocket Sprays

NASA Technical Reports Server (NTRS)

Radke, Christopher D.; Kastengren, Alan L.; Meyer, Terrence R.

2017-01-01

The mixing and atomization of propellants is often characterized by optically dense flow fields and complex breakup dynamics. In the development of propulsion systems, the complexity of relevant physics and the range of spatio-temporal scales often makes computational simulation impractical for full scale injector elements; consequently, continued research into improved systems for experimental flow diagnostics is ongoing. One area of non-invasive flow diagnostics which has seen widespread growth is using synchrotron based x-ray diagostics. Over the past 3 years, a series of water and cryogenic based experiments were performed at the Advanced Photon Source, Argonne National Lab, on a NASA in-house designed swirl co-axial rocket injector, designed for operation using liquid oxygen and liquid methane in support of Project Morpheus. A range of techniques, such as x-ray fluorescence and time-averaged radiography were performed providing qualitative and quantitative mass and phase distributions, and were complemented by investigations using time-resolved radiography and white beam imaging, which provided information on breakup and mixing dynamics. Results of these investigations are presented, and conclusions regarding the viability of x-ray based diagnostics are discussed.

Additively Manufactured Combustion Devices Components for LOX/Methane Applications

NASA Technical Reports Server (NTRS)

Greene, Sandra Elam; Protz, Christopher; Garcia, Chance; Goodman, Dwight; Baker, Kevin

2016-01-01

Marshall Space Flight Center (MSFC) has designed, fabricated, and hot-fire tested a variety of successful injectors, chambers, and igniters for potential liquid oxygen (LOX) and methane (CH4) systems since 2005. The most recent efforts have focused on components with additive manufacturing (AM) to include unique design features, minimize joints, and reduce final machining efforts. Inconel and copper alloys have been used with AM processes to produce a swirl coaxial injector and multiple methane cooled thrust chambers. The initial chambers included unique thermocouple ports for measuring local coolant channel temperatures along the length of the chamber. Results from hot-fire testing were used to anchor thermal models and generate a regeneratively cooled thruster for a 4,000 lbf LOX/CH4 engine. The completed thruster will be hot-fire tested in the summer of 2016 at MSFC. The thruster design can also be easily scaled and used on a 25,000 lbf engine. To further support the larger engine design, an AM gas generator injector has been designed. Hot-fire testing on this injector is planned for the summer of 2016 at MSFC.

Stereo-PIV study of flow inside an eye under cataract surgery

NASA Astrophysics Data System (ADS)

Sakakibara, Jun; Yamashita, Masaki; Kobayashi, Tatsuya; Kaji, Yuichi; Oshika, Tetsuro

2012-04-01

We measured velocity distributions in the anterior chamber of porcine eyes under simulated cataract surgery using stereoscopic particle image velocimetry (stereo-PIV). The surface of the cornea was detected based on the images of laser-induced fluorescent light emitted from fluorescent dye solution introduced in a posterior chamber. A coaxial phacoemulsification procedure was simulated with standard size (standard coaxial phacoemulsification) and smaller (micro coaxial phacoemulsification) surgical instruments. In both cases, an asymmetric flow rate of irrigation was observed, although both irrigation ports had the same dimensions prior to insertion into the eye. In cases where the tip of the handpiece was placed farther away from the top of the cornea, i.e., closer to the crystalline lens, direct impingement of irrigation flow onto the cornea surface was avoided and the flow turned back toward the handpiece along the surface of the corneal endothelium. Viscous shear stress on the corneal endothelium was computed based on the measured mean velocity distribution. The maximum shear stress for most cases exceeded 0.1 Pa, which is comparable to the shear stress that caused detachment of the corneal endothelial cells reported by Kaji et al. in Cornea 24:S55-S58, (2005). When direct impingement of the irrigation flow was avoided, the shear stress was reduced considerably.

A low-temperature ductile shear zone: The gypsum-dominated western extension of the brittle Fella-Sava Fault, Southern Alps.

PubMed

Bartel, Esther Maria; Neubauer, Franz; Heberer, Bianca; Genser, Johann

2014-12-01

Based on structural and fabric analyses at variable scales we investigate the evaporitic gypsum-dominated Comeglians-Paularo shear zone in the Southern Alps (Friuli). It represents the lateral western termination of the brittle Fella-Sava Fault. Missing dehydration products of gypsum and the lack of annealing indicate temperatures below 100 °C during development of the shear zone. Despite of such low temperatures the shear zone clearly exhibits mylonitic flow, thus evidencing laterally coeval activity of brittle and viscous deformation. The dominant structures within the gypsum rocks of the Lower Bellerophon Formation are a steeply to gently S-dipping foliation, a subhorizontal stretching lineation and pure shear-dominated porphyroclast systems. A subordinate simple shear component with dextral displacement is indicated by scattered σ-clasts. Both meso- and microscale structures are characteristic of a subsimple shear type of deformation with components of both coaxial and non-coaxial strain. Shortening in a transpressive regime was accommodated by right-lateral displacement and internal pure shear deformation within the Comeglians-Paularo shear zone. The shear zone shows evidence for a combination of two stretching faults, where stretching occurred in the rheologically weaker gypsum member and brittle behavior in enveloping lithologies.

Design and Testing of Non-Toxic RCS Thrusters for Second Generation Reusable Launch Vehicle

NASA Technical Reports Server (NTRS)

Calvignac, Jacky; Dang, Lisa; Tramel, Terri; Paseur, Lila; Champion, Robert (Technical Monitor)

2003-01-01

Under NASA sponsorship, Northrop Grumman Space Technology (NGST) designed, built and tested two non-toxic, reaction control engines, one using liquid oxygen (LOX) and liquid hydrogen (LH2) and the other using liquid oxygen and ethanol. This paper presents the design and testing of the LOX/LH2 thruster. The two key enabling technologies are the coaxial liquid-on-liquid pintle injector and the fuelcooling duct. The workhorse thruster was hotfire tested at the NASA Marshall Space Flight Center Test Stand 500 in March and April of 2002. All tests were performed at sea-level conditions. During the test program, 7 configurations were tested, including 2 combustion chambers, 3 LOX injector pintle tips, and 4 LHp injector settings. The operating conditions surveyed were 70 to 100% thrust levels, mixture ratios from 3.27 to 4.29, and LH2 duct cooling from 18.0 to 25.5% fuel flow. The copper heat sink chamber was used for 16 burns, each burn lasting from 0.4 to 10 seconds, totaling 51.4 seconds, followed by Haynes chamber testing ranging from 0.9 to 120 seconds, totaling 300.9 seconds. The performance of the engine reached 95% C* efficiency. The temperature on the Haynes chamber remained well below established material limits, with the exception of one localized hot spot. These results demonstrate that both the coaxial liquid-on-liquid pintle injector design and fuel duct concepts are viable for the intended application. The thruster headend design maintained cryogenic injection temperatures while firing, which validates the selected injector design approach for minimal heat soak-back. Also, off -nominal operation without adversely impacting the thermal response of the engine showed the robustness of the duct design, a key design feature for this application. By injecting fuel into the duct, the throat temperatures are manageable, yet the split of fuel through the cooling duct does not compromise the overall combstion efficiency, which indicates that, provided proper design refinement, such a concept could be applied to a high-performance version of the thruster.

Triaxial Swirl Injector Element for Liquid-Fueled Engines

NASA Technical Reports Server (NTRS)

Muss, Jeff

2010-01-01

A triaxial injector is a single bi-propellant injection element located at the center of the injector body. The injector element consists of three nested, hydraulic swirl injectors. A small portion of the total fuel is injected through the central hydraulic injector, all of the oxidizer is injected through the middle concentric hydraulic swirl injector, and the balance of the fuel is injected through an outer concentric injection system. The configuration has been shown to provide good flame stabilization and the desired fuel-rich wall boundary condition. The injector design is well suited for preburner applications. Preburner injectors operate at extreme oxygen-to-fuel mass ratios, either very rich or very lean. The goal of a preburner is to create a uniform drive gas for the turbomachinery, while carefully controlling the temperature so as not to stress or damage turbine blades. The triaxial injector concept permits the lean propellant to be sandwiched between two layers of the rich propellant, while the hydraulic atomization characteristics of the swirl injectors promote interpropellant mixing and, ultimately, good combustion efficiency. This innovation is suited to a wide range of liquid oxidizer and liquid fuels, including hydrogen, methane, and kerosene. Prototype testing with the triaxial swirl injector demonstrated excellent injector and combustion chamber thermal compatibility and good combustion performance, both at levels far superior to a pintle injector. Initial testing with the prototype injector demonstrated over 96-percent combustion efficiency. The design showed excellent high -frequency combustion stability characteristics with oxygen and kerosene propellants. Unlike the more conventional pintle injector, there is not a large bluff body that must be cooled. The absence of a protruding center body enhances the thermal durability of the triaxial swirl injector. The hydraulic atomization characteristics of the innovation allow the design to be rapidly scaled from small in-space applications [500-5,000 lbf (2.2 22.2 kN)] to large thrust engine applications [80,000 lbf (356 kN) and beyond]. The triaxial injector is also less sensitive to eccentricities, manufacturing tolerances, and gap width of many traditional coaxial and pintle injector designs. The triaxial-injector injection orifice configuration provides for high injection stiffness. The low parts count and relatively large injector design features are amenable to low-cost production.

Computation of Transverse Injection Into Supersonic Crossflow With Various Injector Orifice Geometries

NASA Technical Reports Server (NTRS)

Foster, Lancert; Engblom, William A.

2003-01-01

Computational results are presented for the performance and flow behavior of various injector geometries employed in transverse injection into a non-reacting Mach 1.2 flow. 3-D Reynolds-Averaged Navier Stokes (RANS) results are obtained for the various injector geometries using the Wind code with the Mentor s Shear Stress Transport turbulence model in both single and multi-species modes. Computed results for the injector mixing, penetration, and induced wall forces are presented. In the case of rectangular injectors, those longer in the direction of the freestream flow are predicted to generate the most mixing and penetration of the injector flow into the primary stream. These injectors are also predicted to provide the largest discharge coefficients and induced wall forces. Minor performance differences are indicated among diamond, circle, and square orifices. Grid sensitivity study results are presented which indicate consistent qualitative trends in the injector performance comparisons with increasing grid fineness.

Mixing enhancement in a scramjet combustor using fuel jet injection swirl

NASA Astrophysics Data System (ADS)

Flesberg, Sonja M.

The scramjet engine has proven to be a viable means of powering a hypersonic vehicle, especially after successful flights of the X-51 WaveRider and various Hy-SHOT test vehicles. The major challenge associated with operating a scramjet engine is the short residence time of the fuel and oxidizer in the combustor. The fuel and oxidizer have only milliseconds to mix, ignite and combust in the combustion chamber. Combustion cannot occur until the fuel and oxidizer are mixed on a molecular level. Therefore the improvement of mixing is of utmost interest since this can increase combustion efficiency. This study investigated mixing enhancement of fuel and oxidizer within the combustion chamber of a scramjet by introducing swirl to the fuel jet. The investigation was accomplished with numerical simulations using STAR-CCM+ computational fluid dynamic software. The geometry of the University of Virginia Supersonic Combustion Facility was used to model the isolator, combustor and nozzle of a scramjet engine for simulation purposes. Experimental data from previous research at the facility was used to verify the simulation model before investigating the effect of fuel jet swirl on mixing. The model used coaxial fuel jet with a swirling annular jet. Single coaxial fuel jet and dual coaxial fuel jet configurations were simulated for the investigation. The coaxial fuel jets were modelled with a swirling annular jet and non-swirling core jet. Numerical analysis showed that fuel jet swirl not only increased mixing and entrainment of the fuel with the oxidizer but the mixing occurred further upstream than without fuel jet swirl. The burning efficiency was calculated for the all the configurations. An increase in burning efficiency indicated an increase in the mixing of H2 with O2. In the case of the single fuel jet models, the maximum burning efficiency increase due to fuel injection jet swirl was 23.3%. The research also investigated the possibility that interaction between two swirling jets would produce increased mixing and to study how the distance between the two fuel injector exits would affect mixing. Three swirl patterns were investigated: 1) the first swirl pattern as viewed by an observer looking downstream had the right fuel annular jet swirling counter clockwise and the left fuel annular jet swirling clockwise, 2) the second swirl pattern as viewed by an observer looking downstream had the right fuel jet swirling clockwise and the left fuel jet swirling counter clockwise, 3) the third swirl pattern as viewed by an observer looking downstream had both the right and left fuel jet swirling in the same clockwise direction. Each one of the swirl patterns were simulated with the distances between the center points of the fuel jets modelled 3, 4, and 5 times the fuel injector radius. The swirl pattern that produced the greatest increase in burning efficiency differed according to the fuel injector spacing. The maximum increase in burning efficiency compared to the corresponding non-swirling two jet baseline case was 24.6% and was produced by the first swirl pattern with the distance between the center points of the fuel jets being 5 times the fuel injector radius. The burning efficiency for the single jet non-swirling baseline case and the first swirl pattern with the distance between the center points of the fuel jets being 5 times the fuel injector radius was 0.70 and 0.90 respectively indicating a 29% increase due to dual fuel injection swirl.

Laser Schlieren and ultraviolet diagnostics of rocket combustion

NASA Technical Reports Server (NTRS)

Fisher, S. C.

1985-01-01

A low pressure oxygen/hydrogen turbine drive combustor hot-fire test series was conducted on the Turbine Drive Combustor Technology Program. The first objective was to gather data on an axisymmetric combustion system to support anchoring of a new combustion/fluid dynamics computer code under development on the same contract. The second objective was to gain insight into low mixture ratio combustion characteristics of coaxial injector elements.

A tandem mirror hybrid plume plasma propulsion facility

NASA Technical Reports Server (NTRS)

Yang, T. F.; Krueger, W. A.; Peng, S.; Urbahn, J.; Chang-Diaz, F. R.

1988-01-01

This paper discusses a novel concept in electrodeless plasma propulsion, in which the materials problems are ameliorated by an electrodeless magnetic confinement scheme borrowed from the tandem mirror approach to controlled thermonuclear fusion. The concept also features a two-stage magnetic nozzle with an annular hypersonic coaxial gas injector near the throat. The nozzle produces hybrid plume by the coaxial injection of hypersonic neutral gas, and the gas layer thus formed protects the material walls from the hot plasma and, through increased collisions, helps detach it from the diverging magnetic field. The tandem mirror plasma propulsion facility is capable of delivering a variable I(sp). The results of numerical simulation of this concept are presented together with those from an experimental tandem-mirror plasma propulsion device.

Demonstration of Tokamak Ohmic Flux Saving by Transient Coaxial Helicity Injection in the National Spherical Torus Experiment

NASA Astrophysics Data System (ADS)

Raman, R.; Mueller, D.; Nelson, B. A.; Jarboe, T. R.; Gerhardt, S.; Kugel, H. W.; Leblanc, B.; Maingi, R.; Menard, J.; Ono, M.; Paul, S.; Roquemore, L.; Sabbagh, S.; Soukhanovskii, V.

2010-03-01

Transient coaxial helicity injection (CHI) started discharges in the National Spherical Torus Experiment (NSTX) have attained peak currents up to 300 kA and when coupled to induction, it has produced up to 200 kA additional current over inductive-only operation. CHI in NSTX has shown to be energetically quite efficient, producing a plasma current of about 10 A/J of capacitor bank energy. In addition, for the first time, the CHI-produced toroidal current that couples to induction continues to increase with the energy supplied by the CHI power supply at otherwise similar values of the injector flux, indicating the potential for substantial current generation capability by CHI in NSTX and in future toroidal devices.

Characterization of compact-toroid injection during formation, translation, and field penetration

NASA Astrophysics Data System (ADS)

Matsumoto, T.; Roche, T.; Allfrey, I.; Sekiguchi, J.; Asai, T.; Gota, H.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M.; Tajima, T.

2016-11-01

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ˜1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.

Characterization of compact-toroid injection during formation, translation, and field penetration.

PubMed

Matsumoto, T; Roche, T; Allfrey, I; Sekiguchi, J; Asai, T; Gota, H; Cordero, M; Garate, E; Kinley, J; Valentine, T; Waggoner, W; Binderbauer, M; Tajima, T

2016-11-01

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ∼1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation, ejection/translation from the MCPG, and penetration into transverse magnetic fields.

Repetitive laser ignition by optical breakdown of a LOX/H2 rocket combustion chamber with multi-injector head configuration

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Kroupa, Gerhard; Oschwald, Michael

2017-09-01

This paper reports on the repetitive laser ignition by optical breakdown within an experimental rocket combustion chamber. Ignition was performed by focusing a laser pulse generated by a miniaturized diode-pumped Nd:YAG laser system. The system, which delivers 33.2 mJ in 2.3 ns, was mounted directly to the combustion chamber. The ignition process and flame stabilization was investigated using an optical probe system monitoring the flame attachment across the 15 coaxial injector configuration. 1195 successful ignitions were performed proving the reliability of this laser ignition system and its applicability to the propellant combination LOX/hydrogen at temperatures of T_{{{H}_{ 2} }} = 120-282 K and T_{{{O}_{ 2} }} = 110-281 K.

Effect of simple shear flow on photosynthesis rate and morphology of micro algae

NASA Astrophysics Data System (ADS)

Mitsuhashi, S.; Fujimoto, M.; Muramatsu, H.; Tanishita, K.

The convective motion of micro algal suspension gives an advantageous effect on the photosynthetic rate in the bioreactor, however, the nature of convective effect on the photosynthesis has not been fully understood. The propose of this study concerns the nature of photosynthetic rate in a well-defined hydrodynamic shear flow of Spirulina platensis suspension, generated in a double rotating coaxial cylinders. The double rotating coaxial cylinders was installed in the incubator chamber with the controlled illumination intensity and temperature. Two kind of experiments, short and long term experiments, were performed to evaluate the direct effect of shear flow on the photosynthetic rate. The short term experiment indicates that the simple shear flow enables to augment the photosynthesis of Spirulina suspension and simultaneously causes the cell destruction due to the excessive shear stress. The long term experiment for 100 hours reveals that the growth rate and the morphology of Spirulina is sensitive to the external fluid mechanical stimulus. The long term application of mechanical stress on the algae may result in the adaptation of the photosynthetic function and morphology.

Performance of a Liner-on-Target Injector for Staged Z-Pinch Experiments

NASA Astrophysics Data System (ADS)

Conti, F.; Valenzuela, J. C.; Narkis, J.; Krasheninnikov, I.; Beg, F.; Wessel, F. J.; Ruskov, E.; Rahman, H. U.; McGee, E.

2016-10-01

We present the design and characterization of a compact liner-on-target injector, used in the Staged Z-pinch experiments conducted on the UNR-NTF Zebra Facility. Previous experiments and analysis indicate that high-Z gas liners produce a uniform and efficient implosion on a low-Z target plasma. The liner gas shell is produced by an annular solenoid valve and a converging-diverging nozzle designed to achieve a collimated, supersonic, Mach-5 flow. The on-axis target is produced by a coaxial plasma gun, where a high voltage pulse is applied to ionize neutral gas and accelerate the plasma by the J-> × B-> force. Measurements of the liner and target dynamics, resolved by interferometry in space and time, fast imaging, and collection of the emitted light, are presented. The results are compared to the predictions from Computational Fluid Dynamics and MHD simulations that model the injector. Optimization of the design parameters, for upcoming Staged Z-pinch experiments, will be discussed. Advanced Research Projects Agency - Energy, DE-AR0000569.

Characterization of compact-toroid injection during formation, translation, and field penetration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T.

2016-11-15

We have developed a compact toroid (CT) injector system for particle refueling of the advanced beam-driven C-2U field-reversed configuration (FRC) plasma. The CT injector is a magnetized coaxial plasma gun (MCPG), and the produced CT must cross the perpendicular magnetic field surrounding the FRC for the refueling of C-2U. To simulate this environment, an experimental test stand has been constructed. A transverse magnetic field of ∼1 kG is established, which is comparable to the C-2U axial magnetic field in the confinement section, and CTs are fired across it. On the test stand we have been characterizing and studying CT formation,more » ejection/translation from the MCPG, and penetration into transverse magnetic fields.« less

Structural aspects of coaxial oxy-fuel flames

NASA Astrophysics Data System (ADS)

Ditaranto, M.; Sautet, J. C.; Samaniego, J. M.

Oxy-fuel combustion has been proven to increase thermal efficiency and to have a potential for NOx emission reduction. The study of 25-kW turbulent diffusion flames of natural gas with pure oxygen is undertaken on a coaxial burner with quarl. The structural properties are analysed by imaging the instantaneous reaction zone by OH* chemiluminescence and measuring scalar and velocity profiles. The interaction between the flame front and the shear layers present in the coaxial jets depends on the momentum ratio which dictates the turbulent structure development. Flame length and NOx emission sensitivity to air leaks in the combustion chamber are also investigated.

Unsteady Three-Dimensional Simulation of a Shear Coaxial GO2/GH2 Rocket Injector with RANS and Hybrid-RAN-LES/DES Using Flamelet Models

NASA Technical Reports Server (NTRS)

Westra, Doug G.; West, Jeffrey S.; Richardson, Brian R.

2015-01-01

Historically, the analysis and design of liquid rocket engines (LREs) has relied on full-scale testing and one-dimensional empirical tools. The testing is extremely expensive and the one-dimensional tools are not designed to capture the highly complex, and multi-dimensional features that are inherent to LREs. Recent advances in computational fluid dynamics (CFD) tools have made it possible to predict liquid rocket engine performance, stability, to assess the effect of complex flow features, and to evaluate injector-driven thermal environments, to mitigate the cost of testing. Extensive efforts to verify and validate these CFD tools have been conducted, to provide confidence for using them during the design cycle. Previous validation efforts have documented comparisons of predicted heat flux thermal environments with test data for a single element gaseous oxygen (GO2) and gaseous hydrogen (GH2) injector. The most notable validation effort was a comprehensive validation effort conducted by Tucker et al. [1], in which a number of different groups modeled a GO2/GH2 single element configuration by Pal et al [2]. The tools used for this validation comparison employed a range of algorithms, from both steady and unsteady Reynolds Averaged Navier-Stokes (U/RANS) calculations, large-eddy simulations (LES), detached eddy simulations (DES), and various combinations. A more recent effort by Thakur et al. [3] focused on using a state-of-the-art CFD simulation tool, Loci/STREAM, on a two-dimensional grid. Loci/STREAM was chosen because it has a unique, very efficient flamelet parameterization of combustion reactions that are too computationally expensive to simulate with conventional finite-rate chemistry calculations. The current effort focuses on further advancement of validation efforts, again using the Loci/STREAM tool with the flamelet parameterization, but this time with a three-dimensional grid. Comparisons to the Pal et al. heat flux data will be made for both RANS and Hybrid RANSLES/ Detached Eddy simulations (DES). Computation costs will be reported, along with comparison of accuracy and cost to much less expensive two-dimensional RANS simulations of the same geometry.

Transition to turbulence and noise radiation in heated coaxial jet flows

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gloor, Michael, E-mail: gloor@ifd.mavt.ethz.ch; Bühler, Stefan; Kleiser, Leonhard

2016-04-15

Laminar-turbulent transition and noise radiation of a parametrized set of subsonic coaxial jet flows with a hot primary (core) stream are investigated numerically by Large-Eddy Simulation (LES) and direct noise computation. This study extends our previous research on local linear stability of heated coaxial jet flows by analyzing the nonlinear evolution of initially laminar flows disturbed by a superposition of small-amplitude unstable eigenmodes. First, a baseline configuration is studied to shed light on the flow dynamics of coaxial jet flows. Subsequently, LESs are performed for a range of Mach and Reynolds numbers to systematically analyze the influences of the temperaturemore » and the velocity ratios between the primary and the secondary (bypass) stream. The results provide a basis for a detailed analysis of fundamental flow-acoustic phenomena in the considered heated coaxial jet flows. Increasing the primary-jet temperature leads to an increase of fluctuation levels and to an amplification of far-field noise, especially at low frequencies. Strong mixing between the cold bypass stream and the hot primary stream as well as the intermittent character of the flow field at the end of the potential core lead to a pronounced noise radiation at an aft angle of approximately 35{sup ∘}. The velocity ratio strongly affects the shear-layer development and therefore also the noise generation mechanisms. Increasing the secondary-stream velocity amplifies the dominance of outer shear-layer perturbations while the disturbance growth rates in the inner shear layer decrease. Already for r{sub mic} > 40R{sub 1}, where r{sub mic} is the distance from the end of the potential core and R{sub 1} is the core-jet radius, a perfect 1/r{sub mic} decay of the sound pressure amplitudes is observed. The potential-core length increases for higher secondary-stream velocities which leads to a shift of the center of the dominant acoustic radiation in the downstream direction.« less

Development of a Gas-Fed Pulse Detonation Research Engine

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Hutt, John (Technical Monitor)

2001-01-01

In response to the growing need for empirical data on pulse detonation engine performance and operation, NASA Marshall Space Flight Center has developed and placed into operation a low-cost gas-fed pulse detonation research engine. The guiding design strategy was to achieve a simple and flexible research apparatus, which was inexpensive to build and operate. As such, the engine was designed to operate as a heat sink device, and testing was limited to burst-mode operation with run durations of a few seconds. Wherever possible, maximum use was made of standard off-the-shelf industrial or automotive components. The 5-cm diameter primary tube is about 90-cm long and has been outfitted with a multitude of sensor and optical ports. The primary tube is fed by a coaxial injector through an initiator tube, which is inserted directly into the injector head face. Four auxiliary coaxial injectors are also integrated into the injector head assembly. All propellant flow is controlled with industrial solenoid valves. An automotive electronic ignition system was adapted for use, and spark plugs are mounted in both tubes so that a variety of ignition schemes can be examined. A microprocessor-based fiber-optic engine control system was developed to provide precise control over valve and ignition timing. Initial shakedown testing with hydrogen/oxygen mixtures verified the need for Schelkin spirals in both the initiator and primary tubes to ensure rapid development of the detonation wave. Measured pressure wave time-of-flight indicated detonation velocities of 2.4 km/sec and 2.2 km/sec in the initiator and primary tubes, respectively. These values implied a fuel-lean mixture corresponding to an H2 volume fraction near 0.5. The axial distribution for the detonation velocity was found to be essentially constant along the primary tube. Time-resolved thrust profiles were also acquired for both underfilled and overfilled tube conditions. These profiles are consistent with previous time-resolved measurements on single-cycle tubes where the thrust is found to peak as the detonation wave exits the tube, and decay as the tube blows down.

Contoured-gap coaxial guns for imploding plasma liner experiments

NASA Astrophysics Data System (ADS)

Witherspoon, F. D.; Case, A.; Brockington, S.; Cassibry, J. T.; Hsu, S. C.

2014-10-01

Arrays of supersonic, high momentum flux plasma jets can be used as standoff compression drivers for generating spherically imploding plasma liners for driving magneto-inertial fusion, hence the name plasma-jet-driven MIF (PJMIF). HyperV developed linear plasma jets for the Plasma Liner Experiment (PLX) at LANL where two guns were successfully tested. Further development at HyperV resulted in achieving the PLX goal of 8000 μg at 50 km/s. Prior work on contoured-gap coaxial guns demonstrated an approach to control the blowby instability and achieved substantial performance improvements. For future plasma liner experiments we propose to use contoured-gap coaxial guns with small Minirailgun injectors. We will describe such a gun for a 60-gun plasma liner experiment. Discussion topics will include impurity control, plasma jet symmetry and topology (esp. related to uniformity and compactness), velocity capability, and techniques planned for achieving gun efficiency of >50% using tailored impedance matched pulse forming networks. Mach2 and UAH SPH code simulations will be included. Work supported by US DOE DE-FG02-05ER54810.

Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device.

PubMed

Matsumoto, T; Sekiguchi, J; Asai, T; Gota, H; Garate, E; Allfrey, I; Valentine, T; Morehouse, M; Roche, T; Kinley, J; Aefsky, S; Cordero, M; Waggoner, W; Binderbauer, M; Tajima, T

2016-05-01

A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode. A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10(21) m(-3), ∼40 eV, and 0.5-1.0 × 10(19), respectively.

Scaling study of the combustion performance of gas—gas rocket injectors

NASA Astrophysics Data System (ADS)

Wang, Xiao-Wei; Cai, Guo-Biao; Jin, Ping

2011-10-01

To obtain the key subelements that may influence the scaling of gas—gas injector combustor performance, the combustion performance subelements in a liquid propellant rocket engine combustor are initially analysed based on the results of a previous study on the scaling of a gas—gas combustion flowfield. Analysis indicates that inner wall friction loss and heat-flux loss are two key issues in gaining the scaling criterion of the combustion performance. The similarity conditions of the inner wall friction loss and heat-flux loss in a gas—gas combustion chamber are obtained by theoretical analyses. Then the theoretical scaling criterion was obtained for the combustion performance, but it proved to be impractical. The criterion conditions, the wall friction and the heat flux are further analysed in detail to obtain the specific engineering scaling criterion of the combustion performance. The results indicate that when the inner flowfields in the combustors are similar, the combustor wall shear stress will have similar distributions qualitatively and will be directly proportional to pc0.8dt-0.2 quantitatively. In addition, the combustion peformance will remain unchanged. Furthermore, multi-element injector chambers with different geometric sizes and at different pressures are numerically simulated and the wall shear stress and combustion efficiencies are solved and compared with each other. A multielement injector chamber is designed and hot-fire tested at several chamber pressures and the combustion performances are measured in a total of nine hot-fire tests. The numerical and experimental results verified the similarities among combustor wall shear stress and combustion performances at different chamber pressures and geometries, with the criterion applied.

CFD Simulation of Liquid Rocket Engine Injectors

NASA Technical Reports Server (NTRS)

Farmer, Richard; Cheng, Gary; Chen, Yen-Sen; Garcia, Roberto (Technical Monitor)

2001-01-01

Detailed design issues associated with liquid rocket engine injectors and combustion chamber operation require CFD methodology which simulates highly three-dimensional, turbulent, vaporizing, and combusting flows. The primary utility of such simulations involves predicting multi-dimensional effects caused by specific injector configurations. SECA, Inc. and Engineering Sciences, Inc. have been developing appropriate computational methodology for NASA/MSFC for the past decade. CFD tools and computers have improved dramatically during this time period; however, the physical submodels used in these analyses must still remain relatively simple in order to produce useful results. Simulations of clustered coaxial and impinger injector elements for hydrogen and hydrocarbon fuels, which account for real fluid properties, is the immediate goal of this research. The spray combustion codes are based on the FDNS CFD code' and are structured to represent homogeneous and heterogeneous spray combustion. The homogeneous spray model treats the flow as a continuum of multi-phase, multicomponent fluids which move without thermal or velocity lags between the phases. Two heterogeneous models were developed: (1) a volume-of-fluid (VOF) model which represents the liquid core of coaxial or impinger jets and their atomization and vaporization, and (2) a Blob model which represents the injected streams as a cloud of droplets the size of the injector orifice which subsequently exhibit particle interaction, vaporization, and combustion. All of these spray models are computationally intensive, but this is unavoidable to accurately account for the complex physics and combustion which is to be predicted, Work is currently in progress to parallelize these codes to improve their computational efficiency. These spray combustion codes were used to simulate the three test cases which are the subject of the 2nd International Workshop on-Rocket Combustion Modeling. Such test cases are considered by these investigators to be very valuable for code validation because combustion kinetics, turbulence models and atomization models based on low pressure experiments of hydrogen air combustion do not adequately verify analytical or CFD submodels which are necessary to simulate rocket engine combustion. We wish to emphasize that the simulations which we prepared for this meeting are meant to test the accuracy of the approximations used in our general purpose spray combustion models, rather than represent a definitive analysis of each of the experiments which were conducted. Our goal is to accurately predict local temperatures and mixture ratios in rocket engines; hence predicting individual experiments is used only for code validation. To replace the conventional JANNAF standard axisymmetric finite-rate (TDK) computer code 2 for performance prediction with CFD cases, such codes must posses two features. Firstly, they must be as easy to use and of comparable run times for conventional performance predictions. Secondly, they must provide more detailed predictions of the flowfields near the injector face. Specifically, they must accurately predict the convective mixing of injected liquid propellants in terms of the injector element configurations.

Hydroxyl radical-PLIF measurements and accuracy investigation in high pressure gaseous hydrogen/gaseous oxygen combustion

NASA Astrophysics Data System (ADS)

Vaidyanathan, Aravind

In-flow species concentration measurements in reacting flows at high pressures are needed both to improve the current understanding of the physical processes taking place and to validate predictive tools that are under development, for application to the design and optimization of a range of power plants from diesel to rocket engines. To date, non intrusive measurements have been based on calibrations determined from assumptions that were not sufficiently quantified to provide a clear understanding of the range of uncertainty associated with these measurements. The purpose of this work is to quantify the uncertainties associated with OH measurement in a oxygen-hydrogen system produced by a shear, coaxial injector typical of those used in rocket engines. Planar OH distributions are obtained providing instantaneous and averaged distribution that are required for both LES and RANS codes currently under development. This study has evaluated the uncertainties associated with OH measurement at 10, 27, 37 and 53 bar respectively. The total rms error for OH-PLIF measurements from eighteen different parameters was quantified and found as 21.9, 22.8, 22.5, and 22.9% at 10, 27, 37 and 53 bar respectively. These results are used by collaborators at Georgia Institute of Technology (LES), Pennsylvania State University (LES), University of Michigan (RANS) and NASA Marshall (RANS).

Numerical modeling of spray combustion with an advanced VOF method

NASA Technical Reports Server (NTRS)

Chen, Yen-Sen; Shang, Huan-Min; Shih, Ming-Hsin; Liaw, Paul

1995-01-01

This paper summarizes the technical development and validation of a multiphase computational fluid dynamics (CFD) numerical method using the volume-of-fluid (VOF) model and a Lagrangian tracking model which can be employed to analyze general multiphase flow problems with free surface mechanism. The gas-liquid interface mass, momentum and energy conservation relationships are modeled by continuum surface mechanisms. A new solution method is developed such that the present VOF model can be applied for all-speed flow regimes. The objectives of the present study are to develop and verify the fractional volume-of-fluid cell partitioning approach into a predictor-corrector algorithm and to demonstrate the effectiveness of the present approach by simulating benchmark problems including laminar impinging jets, shear coaxial jet atomization and shear coaxial spray combustion flows.

Noise from Supersonic Coaxial Jets. Part 1; Mean Flow Predictions

NASA Technical Reports Server (NTRS)

Dahl, Milo D.; Morris, Philip J.

1997-01-01

Recent theories for supersonic jet noise have used an instability wave noise generation model to predict radiated noise. This model requires a known mean flow that has typically been described by simple analytic functions for single jet mean flows. The mean flow of supersonic coaxial jets is not described easily in terms of analytic functions. To provide these profiles at all axial locations, a numerical scheme is developed to calculate the mean flow properties of a coaxial jet. The Reynolds-averaged, compressible, parabolic boundary layer equations are solved using a mixing length turbulence model. Empirical correlations are developed to account for the effects of velocity and temperature ratios and Mach number on the shear layer spreading. Both normal velocity profile and inverted velocity profile coaxial jets are considered. The mixing length model is modified in each case to obtain reasonable results when the two stream jet merges into a single fully developed jet. The mean flow calculations show both good qualitative and quantitative agreement with measurements in single and coaxial jet flows.

Performance improvement of magnetized coaxial plasma gun by magnetic circuit on a bias coil

NASA Astrophysics Data System (ADS)

Edo, Takahiro; Matsumoto, Tadafumi; Asai, Tomohiko; Kamino, Yasuhiro; Inomoto, Michiaki; Gota, Hiroshi

2016-10-01

A magnetized coaxial plasmoid accelerator has been utilized for compact torus (CT) injection to refuel into fusion reactor core plasma. Recently, CT injection experiments have been conducted on the C-2/C-2U facility at Tri Alpha Energy. In the series of experiments successful refueling, i.e. increased particle inventory of field-reversed configuration (FRC) plasma, has been observed. In order to improve the performance of CT injector and to refuel in the upgraded FRC device, called C-2W, with higher confinement magnetic field, magnetic circuit consisting of magnetic material onto a bias magnetic coil is currently being tested at Nihon University. Numerical work suggests that the optimized bias magnetic field distribution realizes the increased injection velocity because of higher conversion efficiency of Lorenz self force to kinetic energy. Details of the magnetic circuit design as well as results of the test experiment and field calculations will be presented and discussed.

Coaxial Helicity Injection experiments in NSTX*

NASA Astrophysics Data System (ADS)

Raman, R.; Jarboe, T. R.; Gates, D.; Mueller, D.; Schaffer, M. J.; Maqueda, R.; Nelson, B. A.; Menard, J.; Soukhanovskii, V.; Paul, S.; Jardin, S.; Skinner, C. H.; Sabbagh, S.; Paoletti, F.; Stutman, D.; Lao, L.; Nagata, M.

2001-10-01

Coaxial helicity injection (CHI) can potentially eliminate inductive startup and thus the induction solenoid in spherical tori (ST), thereby greatly improving the ST fusion concept. CHI experiments on NSTX have produced 360 kA of toroidal current using about 25 kA of injector current. These have been produced in the preferred 'narrow flux foot print' condition in pulses that were sustained for 300 ms. A rotating n=1 mode, previously observed in optimized discharges on smaller STs driven by CHI and deemed necessary for transporting edge driven current to the interior of the discharge, has been observed for the first time in NSTX CHI discharges. The flux utilization efficiency continues to be high, approaching 100%. EFIT and TSC codes are being used to assess flux closure. This work is supported by the US DOE contract numbers: DE-AC02-76CH03073 and DE-AC05-00R22725.

Large Eddy Simulation of Cryogenic Injection Processes at Supercritical Pressure

NASA Technical Reports Server (NTRS)

Oefelein, Joseph C.; Garcia, Roberto (Technical Monitor)

2002-01-01

This paper highlights results from the first of a series of hierarchical simulations aimed at assessing the modeling requirements for application of the large eddy simulation technique to cryogenic injection and combustion processes in liquid rocket engines. The focus is on liquid-oxygen-hydrogen coaxial injectors at a condition where the liquid-oxygen is injected at a subcritical temperature into a supercritical environment. For this situation a diffusion dominated mode of combustion occurs in the presence of exceedingly large thermophysical property gradients. Though continuous, these gradients approach the behavior of a contact discontinuity. Significant real gas effects and transport anomalies coexist locally in colder regions of the flow, with ideal gas and transport characteristics occurring within the flame zone. The current focal point is on the interfacial region between the liquid-oxygen core and the coaxial hydrogen jet where the flame anchors itself.

Development of a magnetized coaxial plasma gun for compact toroid injection into the C-2 field-reversed configuration device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumoto, T., E-mail: cstd14003@g.nihon-u.ac.jp; Sekiguchi, J.; Asai, T.

A compact toroid (CT) injector was developed for the C-2 device, primarily for refueling of field-reversed configurations. The CTs are formed by a magnetized coaxial plasma gun (MCPG), which consists of coaxial cylindrical electrodes and a bias coil for creating a magnetic field. First, a plasma ring is generated by a discharge between the electrodes and is accelerated by Lorenz self-force. Then, the plasma ring is captured by an interlinkage flux (poloidal flux). Finally, the fully formed CT is ejected from the MCPG. The MCPG described herein has two gas injection ports that are arranged tangentially on the outer electrode.more » A tungsten-coated inner electrode has a head which can be replaced with a longer one to extend the length of the acceleration region for the CT. The developed MCPG has achieved supersonic CT velocities of ∼100 km/s. Plasma parameters for electron density, electron temperature, and the number of particles are ∼5 × 10{sup 21} m{sup −3}, ∼40 eV, and 0.5–1.0 × 10{sup 19}, respectively.« less

Coupling modes between liquid/gas coaxial jets and transverse acoustic waves

NASA Astrophysics Data System (ADS)

Helland, Chad; Hilliker, Cullen; Forliti, David; University of St. Thomas Team

2017-11-01

The interactions between shear flows and acoustic disturbances plays a very important role in many propulsion and energy applications. Liquid jets, either independent or air assisted, respond to acoustic disturbances in a manner that alters the primary and secondary atomization processes. The current study focused on the response of an air-assisted liquid jet to disturbances associated with a transverse acoustic wave. The jet is placed in the pressure node (velocity antinode) region of the resonant mode shape. It has been shown in previous studies, under certain conditions, that the acoustic forces can cause the jet flow to distort and atomize. Both liquid and coaxial gas/ liquid jet flows have been shown to distort via acoustic forces. The purpose of the current study is to understand the predictive characteristics that cause the distortion behaviors of a liquid and coaxial jet flow, and how a how a coaxial flow affects the behavior.

Compact toroid injection fueling in a large field-reversed configuration

NASA Astrophysics Data System (ADS)

Asai, T.; Matsumoto, T.; Roche, T.; Allfrey, I.; Gota, H.; Sekiguchi, J.; Edo, T.; Garate, E.; Takahashi, Ts.; Binderbauer, M.; Tajima, T.

2017-07-01

A repetitively driven compact toroid (CT) injector has been developed for the large field-reversed configuration (FRC) facility of the C-2/C-2U, primarily for particle refueling. A CT is formed and injected by a magnetized coaxial plasma gun (MCPG) exclusively developed for the C-2/C-2U FRC. To refuel the particles of long-lived FRCs, multiple CT injections are required. Thus, a multi-stage discharge circuit was developed for a multi-pulsed CT injection. The drive frequency of this system can be adjusted up to 1 kHz and the number of CT shots per injector is two; the system can be further upgraded for a larger number of injection pulses. The developed MCPG can achieve a supersonic ejection velocity in the range of ~100 km s-1. The key plasma parameters of electron density, electron temperature and the number of particles are ~5  ×  1021 m-3, ~30 eV and 0.5-1.0  ×  1019, respectively. In this project, single- and double-pulsed counter CT injection fueling were conducted on the C-2/C-2U facility by two CT injectors. The CT injectors were mounted 1 m apart in the vicinity of the mid-plane. To avoid disruptive perturbation on the FRC, the CT injectors were operated at the lower limit of the particle inventory. The experiments demonstrated successful refueling with a significant density build-up of 20-30% of the FRC particle inventory per single CT injection without any deleterious effects on the C-2/C-2U FRC.

Absorber arc mitigation during CHI on NSTX

NASA Astrophysics Data System (ADS)

Mueller, D.; Bell, M. G.; Roquemore, A. L.; Raman, R.; Nelson, B. A.; Jarboe, T. R.

2009-11-01

A method of non-inductive startup, referred to as transient coaxial helicity injection (CHI), was successfully developed on the Helicity Injected Torus (HIT-II) experiment and employed on the National Spherical Torus Experiment (NSTX). This technique has produced 160 kA of plasma current on closed flux surfaces. Over 100 kA of the CHI current has been coupled to inductively driven current ramp-up. In transient CHI, a voltage is applied across the insulating gap separating the inner and outer vacuum vessel and gas is introduced at the lower gap (the injector). The resulting current in the injector follows the helical magnetic field connecting the electrodes, forms a toroidal current and expands into the vacuum vessel. At higher CHI current, the poloidal field due to the plasma can connect the inner and outer vessels at the insulating gap at the top (called the absorber) of NSTX and lower the impedance there. This results in arcs in the absorber which are a source of impurities and which reduce the desired current in the injector. Two coils installed in the absorber will be used to reduce the magnetic field across the absorber gap and mitigate the absorber arcs.

Dynamics of High Pressure Reacting Shear Flows

DTIC Science & Technology

2015-10-02

liquid rockets, future gas turbines • When the combustion systems are for propulsion, limited tankage dictates that on-board propellants be stored in...system dynamics • Combustion dynamics always includes acoustic waves, which in enclosed systems can sometimes reach detrimental amplitudes – eg...a high pressure, chemically reacting, multiphase, acoustically driven, shear flow in the form of a coaxial jet flame • Explore how the presence of

Time and flow-direction responses of shear-styress-sensitive liquid crystal coatings

NASA Technical Reports Server (NTRS)

Reda, Daniel C.; Muraqtore, J. J.; Heinick, James T.

1994-01-01

Time and flow-direction responses of shear-stress liquid crystal coatings were exploresd experimentally. For the time-response experiments, coatings were exposed to transient, compressible flows created during the startup and off-design operation of an injector-driven supersonic wind tunnel. Flow transients were visualized with a focusing schlieren system and recorded with a 100 frame/s color video camera.

STUDIES ON THE ANOMALOUS VISCOSITY AND FLOW-BIREFRINGENCE OF PROTEIN SOLUTIONS

PubMed Central

Lawrence, A. S. C.; Needham, Joseph; Shen, Shih-Chang

1944-01-01

1. A coaxial viscosimeter which permits the simultaneous determination of relative and anomalous viscosity and of flow-birefringence is described. Flow-anomaly and flow-birefringence are regarded as characteristic of elongated micelles and molecules. 2. Such methods have been applied to dilute solutions of proteins. The conditions under which the coaxial (Couette) viscosimeter measures the viscosity of the bulk phase and the surface film phase respectively have been investigated and are described. 3. The general behaviour of protein solutions subjected to shear is summarised. PMID:19873384

Advancing Non-Solenoidal Startup on the Pegasus ST

NASA Astrophysics Data System (ADS)

Reusch, J. A.; Barr, J. L.; Bodner, G. M.; Bongard, M. W.; Burke, M. G.; Fonck, R. J.; Pachicano, J. L.; Perry, J. M.; Richner, N. J.; Rodriguez Sanchez, C.; Schlossberg, D. J.

2016-10-01

The Pegasus experiment utilizes compact, edge-localized current sources (Ainj 2 - 4 cm2, Iinj 10 kA, Vinj 1 kV) for non-solenoidal local helicity injection (LHI) startup. Recent campaigns are comparing two injector geometries that vary the differing relative contributions of DC helicity input and non-solenoidal inductive voltages. A predictive 0-D model that treats the plasma as a resistive element with time-varying inductance and enforces Ip limits from Taylor relaxation was tested with inward growth of the plasma current channel using injectors on the outboard midplane. Strong inductive drive arises from plasma shape evolution and poloidal field (PF) induction. A major unknown in the model is the resistive dissipation, and hence the electron confinement. Te (R) profile measurements in LHI show centrally-peaked Te > 100 eV while the plasma is coupled to the injectors, suggesting LHI confinement is not strongly stochastic. A second campaign utilizes new injectors in the lower divertor region. This geometry trades subtler relaxation field programming and reduced PF induction for higher HI rates. Present efforts are developing relaxation methods at high BT, with relaxation at BT , inj > 0.15 T achieved to date via higher Iinj and PF manipulation. Conceptual design studies of coaxial helicity injection (CHI) and ECH heating systems for Pegasus have been initiated to explore direct comparison of LHI to CHI with and without ECH assist. Supported by US DOE Grants DE-FG02-96ER54375, DE-SC0006928.

A contoured gap coaxial plasma gun with injected plasma armature.

PubMed

Witherspoon, F Douglas; Case, Andrew; Messer, Sarah J; Bomgardner, Richard; Phillips, Michael W; Brockington, Samuel; Elton, Raymond

2009-08-01

A new coaxial plasma gun is described. The long term objective is to accelerate 100-200 microg of plasma with density above 10(17) cm(-3) to greater than 200 km/s with a Mach number above 10. Such high velocity dense plasma jets have a number of potential fusion applications, including plasma refueling, magnetized target fusion, injection of angular momentum into centrifugally confined mirrors, high energy density plasmas, and others. The approach uses symmetric injection of high density plasma into a coaxial electromagnetic accelerator having an annular gap geometry tailored to prevent formation of the blow-by instability. The injected plasma is generated by numerous (currently 32) radially oriented capillary discharges arranged uniformly around the circumference of the angled annular injection region of the accelerator. Magnetohydrodynamic modeling identified electrode profiles that can achieve the desired plasma jet parameters. The experimental hardware is described along with initial experimental results in which approximately 200 microg has been accelerated to 100 km/s in a half-scale prototype gun. Initial observations of 64 merging injector jets in a planar cylindrical testing array are presented. Density and velocity are presently limited by available peak current and injection sources. Steps to increase both the drive current and the injected plasma mass are described for next generation experiments.

Multiphysics control of a two-fluid coaxial atomizer supported by electric-charge on the liquid jet

NASA Astrophysics Data System (ADS)

Machicoane, Nathanael; Osuna, Rodrigo; Aliseda, Alberto

2017-11-01

We present an experimental setup to investigate multiphysics control strategies on atomization of a laminar fluid stream by a coaxial turbulent jet. Spray control (i.e. driving the droplet size distribution and the spatio-temporal location of the droplets towards a desired objective) has many potential engineering applications, but requires a mechanistic understanding of the processes that control droplet formation and transport (primary and secondary instabilities, turbulent transport, hydrodynamic and electric forces on the droplets, ...). We characterize experimentally the break-up dynamics in a canonical coaxial atomizer, and the spray structure (droplet size, location, and velocity as a function of time) in a series of open loop conditions with harmonic forcing of the gas swirl ratio, liquid injection rate, the electric field strength at the nozzle and along the spray development region. The effect of these actuators are characterized for different gas Reynolds numbers ranging from 104-106. This open-loop characterization of the injector will be used to develop reduced order models for feedback control, as well as to validate assumptions underlying an adjoint-based computational control strategy. This work is part of a large-scale project funded by an ONR MURI to provide fundamental understanding of the mechanisms for feedback control of sprays.

Control of Compact-Toroid Characteristics by External Copper Shell

NASA Astrophysics Data System (ADS)

Matsumoto, T.; Sekiguchi, J.; Asai, T.; Gota, H.; Roche, T.; Allfrey, I.; Cordero, M.; Garate, E.; Kinley, J.; Valentine, T.; Waggoner, W.; the TAE Team

2015-11-01

A collaborative research project by Tri Alpha Energy and Nihon University has been conducted for several years, which led to the development of a new compact toroid (CT) injector for efficient FRC particle refueling in the C-2U experiment. The CT is formed by a magnetized coaxial plasma gun (MCPG), consisting of coaxial cylindrical electrodes. In CT formation via MCPG, the magnetic helicity content of the generated CT is one of the critical parameters. A bias coil is inserted into the inner electrode to generate a poloidal flux. The resultant bias magnetic field is spread out of MCPG with time due to its low-frequency bias current. To obtain a more effectively distributed bias magnetic field as well as to improve the voltage breakdown between electrodes, the MCPG incorporates a novel ~ 1 mm thick copper shell mounted outside of the outer electrode. This allows for reliable and controlled operation and more robust CT generation. A detailed discussion of the copper shell and experimental test results will be presented.

Application of Townsend avalanche theory to tokamak startup by coaxial helicity injection

NASA Astrophysics Data System (ADS)

Hammond, K. C.; Raman, R.; Volpe, F. A.

2018-01-01

The Townsend avalanche theory is employed to model and interpret plasma initiation in NSTX by Ohmic heating and coaxial helicity injection (CHI). The model is informed by spatially resolved vacuum calculations of electric field and magnetic field line connection length in the poloidal cross-section. The model is shown to explain observations of Ohmic startup including the duration and location of breakdown. Adapting the model to discharges initiated by CHI offers insight into the causes of upper divertor (absorber) arcs in cases where the discharge fails to start in the lower divertor gap. Finally, upper and lower limits are established for vessel gas fill based on requirements for breakdown and radiation. It is predicted that CHI experiments on NSTX-U should be able to use as much as four times the amount of prefill gas employed in CHI experiments in NSTX. This should provide greater flexibility for plasma start-up, as the injector flux is projected to be increased in NSTX-U.

Investigation of transient ignition process in a cavity based scramjet combustor using combined ethylene injectors

NASA Astrophysics Data System (ADS)

Liu, Xiao; Cai, Zun; Tong, Yiheng; Zheng, Hongtao

2017-08-01

Large Eddy Simulation (LES) and experiment were employed to investigate the transient ignition and flame propagation process in a rearwall-expansion cavity scramjet combustor using combined fuel injection schemes. The compressible supersonic solver and three ethylene combustion mechanisms were first validated against experimental data and results show in reasonably good agreement. Fuel injection scheme combining transverse and direct injectors in the cavity provides a benefit mixture distribution and could achieve a successful ignition. Four stages are illustrated in detail from both experiment and LES. After forced ignition in the cavity, initial flame kernel propagates upstream towards the cavity front edge and ignites the mixture, which acts as a continuous pilot flame, and then propagates downstream along the cavity shear layer rapidly to the combustor exit. Cavity shear layer flame stabilization mode can be concluded from the heat release rate and local high temperature distribution during the combustion process.

Studies on Plasmoid Merging using Compact Toroid Injectors

NASA Astrophysics Data System (ADS)

Allfrey, Ian; Matsumoto, Tadafumi; Roche, Thomas; Gota, Hiroshi; Edo, Takahiro; Asai, Tomohiko; Sheftman, Daniel; Osin Team; Dima Team

2017-10-01

C-2 and C-2U experiments have used magnetized coaxial plasma guns (MCPG) to inject compact toroids (CTs) for refueling the long-lived advanced beam-driven field-reversed configuration (FRC) plasma. This refueling method will also be used for the C-2W experiment. To minimize momentum transfer from the CT to the FRC two CTs are injected radially, diametrically opposed and coincident in time. To improve understanding of the CT characteristics TAE has a dedicated test bed for the development of CT injectors (CTI), where plasmoid merging experiments are performed. The test bed has two CTIs on axis with both axial and transverse magnetic fields. The 1 kG magnetic fields, intended to approximate the magnetic field strength and injection angle on C-2W, allow studies of cross-field transport and merging. Both CTIs are capable of injecting multiple CTs at up to 1 kHz. The resulting merged CT lives >100 μs with a radius of 25 cm. More detailed results of CT parameters will be presented.

A Rocket Engine Design Expert System

NASA Technical Reports Server (NTRS)

Davidian, Kenneth J.

1989-01-01

The overall structure and capabilities of an expert system designed to evaluate rocket engine performance are described. The expert system incorporates a JANNAF standard reference computer code to determine rocket engine performance and a state of the art finite element computer code to calculate the interactions between propellant injection, energy release in the combustion chamber, and regenerative cooling heat transfer. Rule-of-thumb heuristics were incorporated for the H2-O2 coaxial injector design, including a minimum gap size constraint on the total number of injector elements. One dimensional equilibrium chemistry was used in the energy release analysis of the combustion chamber. A 3-D conduction and/or 1-D advection analysis is used to predict heat transfer and coolant channel wall temperature distributions, in addition to coolant temperature and pressure drop. Inputting values to describe the geometry and state properties of the entire system is done directly from the computer keyboard. Graphical display of all output results from the computer code analyses is facilitated by menu selection of up to five dependent variables per plot.

A rocket engine design expert system

NASA Technical Reports Server (NTRS)

Davidian, Kenneth J.

1989-01-01

The overall structure and capabilities of an expert system designed to evaluate rocket engine performance are described. The expert system incorporates a JANNAF standard reference computer code to determine rocket engine performance and a state-of-the-art finite element computer code to calculate the interactions between propellant injection, energy release in the combustion chamber, and regenerative cooling heat transfer. Rule-of-thumb heuristics were incorporated for the hydrogen-oxygen coaxial injector design, including a minimum gap size constraint on the total number of injector elements. One-dimensional equilibrium chemistry was employed in the energy release analysis of the combustion chamber and three-dimensional finite-difference analysis of the regenerative cooling channels was used to calculate the pressure drop along the channels and the coolant temperature as it exits the coolant circuit. Inputting values to describe the geometry and state properties of the entire system is done directly from the computer keyboard. Graphical display of all output results from the computer code analyses is facilitated by menu selection of up to five dependent variables per plot.

VPS Process for Copper Components in Thrust Chamber Assemblies

NASA Technical Reports Server (NTRS)

Elam, Sandra; Holmes, Richard; Hickman, Robert; McKechnie, Tim; Thom, George

2005-01-01

For several years, NASA's Marshall Space Flight Center (MSFC) has been working with Plasma Processes, Inc., (PPI) to fabricate thrust chamber liners with GRCop-84. Using the vacuum plasma spray (VPS) process, chamber liners of a variety of shapes and sizes have been created. Each has been formed as a functional gradient material (FGM) that creates a unique protective layer of NiCrAlY on the GRCop-84 liner s hot wall surface. Hot-fire testing was successfully conducted on a subscale unit to demonstrate the liner's durability and performance. Similar VPS technology has also been applied to create functional gradient coatings (FGC) on copper injector faceplates. Protective layers of NiCrAlY and zirconia were applied to both coaxial and impinging faceplate designs. Hot-fire testing is planned for these coated injectors in April 2005. The resulting material systems for both copper alloy components allows them to operate at higher temperatures with improved durability and operating margins.

Picosecond imaging of sprays

NASA Technical Reports Server (NTRS)

Breisacher, Kevin; Liou, Larry; Wang, L.; Liang, X.; Galland, P.; Ho, P. P.; Alfano, R. R.

1994-01-01

Preliminary results from applying a Kerr-Fourier imaging system to a water/air spray produced by a shear coaxial element are presented. The physics behind ultrafast time-gated optical techniques is discussed briefly. A typical setup of a Kerr-Fourier time gating system is presented.

Liquid-hydrogen rocket engine development at Aerojet, 1944 - 1950

NASA Technical Reports Server (NTRS)

Osborn, G. H.; Gordon, R.; Coplen, H. L.; James, G. S.

1977-01-01

This program demonstrated the feasibility of virtually all the components in present-day, high-energy, liquid-rocket engines. Transpiration and film-cooled thrust chambers were successfully operated. The first liquid-hydrogen tests of the coaxial injector was conducted and the first pump to successfully produce high pressures in pumping liquid hydrogen was tested. A 1,000-lb-thrust gaseous propellant and a 3,000-lb-thrust liquid-propellant thrust chamber were operated satisfactorily. Also, the first tests were conducted to evaluate the effects of jet overexpansion and separation on performance of rocket thrust chambers with hydrogen-oxygen propellants.

Feasibility Study of a Pressure-fed Engine for a Water Recoverable Space Shuttle Booster

NASA Technical Reports Server (NTRS)

Gerstl, E.

1972-01-01

Detailed mass properties are presented for a gimbaled, fixed thrust, regeneratively cooled engine having a coaxial pintle injector. The baseline design parameters for this engine are tabulated. Mass properties are also summarized for several other engine configurations i.e., a hinge nozzle using a Techroll seal, a gimbaled duct cooled engine and a regeneratively cooled engine using liquid injection thrust vector control (LITVC). Detailed engine analysis and design trade studies leading to the selection of a regeneratively cooled gimbaled engine and pertaining to the selection of the baseline design configuration are also given.

Injection dynamics of gelled propellants

NASA Astrophysics Data System (ADS)

Yoon, Changjin

Gel propellants have been recognized as attractive candidates for future propulsion systems due to the reduced tendency to spill and the energy advantages over solid propellants. One of strong benefits emphasized in gel propellant applications is a throttling capability, but the accurate flow control is more complicated and difficult than with conventional Newtonian propellants because of the unique rheological behaviors of gels. This study is a computational effort directed to enhance understanding of the injector internal flow characteristics for gel propellants under rocket injection conditions. In simulations, the emphasized rheology is a shear-thinning which represents a viscosity decrease with increasing a shear rate. It is described by a generalized Newtonian fluid constitutive equation and Carreau-Yasuda model. Using this rheological model, two injection schemes are considered in the present study: axially-fed and cross-fed injection for single-element and multi-element impinging injectors, respectively. An axisymmetric model is developed to describe the axially-fed injector flows and fully three-dimensional model is utilized to simulate cross-fed injector flows. Under axially-fed injection conditions investigated, three distinct modes, an unsteady, steady, and hydraulic flip mode, are observed and mapped in terms of Reynolds number and orifice design. In an unsteady mode, quasi-periodic oscillations occur near the inlet lip leading mass pulsations and viscosity fluctuations at the orifice exit. This dynamic behavior is characterized using a time-averaged discharge coefficient, oscillation magnitude and frequency by a parametric study with respect to an orifice design, Reynolds number and rheology. As a result, orifice exit flows for gel propellants appear to be significantly influenced by a viscous damping and flow resistance due to a shear thinning behavior and these are observed in each factors considered. Under conditions driven by a manifold crossflow, unsteady and asymmetric flow structures are revealed as a series of vortices generated from the unstable vena contracta. Here, flows are characterized by an orifice design, manifold/core injection velocity ratio, Reynolds number and rheology. A significant decrease of discharge coefficients is noted with increasing the manifold flow. As the manifold crossflow increases, stronger friction losses are exerted on the leeward, and lead to larger hydraulic losses across the injector. In addition, calculations show that discharge coefficients decrease and the unsteadiness is mitigated as the viscosity increases by fluid rheology variations. A larger and more distinct horseshoe vortex is observed, and pulsation magnitude and viscosity fluctuations are mitigated with increasing viscosity. The oscillation frequency, however, remains unchanged even though the viscosity curves at the high shear rate are modified. All these observations confirm the conclusion that the role of viscous damping and flow resistance is more critical in cross-fed injection conditions than in axially-fed one.

Laser ignition of an experimental combustion chamber with a multi-injector configuration at low pressure conditions

NASA Astrophysics Data System (ADS)

Börner, Michael; Manfletti, Chiara; Kroupa, Gerhard; Oschwald, Michael

2017-09-01

In search of reliable and light-weight ignition systems for re-ignitable upper stage engines, a laser ignition system was adapted and tested on an experimental combustion chamber for propellant injection into low combustion chamber pressures at 50-80 mbar. The injector head pattern consisted of five coaxial injector elements. Both, laser-ablation-driven ignition and laser-plasma-driven ignition were tested for the propellant combination liquid oxygen and gaseous hydrogen. The 122 test runs demonstrated the reliability of the ignition system for different ignition configurations and negligible degradation due to testing. For the laser-plasma-driven scheme, minimum laser pulse energies needed for 100% ignition probability were found to decrease when increasing the distance of the ignition location from the injector faceplate with a minimum of 2.6 mJ. For laser-ablation-driven ignition, the minimum pulse energy was found to be independent of the ablation material tested and was about 1.7 mJ. The ignition process was characterized using both high-speed Schlieren and OH* emission diagnostics. Based on these findings and on the increased fiber-based pulse transport capabilities recently published, new ignition system configurations for space propulsion systems relying on fiber-based pulse delivery are formulated. If the laser ignition system delivers enough pulse energy, the laser-plasma-driven configuration represents the more versatile configuration. If the laser ignition pulse power is limited, the application of laser-ablation-driven ignition is an option to realize ignition, but implies restrictions concerning the location of ignition.

Measurement and analysis of combustion response to transverse combustion instability

NASA Astrophysics Data System (ADS)

Pomeroy, Brian R.

This research aimed to gain a better understanding of the response of a gas-centered swirl coaxial injector to transverse combustion instability. The goals of the research were to develop a combustion chamber that would be able to spontaneously produce transverse combustion instability at elevated pressures and temperatures. Methods were also developed to analyze high-speed video images to understand the response of the injector. A combustion chamber was designed that produced high levels of instabilities. The chamber was capable of pressures as high as 1034 kPa (150 psi) and operated using decomposed 90% hydrogen peroxide and JP-8. The chamber used an array of seven gas-centered swirl coaxial injectors that exhibited linear instability to drive the transverse oscillations. The injector elements would operate in a monopropellant configuration flowing only decomposed hydrogen peroxide or in a bipropellant configuration. The location of the bipropellant injectors could be varied to change the level of the instability in the chamber from 10% of the chamber pressure up to 70% of the chamber pressure. A study element was placed in the center of the chamber where it was observed simultaneously by two high-speed video cameras which recorded a backlit video to show the location of the fuel spray and the location of the emitted CH* chemiluminescence. The videos were synchronized with high frequency pressure measurements to gain a full understanding of the physics in the combustion chamber. Results showed that the study element was coupled with the first mode velocity wave. This was expected due to the first mode velocity anti-node being located in the center of the chamber. The velocity is an absolute maximum twice during each cycle so the coupling with the second mode pressure was also investigated showing a possible coupling with both the velocity and pressure. The results of the first mode velocity showed that, as the velocity wave traveled through the chamber, the fuel spray was first displaced into an oxidizer rich region and secondly followed by a reaction in the direction of travel of the velocity wave as the peak velocity traveled through the region. The deflection into the oxidizer rich region was especially apparent in high-level instabilities. In low-level instabilities, the velocity wave was not strong enough to fully displace the fuel, and instead the oxidizer core was deflected into the fuel annulus causing a reaction in the direction of travel of the velocity wave. Neighboring oxidizer only injectors caused a lower reaction upstream as the neighboring oxidizer was deflected into the fuel annulus. The region of the fluctuating emitted light agreed well in size, shape and location with a correlation between the first mode velocity and combustion leading to the conclusion that the first mode is highly coupled with velocity. The second mode variance did not agree well with either the velocity or pressure correlation leading to a conclusion that it is coupled with both velocity and pressure. When comparing the variance to the pressure or velocity correlation, parts of the variance compared in shape and location to the pressure or velocity correlation, however, this was not true for all regions of response. This leads to a conclusion that both the pressure and velocity can be affecting the second mode. The second mode chemiluminescence emission occurs when the velocity is nearly zero in the chamber leading to the reaction to not be deflected and occurring downstream of the injector. At the same time, the second mode pressure is a minimum so an increase in mass flow could be responsible for the increased reaction. The methods and combustion chamber used to study the response of an injector can be used in the future to study any injector or combination of injectors placed at various locations in the chamber to study pressure or velocity coupling. The chemiluminescence data can be used to develop transfer functions for use in low fidelity computational models and can be used to validate high fidelity CFD.

Measurement of rock mass deformation with grouted coaxial antenna cables

NASA Astrophysics Data System (ADS)

Dowding, C. H.; Su, M. B.; O'Connor, K.

1989-01-01

Techniques presented herein show how reflected voltage pulses from coaxial antenna cable grouted in rock masses can be employed to quantify the type and magnitude of rock mass deformation. This measurement is similar to that obtained from a combined full profile extensometer (to measure local extension) and inclinometer (to measure local shearing). Rock mass movements deform the grouted cable, which locally changes cable capacitance and thereby the reflected wave form of the voltage pulse. Thus, by monitoring changes in these reflection signatures, it is possible to monitor rock mass deformation. This paper presents laboratory measurements necessary to quantitatively interpret the reflected voltage signatures. Cables were sheared and extended to correlate measured cable deformation with reflected voltage signals. Laboratory testing included development of grout mixtures with optimum properties for field installation and performance of a TDR (Time Domain Reflectometry) monitoring system. Finally, the interpretive techniques developed through laboratory measurements were applied to previously collected field data to extract hitherto unrealized information.

Hot-Fire Test Results of an Oxygen/RP-2 Multi-Element Oxidizer-Rich Staged-Combustion Integrated Test Article

NASA Technical Reports Server (NTRS)

Hulka, J. R.; Protz, C. S.; Garcia, C. P.; Casiano, M. J.; Parton, J. A.

2016-01-01

As part of the Combustion Stability Tool Development project funded by the Air Force Space and Missile Systems Center, the NASA Marshall Space Flight Center was contracted to assemble and hot-fire test a multi-element integrated test article demonstrating combustion characteristics of an oxygen/hydrocarbon propellant oxidizer-rich staged-combustion engine thrust chamber. Such a test article simulates flow through the main injectors of oxygen/kerosene oxidizer-rich staged combustion engines such as the Russian RD-180 or NK-33 engines, or future U.S.-built engine systems such as the Aerojet-Rocketdyne AR-1 engine or the Hydrocarbon Boost program demonstration engine. For the thrust chamber assembly of the test article, several configurations of new main injectors, using relatively conventional gas-centered swirl coaxial injector elements, were designed and fabricated. The design and fabrication of these main injectors are described in a companion paper at this JANNAF meeting. New ablative combustion chambers were fabricated based on hardware previously used at NASA for testing at similar size and pressure. An existing oxygen/RP-1 oxidizer-rich subscale preburner injector from a previous NASA-funded program, along with existing and new inter-connecting hot gas duct hardware, were used to supply the oxidizer-rich combustion products to the oxidizer circuit of the main injector of the thrust chamber. Results from independent hot-fire tests of the preburner injector in a combustion chamber with a sonic throat are described in companion papers at this JANNAF conference. The resulting integrated test article - which includes the preburner, inter-connecting hot gas duct, main injector, and ablative combustion chamber - was assembled at Test Stand 116 at the East Test Area of the NASA Marshall Space Flight Center. The test article was well instrumented with static and dynamic pressure, temperature, and acceleration sensors to allow the collected data to be used for combustion analysis model development. Hot-fire testing was conducted with main combustion chamber pressures ranging from 1400 to 2100 psia, and main combustion chamber mixture ratios ranging from 2.4 to 2.9. Different levels of fuel film cooling injected from the injector face were examined ranging from none to about 12% of the total fuel flow. This paper presents the hot-fire test results of the integrated test article. Combustion performance, stability, thermal, and compatibility characteristics of both the preburner and the thrust chamber are described. Another companion paper at this JANNAF meeting includes additional and more detailed test data regarding the combustion dynamics and stability characteristics.

Design and Fabrication of Oxygen/RP-2 Multi-Element Oxidizer-Rich Staged Combustion Thrust Chamber Injectors

NASA Technical Reports Server (NTRS)

Garcia, C. P.; Medina, C. R.; Protz, C. S.; Kenny, R. J.; Kelly, G. W.; Casiano, M. J.; Hulka, J. R.; Richardson, B. R.

2016-01-01

As part of the Combustion Stability Tool Development project funded by the Air Force Space and Missile Systems Center, the NASA Marshall Space Flight Center was contracted to assemble and hot-fire test a multi-element integrated test article demonstrating combustion characteristics of an oxygen/hydrocarbon propellant oxidizer-rich staged-combustion engine thrust chamber. Such a test article simulates flow through the main injectors of oxygen/kerosene oxidizer-rich staged combustion engines such as the Russian RD-180 or NK-33 engines, or future U.S.-built engine systems such as the Aerojet-Rocketdyne AR-1 engine or the Hydrocarbon Boost program demonstration engine. On the current project, several configurations of new main injectors were considered for the thrust chamber assembly of the integrated test article. All the injector elements were of the gas-centered swirl coaxial type, similar to those used on the Russian oxidizer-rich staged-combustion rocket engines. In such elements, oxidizer-rich combustion products from the preburner/turbine exhaust flow through a straight tube, and fuel exiting from the combustion chamber and nozzle regenerative cooling circuits is injected near the exit of the oxidizer tube through tangentially oriented orifices that impart a swirl motion such that the fuel flows along the wall of the oxidizer tube in a thin film. In some elements there is an orifice at the inlet to the oxidizer tube, and in some elements there is a sleeve or "shield" inside the oxidizer tube where the fuel enters. In the current project, several variations of element geometries were created, including element size (i.e., number of elements or pattern density), the distance from the exit of the sleeve to the injector face, the width of the gap between the oxidizer tube inner wall and the outer wall of the sleeve, and excluding the sleeve entirely. This paper discusses the design rationale for each of these element variations, including hydraulic, structural, thermal, combustion performance, and combustion stability considerations. This paper also discusses the fabrication and assembly of the injector components, including the injector body/interpropellant plate, the additive manufactured GRCop-84 faceplate, and the pieces that make up the injector elements including the oxidizer tube, an inlet to the oxidizer tube, and a facenut that includes the fuel tangential inlets and forms the initial recessed volume where oxidizer and fuel first interact. Hot-fire test results of these main injector designs in an integrated test article that includes an oxidizer-rich preburner are described in companion papers at this JANNAF meeting.

Mixing properties of coaxial jets with large velocity ratios and large inverse density ratios

NASA Astrophysics Data System (ADS)

Alexander Schumaker, S.; Driscoll, James F.

2012-05-01

An experimental study was conducted to better understand the mixing properties of coaxial jets as several parameters were systematically varied, including the velocity ratio, density ratio, and the Reynolds number. Diameters of the inner and outer jet were also varied. Coaxial jets are commonly used to mix fluids due to the simplicity of their geometry and the rapid mixing that they provide. A measure of the overall mixing efficiency is the stoichiometric mixing length (Ls), which is the distance along the jet centerline where the two fluids have mixed to some desired concentration, which was selected to be the stoichiometric concentration for H2/O2 and CH4/O2 in this case. For 56 cases, the profiles of mean mixture fraction, rms mixture fraction fluctuations (unmixedness), and Ls were measured using acetone planar laser induced fluorescence diagnostics. Results were compared to three mixing models. The entrainment model of Villermaux and Rehab showed good agreement with the data, indicating that the proper non-dimensional scaling parameter is the momentum flux ratio M. The work extends the existing database of coaxial jet scalar mixing properties because it considers the specific regime of large values of both the velocity ratio and the inverse density ratio, which is the regime in which rocket injectors operate. Also the work focuses on the mixing up to Ls where previous work focused on the mixing up to the end of the inner core. The Reynolds numbers achieved for a number of cases were considerably larger than previous gas mixing studies, which insures that the jet exit boundary conditions are fully turbulent.

Flame stabilization and mixing characteristics in a Stagnation Point Reverse Flow combustor

NASA Astrophysics Data System (ADS)

Bobba, Mohan K.

A novel combustor design, referred to as the Stagnation Point Reverse-Flow (SPRF) combustor, was recently developed that is able to operate stably at very lean fuel-air mixtures and with low NOx emissions even when the fuel and air are not premixed before entering the combustor. The primary objective of this work is to elucidate the underlying physics behind the excellent stability and emissions performance of the SPRF combustor. The approach is to experimentally characterize velocities, species mixing, heat release and flame structure in an atmospheric pressure SPRF combustor with the help of various optical diagnostic techniques: OH PLIF, chemiluminescence imaging, PIV and Spontaneous Raman Scattering. Results indicate that the combustor is primarily stabilized in a region downstream of the injector that is characterized by low average velocities and high turbulence levels; this is also the region where most of the heat release occurs. High turbulence levels in the shear layer lead to increased product entrainment levels, elevating the reaction rates and thereby enhancing the combustor stability. The effect of product entrainment on chemical timescales and the flame structure is illustrated with simple reactor models. Although reactants are found to burn in a highly preheated (1300 K) and turbulent environment due to mixing with hot product gases, the residence times are sufficiently long compared to the ignition timescales such that the reactants do not autoignite. Turbulent flame structure analysis indicates that the flame is primarily in the thin reaction zones regime throughout the combustor, and it tends to become more flamelet like with increasing distance from the injector. Fuel-air mixing measurements in case of non-premixed operation indicate that the fuel is shielded from hot products until it is fully mixed with air, providing nearly premixed performance without the safety issues associated with premixing. The reduction in NOx emissions in the SPRF combustor are primarily due to its ability to stably operate under ultra lean (and nearly premixed) condition within the combustor. Further, to extend the usefulness of this combustor configuration to various applications, combustor geometry scaling rules were developed with the help of simplified coaxial and opposed jet models.

A Pre-ionization System to Limit Neutral Gas in a Compact Toroid Injector

NASA Astrophysics Data System (ADS)

Allfrey, Ian; Roche, Thomas; Matsumoto, Tadafumi; Garate, Eusebio; Gota, Hiroshi; Asai, Tomohiko; the TAE Team

2016-10-01

Fusion plasmas require long lifetimes and high temperatures, both of which are limited by particle loss, among other factors. Therefore, refueling a long-lived advanced beam-driven field-reversed configuration (FRC) plasma in C-2U is necessary, and injecting a supersonic compact toroid (CT) is an effective means of introducing particles into the FRC core. However, neutral gas that trails the CT into the target chamber cools the FRC. Pre-ionization (PI) system assists the break down between electrodes of the CT injector (CTI), so the amount of introduced gas can be lowered by up to a factor of two, effectively increasing the ionization fraction; thus, reducing the amount of neutral gas in the system. Additionally, the PI decreases the delay in CTI breakdown so a highly reproducible operation is achievable. The PI system consists of a fast, high voltage, pulse discharge circuit coupled to a Teflon insulated semi-rigid coaxial cable inserted into the CTI. System details and experimental data will be presented, in addition to issues such as the introduction of impurities and pre-ionizer lifetime.

Distributed coaxial cable crack sensors for crack mapping in RC

NASA Astrophysics Data System (ADS)

Greene, Gary G.; Belarbi, Abdeldjelil; Chen, Genda; McDaniel, Ryan

2005-05-01

New type of distributed coaxial cable sensors for health monitoring of large-scale civil infrastructure was recently proposed and developed by the authors. This paper shows the results and performance of such sensors mounted on near surface of two flexural beams and a large scale reinforced concrete box girder that was subjected to twenty cycles of combined shear and torsion. The main objectives of this health monitoring study was to correlate the sensor's response to strain in the member, and show that magnitude of the signal's reflection coefficient is related to increases in applied load, repeated cycles, cracking, crack mapping, and yielding. The effect of multiple adjacent cracks, and signal loss was also investigated.

Measurement of the Shear Lift Force on a Bubble in a Channel Flow

NASA Technical Reports Server (NTRS)

Nahra, Henry K.; Motil, Brian; Skor, Mark

2005-01-01

Two-phase flow systems play vital roles in the design of some current and anticipated space applications of two-phase systems which include: thermal management systems, transfer line flow in cryogenic storage, space nuclear power facilities, design and operation of thermal bus, life support systems, propulsion systems, In Situ Resource Utilization (ISRU), and space processes for pharmaceutical applications. The design of two-phase flow systems for space applications requires a clear knowledge of the behaviors of the dispersed phase (bubble), its interaction with the continuous phase (liquid) and its effect on heat and mass transfer processes, The need to understand the bubble generation process arises from the fact that for all space applications, the size and distribution of bubbles are extremely crucial for heat and mass transfer control. One important force in two-phase flow systems is the lift force on a bubble or particle in a liquid shear flow. The shear lift is usually overwhelmed by buoyancy in normal gravity, but it becomes an important force in reduced gravity. Since the liquid flow is usually sheared because of the confining wall, the trajectories of bubbles and particles injected into the liquid flow are affected by the shear lift in reduced gravity. A series of experiments are performed to investigate the lift force on a bubble in a liquid shear flow and its effect on the detachment of a bubble from a wall under low gravity conditions. Experiments are executed in a Poiseuille flow in a channel. An air-water system is used in these experiments that are performed in the 2.2 second drop tower. A bubble is injected into the shear flow from a small injector and the shear lift is measured while the bubble is held stationary relative to the fluid. The trajectory of the bubble prior, during and after its detachment from the injector is investigated. The measured shear lift force is calculated from the trajectory of the bubble at the detachment point. These values for the shear lift are then compared with the theoretical predictions from various published works on shear lift in the open literature, which include asymptotic solutions at low bubble Reynolds number, potential flow predictions and numerical studies that deal with intermediate bubble Reynolds numbers.

The Breakup Mechanism and the Spray Pulsation Behavior of a Three-Stream Atomizer

NASA Astrophysics Data System (ADS)

Ng, Chin; Dord, Anne; Aliseda, Alberto

2011-11-01

In many processes of industrial importance, such as gasification, the liquid to gas mass ratio injected at the atomizer exceeds the limit of conventional two-fluid coaxial atomizers. To maximize the shear rate between the atomization gas and the liquid while maintaining a large contact area, a secondary gas stream is added at the centerline of the spray, interior to the liquid flow, which is annular in this configuration. This cylindrical gas jet has low momentum and does not contribute to the breakup process, which is still dominated by the high shear between the concentric annular liquid flow and the high momentum gas stream. The presence of two independently controlled gas streams leads to the appearance of a hydrodynamic instability that manifests itself in pulsating liquid flow rates and droplet sizes. We study the dependency of the atomization process on the relative flow rates of the three streams. We measure the size distribution, droplet number density and total liquid volumetric flow rate as a function of time, for realistic Weber and Ohnesorge numbers. Analysis of the temporal evolution of these physical variables reveals the dominant frequency of the instability and its effect on the breakup and dispersion of droplets in the spray. We present flow visualization and Phase Doppler Particle Analyzer results that provide insight into the behavior of this complex coaxial shear flow.

Non-Solenoidal Startup via Helicity Injection in the Pegasus ST

NASA Astrophysics Data System (ADS)

Bongard, M. W.; Bodner, G. M.; Burke, M. G.; Fonck, R. J.; Pachicano, J. L.; Perry, J. M.; Pierren, C.; Richner, N. J.; Rodriguez Sanchez, C.; Schlossberg, D. J.; Reusch, J. A.; Weberski, J. D.

2017-10-01

Research on the A 1 . 2 Pegasus ST is developing the physics and technology basis for optimal non-solenoidal tokamak startup. Recent work explores startup via Local Helicity Injection (LHI) using compact, multi-MW current sources placed at the plasma edge in the lower divertor region. This minimizes inductive drive from poloidal fields and dynamic shaping. Plasmas with Ip <= 200 kA, Δtpulse 20 ms and BT <= 0 . 15 T are produced to date, sustained by two injectors with Ainj = 4 cm2 , Vinj 1 . 5 kV, and Iinj 8 kA, facilitated by improvements to the injectors, limiters, and divertor plates that mitigate deleterious PMI. These plasmas feature anomalous, reconnection-driven ion heating with Ti >=Te >= 50 - 100 eV and large-amplitude MHD activity driven by the injectors. Under some conditions, MHD fluctuations abruptly decrease by over an order of magnitude without loss of LHI drive, improving realized Ip , and suggesting short-wavelength modes may relate to the current drive mechanism. The high IN >= 10 , ion heating, and low li driven by LHI, and the favorable stability of A 1 STs allows access to record βt 100 % and high βN 6 . 5 . Such high-βt plasmas have a minimum | B | well spanning 50 % of the plasma volume. Enhancements to the Pegasus facility are considered to increase BT towards NSTX-U levels; establish coaxial helicity injection capabilities; and add auxiliary heating and current drive. Work supported by US DOE Grant DE-FG02-96ER54375.

Normal stress differences and beyond-Navier-Stokes hydrodynamics

NASA Astrophysics Data System (ADS)

Alam, Meheboob; Saha, Saikat

2017-06-01

A recently proposed beyond-Navier-Stokes order hydrodynamic theory for dry granular fluids is revisited by focussing on the behaviour of the stress tensor and the scaling of related transport coefficients in the dense limit. For the homogeneous shear flow, it is shown that the eigen-directions of the second-moment tensor and those of the shear tensor become co-axial, thus making the first normal stress difference (N1) to zero in the same limit. In contrast, the origin of the second normal stress difference (N2) is tied to the `excess' temperature along the mean-vorticity direction and the imposed shear field, respectively, in the dilute and dense flows. The scaling relations for transport coefficients are suggested based on the present theory.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Technical Reports Server (NTRS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-01-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Astrophysics Data System (ADS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-07-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Effect of vane twist on the performance of dome swirlers for gas turbine airblast atomizers

NASA Astrophysics Data System (ADS)

Micklow, Gerald J.; Dogra, Anju S.; Nguyen, H. Lee

1990-06-01

For advanced gas turbine engines, two combustor systems, the lean premixed/prevaporized (LPP) and the rich burn/quick quench/lean burn (RQL) offer great potential for reducing NO(x) emissions. An important consideration for either concept is the development of an advanced fuel injection system that will provide a stable, efficient, and very uniform combustion system over a wide operating range. High-shear airblast fuel injectors for gas turbine combustors have exhibited superior atomization and mixing compared with pressure-atomizing fuel injectors. This improved mixing has lowered NO(x) emissions and the pattern factor, and has enabled combustors to alternate fuels while maintaining a stable, efficient combustion system. The performance of high-shear airblast fuel injectors is highly dependent on the design of the dome swirl vanes. The type of swirl vanes most widely used in gas turbine combustors are usually flat for ease of manufacture, but vanes with curvature will, in general, give superior aerodynamic performance. The design and performance of high-turning, low-loss curved dome swirl vanes with twist along the span are investigated. The twist induces a secondary vortex flow pattern which will improve the atomization of the fuel, thereby producing a more uniform fuel-air distribution. This uniform distribution will increase combustion efficiency while lowering NO(x) emissions. A systematic swirl vane design system is presented based on one-, two-, and three-dimensional flowfield calculations, with variations in vane-turning angle, rate of turning, vane solidity, and vane twist as design parameters.

Fuel Injector With Shear Atomizer

NASA Technical Reports Server (NTRS)

Beal, George W.; Mills, Virgil L.; Smith, Durward B., II; Beacom, William F.

1995-01-01

Atomizer for injecting liquid fuel into combustion chamber uses impact and swirl to break incoming stream of fuel into small, more combustible droplets. Slanted holes direct flow of liquid fuel to stepped cylindrical wall. Impact on wall atomizes liquid. Air flowing past vanes entrains droplets of liquid in swirling flow. Fuel injected at pressure lower than customarily needed.

Experimental and simulational result multipactors in 112 MHz QWR injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xin, T.; Ben-Zvi, I.; Belomestnykh, S.

2015-05-03

The first RF commissioning of 112 MHz QWR superconducting electron gun was done in late 2014. The coaxial Fundamental Power Coupler (FPC) and Cathode Stalk (stalk) were installed and tested for the first time. During this experiment, we observed several multipacting barriers at different gun voltage levels. The simulation work was done within the same range. The comparison between the experimental observation and the simulation results are presented in this paper. The observations during the test are consisted with the simulation predictions. We were able to overcome most of the multipacting barriers and reach 1.8 MV gun voltage under pulsedmore » mode after several round of conditioning processes.« less

Multi-injector modeling of transverse combustion instability experiments

NASA Astrophysics Data System (ADS)

Shipley, Kevin J.

Concurrent simulations and experiments are used to study combustion instabilities in a multiple injector element combustion chamber. The experiments employ a linear array of seven coaxial injector elements positioned atop a rectangular chamber. Different levels of instability are driven in the combustor by varying the operating and geometry parameters of the outer driving injector elements located near the chamber end-walls. The objectives of the study are to apply a reduced three-injector model to generate a computational test bed for the evaluation of injector response to transverse instability, to apply a full seven-injector model to investigate the inter-element coupling between injectors in response to transverse instability, and to further develop this integrated approach as a key element in a predictive methodology that relies heavily on subscale test and simulation. To measure the effects of the transverse wave on a central study injector element two opposing windows are placed in the chamber to allow optical access. The chamber is extensively instrumented with high-frequency pressure transducers. High-fidelity computational fluid dynamics simulations are used to model the experiment. Specifically three-dimensional, detached eddy simulations (DES) are used. Two computational approaches are investigated. The first approach models the combustor with three center injectors and forces transverse waves in the chamber with a wall velocity function at the chamber side walls. Different levels of pressure oscillation amplitudes are possible by varying the amplitude of the forcing function. The purpose of this method is to focus on the combustion response of the study element. In the second approach, all seven injectors are modeled and self-excited combustion instability is achieved. This realistic model of the chamber allows the study of inter-element flow dynamics, e.g., how the resonant motions in the injector tubes are coupled through the transverse pressure waves in the chamber. The computational results are analyzed and compared with experiment results in the time, frequency and modal domains. Results from the three injector model show how applying different velocity forcing amplitudes change the amplitude and spatial location of heat release from the center injector. The instability amplitudes in the simulation are able to be tuned to experiments and produce similar modal combustion responses of the center injector. The reaction model applied was found to play an important role in the spatial and temporal heat release response. Only when the model was calibrated to ignition delay measurements did the heat release response reflect measurements in the experiment. While insightful the simulations are not truly predictive because the driving frequency and forcing function amplitude are input into the simulation. However, the use of this approach as a tool to investigate combustion response is demonstrated. Results from the seven injector simulations provide an insightful look at the mechanisms driving the instability in the combustor. The instability was studied over a range of pressure fluctuations, up to 70% of mean chamber pressure produced in the self-exited simulation. At low amplitudes the transverse instability was found to be supported by both flame impingement with the side wall as well as vortex shedding at the primary acoustic frequency. As instability level grew the primary supporting mechanism shifted to just vortex impingement on the side walls and the greatest growth was seen as additional vortices began impinging between injector elements at the primary acoustic frequency. This research reveals the advantages and limitations of applying these two modeling techniques to simulate multiple injector experiments. The advantage of the three injector model is a simplified geometry which results in faster model development and the ability to more rapidly study the injector response under varying velocity amplitudes. The possibly faster run time is offset though by the need to run multiple cases to calibrate the model to the experiment. The model is also limited to studying the central injector effect and lacks heat release sources from the outer injectors and additional vortex interactions as shown in the seven injector simulation. The advantage of the seven injector model is that the whole domain can be explored to provide a better understanding about influential processes but does require longer development and run time due to the extensive gridding requirement. Both simulations have proven useful in exploring transverse combustion instability and show the need to further develop subscale experiments and companions simulations in developing a full-scale combustion instability prediction capability.

On the Behavior of a Shear-Coaxial Jet, Spanning Sub- to Supercritical Pressures, with and without an Externally Imposed Transverse Acoustic Field

DTIC Science & Technology

2006-05-01

rocket engines (LRE) have experienced high-frequency combustion instability, which impose an acoustic field in the combustion chamber. The acoustic...Graduate School iii ABSTRACT In the past, liquid rocket engines (LRE) have experienced high-frequency combustion instability, which impose an...49 3.5 Instrumentation

Quality Characteristics of Marinated Chicken Breast as Influenced by the Methods of Mechanical Processing

PubMed Central

Kim, Hack-Youn; Kim, Kon-Joong; Lee, Jong-Wan; Kim, Gye-Woong; Choe, Ju-Hui; Kim, Hyun-Wook; Yoon, Yohan; Kim, Cheon-Jei

2015-01-01

The aim of this study was to investigate the effects of various marination processes on the quality characteristics of chicken breast prepared with chicken feet gelatin and wheat fiber. The chicken feet gelatin was swollen with hydrochloric solution (0.1 N HCl, pH 1.31±0.02) and dehydrated by freeze-drying. The composition (w/w) of the marinade was water (10%), soy sauce (12%), phosphate (0.3%), wheat fiber (1.5%), and chicken feet gelatin (1.5%). Three samples of chicken breast were manufactured with Tumbler (only tumbler), Tenderizer (tenderizer and tumbler), and Injector (injector and tumbler). The water content of the Injector sample was significantly higher than those of the Tumbler and Tenderizer samples (p<0.05). During heating, the lightness of all chicken breasts increased and the redness decreased. The tumbling and cooking yield of the Injector sample were significantly higher than those of the Tumbler and Tenderizer samples (p<0.05). The shear force of the Tenderizer sample was significantly lower than that of the Tumbler and Injector samples (p<0.05). No significant differences, except for color, were observed in the sensory analysis of the samples. Thus, the proper selection of mechanical processing is important to improve the quality characteristics of marinated chicken breast, considering the types of final products. PMID:26761806

Analysis of Alfven eigenmode destabilization in DIII-D high poloidal β discharges using a Landau closure model

NASA Astrophysics Data System (ADS)

Varela, J.; Spong, D. A.; Garcia, L.; Huang, J.; Murakami, M.; Garofalo, A. M.; Qian, J. P.; Holcomb, C. T.; Hyatt, A. W.; Ferron, J. R.; Collins, C. S.; Ren, Q. L.; McClenaghan, J.; Guo, W.

2018-07-01

Alfvén eigenmodes are destabilized at the DIII-D pedestal during transient beta drops in high poloidal β discharges with internal transport barriers (ITBs), driven by n  =  1 external kink modes, leading to energetic particle losses. There are two different scenarios in the thermal β recovery phase: with bifurcation (two instability branches with different frequencies) or without bifurcation (single instability branch). We use the reduced MHD equations in a full 3D system, coupled with equations of density and parallel velocity moments for the energetic particles as well as the geodesic acoustic wave dynamics, to study the properties of the instabilities observed in the DIII-D high poloidal β discharges and identify the conditions to trigger the bifurcation. The simulations suggest that instabilities with lower frequency in the bifurcation case are ballooning modes driven at the plasma pedestal, while the instability branch with higher frequencies are low n (n  <  4) toroidal Alfvén eigenmodes nearby the pedestal. The reverse shear region between the middle and plasma periphery in the non-bifurcated case avoids the excitation of ballooning modes at the pedestal, although toroidal Alfvén eigenmodes and reverse shear Alfvén eigenmodes are unstable in the reverse shear region. The n  =  1 and n  =  2 Alfvén eigenmode activity can be suppressed or minimized if the neutral beam injector (NBI) intensity is lower than the experimental value (). In addition, if the beam energy or neutral beam injector voltage is lower than in the experiment (), the resonance between beam and thermal plasma is weaker. The and 6 AE activity can not be fully suppressed, although the growth rate and frequency is smaller for an optimized neutral beam injector operation regime. In conclusion, AE activity in high poloidal β discharges can be minimized for optimized NBI operation regimes.

An integral turbulent kinetic energy analysis of free shear flows

NASA Technical Reports Server (NTRS)

Peters, C. E.; Phares, W. J.

1973-01-01

Mixing of coaxial streams is analyzed by application of integral techniques. An integrated turbulent kinetic energy (TKE) equation is solved simultaneously with the integral equations for the mean flow. Normalized TKE profile shapes are obtained from incompressible jet and shear layer experiments and are assumed to be applicable to all free turbulent flows. The shear stress at the midpoint of the mixing zone is assumed to be directly proportional to the local TKE, and dissipation is treated with a generalization of the model developed for isotropic turbulence. Although the analysis was developed for ducted flows, constant-pressure flows were approximated with the duct much larger than the jet. The axisymmetric flows under consideration were predicted with reasonable accuracy. Fairly good results were also obtained for the fully developed two-dimensional shear layers, which were computed as thin layers at the boundary of a large circular jet.

Measurement of water pressure and deformation with time domain reflectometry cables

NASA Astrophysics Data System (ADS)

Dowding, Charles H.; Pierce, Charles E.

1995-05-01

Time domain reflectometry (TDR) techniques can be deployed to measure water pressures and relative dam abutment displacement with an array of coaxial cables either drilled and grouted or retrofitted through existing passages. Application of TDR to dam monitoring requires determination of appropriate cable types and methods to install these cables in existing dams or during new construction. This paper briefly discusses currently applied and developing TDR techniques and describes initial design considerations for TDR-based dam instrumentation. Water pressure at the base of or within the dam can be determined by measuring the water level within a hollow or air-filled coaxial cable. The ability to retrofit existing porous stone-tipped piezometers is an attractive attribute of the TDR system. Measurement of relative lateral movement can be accomplished by monitoring local shearing of a solid polyethylene-filled coaxial cable at the interface of the dam base and foundation materials or along adversely oriented joints. Uplift can be recorded by measuring cable extension as the dam displaces upward off its foundation. Since each monitoring technique requires measurements with different types of coaxial cables, a variety may be installed within the array. Multiplexing of these cables will allow monitoring from a single pulser, and measurements can be recorded on site or remotely via a modem at any time.

An Optimization-Based Approach to Injector Element Design

NASA Technical Reports Server (NTRS)

Tucker, P. Kevin; Shyy, Wei; Vaidyanathan, Rajkumar; Turner, Jim (Technical Monitor)

2000-01-01

An injector optimization methodology, method i, is used to investigate optimal design points for gaseous oxygen/gaseous hydrogen (GO2/GH2) injector elements. A swirl coaxial element and an unlike impinging element (a fuel-oxidizer-fuel triplet) are used to facilitate the study. The elements are optimized in terms of design variables such as fuel pressure drop, APf, oxidizer pressure drop, deltaP(sub f), combustor length, L(sub comb), and full cone swirl angle, theta, (for the swirl element) or impingement half-angle, alpha, (for the impinging element) at a given mixture ratio and chamber pressure. Dependent variables such as energy release efficiency, ERE, wall heat flux, Q(sub w), injector heat flux, Q(sub inj), relative combustor weight, W(sub rel), and relative injector cost, C(sub rel), are calculated and then correlated with the design variables. An empirical design methodology is used to generate these responses for both element types. Method i is then used to generate response surfaces for each dependent variable for both types of elements. Desirability functions based on dependent variable constraints are created and used to facilitate development of composite response surfaces representing the five dependent variables in terms of the input variables. Three examples illustrating the utility and flexibility of method i are discussed in detail for each element type. First, joint response surfaces are constructed by sequentially adding dependent variables. Optimum designs are identified after addition of each variable and the effect each variable has on the element design is illustrated. This stepwise demonstration also highlights the importance of including variables such as weight and cost early in the design process. Secondly, using the composite response surface that includes all five dependent variables, unequal weights are assigned to emphasize certain variables relative to others. Here, method i is used to enable objective trade studies on design issues such as component life and thrust to weight ratio. Finally, combining results from both elements to simulate a trade study, thrust-to-weight trends are illustrated and examined in detail.

First Production of C60 Nanoparticle Plasma Jet for Study of Disruption Mitigation for ITER

NASA Astrophysics Data System (ADS)

Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; Brockington, S.; Case, A.; Messer, S. J.; Witherspoon, F. D.

2012-10-01

Unique fast response and large mass-velocity delivery of nanoparticle plasma jets (NPPJs) provide a novel application for ITER disruption mitigation, runaway electrons diagnostics and deep fueling. NPPJs carry a much larger mass than usual gases. An electromagnetic plasma gun provides a very high injection velocity (many km/s). NPPJ has much higher ram pressure than any standard gas injection method and penetrates the tokamak confining magnetic field. Assimilation is enhanced due to the NP large surface-to-volume ratio. Radially expanding NPPJs help achieving toroidal uniformity of radiation power. FAR-TECH's NPPJ system was successfully tested: a coaxial plasma gun prototype (˜35 cm length, 96 kJ energy) using a solid state TiH2/C60 pulsed power cartridge injector produced a hyper-velocity (>4 km/s), high-density (>10^23 m-3), C60 plasma jet in ˜0.5 ms, with ˜1-2 ms overall response-delivery time. We present the TiH2/C60 cartridge injector output characterization (˜180 mg of sublimated C60 gas) and first production results of a high momentum C60 plasma jet (˜0.6 g.km/s).

Integrated Fuel Injection and Mixing System with Impingement Cooling Face

NASA Technical Reports Server (NTRS)

Mansour, Adel B. (Inventor); Harvey, Rex J. (Inventor); Tacina, Robert R. (Inventor); Laing, Peter (Inventor)

2003-01-01

An atomizing injector includes a metering set having a swirl chamber, a spray orifice and one or more feed slots etched in a thin plate. The swirl chamber is etched in a first side of the plate and the spray orifice is etched through a second side to the center of the swirl chamber. Fuel feed slots extend non-radially to the swirl chamber. The injector also includes integral swirler structure. The swirler structure includes a cylindrical air swirler passage, also shaped by etching, through at least one other thin plate. The cylindrical air swirler passage is located in co-axial relation to the spray orifice of the plate of the fuel metering set such that fuel directed through the spray orifice passes through the air swirler passage and swirling air is imparted to the fuel such that the fuel has a swirling component of motion. At least one air feed slot is provided in fluid communication with the air swirler passage and extends in non-radial relation thereto. Air supply passages extend through the plates of the metering set and the swirler structure to feed the air feed slot in each plate of the swirler structure.

Evidence from Fold Vergence for Coaxial Ductile Flow within the Otago Subduction Wedge, South Island, New Zealand

NASA Astrophysics Data System (ADS)

Rahl, J. M.; Brandon, M. T.

2001-12-01

There has been a long-standing debate about the tectonic significance of the highly folded Otago schist, which is exposed in the Otago uplift on the South Island of New Zealand. This uplift marks the forearc high of a long-lived subduction wedge that flanked the Mesozoic Gondwana margin. The exhumed metamorphic rocks record temperatures up to ~450 C and depths up to ~25 km. The dominant foliation is generally gently dipping, with attitudes that follow the form of the uplift. Mesoscale folds are common, and some regional-scale fold are recognized as well. Previous workers have argued that deformation within the Otago Schist resulted from trenchward shearing above a subducting oceanic plate, but there has been little evidence for systematic fold vergence across the uplift to support this idea. We describe here a new method for analysing the average vergence of a pervasively folded unit, with the goal to test the degree of non-coaxiality associated with ductile deformation within the Otago wedge. Our analysis exploits a new database, compiled by the New Zealand IGNS, which summarizes thousands of structural measurements for the Otago Schist. Vergence is defined in the usual manner as the asymmetry of the fold relative to its axial plane. This asymmetry is attributed to shear-induced rotation at the scale of the fold. Non-coaxial shear can be locally induced, especially in strongly layered schist sequences. We want to know if the fold vergence is systematically developed at the regional scale. Each fold is represented by a vector parallel to the fold axis, with a direction defined by the right-handed rotation implied by the vergence. We argue that the net vergence is well approximated by the Fisher vector mean of the vergence vectors. In addition, we consider the spatial distribution of the vergence vectors across the uplift, with a specific focus on the structural boundary between the Caples and Torlesse, two accretionary units that make up the wedge. We find that there is no systematic vergence at the regional scale or localized along the Torlesse/Caples boundary. We do find local domains at the 10 km scale with a consistent vergence direction, but at large scales, the vergence pattern becomes averaged out. These result support the idea that the Otago schist formed by vertical shortening within a regional-scale coaxial flow field, perhaps driven by underplating beneath the uplift. Furthermore, the lack of a regional-scale vergence implies very weak coupling across the subduction zone.

Experimental Results from a Flat Plate, Turbulent Boundary Layer Modified for the Purpose of Drag Reduction

NASA Astrophysics Data System (ADS)

Elbing, Brian R.

2006-11-01

Recent experiments on a flat plate, turbulent boundary layer at high Reynolds numbers (>10^7) were performed to investigate various methods of reducing skin friction drag. The methods used involved injecting either air or a polymer solution into the boundary layer through a slot injector. Two slot injectors were mounted on the model with one located 1.4 meters downstream of the nose and the second located 3.75 meters downstream. This allowed for some synergetic experiments to be performed by varying the injections from each slot and comparing the skin friction along the plate. Skin friction measurements were made with 6 shear stress sensors flush mounted along the stream-wise direction of the model.

Overview of Non-Solenoidal Startup Studies in the Pegasus ST

NASA Astrophysics Data System (ADS)

Bongard, M. W.; Barr, J. L.; Bodner, G. M.; Burke, M. G.; Fonck, R. J.; Pachicano, J. L.; Perry, J. M.; Reusch, J. A.; Richner, N. J.; Rodriguez Sanchez, C.; Schlossberg, D. J.

2016-10-01

Local helicity injection (LHI) is a non-solenoidal startup method pursued on Pegasus utilizing compact, high power current sources (Ainj 2 - 4 cm2, Iinj 10 kA, Vinj 1 kV) at the plasma edge. Outboard injectors (Ninj = 4 , Ainj = 8 cm2) produce Ip 170 kA plasmas compatible with Ohmic drive. A 0-D model that treats the plasma as a resistive element with time-varying inductance and enforces Ip limits from Taylor relaxation is used to interpret experimental Ip(t) in several scenarios. Strong inductive drive arises from the plasma shape evolution, in addition to poloidal field induction. A new injector system has recently been installed in the lower divertor region (Ninj = 2 , Ainj = 8 cm2) to explore the implications of geometric placement of the helicity injectors on LHI startup. This geometry supports tests of reconnection dynamics seen in NIMROD simulations, high-BT effects expected in larger devices, and LHI electron confinement with and without inductive assist. Plasmas with Ip > 130 kA, Vinj 0.5 kV, Δtpulse 8 ms and BT /BT , max <= 50 % are produced with the inboard system to date, consistent with performance expectations. Higher Ip is expected with increased BT, Vinj, and Δtpulse . Thomson scattering data in both geometries indicate high Te >= 100 eV during LHI, suggesting the confinement is not strongly stochastic. Conceptual design work is exploring the feasibility of coaxial helicity injection and ECH heating on Pegasus in addition to LHI. Work supported by US DOE Grant DE-FG02-96ER54375.

A comparison of the performance of 1st order and 2nd order turbulence models when solving the RANS equations in reproducing the liquid film length unsteady response to momentum flux ratio in Gas-Centered Swirl-Coaxial Injectors in Rocket Engine Applications

DTIC Science & Technology

2012-06-07

scheme for the VOF requires the use of the explicit solver to advance the solution in time. The drawback of using the explicit solver is that such ap...proach required much smaller time steps to guarantee that a converged and stable solution is obtained during each fractional time step (Global...Comparable results were obtained for the solutions with the RSM model. 50x 25x 100x25x 25x200x 0.000 0.002 0.004 0.006 0.008 0.010 0 100 200 300

Validation of a Pressure-Based Combustion Simulation Tool Using a Single Element Injector Test Problem

NASA Technical Reports Server (NTRS)

Thakur, Siddarth; Wright, Jeffrey

2006-01-01

The traditional design and analysis practice for advanced propulsion systems, particularly chemical rocket engines, relies heavily on expensive full-scale prototype development and testing. Over the past decade, use of high-fidelity analysis and design tools such as CFD early in the product development cycle has been identified as one way to alleviate testing costs and to develop these devices better, faster and cheaper. Increased emphasis is being placed on developing and applying CFD models to simulate the flow field environments and performance of advanced propulsion systems. This necessitates the development of next generation computational tools which can be used effectively and reliably in a design environment by non-CFD specialists. A computational tool, called Loci-STREAM is being developed for this purpose. It is a pressure-based, Reynolds-averaged Navier-Stokes (RANS) solver for generalized unstructured grids, which is designed to handle all-speed flows (incompressible to hypersonic) and is particularly suitable for solving multi-species flow in fixed-frame combustion devices. Loci-STREAM integrates proven numerical methods for generalized grids and state-of-the-art physical models in a novel rule-based programming framework called Loci which allows: (a) seamless integration of multidisciplinary physics in a unified manner, and (b) automatic handling of massively parallel computing. The objective of the ongoing work is to develop a robust simulation capability for combustion problems in rocket engines. As an initial step towards validating this capability, a model problem is investigated in the present study which involves a gaseous oxygen/gaseous hydrogen (GO2/GH2) shear coaxial single element injector, for which experimental data are available. The sensitivity of the computed solutions to grid density, grid distribution, different turbulence models, and different near-wall treatments is investigated. A refined grid, which is clustered in the vicinity of the solid walls as well as the flame, is used to obtain a steady state solution which may be considered as the best solution attainable with the steady-state RANS methodology. From a design point of view, quick turnaround times are desirable; with this in mind, coarser grids are also employed and the resulting solutions are evaluated with respect to the fine grid solution.

Fuel Injector: Air swirl characterization aerothermal modeling, phase 2, volume 2

NASA Technical Reports Server (NTRS)

Nikjooy, M.; Mongia, H. C.; Mcdonell, V. G.; Samuelson, G. S.

1993-01-01

A well integrated experimental/analytical investigation was conducted to provide benchmark quality data relevant to prefilming type airblast fuel nozzle and its interaction with combustor dome air swirler. The experimental investigation included a systematic study of both single-phase flows that involved single and twin co-axial jets with and without swirl. A two-component Phase Doppler Particle Analyzer (PDPA) equipment was used to document the interaction of single and co-axial air jets with glass beads that simulate nonevaporating spray and simultaneously avoid the complexities associated with fuel atomization processes and attendant issues about the specification of relevant boundary conditions. The interaction of jets with methanol spray produced by practical airblast nozzle was also documented in the spatial domain of practical interest. Model assessment activities included the use of three turbulence models (k-epsilon, algebraic second moment (ASM) and differential second moment (DSM)) for the carrier phase, deterministic or stochastic Lagrangian treatment of the dispersed phase, and advanced numerical schemes. Although qualitatively good comparison with data was obtained for most of the cases investigated, the model deficiencies in regard to modeled dissipation rate transport equation, single length scale, pressure-strain correlation, and other critical closure issues need to be resolved before one can achieve the degree of accuracy required to analytically design combustion systems.

Fuel injector: Air swirl characterization aerothermal modeling, phase 2, volume 1

NASA Technical Reports Server (NTRS)

Nikjooy, M.; Mongia, H. C.; Mcdonell, V. G.; Samuelsen, G. S.

1993-01-01

A well integrated experimental/analytical investigation was conducted to provide benchmark quality relevant to a prefilming type airblast fuel nozzle and its interaction with the combustor dome air swirler. The experimental investigation included a systematic study of both single-phase flows that involved single and twin co-axial jets with and without swirl. A two-component Phase Doppler Particle Analyzer (PDPA) was used to document the interaction of single and co-axial air jets with glass beads that simulate nonevaporating spray and simultaneously avoid the complexities associated with fuel atomization processes and attendant issues about the specification of relevant boundary conditions. The interaction of jets with methanol spray produced by practical airblast nozzle was also documented in the spatial domain of practical interest. Model assessment activities included the use of three turbulence models (k-epsilon, algebraic second moment (ASM), and differential second moment (DSM)) for the carrier phase, deterministic or stochastic Lagrangian treatment of the dispersed phase, and advanced numerical schemes. Although qualitatively good comparison with data was obtained for most of the cases investigated, the model deficiencies in regard to modeled dissipation rate transport equation, single length scale, pressure-strain correlation, and other critical closure issues need to be resolved before one can achieve the degree of accuracy required to analytically design combustion systems.

Nonlinear MHD simulation of current drive by multi-pulsed coaxial helicity injection in spherical torus

NASA Astrophysics Data System (ADS)

Kanki, Takashi; Nagata, Masayoshi; Kagei, Yasuhiro

2011-10-01

The dynamics of structures of magnetic field, current density, and plasma flow generated during multi-pulsed coaxial helicity injection in spherical torus is investigated by 3-D nonlinear MHD simulations. During the driven phase, the flux and current amplifications occur due to the merging and magnetic reconnection between the preexisting plasma in the confinement region and the ejected plasma from the gun region involving the n = 1 helical kink distortion of the central open flux column (COFC). Interestingly, the diamagnetic poloidal flow which tends toward the gun region is then observed due to the steep pressure gradients of the COFC generated by ohmic heating through an injection current winding around the inboard field lines, resulting in the formation of the strong poloidal flow shear at the interface between the COFC and the core region. This result is consistent with the flow shear observed in the HIST. During the decay phase, the configuration approaches the axisymmetric MHD equilibrium state without flow because of the dissipation of magnetic fluctuation energy to increase the closed flux surfaces, suggesting the generation of ordered magnetic field structure. The parallel current density λ concentrated in the COFC then diffuses to the core region so as to reduce the gradient in λ, relaxing in the direction of the Taylor state.

Neural Network and Response Surface Methodology for Rocket Engine Component Optimization

NASA Technical Reports Server (NTRS)

Vaidyanathan, Rajkumar; Papita, Nilay; Shyy, Wei; Tucker, P. Kevin; Griffin, Lisa W.; Haftka, Raphael; Fitz-Coy, Norman; McConnaughey, Helen (Technical Monitor)

2000-01-01

The goal of this work is to compare the performance of response surface methodology (RSM) and two types of neural networks (NN) to aid preliminary design of two rocket engine components. A data set of 45 training points and 20 test points obtained from a semi-empirical model based on three design variables is used for a shear coaxial injector element. Data for supersonic turbine design is based on six design variables, 76 training, data and 18 test data obtained from simplified aerodynamic analysis. Several RS and NN are first constructed using the training data. The test data are then employed to select the best RS or NN. Quadratic and cubic response surfaces. radial basis neural network (RBNN) and back-propagation neural network (BPNN) are compared. Two-layered RBNN are generated using two different training algorithms, namely solverbe and solverb. A two layered BPNN is generated with Tan-Sigmoid transfer function. Various issues related to the training of the neural networks are addressed including number of neurons, error goals, spread constants and the accuracy of different models in representing the design space. A search for the optimum design is carried out using a standard gradient-based optimization algorithm over the response surfaces represented by the polynomials and trained neural networks. Usually a cubic polynominal performs better than the quadratic polynomial but exceptions have been noticed. Among the NN choices, the RBNN designed using solverb yields more consistent performance for both engine components considered. The training of RBNN is easier as it requires linear regression. This coupled with the consistency in performance promise the possibility of it being used as an optimization strategy for engineering design problems.

Development of comprehensive numerical schemes for predicting evaporating gas-droplets flow processes of a liquid-fueled combustor

NASA Technical Reports Server (NTRS)

Chen, C. P.

1990-01-01

An existing Computational Fluid Dynamics code for simulating complex turbulent flows inside a liquid rocket combustion chamber was validated and further developed. The Advanced Rocket Injector/Combustor Code (ARICC) is simplified and validated against benchmark flow situations for laminar and turbulent flows. The numerical method used in ARICC Code is re-examined for incompressible flow calculations. For turbulent flows, both the subgrid and the two equation k-epsilon turbulence models are studied. Cases tested include idealized Burger's equation in complex geometries and boundaries, a laminar pipe flow, a high Reynolds number turbulent flow, and a confined coaxial jet with recirculations. The accuracy of the algorithm is examined by comparing the numerical results with the analytical solutions as well as experimented data with different grid sizes.

Interferometer density measurements of a high-velocity plasmoid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Case, A.; Messer, S.; Bomgardner, R.

2010-05-15

The plasmoid produced by a half-scale contoured gap coaxial plasma accelerator using ablative polyethylene capillary plasma injectors is measured using a quadrature heterodyne HeNe interferometer. The plasmoid is found to have a sharp rise in density at the leading edge, with a gradual falloff after the peak density. For this early test series, an average bulk density of 5x10{sup 14} cm{sup -3} is observed, with densities up to 8x10{sup 14} cm{sup -3} seen on some shots. Although plasmoid mass is only about 58 mug due to the low current and injected mass used in these tests, good shot-to-shot repeatability ismore » attained making analysis relatively straightforward, thus providing a solid foundation for interpreting future experimental results.« less

Influence of large-scale motion on turbulent transport for confined coaxial jets. Volume 2: Navier-Stokes calculations of swirling and nonswirling confined coaxial jets

NASA Technical Reports Server (NTRS)

Weinberg, B. C.; Mcdonald, H.

1986-01-01

The existence of large scale coherent structures in turbulent shear flows has been well documented. Discrepancies between experimental and computational data suggest a necessity to understand the roles they play in mass and momentum transport. Using conditional sampling and averaging on coincident two-component velocity and concentration velocity experimental data for swirling and nonswirling coaxial jets, triggers for identifying the structures were examined. Concentration fluctuation was found to be an adequate trigger or indicator for the concentration-velocity data, but no suitable detector was located for the two-component velocity data. The large scale structures are found in the region where the largest discrepancies exist between model and experiment. The traditional gradient transport model does not fit in this region as a result of these structures. The large scale motion was found to be responsible for a large percentage of the axial mass transport. The large scale structures were found to convect downstream at approximately the mean velocity of the overall flow in the axial direction. The radial mean velocity of the structures was found to be substantially greater than that of the overall flow.

Tunable engineered skin mechanics via coaxial electrospun fiber core diameter.

PubMed

Blackstone, Britani Nicole; Drexler, Jason William; Powell, Heather Megan

2014-10-01

Autologous engineered skin (ES) offers promise as a treatment for massive full thickness burns. Unfortunately, ES is orders of magnitude weaker than normal human skin causing it to be difficult to apply surgically and subject to damage by mechanical shear in the early phases of engraftment. In addition, no manufacturing strategy has been developed to tune ES biomechanics to approximate the native biomechanics at different anatomic locations. To enhance and tune ES biomechanics, a coaxial (CoA) electrospun scaffold platform was developed from polycaprolactone (PCL, core) and gelatin (shell). The ability of the coaxial fiber core diameter to control both scaffold and tissue mechanics was investigated along with the ability of the gelatin shell to facilitate cell adhesion and skin development compared to pure gelatin, pure PCL, and a gelatin-PCL blended fiber scaffold. CoA ES exhibited increased cellular adhesion and metabolism versus PCL alone or gelatin-PCL blend and promoted the development of well stratified skin with a dense dermal layer and a differentiated epidermal layer. Biomechanics of the scaffold and ES scaled linearly with core diameter suggesting that this scaffold platform could be utilized to tailor ES mechanics for their intended grafting site and reduce graft damage in vitro and in vivo.

Experimental investigations of the time and flow-direction responses of shear-stress-sensitive liquid crystal coatings

NASA Technical Reports Server (NTRS)

Reda, Daniel C.; Muratore, Joseph J., Jr.; Heineck, James T.

1993-01-01

Time and flow-direction responses of shearstress-sensitive liquid crystal coatings were explored experimentally. For the time-response experiments, coatings were exposed to transient, compressible flows created during the startup and off-design operation of an injector-driven supersonic wind tunnel. Flow transients were visualized with a focusing Schlieren system and recorded with a 1000 frame/sec color video camera. Liquid crystal responses to these changing-shear environments were then recorded with the same video system, documenting color-play response times equal to, or faster than, the time interval between sequential frames (i.e., 1 millisecond). For the flow-direction experiments, a planar test surface was exposed to equal-magnitude and known-direction surface shear stresses generated by both normal and tangential subsonic jet-impingement flows. Under shear, the sense of the angular displacement of the liquid crystal dispersed (reflected) spectrum was found to be a function of the instantaneous direction of the applied shear. This technique thus renders dynamic flow reversals or flow divergences visible over entire test surfaces at image recording rates up to 1 KHz. Extensions of the technique to visualize relatively small changes in surface shear stress direction appear feasible.

Advanced Transportation Systems, Alternate Propulsion Subsystem Concepts

NASA Technical Reports Server (NTRS)

1997-01-01

An understanding of the basic flow of of the subject hybrid model has been gained through this series of testing. Changing injectors (axial vs. radial) and inhibiting the flow between the upstream plenum and the CP section changes the basic flow structure, as evidenced by streamline and velocity contour plots. Numerous shear layer structures were identified in the test configurations; these structures include both standing and traveling vortices which may affect combustion ion stability. Standing vortices may play a role in the heat addition process as the oxidizer enters the motor, while traveling vortices may be instability mechanisms in themselves. Finally, the flow visualization and LVD measurements give insight into determining the effects of flow induced shear layers.

Swirl-Stabilized Injector Flow and Combustion Dynamics for Liquid Propellants at Supercritical Conditions

DTIC Science & Technology

2007-02-08

was employed to study the vapor cavitation during liquid carbon dioxide expansion through a sharp-orifice nozzle. Numerical experiments demonstrated...Combustion Dynamics for 6b. GRANT NUMBER Liquid Propellants at Supercritical Conditions FA9550-04-1-0014 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...fundamental knowledge of supercritical combustion of liquid propellants under conditions representative of contemporary rocket engines. Both shear and

Cryogenic High-Pressure Shear-Coaxial Jets Exposed to Transverse Acoustic Forcing

DTIC Science & Technology

2011-12-13

formation. Detailed studies on the development and growth of natural instabilities in a single circular jet6 or a single circular jet with coflow7...reveal two of the most significant natural modes of instability: the axisymmetric and the first azimuthal or helical modes. These modes have comparable... natural as well as externally imposed flow conditions such as pressure or velocity perturbations, affecting their development, may be used to assess

Large eddy simulations of a transcritical round jet submitted to transverse acoustic modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez-Flesca, M.; CNES DLA, 52 Rue Jacques Hillairet, 75612 Paris Cedex; Schmitt, T.

This article reports numerical computations of a turbulent round jet of transcritical fluid (low temperature nitrogen injected under high pressure conditions) surrounded by the same fluid at rest under supercritical conditions (high temperature and high pressure) and submitted to transverse acoustic modulations. The numerical framework relies on large eddy simulation in combination with a real-gas description of thermodynamics and transport properties. A stationary acoustic field is obtained by modulating the normal acoustic velocity at the lateral boundaries of the computational domain. This study specifically focuses on the interaction of the jet with the acoustic field to investigate how the roundmore » transcritical jet changes its shape and mixes with the surrounding fluid. Different modulation amplitudes and frequencies are used to sweep a range of conditions. When the acoustic field is established in the domain, the jet length is notably reduced and the jet is flattened in the spanwise direction. Two regimes of oscillation are identified: for low Strouhal numbers a large amplitude motion is observed, while for higher Strouhal numbers the jet oscillates with a small amplitude around the injector axis. The minimum length is obtained for a Strouhal number of 0.3 and the jet length increases with increasing Strouhal numbers after reaching this minimum value. The mechanism of spanwise deformation is shown to be linked with dynamical effects resulting from reduction of the pressure in the transverse direction in relation with increased velocities on the two sides of the jet. A propagative wave is then introduced in the domain leading to similar effects on the jet, except that a bending is also observed in the acoustic propagation direction. A kinematic model, combining hydrodynamic and acoustic contributions, is derived in a second stage to represent the motion of the jet centerline. This model captures details of the numerical simulations quite well. These various results can serve to interpret observations made on more complex flow configurations such as coaxial jets or jet flames formed by coaxial injectors.« less

The lateral boundary of a metamorphic core complex: The Moutsounas shear zone on Naxos, Cyclades, Greece☆

PubMed Central

Cao, Shuyun; Neubauer, Franz; Bernroider, Manfred; Liu, Junlai

2013-01-01

We describe the structure, microstructures, texture and paleopiezometry of quartz-rich phyllites and marbles along N-trending Moutsounas shear zone at the eastern margin of the Naxos metamorphic core complex (MCC). Fabrics consistently indicate a top-to-the-NNE non-coaxial shear and formed during the main stage of updoming and exhumation between ca. 14 and 11 Ma of the Naxos MCC. The main stage of exhumation postdates the deposition of overlying Miocene sedimentary successions and predates the overlying Upper Miocene/Pliocene conglomerates. Detailed microstructural and textural analysis reveals that the movement along the Moutsounas shear zone is associated with a retrograde greenschist to subgreenschist facies overprint of the early higher-temperature rocks. Paleopiezometry on recrystallized quartz and calcite yields differential stresses of 20–77 MPa and a strain rate of 10−15–10−13 s−1 at 350 °C for quartz and ca. 300 °C for calcite. Chlorite geothermometry of the shear zone yields two temperature regimes, 300–360 °C, and 200–250 °C. The lower temperature group is interpreted to result from late-stage hydrothermal overprint. PMID:26523079

Mixing in Shear Coaxial Jets (Briefing Charts)

DTIC Science & Technology

2013-08-01

relevant boundary layers 9. Thermodynamic states (2 phase, 1 phase) 10. Transverse Acoustic mode from chamber/siren, f=f(c, geometry St=fDij/Uij 11...stability theory for inviscid instability of a hyperbolic tangent velocity profile for free boundary layers • U(y)=0.5[1 + tanh(y)] • Chigier and Beer , 1964...acoustics Natural OJ excited IJ excited From Chigier NA. and Beer JM, The Flow Region Near the Nozzle in Double Concentric Jets, J of

Mass and Momentum Turbulent Transport Experiments with Confined Coaxial Jets

NASA Technical Reports Server (NTRS)

Johnson, B. V.; Bennett, J. C.

1981-01-01

Downstream mixing of coaxial jets discharging in an expanded duct was studied to obtain data for the evaluation and improvement of turbulent transport models currently used in a variety of computational procedures throughout the propulsion community for combustor flow modeling. Flow visualization studies showed four major shear regions occurring; a wake region immediately downstream of the inlet jet inlet duct; a shear region further downstream between the inner and annular jets; a recirculation zone; and a reattachment zone. A combination of turbulent momentum transport rate and two velocity component data were obtained from simultaneous measurements with a two color laser velocimeter (LV) system. Axial, radial and azimuthal velocities and turbulent momentum transport rate measurements in the r-z and r-theta planes were used to determine the mean value, second central moment (or rms fluctuation from mean), skewness and kurtosis for each data set probability density function (p.d.f.). A combination of turbulent mass transport rate, concentration and velocity data were obtained system. Velocity and mass transport in all three directions as well as concentration distributions were used to obtain the mean, second central moments, skewness and kurtosis for each p.d.f. These LV/LIF measurements also exposed the existence of a large region of countergradient turbulent axial mass transport in the region where the annular jet fluid was accelerating the inner jet fluid.

The flow field of an underexpanded H2 jet coaxially injected into a hot free or ducted supersonic jet of air or nitrogen

NASA Technical Reports Server (NTRS)

Jenkins, R. V.

1977-01-01

Experimental data obtained in an investigation of the mixing of an underexpanded hydrogen jet in a supersonic flow both with and without combustion are presented. Tests were conducted in a Mach 2 test stream with both air and nitrogen as test media. Total temperature of the test stream was 2170 K, and static exit pressure was about one atmosphere. The static pressure at the exit of the hydrogen injector's Mach 2 nozzle was about two atmospheres. Primary measurements included shadowgraphs and pitot pressure surveys of the flow field. Pitot surveys and wall static pressures were measured for the case where the entire flow was shrouded. The results are compared to similar experimental data and theoretical predictions for the matched pressure case.

Design optimization of RF lines in vacuum environment for the MITICA experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Muri, Michela, E-mail: michela.demuri@igi.cnr.it; Consorzio RFX, Corso Stati Uniti, 4, I-35127 Padova; Pavei, Mauro

This contribution regards the Radio Frequency (RF) transmission line of the Megavolt ITER Injector and Concept Advancement (MITICA) experiment. The original design considered copper coaxial lines of 1″ 5/8, but thermal simulations under operating conditions showed maximum temperatures of the lines at regime not compatible with the prescription of the component manufacturer. Hence, an optimization of the design was necessary. Enhancing thermal radiation and increasing the conductor size were considered for design optimization: thermal analyses were carried out to calculate the temperature of MITICA RF lines during operation, as a function of the emissivity value and of other geometrical parameters.more » Five coating products to increase the conductor surface emissivity were tested, measuring the outgassing behavior of the selected products and the obtained emissivity values.« less

Comparison of performance of inclinometer casing and TDR technique

NASA Astrophysics Data System (ADS)

Aghda, S. M. Fatemi; Ganjalipour, K.; Nabiollahi, K.

2018-03-01

TDR (Time Domain Reflectometry) and GPR (Ground Penetrating Radar) are two of the electromagnetic methods in applied geophysics, which using them for various applications are developing. The Time Domain Reflectometry is a remote sensing method that has been used for years to determine the nature of the materials and spatial location. The use of TDR system has led to innovative applications of it and comparing it with previous measuring techniques, since it has developed. In this study, not only a summary of the basics of TDR application for monitoring of ground deformation is offered, but also a comparison of this technology with other measurement techniques (inclinometer casing) is provided. Actually, this paper presents a case study in which the opportunity arose to compare these two technologies in detecting subsurface deformation in slopes. A TDR system includes a radar wave receiver & generator, a transmission line and a waveguide. The generated electro-magnetic pulse moves toward the waveguide within the conductor cable and enters the test environment. For this study, slopes overlooking the Darian dam bottom outlet, power house and spillway were instrumented with RG59/U coaxial cables for TDR monitoring and slope inclinometer. Coaxial cables - as a TDR sensor - and inclinometer casings were installed in a same bore hole where coaxial cable was attached to the inclinometer casing. Shear and tensile deformations of the cable, which is caused by ground movements, significantly impacts on cable reflection coefficient. In Darian dam boreholes, the cable points subject to the shear and stretch were correlated with deformation points of the inclinometer casings in incremental displacement graphs. This study shows that TDR technique is more sensitive than inclinometer casing for small movement in the slide planes. Because manual processing of TDR data is hard and need experienced personnel, the authors have designed an algorithm to compare the shape of the new TDR waveforms with the base reading waveform in order to monitor the subsurface deformations.

Tunable Engineered Skin Mechanics via Coaxial Electrospun Fiber Core Diameter

PubMed Central

Blackstone, Britani Nicole; Drexler, Jason William

2014-01-01

Autologous engineered skin (ES) offers promise as a treatment for massive full thickness burns. Unfortunately, ES is orders of magnitude weaker than normal human skin causing it to be difficult to apply surgically and subject to damage by mechanical shear in the early phases of engraftment. In addition, no manufacturing strategy has been developed to tune ES biomechanics to approximate the native biomechanics at different anatomic locations. To enhance and tune ES biomechanics, a coaxial (CoA) electrospun scaffold platform was developed from polycaprolactone (PCL, core) and gelatin (shell). The ability of the coaxial fiber core diameter to control both scaffold and tissue mechanics was investigated along with the ability of the gelatin shell to facilitate cell adhesion and skin development compared to pure gelatin, pure PCL, and a gelatin-PCL blended fiber scaffold. CoA ES exhibited increased cellular adhesion and metabolism versus PCL alone or gelatin-PCL blend and promoted the development of well stratified skin with a dense dermal layer and a differentiated epidermal layer. Biomechanics of the scaffold and ES scaled linearly with core diameter suggesting that this scaffold platform could be utilized to tailor ES mechanics for their intended grafting site and reduce graft damage in vitro and in vivo. PMID:24712409

Shearing-induced asymmetry in entorhinal grid cells.

PubMed

Stensola, Tor; Stensola, Hanne; Moser, May-Britt; Moser, Edvard I

2015-02-12

Grid cells are neurons with periodic spatial receptive fields (grids) that tile two-dimensional space in a hexagonal pattern. To provide useful information about location, grids must be stably anchored to an external reference frame. The mechanisms underlying this anchoring process have remained elusive. Here we show in differently sized familiar square enclosures that the axes of the grids are offset from the walls by an angle that minimizes symmetry with the borders of the environment. This rotational offset is invariably accompanied by an elliptic distortion of the grid pattern. Reversing the ellipticity analytically by a shearing transformation removes the angular offset. This, together with the near-absence of rotation in novel environments, suggests that the rotation emerges through non-coaxial strain as a function of experience. The systematic relationship between rotation and distortion of the grid pattern points to shear forces arising from anchoring to specific geometric reference points as key elements of the mechanism for alignment of grid patterns to the external world.

Mixing in Shear Coaxial Jets with and without Acoustics (Briefing Charts)

DTIC Science & Technology

2012-05-21

and heat transfer fluctuations in a rocket engine – Irreparable damage can occur in əs • Combustion Instability caused a 4-yr delay in the...common choice for cryogenic liquid rocket engines • Interactions of transverse acoustics with injector’s own modes and mixing needs to be understood...Pr = 0.44 • LAR-thin , Pr = 0.44, J = 0.5 POM 2 POM 1 Average Snapshot Power Spectral Densities (PSD) of Temporal Coefficients of POMs 1 and 2

Design and Testing of Non-Toxic RCS Thrusters for Second Generation Reusable Launch Vehicle

NASA Technical Reports Server (NTRS)

Calvignac, Jacky; Tramel, Terri

2003-01-01

The current NASA Space Shuttle auxiliary propulsion system utilizes nitrogen tetroxide (NTO) and monomethylhydrazine (MMH), hypergolic propellants. This use of these propellants has resulted in high levels of maintenance and precautions that contribute to costly launch operations. By employing alternate propellant combinations, those less toxic to humans, the hazards and time required between missions can be significantly reduced. Use of alternate propellants can thereby increase the efficiency and lower the cost in launch operations. In support of NASA's Space Launch Initiative (SLI), TRW proposed a three-phase project structured to significantly increase the technology readiness of a high-performance reaction control subsystem (RCS) thruster using non-toxic propellant for an operationally efficient and reusable auxiliary propulsion system (APS). The project enables the development of an integrated primary/vernier thruster capable of providing dual-thrust levels of both 1000-lbf class thrust and 25-lbf thrust. The intent of the project is to reduce the risk associated with the development of an improved RCS flight design that meets the primary NASA objectives of improved safety and reliability while reducing systems operations and maintenance costs. TRW proposed two non-toxic auxiliary propulsion engine designs, one using liquid oxygen and liquid hydrogen and the other using liquid oxygen and liquid ethanol, as candidates to meet the goals of reliability and affordability at the RCS level. Both of these propellant combinations offer the advantage of a safe environment for maintenance, while at the same time providing adequate to excellent performance for a conventional liquid propulsion systems. The key enabling technology incorporated in both TRW thrusters is the coaxial liquid on liquid pintle injector. This paper will concentrate on only the design and testing of one of the thrusters, the liquid oxygen (LOX) and liquid hydrogen (LH2) thruster. The LOX/LH2 thruster design includes a LOX-centered pintle injector, consisting of two rows of slots that create a radial spoke spray pattern in the combustion chamber. The main fuel injector creates a continuous sheet of LH2 originating upstream of the LOX pintle injector. The two propellants impinge at the pintle slots, where the resulting momentum ratio and spray pattern determines the combustion efficiency and thermal effects on the hardware. Another enabling technology used in the design of this thruster is fuel film cooling through a duct, lining the inner wall of the combustion chamber barrel section. The duct is also acts as a secondary fuel injection point. The variation in the amount of LH2 used for the duct allows for adjustments in the cooling capacity for the thruster. The Non-Toxic LOX-LH2 RCS Workhorse Thruster was tested at the NASA Marshall Space Flight Center's Test Stand 500. Hot-fire tests were conducted between March 08, 2002 and April 05, 2002. All testing during the program base period were performed at sea-level conditions. During the test program, 7 configurations were tested, including 2 combustion chambers, 3 LOX injector pintle tips, and 4 LH2 injector stroke settings. The operating conditions that were surveyed varied thrust levels, mixture ratio and LH2 duct cooling flow. The copper heat sink chamber was used for 16 burns, each burn lasting from 0.4 to 10 seconds, totaling 51.4 seconds, followed by Haynes chamber testing ranging from 0.9 to 120 seconds, totaling 300.9 seconds. The total accumulated burn time for the test program is 352.3 seconds. C* efficiency was calculated and found to be within expectable limits for most operating conditions. The temperature on the Haynes combustion chamber remained below established material limits, with the exception of one localized hot spot. The test results demonstrate that both the coaxial liquid-on-liquid pintle injector design and fuel duct concepts are viable for the intended application. The thruster head-e design maintained cryogenic injection temperatures while firing, which validates the concept for minimal heat soak back. By injecting fuel into the duct, the throat temperatures were manageable, yet the split of fuel through the cooling duct does not compromise the overall combustion efficiency, which indicates that, provided proper design refinement, such a concept can be applied to a high-performance version of the thruster. These hot fire tests demonstrate the robustness of the duct design concept and good capability to withstand off-nominal operating conditions without adversely impacting the thermal response of the engine, a key design feature for a cryogenic thruster.

Catalase-only nanoparticles prepared by shear alone: Characteristics, activity and stability evaluation.

PubMed

Huang, Xiao-Nan; Du, Xin-Ying; Xing, Jin-Feng; Ge, Zhi-Qiang

2016-09-01

Catalase is a promising therapeutic enzyme; however, it carries risks of inactivation and rapid degradation when it is used in practical bioprocess, such as delivery in vivo. To overcome the issue, we made catalase-only nanoparticles using shear stress alone at a moderate shear rate of 217s(-1) in a coaxial cylinder flow cell. Properties of nanoparticles, including particle size, polydispersity index and zeta potential, were characterized. The conformational changes of pre- and post-sheared catalase were determined using spectroscopy techniques. The results indicated that the conformational changes of catalase and reduction in α-helical content caused by shear alone were less significant than that by desolvation method. Catalase-only nanoparticles prepared by single shear retained over 90% of its initial activity when compared with the native catalase. Catalase nanoparticles lost only 20% of the activity when stored in phosphate buffer solution for 72h at 4°C, whereas native catalase lost 53% under the same condition. Especially, the activity of nanogranulated catalase was decreased only slightly in the simulated intestinal fluid containing α-chymotrypsin during 4h incubation at 37°C, implying that the catalase nanoparticle was more resistant to the degradation of proteases than native catalase molecules. Overall, catalase-only nanoparticles offered a great potential to stabilize enzymes for various pharmaceutical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Velocity measurements in the near field of a diesel fuel injector by ultrafast imagery

NASA Astrophysics Data System (ADS)

Sedarsky, David; Idlahcen, Saïd; Rozé, Claude; Blaisot, Jean-Bernard

2013-02-01

This paper examines the velocity profile of fuel issuing from a high-pressure single-orifice diesel injector. Velocities of liquid structures were determined from time-resolved ultrafast shadow images, formed by an amplified two-pulse laser source coupled to a double-frame camera. A statistical analysis of the data over many injection events was undertaken to map velocities related to spray formation near the nozzle outlet as a function of time after start of injection. These results reveal a strong asymmetry in the liquid profile of the test injector, with distinct fast and slow regions on opposite sides of the orifice. Differences of ˜100 m/s can be observed between the `fast' and `slow' sides of the jet, resulting in different atomization conditions across the spray. On average, droplets are dispersed at a greater distance from the nozzle on the `fast' side of the flow, and distinct macrostructure can be observed under the asymmetric velocity conditions. The changes in structural velocity and atomization behavior resemble flow structures which are often observed in the presence of string cavitation produced under controlled conditions in scaled, transparent test nozzles. These observations suggest that widely used common-rail supply configurations and modern injectors can potentially generate asymmetric interior flows which strongly influence diesel spray morphology. The velocimetry measurements presented in this work represent an effective and relatively straightforward approach to identify deviant flow behavior in real diesel sprays, providing new spatially resolved information on fluid structure and flow characteristics within the shear layers on the jet periphery.

Numerical investigation of design and operational parameters on CHI spheromak performance

NASA Astrophysics Data System (ADS)

O'Bryan, J. B.; Romero-Talamas, C. A.; Woodruff, S.

2016-10-01

Nonlinear, extended-MHD computation with the NIMROD code is used to explore magnetic self-organization and performance with respect to externally controllable parameters in spheromaks formed with coaxial helicity injection. The goal of this study is to inform the design and operational parameters of proposed proof-of-principle spheromak experiment. The calculations explore multiple distinct phases of evolution (including adiabatic magnetic compression), which must be explored and optimized separately. Results indicate that modest changes to the design and operation of past experiments, e.g. SSPX [E.B. Hooper et al. PPCF 2012], could have significantly improved the plasma-current injector coupling efficiency and performance, particularly with respect to peak temperature and lifetime. Though we frequently characterize performance relative to SSPX, we are also exploring fundamentally different designs and modes of operation, e.g. flux compression. This work is supported by DAPRA under Grant No. N66001-14-1-4044.

Experimental investigation of coaxial-gun-formed plasmas injected into a background transverse magnetic field or plasma

NASA Astrophysics Data System (ADS)

Zhang, Yue; Fisher, Dustin M.; Gilmore, Mark; Hsu, Scott C.; Lynn, Alan G.

2018-05-01

Injection of coaxial-gun-formed magnetized plasmas into a background transverse vacuum magnetic field or into a background magnetized plasma has been studied in the helicon-cathode (HelCat) linear plasma device at the University of New Mexico [M. Gilmore et al., J. Plasma Phys. 81, 345810104 (2015)]. A magnetized plasma jet launched into a background transverse magnetic field shows emergent kink stabilization of the jet due to the formation of a sheared flow in the jet above the kink stabilization threshold 0.1kVA [Y. Zhang et al., Phys. Plasmas 24, 110702 (2017)]. Injection of a spheromak-like plasma into a transverse background magnetic field led to the observation of finger-like structures on the side with a stronger magnetic field null between the spheromak and the background field. The finger-like structures are consistent with magneto-Rayleigh-Taylor instability. Jets or spheromaks launched into a background, low-β magnetized plasma show similar behavior as above, respectively, in both cases.

Kinematic evolution of the Mbakop Pan-African granitoids (western Cameroon domain): An integrated AMS and EBSD approach

NASA Astrophysics Data System (ADS)

Bella Nké, B. E.; Njanko, T.; Mamtani, M. A.; Njonfang, E.; Rochette, P.

2018-06-01

This study integrates anisotropy of magnetic susceptibility, microstructural and crystallographic preferred orientation (CPO) data from the Mbakop granitic pluton (MGP; Pan-African age) in order to decipher its kinematic evolution. The MGP lies close to NE-SW branch of Central Cameroon Shear Zone (CCSZ) and is emplaced in gneissic basement. High mean magnetic susceptibility and presence of multi-domain magnetite are recorded. Quartz CPO measured using Electron Backscatter diffraction reveals dominance of rhomb , prism and prism slip in different samples, which is consistent with microstructures developed under upper greenschist/amphibolite facies conditions. Quartz CPO along with other kinematic indicators (feldspar porphyroclasts/mineral fish) indicate non-coaxial deformation was important during tectonic evolution of the MGP. Contrasting sense of shear is recorded implying multi-stage mylonitization in the Western Cameroon Domain. Top-towards-south sense of shear is related to regional D2 deformation (613-585 Ma), while top-towards-north is related to D3 (585-540 Ma). The magnetic fabric in MGP records D3. The obliquity between mean orientation of magnetic foliation (N12°E) and the NE-SW CCSZ branch (N48°E) gives kinematic vorticity number of 0.95. This indicates dominantly simple shear with a minor pure shear component. It is concluded that regional transpression was important during MGP emplacement.

Overview of the Fusion Z-Pinch Experiment FuZE

NASA Astrophysics Data System (ADS)

Weber, T. R.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; McLean, H. S.; Tummel, K. K.; Higginson, D. P.; Schmidt, A. E.; UW/LLNL Team

2016-10-01

Previously, the ZaP device, at the University of Washington, demonstrated sheared flow stabilized (SFS) Z-pinch plasmas. Instabilities that have historically plagued Z-pinch plasma confinement were mitigated using sheared flows generated from a coaxial plasma gun of the Marshall type. Based on these results, a new SFS Z-pinch experiment, the Fusion Z-pinch Experiment (FuZE), has been constructed. FuZE is designed to investigate the scaling of SFS Z-pinch plasmas towards fusion conditions. The experiment will be supported by high fidelity physics modeling using kinetic and fluid simulations. Initial plans are in place for a pulsed fusion reactor following the results of FuZE. Notably, the design relies on proven commercial technologies, including a modest discharge current (1.5 MA) and voltage (40 kV), and liquid metal electrodes. Supported by DoE FES, NNSA, and ARPA-E ALPHA.

Properties of two-fluid flowing equilibria observed in double-pulsing coaxial helicity injection on HIST

NASA Astrophysics Data System (ADS)

Kanki, T.; Nagata, M.

2013-10-01

Multi-pulsing coaxial helicity injection (M-CHI) method which aims to achieve both quasi-steady sustainment and good confinement has been proposed as a refluxing scenario of the CHI. To explore the usefulness of the M-CHI for spherical torus (ST) configurations, the double-pulsing operations have been carried out in the HIST, verifying the flux amplification and the formation of the closed flux surfaces after the second CHI pulse. The purpose of this study is to investigate the properties of the magnetic field and plasma flow structures during the sustainment by comparing the results of plasma flow, density, and magnetic fields measurements with those of two-fluid equilibrium calculations. The two-fluid flowing equilibrium model which is described by a pair of generalized Grad-Shafranov equations for ion and electron surface variables and Bernoulli equations for density is applied to reconstruct the ST configuration with poloidal flow shear observed in the HIST. Due to the negative steep density gradient in high field side, the toroidal field has a diamagnetic profile (volume average beta, < β > = 68 %) in the central open flux column region. The ion flow velocity with strong flow shear from the separatrix in the inboard side to the core region is the opposite direction to the electron flow velocity due to the diamagentic drift through the density gradient. The electric field is relatively small in the whole region, and thus the Lorentz force nearly balances with the two-fluid effect which is particularly significant in a region with the steep density gradient due to the ion and electron diamagnetic drifts.

Investigation of MHD Instabilities in Jets and Bubbles Using a Compact Coaxial Plasma Gun in a Background Magnetized Plasma

NASA Astrophysics Data System (ADS)

Zhang, Y.; Fisher, D. M.; Wallace, B.; Gilmore, M.; Hsu, S. C.

2016-10-01

A compact coaxial plasma gun is employed for experimental investigation of launching plasma into a lower density background magnetized plasma. Experiments are being conducted in the linear device HelCat at UNM. Four distinct operational regimes with qualitatively different dynamics are identified by fast CCD camera images. For regime I plasma jet formation, a global helical magnetic configuration is determined by a B-dot probe array data. Also the m =1 kink instability is observed and verified. Furthermore, when the jet is propagating into background magnetic field, a longer length and lifetime jet is formed. Axial shear flow caused by the background magnetic tension force contributes to the increased stability of the jet body. In regime II, a spheromak-like plasma bubble formation is identified when the gun plasma is injected into vacuum. In contrast, when the bubble propagates into a background magnetic field, the closed magnetic field configuration does not hold anymore and a lateral side, Reilgh-Taylor instability develops. Detailed experimental data and analysis will be presented for these cases.

Influence of large-scale motion on turbulent transport for confined coaxial jets. Volume 1: Analytical analysis of the experimental data using conditional sampling

NASA Technical Reports Server (NTRS)

Brondum, D. C.; Bennett, J. C.

1986-01-01

The existence of large scale coherent structures in turbulent shear flows has been well documented. Discrepancies between experimental and computational data suggest a necessity to understand the roles they play in mass and momentum transport. Using conditional sampling and averaging on coincident two component velocity and concentration velocity experimental data for swirling and nonswirling coaxial jets, triggers for identifying the structures were examined. Concentration fluctuation was found to be an adequate trigger or indicator for the concentration-velocity data, but no suitable detector was located for the two component velocity data. The large scale structures are found in the region where the largest discrepancies exist between model and experiment. The traditional gradient transport model does not fit in this region as a result of these structures. The large scale motion was found to be responsible for a large percentage downstream at approximately the mean velocity of the overall flow in the axial direction. The radial mean velocity of the structures was found to be substantially greater than that of the overall flow.

Combustion response to acoustic perturbation in liquid rocket engines

NASA Astrophysics Data System (ADS)

Ghafourian, Akbar

An experimental study of the effect of acoustic perturbations on combustion behavior of a model liquid propellant rocket engine has been carried out. A pair of compression drivers were used to excite transverse and longitudinal acoustic fields at strengths of up to 156.6 dB and 159.5 dB respectively in the combustion chamber of the experimental rocket engine. Propellant simulants were injected into the combustion chamber through a single element shear coaxial injector. Water and air were used in cold flow studies and ethanol and oxygen-enriched air were used as fuel and oxidizer in reacting hot flow studies. In cold flow studies an imposed transverse acoustic field had a more pronounced effect on the spray pattern than a longitudinal acoustic fields. A transverse acoustic field widened the spray by as much as 33 percent and the plane of impingement of the spray with chamber walls moved up closer to the injection plane. The behavior was strongly influenced by the gas phase velocity but was less sensitive to changes in the liquid phase velocity. In reacting hot flow studies the effects of changes in equivalence ratio, excitation amplitude, excitation frequency, liquid and gas phase velocity and chamber pressure on the response of the injector to imposed high frequency transverse acoustic excitation were measured. Reducing the equivalence ratio from 7.4 to 3.8 increased the chamber pressure response to the imposed excitation at 3000 Hz. Increasing the excitation amplitude from 147 dB to 155.6 dB at 3000 Hz increased the chamber pressure response to the excitation. In the frequency range of 1240 Hz to 3220 Hz, an excitation frequency of 3000 Hz resulted in the largest response of the chamber pressure indicating the importance of fluid dynamic coupling. Increasing the liquid phase velocity from 9.2 m/sec to 22.7 m/sec, did not change the amplitude of the chamber pressure response to excitation. This implied the importance of local equivalence ratio and not the overall equivalence ratio on chamber pressure response to excitation. Increasing the chamber pressure from 1.5 atm to 3.1 atm and gas phase velocity from 93.2 m/sec to 105.1 m/sec significantly increased the chamber pressure response to acoustic excitation. This emphasized the significance of the gas phase density and velocity. Measurements of the free radical C2 emission zone and Schlieren images indicated that transverse acoustic excitation moved the combustion zone closer to the injection plane and longitudinal acoustic excitation widened the combustion zone. The histogram of these images indicates that the area over which combustion takes place in the chamber increases under imposed acoustic excitation. This implied that more propellants combust prior to exiting from the exhaust nozzle under unsteady conditions.

Experimental investigation of recirculating cells in laminar coaxial jets.

NASA Technical Reports Server (NTRS)

Warpinski, N. R.; Nagib, H. M.; Lavan, Z.

1972-01-01

Utilizing several unique means of introducing smoke into the flow field for careful visualization in addition to hot-wire techniques, experiments are performed in a specially designed facility producing laminar flows up to considerably high Reynolds numbers. Characteristics of the cells and the flow conditions that bring them about are documented by smoke photographs in the Reynolds number velocity ratio plane and the results are compared to previous analytical predictions. The cells are found to fall into three categories with different flow characteristics involving unsteadiness in position, and shear layer instabilities which result in higher mixing with the outer streams.-

Studies in fat grafting: Part I. Effects of injection technique on in vitro fat viability and in vivo volume retention.

PubMed

Chung, Michael T; Paik, Kevin J; Atashroo, David A; Hyun, Jeong S; McArdle, Adrian; Senarath-Yapa, Kshemendra; Zielins, Elizabeth R; Tevlin, Ruth; Duldulao, Chris; Hu, Michael S; Walmsley, Graham G; Parisi-Amon, Andreina; Momeni, Arash; Rimsa, Joe R; Commons, George W; Gurtner, Geoffrey C; Wan, Derrick C; Longaker, Michael T

2014-07-01

Fat grafting has become increasingly popular for the correction of soft-tissue deficits at many sites throughout the body. Long-term outcomes, however, depend on delivery of fat in the least traumatic fashion to optimize viability of the transplanted tissue. In this study, the authors compare the biological properties of fat following injection using two methods. Lipoaspiration samples were obtained from five female donors, and cellular viability, proliferation, and lipolysis were evaluated following injection using either a modified Coleman technique or an automated, low-shear device. Comparisons were made to minimally processed, uninjected fat. Volume retention was also measured over 12 weeks after injection of fat under the scalp of immunodeficient mice using either the modified Coleman technique or the Adipose Tissue Injector. Finally, fat grafts were analyzed histologically. Fat viability and cellular proliferation were both significantly greater with the Adipose Tissue Injector relative to injection with the modified Coleman technique. In contrast, significantly less lipolysis was noted using the automated device. In vivo fat volume retention was significantly greater than with the modified Coleman technique at the 4-, 6-, 8-, and 12-week time points. This corresponded to significantly greater histologic scores for healthy fat and lower scores for injury following injection with the device. Biological properties of injected tissues reflect how disruptive and harmful techniques for placement of fat may be, and the authors' in vitro and in vivo data both support the use of the automated, low-shear devices compared with the modified Coleman technique.

Studies in Fat Grafting: Part I. Effects of Injection Technique on in vitro Fat Viability and in vivo Volume Retention

PubMed Central

Chung, Michael T.; Paik, Kevin J.; Atashroo, David A.; Hyun, Jeong S.; McArdle, Adrian; Senarath-Yapa, Kshemendra; Zielins, Elizabeth R.; Tevlin, Ruth; Duldulao, Chris; Hu, Michael S.; Walmsley, Graham G.; Parisi-Amon, Andreina; Momeni, Arash; Rimsa, Joe R.; Commons, George W.; Gurtner, Geoffrey C.; Wan, Derrick C.; Longaker, Michael T.

2014-01-01

Background Fat grafting has become increasingly popular for the correction of soft tissue deficits at many sites throughout the body. Long-term outcomes, however, depend on delivery of fat in the least traumatic fashion to optimize viability of the transplanted tissue. In this study, we compare the biologic properties of fat following injection using two methods. Methods Lipoaspiration samples were obtained from five female donors and cellular viability, proliferation, and lipolysis were evaluated following injection using either a modified Coleman technique or an automated, low shear device. Comparisons were made to minimally processed, uninjected fat. Volume retention was also measured over twelve weeks following injection of fat under the scalp of immunodeficient mice using either the modified Coleman technique or the Adipose Tissue Injector. Finally, fat grafts were analyzed histologically. Results Fat viability and cellular proliferation were both significantly greater with the Adipose Tissue Injector relative to injection with the modified Coleman technique. In contrast, significantly less lipolysis was noted using the automated device. In vivo fat volume retention was significantly greater than with the modified Coleman technique at 4, 6, 8, and 12 week time points. This corresponded with significantly greater histological scores for healthy fat and lower scores for injury following injection with the device. Conclusions Biological properties of injected tissues reflect how disruptive and harmful techniques for placement of fat may be, and our in vitro and in vivo data both support the use of the automated, low shear devices compared to the modified Coleman technique. PMID:24622574

Progress with MGI and CHI Research on NSTX-U

NASA Astrophysics Data System (ADS)

Raman, R.; Lay, W.-S.; Jarboe, T. R.; Nelson, B. A.; Mueller, D.; Gerhardt, S. P.; Ebrahimi, F.; Jardin, S. C.; Taylor, G.

2016-10-01

NSTX-U experiments on Massive Gas Injection (MGI) will offer new insight to the MGI database by studying gas assimilation efficiencies for MGI gas injection from different poloidal locations. In support of this research, two ITER-type MGI valves have been successfully commissioned on NSTX-U. Results from the planned experiment `Comparison of Private Flux Region with Conventional Mid-plane MGI on NSTX-U', will be reported. In support of planned Coaxial Helicity Injection (CHI) research on NSTX-U, a new high-resolution grid has been generated for TSC simulations of CHI. This improves the resolution of the CHI injector region, and better models the closely-spaced divertor coils on NSTX-U. These new simulations support previous analysis that suggests a solenoid-free plasma current initiation capability of more than 400kA on NSTX-U. This work is supported by U.S. DOE Contracts: DE-AC02-09CH11466, DE-FG02-99ER54519 AM08, and DE-SC0006757.

CHI during an ohmic discharge in HIT-II

NASA Astrophysics Data System (ADS)

Mueller, Dennis; Nelson, Brian A.; Redd, Aaron J.; Hamp, William T.

2004-11-01

Coaxial Helicity Injection (CHI) has been used on the National Spherical Torus Experiment (NSTX), the Helicity Injected Torus (HIT) and HIT-II to initiate plasma and to drive up to 400 kA of toroidal current. The primary goal of the CHI systems is to provide a start-up plasma with substantial toroidal current that can be heated and sustained with other methods. We have investigated the use of CHI systems to add current to an established, inductively driven plasma. This may be an attractive method to add edge current that may modify the stability characteristics of the discharge or modify the particle and energy transport in a spherical torus. For example, divertor biasing experiments have been successful in modifying particle and energy transport in the scrape-off layer of tokamaks. Use of IGBT power supplies to modulate the injector current makes analysis of current penetration feasible by comparisons of before and after CHI using EFIT analysis of the data.

Numerical investigation of design and operation parameters on CHI spheromak performance

NASA Astrophysics Data System (ADS)

O'Bryan, J. B.; Romero-Talamás, C. R.; Woodruff, S.

2017-10-01

Nonlinear, numerical computation with the NIMROD code is used to explore magnetic self-organization in spheromaks formed with coaxial helicity injection, particularly with regard to how externally controllable parameters affect the resulting spheromak performance. The overall goal of our study is to inform the design and operational parameters of a future proof-of-principle spheromak experiment. Our calculations start from vacuum magnetic fields and model multiple distinct phases of evolution. Results indicate that modest changes to the design and operation of past experiments, e.g. SSPX [E.B. Hooper et al. PPCF 2012], could have significantly improved the plasma-current injector coupling efficiency and performance, particularly with respect to peak temperature and lifetime. While we frequently characterize performance relative to SSPX, our conclusions extrapolate to fundamentally different experimental designs. We also explore adiabatic magnetic compression of spheromaks, which may allow for a small-scale, high-performance and high-yield pulsed neutron source. This work is supported by DAPRA under Grant No. N66001-14-1-4044.

Oblique sinistral transpression in the Arabian shield: The timing and kinematics of a Neoproterozoic suture zone

USGS Publications Warehouse

Johnson, P.R.; Kattan, F.

2001-01-01

The Hulayfah-Ad Dafinah-Ruwah fault zone is a belt of highly strained rocks that extends in a broad curve across the northeastern Arabian shield. It is a subvertical shear zone, 5-30 km wide and over 600 km long, and is interpreted as a zone of oblique sinistral transpression that forms the suture between the Afif terrane and the Asir-Jiddah-Hijaz-Hulayfah superterrane. Available data suggest that the terranes began to converge sometime after 720 Ma, were in active contact at about 680 Ma, and were in place, with suturing complete, by 630 Ma, The fault zone was affected by sinistral horizontal and local vertical shear, and simultaneous flattening and fault-zone-parallel extension. Structures include sinistral sense-of-shear indicators, L-S tectonite, and coaxial stretching lineations and fold axes. The stretching lineations switch from subhorizontal to subvertical along the fault zone indicating significant variation in finite strain consistent with an origin by oblique transpression. The sense of shear on the fault zone suggests sinistral trajectories for the converging terranes, although extrapolating the shear sense of the suture zone to infer far-field motion must be done with caution. The amalgamation model derived from the chronologic and structural data for the fault zone modifies an existing model of terrane amalgamation and clarifies the definitions of two deformational events (the Nabitah orogeny and the Najd fault system) that are widely represented in the Arabian shield. ?? 2001 Elsevier Science B.V.

Liquid Oxygen/Liquid Methane Component Technology Development at MSFC

NASA Technical Reports Server (NTRS)

Robinson, Joel W.

2010-01-01

The National Aeronautics & Space Administration (NASA) has identified Liquid Oxygen (LOX)/Liquid Methane (LCH4) as a potential propellant combination for future space vehicles based upon exploration studies. The technology is estimated to have higher performance and lower overall systems mass compared to existing hypergolic propulsion systems. Besides existing in-house risk reduction activities, NASA has solicited from industry their participation on component technologies based on the potential application to the lunar ascent main engine (AME). Contracted and NASA efforts have ranged from valve technologies to engine system testbeds. The application for the AME is anticipated to be an expendable, pressure-fed engine for ascent from the moon at completion of its lunar stay. Additionally, the hardware is expected to provide an abort capability prior to landing, in the event that descent systems malfunction. For the past 4 years, MSFC has been working with the Glenn Research Center and the Johnson Space Center on methane technology development. This paper will focus on efforts specific to MSFC in pursuing ignition, injector performance, chamber material assessments and cryogenic valve technologies. Ignition studies have examined characteristics for torch, spark and microwave systems. Injector testing has yielded insight into combustion performance for shear, swirl and impinging type injectors. The majority of chamber testing has been conducted with ablative and radiatively cooled chambers with planned activities for regenerative and transpiration cooled chambers. Lastly, an effort is underway to examine the long duration exposure issues of cryogenic valve internal components. The paper will summarize the status of these efforts.

Introducing biomimetic shear and ion gradients to microfluidic spinning improves silk fiber strength.

PubMed

Li, David; Jacobsen, Matthew M; Gyune Rim, Nae; Backman, Daniel; Kaplan, David L; Wong, Joyce Y

2017-05-31

Silkworm silk is an attractive biopolymer for biomedical applications due to its high mechanical strength and biocompatibility; as a result, there is increasing interest in scalable devices to spin silk and recombinant silk so as to improve and customize their properties for diverse biomedical purposes (Vepari and Kaplan 2007 Prog. Polym. Sci. 32 ). While artificial spinning of regenerated silk fibroins adds tunability to properties such as degradation rate and surface functionalization, the resulting fibers do not yet approach the mechanical strength of native silkworm silk. These drawbacks reduce the applicability and attractiveness of artificial silk (Kinahan et al 2011 Biomacromolecules 12 ). Here, we used computational fluid dynamic simulations to incorporate shear in tandem with biomimetic ion gradients by coupling a modular novel glass microfluidic device to our previous co-axial flow device. Fibers spun with this combined apparatus demonstrated a significant increase in mechanical strength compared to fibers spun with the basic apparatus alone, with a three-fold increase in Young's modulus and extensibility and a twelve-fold increase in toughness. These results thus demonstrate the critical importance of ionic milieu and shear stress in spinning strong fibers from solubilized silk fibroin.

Structural analysis of sheath folds in the Sylacauga Marble Group, Talladega slate belt, southern Appalachians

USGS Publications Warehouse

Mies, J.W.

1993-01-01

Remnant blocks of marble from the Moretti-Harrah dimension-stone quarry provide excellent exposure of meter-scale sheath folds. Tubular structures with elliptical cross-sections (4 ???Ryz ??? 5) are the most common expression of the folds. The tubes are elongate subparallel to stretching lineation and are defined by centimeter-scale layers of schist. Eccentrically nested elliptical patterns and opposing asymmetry of folds ('S' and 'Z') are consistent with the sheath-fold interpretation. Sheath folds are locally numerous in the Moretti-Harrah quarry but are not widely distributed in the Sylacauga Marble Group; reconnaissance in neighboring quarries provided no additional observations. The presence of sheath folds in part of the Talladega slate belt indicates a local history of plastic, non-coaxial deformation. Such a history of deformation is substantiated by petrographic study of an extracted hinge from the Moretti-Harrah quarry. The sheath folds are modeled as due to passive amplification of initial structures during simple shear, using both analytic geometry and graphic simulation. As indicated by these models, relatively large shear strains (y ??? 9) and longitudinal initial structures are required. The shear strain presumably relates to NW-directed displacement of overlying crystalline rocks during late Paleozoic orogeny. ?? 1993.

Petrofabrics of high-pressure rocks exhumed at the slab-mantle interface from the "point of no return" in a subduction zone (Sivrihisar, Turkey)

NASA Astrophysics Data System (ADS)

Whitney, Donna L.; Teyssier, Christian; Seaton, Nicholas C. A.; Fornash, Katherine F.

2014-12-01

The highest pressure recorded by metamorphic rocks exhumed from oceanic subduction zones is 2.5 GPa, corresponding to the maximum decoupling depth (MDD) (80 ± 10 km) identified in active subduction zones; beyond the MDD (the "point of no return") exhumation is unlikely. The Sivrihisar massif (Turkey) is a coherent terrane of lawsonite eclogite and blueschist facies rocks in which assemblages and fabrics record P-T-fluid-deformation conditions during exhumation from 80 to 45 km. Crystallographic fabrics and other features of high-pressure metasedimentary and metabasaltic rocks record transitions during exhumation. In quartzite, microstructures and crystallographic fabrics record deformation in the dislocation creep regime, including dynamic recrystallization during decompression, and a transition from prism slip to activation of rhomb and basal slip that may be related to a decrease in water fugacity during decompression ( 2.5 to 1.5 GPa). Phengite, lawsonite, and omphacite or glaucophane in quartzite and metabasalt remained stable during deformation, and omphacite developed an L-type crystallographic fabric. In marble, aragonite developed columnar textures with strong crystallographic fabrics that persisted during partial to complete dynamic recrystallization that was likely achieved in the stability field of aragonite (P > 1.2 GPa). Results of kinematic vorticity analysis based on lawsonite shape fabrics are consistent with shear criteria in quartzite and metabasalt and indicate a large component of coaxial deformation in the exhuming channel beneath a simple shear dominated interface. This large coaxial component may have multiplied the exhuming power of the subduction channel and forced deeply subducted rocks to flow back from the point of no return.

Producing High-Performance, Stable, Sheared-Flow Z-Pinches in the FuZE project

NASA Astrophysics Data System (ADS)

Golingo, R. P.; Shumlak, U.,; Nelson, B. A.; Claveau, E. L.; Forbes, E. G.; Stepanov, A. D.; Weber, T. R.; Zhang, Y.; McLean, H. S.; Tummel, K. K.; Higginson, D. P.; Schmidt, A. E.; University of Washington (UW) Collaboration; Lawrence Livermore National Laboratory (LLNL) Collaboration

2017-10-01

The Fusion Z-Pinch Experiment (FuZE) has made significant strides towards generating high-performance, stable Z-pinch plasmas with goals of ne = 1018 cm-3 and T =1 keV. The Z-pinch plasmas are stabilized with a sheared axial flow that is driven by a coaxial accelerator. The new FuZE device has been constructed and reproduces the major scientific achievements the ZaP project at the University of Washington; ne = 1016 cm-3,T = 100 eV, r<1 cm, and tstable >20 μs. These parameters are measured with an array of magnetic field probes, spectroscopy, and fast framing cameras. The plasma parameters are achieved using a small fraction of the maximum energy storage and gas injection capability of the FuZE device. Higher density, ne = 5×1017 cm-3, and temperature, T = 500 eV, Z-pinch plasmas are formed by increasing the pinch current. At the higher voltages and currents, the ionization rates in the accelerator increase. By modifying the neutral gas profile in the accelerator, the plasma flow from the accelerator is maintained, driving the flow shear. Formation and sustainment of the sheared-flow Z-pinch plasma will be discussed. Experimental data demonstrating high performance plasmas in a stable Z-pinches will be shown. This work is supported by an award from US ARPA-E.

The LS-STAG immersed boundary method for non-Newtonian flows in irregular geometries: flow of shear-thinning liquids between eccentric rotating cylinders

NASA Astrophysics Data System (ADS)

Botella, Olivier; Ait-Messaoud, Mazigh; Pertat, Adrien; Cheny, Yoann; Rigal, Claire

2015-04-01

This paper presents the extension of a well-established immersed boundary/cut-cell method, the LS-STAG method (Cheny and Botella in J Comput Phys 229:1043-1076, 2010), to non-Newtonian flow computations in 2D irregular geometries. One of the distinguished features of our IB method is to use level-set techniques in the cut-cells near the irregular boundary, where accurate discretization is of paramount importance for stability and accuracy of the computations. For this purpose, we present here an accurate discretization of the velocity gradients and shear rate in the cut-cells that fits elegantly in the framework of the velocity-pressure-stress staggered arrangement and the special quadratures developed previously for viscoelastic flows. After assessing the accuracy of the discretization on a benchmark solution for power-law fluids, the LS-STAG code is applied to the flow of various shear-thinning xanthan solutions in a wide-gap, non-coaxial, Taylor-Couette reactor for which rheological characterization, experimental flow measurements (PIV) and FLUENT simulations have recently been performed in our group. Our numerical investigation will give new insight on the flow patterns (onset, size and position of the recirculation zone) and will firmly correlate them to global flow properties such as shear-thinning index, generalized Reynolds number and torque ratio at the cylinders.

Study on effect of mixing mechanism by the transverse gaseous injection flow in scramjet engine with variable parameters

NASA Astrophysics Data System (ADS)

Yadav, Siddhita; Pandey, K. M.

2018-04-01

In scramjet engine the mixing mechanism of fuel and atmospheric air is very complicated, because the fuel have time in milliseconds for mixing with atmospheric air in combustion chamber having supersonic speed. Mixing efficiency of fuel and atmospheric air depends on mainly these parameters: Aspect ratio of injector, vibration amplitude, shock type, number of injector, jet to transverse flow momentum flux ratio, injector geometry, injection angle, molecular weight, incoming air stream angle, jet to transverse flow pressure ratio, spacing variation, mass flow rate of fuel etc. here is a very brief study of these parameters from previously done research on these parameters for the improvement of mixing efficiency. The mixing process have the significant role for the working of engine, and mixing between the atmospheric air and the jet fuel is significant factor for improving the overall thrust of the engine. The results obtained by study of papers are obtained by the 3D-Reynolds Average-Nervier-Stokes(RANS) equations along with the 2-equation k-ω shear-stress-transport (SST) turbulence model. Engine having multi air jets have 60% more mixing efficiency than single air jet, thus if the jets are increased, the mixing efficiency of engine can also be increased up to 150% by changing jet from 1 to 16. When using delta shape of injector the mixing efficiency is inversely proportional to the pressure ratio. When the fuel is injected inside the combustor from the top and bottom walls of the engine efficiency of mixing in reacting zone is higher than the single wall injection and in comparison to parallel flow, the transverse type flow is better as the atmospheric air jet can penetrate smoothly in the fuel jets and mixes well in less time. Hence this study of parameters and their effects on mixing can enhance the efficiency of mixing in engine.

Multi-ported, internally recuperated burners for direct flame impingement heating applications

DOEpatents

Abbasi, Hamid A.; Kurek, Harry; Chudnovsky, Yaroslav; Lisienko, Vladimir G.; Malikov, German K.

2010-08-03

A direct flame impingement method and apparatus employing at least one multi-ported, internally recuperated burner. The burner includes an innermost coaxial conduit having a first fluid inlet end and a first fluid outlet end, an outermost coaxial conduit disposed around the innermost coaxial conduit and having a combustion products outlet end proximate the first fluid inlet end of the innermost coaxial conduit and a combustion products inlet end proximate the first fluid outlet end of the innermost coaxial conduit, and a coaxial intermediate conduit disposed between the innermost coaxial conduit and the outermost coaxial conduit, whereby a second fluid annular region is formed between the innermost coaxial conduit and the intermediate coaxial conduit and a combustion products annular region is formed between the intermediate coaxial conduit and the outermost coaxial conduit. The intermediate coaxial conduit has a second fluid inlet end proximate the first fluid inlet end of the innermost coaxial conduit and a second fluid outlet end proximate the combustion products inlet end of the outermost coaxial conduit.

Plasmoids formation in a laboratory and large-volume flux closure during simulations of Coaxial Helicity Injection in NSTX-U

NASA Astrophysics Data System (ADS)

Ebrahimi, Fatima

2016-10-01

In NSTX-U, transient Coaxial Helicity Injection (CHI) is the primary method for current generation without reliance on the solenoid. A CHI discharge is generated by driving current along open field lines (the injector flux) that connect the inner and outer divertor plates on NSTX/NSTX-U, and has generated over 200 kA of toroidal current on closed flux surfaces in NSTX. Extrapolation of the concept to larger devices requires an improved understanding of the physics of flux closure and the governing parameters that maximizes the fraction of injected flux that is converted to useful closed flux. Here, through comprehensive resistive MHD NIMROD simulations conducted for the NSTX and NSTX-U geometries, two new major findings will be reported. First, formation of an elongated Sweet-Parker current sheet and a transition to plasmoid instability has for the first time been demonstrated by realistic global simulations. This is the first observation of plasmoid instability in a laboratory device configuration predicted by realistic MHD simulations and then supported by experimental camera images from NSTX. Second, simulations have now, for the first time, been able to show large fraction conversion of injected open flux to closed flux in the NSTX-U geometry. Consistent with the experiment, simulations also show that reconnection could occur at every stage of the helicity injection phase. The influence of 3D effects, and the parameter range that supports these important new findings is now being studied to understand the impact of toroidal magnetic field and the electron temperature, both of which are projected to increase in larger ST devices. Work supported by DOE DE-SC0010565.

Computational study of fuel injection in a shcramjet inlet

NASA Astrophysics Data System (ADS)

Parent, Bernard

The primary objective of this investigation is to present the mixing of fuel with air in the inlet of a shock-induced combustion ramjet (shcramjet). The study is limited to non-reacting hydrogen-air mixing in an external-compression inlet at a flight Mach number of 11 and at a dynamic pressure of 1400 psf (67032 Pa), using an array of cantilevered ramp injectors. A numerical method based on the Yee-Roe scheme and block-implicit approximate factorization is developed to solve the FANS equations closed by the Wilcox ko turbulence model. A new acceleration technique for streamwise-separated hypersonic flow, dubbed the "marching window", is presented. The dilatational dissipation correction is seen to affect the mixing efficiency considerably for a cantilevered ramp injector flowfield even at a vanishing convective Mach number, due to the high turbulent Mach number generated by the high cross-stream shear induced by the ramp-generated axial vortices. Due to the fuel being injected at a very high speed, fuel injection in the inlet is found to increase considerably the thrust potential, with a gain exceeding the loss by 40--120%. Losses due to skin friction are seen to play a significant role in the inlet, as they are estimated to make up as much as 50--70% of the thrust potential losses. The use of a turbulence model that can predict accurately the wall shear stress is hence crucial in assessing the losses accurately in a shcramjet inlet. Substituting the second inlet shock by a Prandtl-Meyer compression fan is encouraged as it decreases the thrust potential losses, reduces the risk of premature ignition by reducing the static temperature, while decreasing the mixing efficiency by a mere 6%. One approach that is observed herein to be successful at increasing the mixing efficiency in the inlet is by alternating the injection angle along the injector array. The use of two injection angles of 9 and 16 degrees is seen to result in a 32% increase in the mixing efficiency at the expense of a 14% increase in the losses when compared to a single injection angle of 10 degrees. Using alternating injection angles, the mixing efficiency reaches as much as 0.47 at the inlet exit.

Flux amplification in helicity injected spherical tori

NASA Astrophysics Data System (ADS)

Tang, X. Z.; Boozer, A. H.

2005-04-01

An important measure of the effective current drive by helicity injection into spheromaks and spherical tori is provided by the flux amplification factor, defined as the ratio between the closed poloidal flux in the relaxed mean field and the initial injector vacuum poloidal flux. Flux amplification in magnetic helicity injection is governed by a resonant behavior for Taylor-relaxed plasmas satisfying j =kB. Under the finite net toroidal flux constraint in a spherical torus (ST), the constrained linear resonance k1c is upshifted substantially from the primary Jensen-Chu resonance k1 that was known to be responsible for flux amplification in spheromak formation. Standard coaxial helicity injection into a ST operates at large M, with M the characteristic dimensionless parameter defined as the ratio between the toroidal flux in the discharge chamber and the injector poloidal flux. Meaningful flux amplification for ST plasmas is limited by a critical kr at which edge toroidal field reverses its direction. The kr is downshifted from k1 by a small amount inversely proportional to M. The maximum flux amplification factor Ar≡A(k=kr) scales linearly with M. At the other end of k, substantial flux amplification A(k =ko)˜1 becomes available for ko that scales inversely proportional to M, a significant departure from that in spheromak formation. These important parameters follow the inequality ko

Investigation of the adhesive bonding technology for the insulator structure of EAST neutral beam injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Jiang-Long, E-mail: jlwei@ipp.ac.cn; Li, Jun; Hu, Chun-Dong

A key issue on the development of EAST ion source was the junction design of insulator structure, which consists of three insulators and four supporting flanges of electrode grid. Because the ion source is installed on the vertical plane, the insulator structure has to withstand large bending and shear stress due to the gravity of whole ion source. Through a mechanical analysis, it was calculated that the maximum bending normal stress was 0.34 MPa and shear stress was 0.23 MPa on the insulator structure. Due to the advantages of simplicity and high strength, the adhesive bonding technology was applied tomore » the junction of insulator structure. A tensile testing campaign of different junction designs between insulator and supporting flange was performed, and a junction design of stainless steel and fiber enhanced epoxy resin with epoxy adhesive was determined. The insulator structure based on the determined design can satisfy both the requirements of high-voltage holding and mechanical strength.« less

Blunt body near wake flow field at Mach 6

NASA Technical Reports Server (NTRS)

Horvath, Thomas J.; McGinley, Catherine B.; Hannemann, Klaus

1996-01-01

Tests were conducted in a Mach 6 flow to examine the reattachment process of an axisymmetric free shear layer associated with the near wake of a 70 deg. half angle, spherically blunted cone with a cylindrical after body. Model angle of incidence was fixed at 0 deg. and free-stream Reynolds numbers based on body diameter ranged from 0.5 x 10(exp 6) to 4 x 10(exp 6). The sensitivity of wake shear layer transition on reattachment heating was investigated. The present perfect gas study was designed to compliment results obtained previously in facilities capable of producing real gas effects. The instrumented blunted cone model was designed primarily for testing in high enthalpy hypervelocity shock tunnels in both this country and abroad but was amenable for testing in conventional hypersonic blowdown wind tunnels as well. Surface heating rates were inferred from temperature - time histories from coaxial surface thermocouples on the model forebody and thin film resistance gages along the model base and cylindrical after body. General flow feature (bow shock, wake shear layer, and recompression shock) locations were visually identified by schlieren photography. Mean shear layer position and growth were determined from intrusive pitot pressure surveys. In addition, wake surveys with a constant temperature hot-wire anemometer were utilized to qualitatively characterize the state of the shear layer prior to reattachment. Experimental results were compared to laminar perfect gas predictions provided by a 3-D Navier Stokes code (NSHYP). Shear layer impingement on the instrumented cylindrical after body resulted in a localized heating maximum that was 21 to 29 percent of the forebody stagnation point heating. Peak heating resulting from the reattaching shear layer was found to be a factor of 2 higher than laminar predictions, which suggested a transitional shear layer. Schlieren flow visualization and fluctuating voltage time histories and spectra from the hot wire surveys across the shear layer substantiate this observation. The sensitivity of surface heating to forebody roughness was characterized for a reattaching shear layer. For example, at R(sub infinity), d = 4 x 10(exp 6), when the shear layer was transitional, the magnitude of peak heating from shear layer impingement was reduced by approximately 24 percent when transition grit was applied to the forebody. The spatial location of the local peak, however, remained unchanged.

An Internal Coaxial Cable Electrical Connector For Use In Downhole Tools

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron; Briscoe, Michael

2005-11-29

A coaxial cable electrical connector more specifically an internal coaxial cable connector placed within a coaxial cable and its constituent components. A coaxial cable connector is in electrical communcation with an inductive transformer and a coaxial cable. The connector is in electrical communication with the outer housing of the inductive transfonner. A generally coaxial center conductor, a portion of which could be the coil in the inductive transformer, passes through the connector, is electrically insulated from the connector, and is in electrical communication with the conductive care of the coaxial cable. A plurality of bulbous pliant tabs on the coaxial cable connector mechanically engage the inside diameter of the coaxial cable thus grounding the transformer to the coaxial cable. The coaxial cable and inductive transformer are disposed within downhole tools to transmit electrical signals between downhole tools within a drill string.

Influence of nanodispersed modifications of magnetite powders on spray nozzle efficiency of diesel engine injector

NASA Astrophysics Data System (ADS)

Saidov, M. A.; Perekrestov, A. P.

2017-10-01

The paper presents data on the impact of new environmental requirements relating to the quality of diesel fuel on the anti-wear properties of fuel. Anti-wear additive is proposed as a material for increasing the tribotechnical characteristics of diesel fuel. This additive consists of diesel fuel with micelles contained in it, formed on the basis of molecules of solid plasticity lubrication of iron oxide (Fe3O4) - magnetite, and with surrounding molecules of oleic acid (C18H34O2). The additive has low shear resistance and increased lubricity of diesel fuel when this additive is introduced into it.

Measurements of Doppler-ion temperature and flow in the multi-pulsing CHI experiment on HIST

NASA Astrophysics Data System (ADS)

Hanao, T.; Ishihara, M.; Hirono, H.; Hyobu, T.; Ito, K.; Matsumoto, K.; Nakayama, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2012-10-01

The steady-state current sustainment of spherical torus (ST) configurations is expected to be achieved by Multi-pulsing Coaxial Helicity Injection (M-CHI) method. In the double-pulsing discharges, the plasma current can be sustained much longer against the resistive decay compared to the single CHI. The M-CHI has capabilities as a static ion heating method. Ion Doppler Spectrometer (IDS) measurements confirmed a significant increase in the ion temperature after the second CHI pulse. The ion heating mechanism is an important issue to be explored in the M-CHI experiments. It is considered due to the magnetic reconnection process of plasmoids and/or the damping of the Alfven wave. The ion heating becomes suppressed around the separatrix layer in the high field side where the amplitude of the magnetic fluctuations is minimized due to the poloidal flow shear. The shear flow generation is caused by ExB drift and ion diamagnetic drift. The contribution from the diamagnetic drift on the shear flow can be evaluated by measuring the flow velocity of hydrogen and impurity ions by using Mach probe and IDS. We will discuss the dependence of the ion heating characteristics on the variation of the density gradient by varying TF coil current.

Blunt Body Near-Wake Flow Field at Mach 10

NASA Technical Reports Server (NTRS)

Horvath, Thomas; Hannemann, Klaus

1997-01-01

Tests were conducted in a Mach 10 air flow to examine the reattachment process of a free shear layer associated with the near wake of a 70 deg half angle, spherically blunted cone having a cylindrical after body. The nominal free-stream Reynolds number based on model diameter ranged from 0.25 x l0(exp 6) to 1 x l0(exp 6) and the angle of incidence set at 0 and +/- 20 deg. The present study was designed to complement previously reported Mach 6 perfect air tests as well as results obtained in several hypervelocity facilities capable of producing real gas effects. Surface heating rates were inferred from temperature time histories from coaxial surface thermocouples on the model forebody and thin film resistance gages along the model base and cylindrical after body. Limited forebody, base, and support sting surface pressures were obtained with piezoresistive Experimental results are compared to laminar perfect gas predictions provided by a 3-0 Navier Stokes code (NSHYP). Shear layer impingement on the instrumented cylindrical after body resulted in a localized heating maximum that was 16 to 18percent of the forebody stagnation point and a factor of 2 higher than laminar predictions, suggesting a transitional or turbulent shear layer. transducers.

First demonstration of simultaneous measurement of beam current, beam position, and beam tilt on induction linac using combined B-dot monitor

NASA Astrophysics Data System (ADS)

He, Xiaozhong; Pang, Jian; Chen, Nan; Li, Qin; Dai, Wenhua; Ma, Chaofan; Zhao, Liangchao; Gao, Feng; Dai, Zhiyong

2017-06-01

The authors previously reported that the axial B-dots can be used to directly measure the beam tilt and demonstrated that the axial B-dots are applicable to a coaxial calibration stand. In this study, a combined B-dot monitor composed of four axial B-dot loops and four azimuthal ones is tested for the simultaneous measurement of the time-varying beam current, beam offset, and beam tilt at the output of the injector of the DRAGON-I induction linac. In the experiments, the beam offset and beam tilt at the position of the monitor are proportionally adjusted using a pair of steering coils. Eight waveforms acquired from the B-dot monitor are analyzed to reconstruct the time-varying beam current, beam offset, and beam tilt. The original signals of both the azimuthal B-dot and the axial B-dot ports change significantly with respect to the current applied to the steering coils. The measured beam tilt is linearly dependent on the current applied to the steering coils and agrees well with the measured beam offset.

A tandem mirror hybrid plume plasma propulsion facility

NASA Technical Reports Server (NTRS)

Chang-Diaz, F. R.; Yang, T. F.; Krueger, W. A.; Peng, S.; Urbahn, J.; Yao, X.; Griffin, D.

1988-01-01

A concept in electrodeless plasma propulsion, which is also capable of delivering a variable Isp, is presented. The concept involves a three-stage system of plasma injection, heating, and subsequent ejection through a magnetic nozzle. The nozzle produces the hybrid plume by the coaxial injection of hypersonic neutral gas. The gas layer, thus formed, protects the material walls from the hot plasma and, through increased collisions, helps detach it from the diverging magnetic field. The physics of this concept is evaluated numerically through full spatial and temporal simulations; these explore the operating characteristics of such a device over a wide region of parameter space. An experimental facility to study the plasma dynamics in the hybrid plume was built. The device consists of a tandem mirror operating in an asymmetric mode. A later upgrade of this system will incorporate a cold plasma injector at one end of the machine. Initial experiments involve the full characterization of the operating envelope, as well as extensive measurements of plasma properties at the exhaust. The results of the numerical simulations are described.

Experimental studies of characteristic combustion-driven flows for CFD validation

NASA Technical Reports Server (NTRS)

Santoro, R. J.; Moser, M.; Anderson, W.; Pal, S.; Ryan, H.; Merkle, C. L.

1992-01-01

A series of rocket-related studies intended to develop a suitable data base for validation of Computational Fluid Dynamics (CFD) models of characteristic combustion-driven flows was undertaken at the Propulsion Engineering Research Center at Penn State. Included are studies of coaxial and impinging jet injectors as well as chamber wall heat transfer effects. The objective of these studies is to provide fundamental understanding and benchmark quality data for phenomena important to rocket combustion under well-characterized conditions. Diagnostic techniques utilized in these studies emphasize determinations of velocity, temperature, spray and droplet characteristics, and combustion zone distribution. Since laser diagnostic approaches are favored, the development of an optically accessible rocket chamber has been a high priority in the initial phase of the project. During the design phase for this chamber, the advice and input of the CFD modeling community were actively sought through presentations and written surveys. Based on this procedure, a suitable uni-element rocket chamber was fabricated and is presently under preliminary testing. Results of these tests, as well as the survey findings leading to the chamber design, were presented.

Fundamental Mixing and Combustion Experiments for Propelled Hypersonic Flight

NASA Technical Reports Server (NTRS)

Cutler, A. D.; Diskin, G. S.; Danehy, P. M.; Drummond, J. P.

2002-01-01

Two experiments have been conducted to acquire data for the validation of computational fluid dynamics (CFD) codes used in the design of supersonic combustors. The first experiment is a study of a supersonic coaxial jet into stagnant air in which the center jet is of a light gas, the coflow jet is of air, and the mixing layer between them is compressible. The jet flow field is characterized using schlieren imaging, surveys with Pitot, total temperature and gas sampling probes, and RELIEF velocimetry. VULCAN, a structured grid CFD code, is used to solve for the nozzle and jet flow. The second experiment is a study of a supersonic combustor consisting of a diverging duct with single downstream-angled wall injector. Entrance Mach number is 2 and enthalpy is nominally that of Mach 7 flight. Coherent anti-Stokes Raman spectroscopy (CARS) has been used to obtain nitrogen temperature in planes of the flow, and surface pressures and temperatures have also been acquired. Modern-design-of-experiment techniques have been used to maximize the quality of the data set.

BHQ revisited (1) - Looking at grain size

NASA Astrophysics Data System (ADS)

Heilbronner, Renée; Kilian, Rüdiger; Tullis, Jan

2016-04-01

Black Hills Quartzite (BHQ) has been used extensively in experimental rock deformation for numerous studies. Coaxial and general shear experiments have been carried out, for example, to define the dislocation creep regimes of quartz (Hirth & Tullis, 1992), to determine the effect of annealing (Heilbronner & Tullis, 2002) or to study the development of texture and microstructure with strain (Heilbronner & Tullis, 2006). BHQ was also used to determine the widely used quartz piezometer by Stipp & Tullis (2003). Among the microstructure analyses that were performed in those original papers, grain size was usually determined using CIP misorientation images. However, the CIP method (= computer-integrated polarization microscopy, details in Heilbronner and Barrett, 2014) is only capable of detecting the c-axis orientation of optically uniaxial materials and hence is only capable of detecting grain boundaries between grains that differ in c-axis orientation. One of the puzzling results we found (Heilbronner & Tullis, 2006) was that the recrystallized grain size seemed to depend on the crystallographic preferred orientation of the domain. In other words the grain size did not only depend on the flow stress but also on the orientation of the c-axis w/r to the shear direction. At the time, no EBSD analysis (electron back scatter diffraction) was carried out and hence the full crystallographic orientation was not known. In principle it is therefore possible that we missed some grain boundaries (between grains with parallel c-axes) and miscalculated our grain sizes. In the context of recent shear experiments on quartz gouge at the brittle-viscous transition (see Richter et al., this conference), where EBSD is used to measure the recrystallized grain size, we wanted to re-measure the CIP grain sizes of our 2006 samples (deformed in regime 1, 2 and 3 of dislocation) in exactly the same way. In two companion posters we use EBSD orientation imaging to repeat, refine and expand the microstructure and texture analysis of Heilbronner & Tullis (2006). Here, in poster (1), we focus on the recrystallized grain size with the aim of (a) comparing CIP- and EBSD derived grain size measurements, (b) of comparing the recrystallized grain size of coaxially deformed and sheared BHQ and (c) in order to confirm that the quartz piezometer indeed depends on texture, and (d) to test if it also depends on the type of deformation (irrotational versus rotational deformation). References cited: Heilbronner, R., and S.D. Barrett (2014) Image Analysis in Earth Sciences, Springer. Heilbronner, R., and J. Tullis (2002), The effect of static annealing on micro- structure and crystallographic preferred orientations of quartzites experimentally deformed in axial compression and shear, Geol. Soc. Spec. Publ., 200, 191 - 218. Heilbronner, R., and J. Tullis (2006), Evolution of c axis pole figures and grain size during dynamic recrystallization: Results from experimentally sheared quartzite. JGR, 111, B10202, doi:10.1029/2005JB004194, 2006 Hirth, G., and J. Tullis (1992), Dislocation creep regimes in quartz aggregates, JSG, 14, 145-159. Stipp, M., and J. Tullis (2003), The recrystallized grain size piezometer for quartz, Geophys. Res. Lett., 30(21), 2088, doi:10.1029/2003GL018444.

Gas Turbine Engine Staged Fuel Injection Using Adjacent Bluff Body and Swirler Fuel Injectors

NASA Technical Reports Server (NTRS)

Snyder, Timothy S. (Inventor)

2015-01-01

A fuel injection array for a gas turbine engine includes a plurality of bluff body injectors and a plurality of swirler injectors. A control operates the plurality of bluff body injectors and swirler injectors such that bluff body injectors are utilized without all of the swirler injectors at least at low power operation. The swirler injectors are utilized at higher power operation.

An experimental study of planar heterogeneous supersonic confined jets

NASA Astrophysics Data System (ADS)

Tanis, Frederick J., Jr.

1994-12-01

The effects of varying the exit pressure of a supersonic helium jet exhausting coaxially with two parallel supersonic air streams into a constant area duct were investigated. The method used to evaluate the mass entrainment rate was to measure helium molar concentration profiles and mass flux across the duct using a binary gas probe then calculate the mass entrainment into the helium jet. In order to conduct this study a novel binary gas probe was developed which allowed helium concentration and mass flux data to be obtained during continuous traverses across the supersonic flowfield. High exit pressure ratio (EPR) led to improved overall mixing compared to the baseline case with an EPR near unity. The high EPR caused low mass entrainment along the jet shear layers due to high convective Mach numbers and velocity ratios, but the high EPR caused oblique shocks to form which reflected off the duct walls and intersected with the helium jet several times causing significant mass entrainment due to numerous shock-shear layer interactions (SSLI's). A correlation between the vorticity generated during a SSLI and the mass entrainment into the jet was developed.

Cyclic axial-torsional deformation behavior of a cobalt-base superalloy

NASA Technical Reports Server (NTRS)

Bonacuse, Peter J.; Kalluri, Sreeramesh

1992-01-01

Multiaxial loading, especially at elevated temperature, can cause the inelastic response of a material to differ significantly from that predicted by simple flow rules, i.e., von Mises or Tresca. To quantify some of these differences, the cyclic high-temperature, deformation behavior of a wrought cobalt-based superalloy, Haynes 188, is investigated under combined axial and torsional loads. Haynes 188 is currently used in many aerospace gas turbine and rocket engine applications, e.g., the combustor liner for the T800 turboshaft engine for the RAH-66 Comanche helicopter and the liquid oxygen posts in the main injector of the space shuttle main engine. The deformation behavior of this material is assessed through the examination of hysteresis loops generated from a biaxial fatigue test program. A high-temperature axial, torsional, and combined axial-torsional fatigue data base has been generated on Haynes 188 at 760 C. Cyclic loading tests have been conducted on uniform gauge section tubular specimens in a servohydraulic axial-torsional test rig. Test control and data acquisition were accomplished with a minicomputer. In this paper, the cyclic hardening characteristics and typical hysteresis loops in the axial stress versus axial strain, shear stress versus engineering shear strain, axial strain versus engineering shear strain, and axial stress versus shear stress spaces are presented for cyclic, in-phase and out-of-phase, axial torsional tests. For in-phase tests three different values of the proportionality constant, lambda (ratio of engineering shear strain amplitude to axial strain amplitude), are examined, viz., 0.86, 1.73, and 3.46. In the out-of-phase tests, three different values of the phase angle, phi (between the axial and engineering shear strain waveforms), are studied, viz., 30, 60, and 90 deg with lambda = 1.73. The cyclic hardening behaviors of all the tests conducted on Haynes 188 at 760 C are evaluated using the von Mises equivalent stress-strain and the maximum shear stress-maximum engineering shear strain (Tresca) curves. Comparisons are also made between the hardening behaviors of cyclic axial, torsional, and combined in-phase and out-of-phase axial-torsional fatigue tests. These comparisons are accomplished through simple Ramberg-Osgood type stress-strain functions for cyclic, axial stress-strain and shear stress-engineering shear strain curves.

Rheological and interfacial properties at the equilibrium of almond gum tree exudate (Prunus dulcis) in comparison with gum arabic.

PubMed

Mahfoudhi, Nesrine; Sessa, Mariarenata; Ferrari, Giovanna; Hamdi, Salem; Donsi, Francesco

2016-06-01

Almond gum contains an arabinogalactan-type polysaccharide, which plays an important role in defining its interfacial and rheological properties. In this study, rheological and interfacial properties of almond gum and gum arabic aqueous dispersions were comparatively investigated. The interfacial tension of almond gum and gum arabic aqueous dispersions was measured using the pendant drop method in hexadecane. The asymptotic interfacial tension values for almond gum were significantly lower than the corresponding values measured for gum arabic, especially at high concentration. Rheological properties were characterized by steady and oscillatory tests using a coaxial geometry. Almond gum flow curves exhibited a shear thinning non-Newtonian behavior with a tendency to a Newtonian plateau at low shear rate, while gum arabic flow curves exhibited such behavior only at high shear rate. The influence of temperature (5-50  ℃) on the flow curves was studied at 4% (m/m) gum concentration and the Newtonian viscosities at infinite and at zero shear rate, for gum arabic and almond gum, respectively, were accurately fitted by an Arrhenius-type equation. The dynamic properties of the two gum dispersions were also studied. Both gum dispersions exhibited viscoelastic properties, with the viscous component being predominant in a wider range of concentrations for almond gum, while for gum arabic the elastic component being higher than the elastic one especially at higher concentrations.The rheological and interfacial tension properties of almond gum suggest that it may represent a possible substitute of gum arabic in different food applications. © The Author(s) 2015.

The structure of the Temsamane fold-and-thrust stack (eastern Rif, Morocco): Evolution of a transpressional orogenic wedge

NASA Astrophysics Data System (ADS)

Jabaloy-Sánchez, Antonio; Azdimousa, Ali; Booth-Rea, Guillermo; Asebriy, Lahcen; Vázquez-Vílchez, Mercedes; Martínez-Martínez, José Miguel; Gabites, Janet

2015-11-01

The structure of the Temsamane fold-and-thrust stack corresponds to four units limited by anastomosing ductile shear zones cutting a trend of south verging recumbent folds. This ductile stack was formed in an inclined left-handed transpressional zone at the North African paleomargin during Chattian to Langhian times producing two main deformational events. The first event (Dp) produced a Sp/Lp planar linear fabric generated in a non-coaxial deformation with a top-to-the-WSW sense of movement and was associated to metamorphic P-T conditions varying from late diagenesis in the southernmost Temsamane outcrops to epizone in the north. According to the 40Ar/39Ar ages, this deformation occurred at Chattian-Aquitanian times. The second deformational event (Dc event) generated ENE-WSW trending folds with SSE vergence and a set of anastomosing shear zones with Sm/Lm planar linear fabric. The latter units were generated at around 15 Ma (Langhian), and indicate a strong localization of the simple shear component of the transpression. Moreover, this orientation is compatible with the kinematics of the Temsamane detachment, which can explain most of the uplift of the Temsamane rocks from the middle to the uppermost crust. The described evolution indicates that collision between the western Mediterranean terranes and the North African paleomargin and the formation of the Rifean orogenic wedge occurred at Chattian to Langhian times.

Characteristics of Muti-pulsing CHI driven ST plasmas on HIST

NASA Astrophysics Data System (ADS)

Ishihara, M.; Hanao, T.; Ito, K.; Matsumoto, K.; Higashi, T.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2011-10-01

The flux amplification and sustainment of the ST configurations by operating in Multi-pulsing Coaxial Helicity Injection (M-CHI) method have been demonstrated on HIST. The multi-pulsing experiment was demonstrated in the SSPX spheromak device at LLNL. In the double pulsing discharges, we have observed that the plasma current has been sustained much longer against the resistive decay as compared to the single CHI. We have measured the radial profiles of the flow velocities by using Ion Doppler Spectrometer and Mach probes. The result shows that poloidal shear flow exists between the open flux column and the most outer closed flux surface. The poloidal velocity shear at the interface may be caused by the ion diamagnetic drift, because of a steep density gradient there. The radial electric field is determined by the flow velocities and the ion pressure gradient through the radial momentum balance equation. We have investigated the contribution of ExB or the ion pressure gradient on the poloidal velocity shear by comparing the impurity ion flow obtained from the IDS with the bulk ion flow from the Mach probe. It should be noted that the diamagnetic drift velocity of the impurity is much smaller than ExB drift velocity. We will discuss characteristics of M-CHI-driven ST plasmas by varying TF coil current and the line averaged electron density.

Effects of Mean Flow Profiles on the Instability of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Vedantam, NandaKishore; Parthasarathy, Ramkumar N.

2004-01-01

The effects of the mean velocity profiles on the instability characteristics in the near-injector region of axisymmetric low density gas jets injected vertically upwards into a high-density gas medium were investigated using linear inviscid stability analysis. The flow was assumed to be isothermal and locally parallel. Three velocity profiles, signifying different changes in the mean velocity in the shear layer, were used in the analysis. The effects of the inhomogeneous shear layer and the Froude number (signifying the effects of gravity) on the instability for each set of mean profiles were delineated. At a large Froude number (negligible gravity), a critical density ratio was found for the three profiles at which the jet became absolutely unstable. The critical density ratio for each velocity profile was increased as the Froude number was reduced. A critical Froude number was found for the three sets of profiles, below which the jet was absolutely unstable for all the density ratios less than unity, which demarcated the jet flow into the momentum-driven regime and the buoyancy-driven regime.

Measurements of droplet size in shear-driven atomization using ultra-small angle x-ray scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kastengren, A.; Ilavsky, J.; Viera, Juan Pablo

Measurements of droplet size in optically-thick, non-evaporating, shear-driven sprays have been made using ultra-small angle x-ray scattering (USAXS). The sprays are produced by orifice-type nozzles coupled to diesel injectors, with measurements conducted from 1 – 24 mm from the orifice, spanning from the optically-dense near-nozzle region to more dilute regions where optical diagnostics are feasible. The influence of nozzle diameter, liquid injection pressure, and ambient density were examined. The USAXS measurements reveal few if any nanoscale droplets, in conflict with a popular computational model of diesel spray breakup. The average droplet diameter rapidly decreases with downstream distance from the nozzlemore » until a plateau value is reached, after which only small changes are seen in droplet diameter. This plateau droplet size is consistent with the droplets being small enough to be stable with respect to further breakup. As a result, liquid injection pressure and nozzle diameter have the biggest impact on droplet size, while ambient density has a smaller effect.« less

Measurements of droplet size in shear-driven atomization using ultra-small angle x-ray scattering

DOE PAGES

Kastengren, A.; Ilavsky, J.; Viera, Juan Pablo; ...

2017-03-16

Measurements of droplet size in optically-thick, non-evaporating, shear-driven sprays have been made using ultra-small angle x-ray scattering (USAXS). The sprays are produced by orifice-type nozzles coupled to diesel injectors, with measurements conducted from 1 – 24 mm from the orifice, spanning from the optically-dense near-nozzle region to more dilute regions where optical diagnostics are feasible. The influence of nozzle diameter, liquid injection pressure, and ambient density were examined. The USAXS measurements reveal few if any nanoscale droplets, in conflict with a popular computational model of diesel spray breakup. The average droplet diameter rapidly decreases with downstream distance from the nozzlemore » until a plateau value is reached, after which only small changes are seen in droplet diameter. This plateau droplet size is consistent with the droplets being small enough to be stable with respect to further breakup. As a result, liquid injection pressure and nozzle diameter have the biggest impact on droplet size, while ambient density has a smaller effect.« less

Comparison of JP-8 Sprays from a Hydraulically Actuated Electronically Controlled Unit Injector and a Common Rail Injector

DTIC Science & Technology

2015-10-01

acquired of a calibration plate to provide scaling for the injector orifices. The determined scaling factor for the images was 0.3 µm/pixel. A circle...Controlled Unit Injector and a Common Rail Injector by Matthew Kurman, Michael Tess, Luis Bravo, Chol-Bum Kweon, and Craig Hershey Reprinted...Comparison of JP-8 Sprays from a Hydraulically Actuated Electronically Controlled Unit Injector and a Common Rail Injector by Matthew Kurman

An Internal Coaxial Cable Electrical Connector For Use In Downhole Tools

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron; Briscoe, Michael

2005-09-20

A seal for a coaxial cable electrical connector more specifically an internal seal for a coaxial cable connector placed within a coaxial cable and its constituent components. A coaxial cable connector is in electrical communcation with an inductive transformer and a coaxial cable. The connector is in electrical communication with the outer housing of the inductive transformer. A generally coaxial center conductor, a portion of which could be the coil in the inductive transformer, passes through the connector, is electrically insulated from the connector, and is in electrical communication with the conductive core of the coaxial cable. The electrically insulating material also doubles as a seal to safegaurd against penetration of fluid, thus protecting against shorting out of the electrical connection. The seal is a multi-component seal, which is pre-compressed to a desired pressure rating. The coaxial cable and inductive transformer are disposed within downhole tools to transmit electrical signals between downhole tools within a drill string. The internal coaxial cable connector and its attendant seal can be used in a plurality of downhole tools, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.

Casting Apparatus Including A Gas Driven Molten Metal Injector And Method

DOEpatents

Meyer, Thomas N.

2004-06-01

The casting apparatus (50) includes a holding vessel (10) for containing a supply of molten metal (12) and a casting mold (52) located above the holding vessel (10) and having a casting cavity (54). A molten metal injector (14) extends into the holding vessel (10) and is at least partially immersed in the molten metal (12) in the holding vessel (10). The molten metal injector (14) is in fluid communication with the casting cavity (54). The molten metal injector (14) has an injector body (16) defining an inlet opening (24) for receiving molten metal into the injector body (16). A gas pressurization source (38) is in fluid communication with the injector body (16) for cyclically pressurizing the injector body (16) and inducing molten metal to flow from the injector body (16) to the casting cavity (54). An inlet valve (42) is located in the inlet opening (24) in the injector body (16) for filling molten metal into the injector body (16). The inlet valve (42) is configured to prevent outflow of molten metal from the injector body (16) during pressurization and permit inflow of molten metal into the injector body (16) after pressurization. The inlet valve (42) has an inlet valve actuator (44) located above the surface of the supply of molten metal (12) and is operatively connected to the inlet valve (42) for operating the inlet valve (42) between open and closed positions.

Space Storable Propellant Performance Gas/Liquid Like-Doublet Injector Characterization

NASA Technical Reports Server (NTRS)

Falk, A. Y.

1972-01-01

A 30-month applied research program was conducted, encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space-storable propellants. The gas/liquid propellant combination selected for study was FLOX (82.6% F2)/ambient temperature gaseous methane. The injector pattern characterized was the like-(self)-impinging doublet. Program effort was apportioned into four basic technical tasks: injector and thrust chamber design, injector and thrust chamber fabrication, performance evaluation testing, and data evaluation and reporting. Analytical parametric combustion analyses and cold flow distribution and atomization experiments were conducted with injector segment models to support design of injector/thrust chamber combinations for hot fire evaluation. Hot fire tests were conducted to: (1) optimize performance of the injector core elements, and (2) provide design criteria for the outer zone elements so that injector/thrust chamber compatibility could be achieved with only minimal performance losses.

Space transportation booster engine thrust chamber technology, large scale injector

NASA Technical Reports Server (NTRS)

Schneider, J. A.

1993-01-01

The objective of the Large Scale Injector (LSI) program was to deliver a 21 inch diameter, 600,000 lbf thrust class injector to NASA/MSFC for hot fire testing. The hot fire test program would demonstrate the feasibility and integrity of the full scale injector, including combustion stability, chamber wall compatibility (thermal management), and injector performance. The 21 inch diameter injector was delivered in September of 1991.

Physics objectives of PI3 spherical tokamak program

NASA Astrophysics Data System (ADS)

Howard, Stephen; Laberge, Michel; Reynolds, Meritt; O'Shea, Peter; Ivanov, Russ; Young, William; Carle, Patrick; Froese, Aaron; Epp, Kelly

2017-10-01

Achieving net energy gain with a Magnetized Target Fusion (MTF) system requires the initial plasma state to satisfy a set of performance goals, such as particle inventory (1021 ions), sufficient magnetic flux (0.3 Wb) to confine the plasma without MHD instability, and initial energy confinement time several times longer than the compression time. General Fusion (GF) is now constructing Plasma Injector 3 (PI3) to explore the physics of reactor-scale plasmas. Energy considerations lead us to design around an initial state of Rvessel = 1 m. PI3 will use fast coaxial helicity injection via a Marshall gun to create a spherical tokamak plasma, with no additional heating. MTF requires solenoid-free startup with no vertical field coils, and will rely on flux conservation by a metal wall. PI3 is 5x larger than SPECTOR so is expected to yield magnetic lifetime increase of 25x, while peak temperature of PI3 is expected to be similar (400-500 eV) Physics investigations will study MHD activity and the resistive and convective evolution of current, temperature and density profiles. We seek to understand the confinement physics, radiative loss, thermal and particle transport, recycling and edge physics of PI3.

Plasma Igniter for Reliable Ignition of Combustion in Rocket Engines

NASA Technical Reports Server (NTRS)

Martin, Adam; Eskridge, Richard

2011-01-01

A plasma igniter has been developed for initiating combustion in liquid-propellant rocket engines. The device propels a hot, dense plasma jet, consisting of elemental fluorine and fluorine compounds, into the combustion chamber to ignite the cold propellant mixture. The igniter consists of two coaxial, cylindrical electrodes with a cylindrical bar of solid Teflon plastic in the region between them. The outer electrode is a metal (stainless steel) tube; the inner electrode is a metal pin (mild steel, stainless steel, tungsten, or thoriated-tungsten). The Teflon bar fits snugly between the two electrodes and provides electrical insulation between them. The Teflon bar may have either a flat surface, or a concave, conical surface at the open, down-stream end of the igniter (the igniter face). The igniter would be mounted on the combustion chamber of the rocket engine, either on the injector-plate at the upstream side of the engine, or on the sidewalls of the chamber. It also might sit behind a valve that would be opened just prior to ignition, and closed just after, in order to prevent the Teflon from melting due to heating from the combustion chamber.

Radio frequency coaxial feedthrough device

DOEpatents

Owens, Thomas L.; Baity, Frederick W.; Hoffman, Daniel J.; Whealton, John H.

1987-01-01

A radio frequency coaxial vacuum feedthrough is provided which utilizes a cylindrical ceramic vacuum break formed of an alumina ceramic. The cylinder is coaxially disposed and brazed between tapered coaxial conductors to form a vacuum sealed connection between a pressurized upstream coaxial transmission line and a utilization device located within a vacuum container. The feedthrough provides 50 ohm matched impedance RF feedthrough up to about 500 MHz at power levels in the multimegawatt range.

Internal coaxial cable seal system

DOEpatents

Hall, David R.; Sneddon, Cameron; Dahlgren, Scott Steven; Briscoe, Michael A.

2006-07-25

The invention is a seal system for a coaxial cable and is placed within the coaxial cable and its constituent components. A series of seal stacks including load ring components and elastomeric rings are placed on load bearing members within the coaxial cable sealing the annular space between the coaxial cable and an electrical contact passing there through. The coaxial cable is disposed within drilling components to transmit electrical signals between drilling components within a drill string. The seal system can be used in a variety of downhole components, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.

Needleless coaxial electrospinning: A novel approach to mass production of coaxial nanofibers.

PubMed

Vysloužilová, Lucie; Buzgo, Matej; Pokorný, Pavel; Chvojka, Jiří; Míčková, Andrea; Rampichová, Michala; Kula, Jiří; Pejchar, Karel; Bílek, Martin; Lukáš, David; Amler, Evžen

2017-01-10

Herein, we describe a simple spinneret setup for needleless coaxial electrospinning that exceeds the limited production capacity of current approaches. The proposed weir spinneret enables coaxial electrospinning from free liquid surface. This approach leads to the formation of coaxial nanofibers with higher and uniform shell/core ratio, which results in the possibility of better tuning of the degradation rate. The throughput and quality increase favor the broader application of coaxial nanofibers from weir spinnerets as systems for controlled drug delivery in regenerative medicine and tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

A Survey of Theoretical and Experimental Coaxial Rotor Aerodynamic Research

NASA Technical Reports Server (NTRS)

Coleman, Colin P.

1997-01-01

The recent appearance of the Kamov Ka-50 helicopter and the application of coaxial rotors to unmanned aerial vehicles have renewed international interest in the coaxial rotor configuration. This report addresses the aerodynamic issues peculiar to coaxial rotors by surveying American, Russian, Japanese, British, and German research. (Herein, 'coaxial rotors' refers to helicopter, not propeller, rotors. The intermeshing rotor system was not investigated.) Issues addressed are separation distance, load sharing between rotors, wake structure, solidity effects, swirl recovery, and the effects of having no tail rotor. A general summary of the coaxial rotor configuration explores the configuration's advantages and applications.

Studies of Elementary Reactions of Chemical Importance in the Atmospheres of Planets

NASA Technical Reports Server (NTRS)

Nesbitt, Fred L.

2001-01-01

The methyl self-reaction was studied at T = 298 K and 202 K and at three different pressures, P = 0.5, 1.0, and 2.1 Torr. The experimental measurements were performed in our discharge flow-mass spectrometer (DF-MS) apparatus. The methyl radicals were generated by the reaction of F with methane. Passing a mixture of molecular fluorine, F2, in helium through a microwave cavity generated the atomic fluorine reagent. The atomic F enters the flow tube through a rear port on the flow tube. The methane reagent enters the flow tube through a movable injector located coaxial in the flow tube. The decay of methyl radical signal was monitored at a mass/charge ratio (m/z) of 15 as a function of the injector distance. To minimize secondary chemistry from the reaction CH3 + F to CH2 + HF the initial [CH4](sub 0)/[F](sub 0) was above 37.0 and typically 100. This ensures a 1:1 relationship between initial [F] and [CH3]. A titration of F with excess Cl2 yields the initial [F](sub 0). Our experimental methodology to accurately measure the mass spectrometer scaling factor, i.e., the relationship between initial signal and [CH3](sub 0) has been improved. Now we measure the CH3 signal decay under exponential decay conditions at low initial [F](sub 0), 3x10(exp 11) molecule/cc, in the presence of Cl2. This minimizes the second-order decay contributed by the CH3 self-reaction and a simple extrapolation of the 1n(signal) vs time plot to t = 0 gives the initial signal. This provides the desired relationship between initial signal at 15 amu and [CH3](sub 0). The resulting calibration is then applied to the observed decay of the CH3 signal at high concentrations of CH3 assuming linearity of this scaling factor.

Acetalated Dextran Microparticulate Vaccine Formulated via Coaxial Electrospray Preserves Toxin Neutralization and Enhances Murine Survival Following Inhalational Bacillus Anthracis Exposure.

PubMed

Gallovic, Matthew D; Schully, Kevin L; Bell, Matthew G; Elberson, Margaret A; Palmer, John R; Darko, Christian A; Bachelder, Eric M; Wyslouzil, Barbara E; Keane-Myers, Andrea M; Ainslie, Kristy M

2016-10-01

Subunit formulations are regarded as the safest type of vaccine, but they often contain a protein-based antigen that can result in significant challenges, such as preserving antigenicity during formulation and administration. Many studies have demonstrated that encapsulation of protein antigens in polymeric microparticles (MPs) via emulsion techniques results in total IgG antibody titers comparable to alum formulations, however, the antibodies themselves are non-neutralizing. To address this issue, a coaxial electrohydrodynamic spraying (electrospray) technique is used to formulate a microparticulate-based subunit anthrax vaccine under conditions that minimize recombinant protective antigen (rPA) exposure to harsh solvents and high shear stress. rPA and the adjuvant resiquimod are encapsulated either in separate or the same acetalated dextran MPs. Using a murine model, the electrospray formulations lead to higher IgG2a subtype titers as well as comparable total IgG antibody titers and toxin neutralization relative to the FDA-approved vaccine (BioThrax). BioThrax provides no protection against a lethal inhalational challenge of the highly virulent Ames Bacillus anthracis anthrax strain, whereas 50% of the mice vaccinated with separately encapsulated electrospray MPs survive. Overall, this study demonstrates the potential use of electrospray for encapsulating protein antigens in polymeric MPs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual-water mixture fuel burner

DOEpatents

Brown, Thomas D.; Reehl, Douglas P.; Walbert, Gary F.

1986-08-05

A coal-water mixture (CWM) burner includes a conically shaped rotating cup into which fuel comprised of coal particles suspended in a slurry is introduced via a first, elongated inner tube coupled to a narrow first end portion of the cup. A second, elongated outer tube is coaxially positioned about the first tube and delivers steam to the narrow first end of the cup. The fuel delivery end of the inner first tube is provided with a helical slot on its lateral surface for directing the CWM onto the inner surface of the rotating cup in the form of a uniform, thin sheet which, under the influence of the cup's centrifugal force, flows toward a second, open, expanded end portion of the rotating cup positioned immediately adjacent to a combustion chamber. The steam delivered to the rotating cup wets its inner surface and inhibits the coal within the CWM from adhering to the rotating cup. A primary air source directs a high velocity air flow coaxially about the expanded discharge end of the rotating cup for applying a shear force to the CWM in atomizing the fuel mixture for improved combustion. A secondary air source directs secondary air into the combustion chamber adjacent to the outlet of the rotating cup at a desired pitch angle relative to the fuel mixture/steam flow to promote recirculation of hot combustion gases within the ignition zone for increased flame stability.

Effects of fuel-injector design on ultra-lean combustion performance

NASA Technical Reports Server (NTRS)

Anderson, D. N.

1981-01-01

Emissions data were obtained for six fuel injector configurations tested with ultra lean combustion. Fuel injectors included three multiple source designs and three configurations using a single air assist injector. Only the multiple source fuel injectors provided acceptable emissions. Values of 16g CO/kg fuel, 1.9g HC/kg fuel, and 19.g NO2/kg fuel were obtained for the combustion temperature range of 1450 to 1700 K for both a high blockage 19 source injector and a low blockage 41 source injector. It was shown that high fuel injector pressure drop may not be required to achieve low emissions performance at high inlet air temperature when the fuel is well dispersed in the airstream.

The near field of coaxial jets: A numerical study

NASA Astrophysics Data System (ADS)

Balarac, Guillaume; Métais, Olivier

2005-06-01

The near-field behavior of coaxial jets is studied through direct numerical simulation (DNS) with a particular focus on the influence of the inner shear layer steepness characterized by its momentum thickness θ01 thus mimicking the variation in the lip thickness of a real jet nozzle. We investigate the two distinct jet regimes ru>ruc for which a recirculation bubble is present near the jet inlet and ruruc case, variations of θ01 strongly affect the shape and the downstream extent of the recirculation bubble. The DNS allow to show the strong dependency of the inner and outer potential core lengths and of the critical value ruc on the jet inlet velocity profile. We finally revisit the theoretical model originally proposed by Rehab, Villermaux, and Hopfinger ["Flow regimes of large-velocity-ratio coaxial jets," J. Fluid Mech. 345, 357 (1997)] first aimed at the prediction of the variations of various jet characteristics as a function of ru. The model is extended to determine the dependency of the jet characteristics with θ01. A very good correspondence between the theoretical predictions and the numerical results is obtained.

Non-invasive hyperthermia apparatus including coaxial applicator having a non-invasive radiometric receiving antenna incorporated therein and method of use thereof

DOEpatents

Ross, Michael P.

1996-01-01

A coaxial hyperthermia applicator for applying non-invasively electromagnetic energy to a body against which it is placed. The coaxial applicator antenna has formed integrally within it a non-invasive radiometric antenna for receiving thermoelectromagnetic emissions. The coaxial-configured applicator produces a bell-shaped radiation pattern symmetric about the axis of symmetry of the coaxial applicator. Integrating the radiometric antenna within the coaxial applicator produces a single device that performs dual functions. The first function is to transmit non-invasively energy for heating a subcutaneous tumor. The second function is to receive non-invasively thermal electromagnetic radiation from the tumor by which temperature is sensed and fed back to control the output of the coaxial applicator.

Non-invasive hyperthermia apparatus including coaxial applicator having a non-invasive radiometric receiving antenna incorporated therein and method of use thereof

DOEpatents

Ross, M.P.

1996-08-27

A coaxial hyperthermia applicator is disclosed for applying non-invasively electromagnetic energy to a body against which it is placed. The coaxial applicator antenna has formed integrally within it a non-invasive radiometric antenna for receiving thermoelectromagnetic emissions. The coaxial-configured applicator produces a bell-shaped radiation pattern symmetric about the axis of symmetry of the coaxial applicator. Integrating the radiometric antenna within the coaxial applicator produces a single device that performs dual functions. The first function is to transmit non-invasively energy for heating a subcutaneous tumor. The second function is to receive non-invasively thermal electromagnetic radiation from the tumor by which temperature is sensed and fed back to control the output of the coaxial applicator. 11 figs.

Coaxial connector for use with printed circuit board edge connector

DOEpatents

Howard, Donald R.; MacGill, Robert A.

1989-01-01

A coaxial cable connector for interfacing with an edge connector for a printed circuit board whereby a coaxial cable can be interconnected with a printed circuit board through the edge connector. The coaxial connector includes a body having two leg portions extending from one side for receiving the edge connector therebetween, and a tubular portion extending from an opposing side for receiving a coaxial cable. A cavity within the body receives a lug of the edge connector and the center conductor of the coaxial cable. Adjacent lugs of the edge connector can be bend around the edge connector housing to function as spring-loaded contacts for receiving the coaxial connector. The lugs also function to facilitate shielding of the center conductor where fastened to the edge connector lug.

Oppositely dipping thrusts and transpressional imbricate zone in the Central Eastern Desert of Egypt

NASA Astrophysics Data System (ADS)

Abd El-Wahed, Mohamed A.

2014-12-01

This paper documents the 40-60 km wide ENE-WSW trending Mubarak-Barramiya shear belt (MBSB) in the Central Eastern Desert of Egypt by examining its structural styles, kinematics and geometry. Our study revealed the existence of prevalent dextral and minor sinistral conjugate shear zones. The MBSB is metamorphic belt (greenschist-amphibolite) characterized by at least three post-collisional (740-540 Ma) ductile Neoproterozoic deformation events (D1, D2 and D3) followed by a brittle neotectonic deformation (D4). D1 event produced early top-to-the-northwest thrust displacements due to NW-SE shortening. D2 produced discrete zones of NNW-trending upright folds and culminated in initiation of major NW-trending sinistral shear zones of the Najd Fault System (NFS, at c. 640-540 Ma ago) as well as steeply dipping S2 foliation, and shallowly plunging L2 lineation. NW-to NNW-trending F2 folds are open to steep and vary in plunge from horizontal to vertical. D2 deformational fabrics are strongly overprinted by D3 penetrative structures. D3 is characterized by a penetrative S3 foliation, steeply SE- to NW-plunging and shallowly NE-plunging stretching lineations (L3), asymmetric and sheath folds (F3) consistent with dextral sense of movement exhibited by delta- and sigma-type porphyroclast systems and asymmetric boudinage fabrics. D2-D3 represent a non-coaxial progressive event formed in a dextral NE- over NW-sinistral shear zone during a partitioned transpression in response to E-W-directed compression during oblique convergence between East and West Gondwana developed due to closure of the Mozambique Ocean and amalgamation of the Arabian-Nubian Shield in Cryogenian-early Ediacaran time.

Thin semi-rigid coaxial cables for cryogenics applications

NASA Astrophysics Data System (ADS)

Kushino, Akihiro; Kasai, Soichi

2013-03-01

We have developed cryogenic coaxial cables for low temperature signal readout from sensitive devices, such as transition edge sensors, superconducting tunnel junctions, and kinetic inductance detectors. In order to reduce heat penetration into cryogenic stages, low thermal conductivity metals were chosen for both center and outer electrical conductors. Various types of coaxial cables, employing stainless-steel, cupro-nickel, brass, beryllium-copper, phosphor-bronze, niobium, and niobium-titanium, were manufactured using drawing dies. Thermal and electrical properties were investigated between 1 and 8 K. Coaxial cables made of copper alloys showed thermal conductance roughly consistent with literature, meanwhile Nb coaxial cable must be affected by the drawing process and thermal conductance was lowered. Attenuation of superconducting Nb and NbTi coaxial cables were observed to be adequately small up to above 10 GHz compared to those of normal conducting coaxial cables, which are subject to the Wiedemann-Franz law. We also measured normal conducting coaxial cables with silver-plated center conductors to improve high frequency performance.

Coaxial plasma thrusters for high specific impulse propulsion

NASA Technical Reports Server (NTRS)

Schoenberg, Kurt F.; Gerwin, Richard A.; Barnes, Cris W.; Henins, Ivars; Mayo, Robert; Moses, Ronald, Jr.; Scarberry, Richard; Wurden, Glen

1991-01-01

A fundamental basis for coaxial plasma thruster performance is presented and the steady-state, ideal MHD properties of a coaxial thruster using an annular magnetic nozzle are discussed. Formulas for power usage, thrust, mass flow rate, and specific impulse are acquired and employed to assess thruster performance. The performance estimates are compared with the observed properties of an unoptimized coaxial plasma gun. These comparisons support the hypothesis that ideal MHD has an important role in coaxial plasma thruster dynamics.

High pressure electrical insulated feed thru connector

DOEpatents

Oeschger, Joseph E.; Berkeland, James E.

1979-11-13

A feed-thru type hermetic electrical connector including at least one connector pin feeding through an insulator block within the metallic body of the connector shell. A compression stop arrangement coaxially disposed about the insulator body is brazed to the shell, and the shoulder on the insulator block bears against this top in a compression mode, the high pressure or internal connector being at the opposite end of the shell. Seals between the pin and an internal bore at the high pressure end of the insulator block and between the insulator block and the metallic shell at the high pressure end are hermetically brazed in place, the first of these also functioning to transfer the axial compressive load without permitting appreciable shear action between the pin and insulator block.

Pneumothorax Complicating Coaxial and Non-coaxial CT-Guided Lung Biopsy: Comparative Analysis of Determining Risk Factors and Management of Pneumothorax in a Retrospective Review of 650 Patients.

PubMed

Nour-Eldin, Nour-Eldin A; Alsubhi, Mohammed; Emam, Ahmed; Lehnert, Thomas; Beeres, Martin; Jacobi, Volkmar; Gruber-Rouh, Tatjana; Scholtz, Jan-Erik; Vogl, Thomas J; Naguib, Nagy N

2016-02-01

To assess the scope and determining risk factors related to the development of pneumothorax throughout CT-guided biopsy of pulmonary lesions in coaxial and non-coaxial techniques and the outcome of its management. The study included CT-guided percutaneous lung biopsies in 650 consecutive patients (407 males, 243 females; mean age 54.6 years, SD 5.2) from November 2008 to June 2013 in a retrospective design. Patients were classified according to lung biopsy technique into coaxial group (318 lesions) and non-coaxial group (332 lesions). Exclusion criteria for biopsy were lesions <5 mm in diameter, uncorrectable coagulopathy, positive-pressure ventilation, severe respiratory compromise, pulmonary arterial hypertension, or refusal of the procedure. Risk factors related to the occurrence of pneumothorax were classified into: (a) Technical risk factors, (b) patient-related risk factors, and (c) lesion-associated risk factors. Radiological assessments were performed by two radiologists in consensus. Mann-Whitney U test and Fisher's exact tests were used for statistical analysis. p values <0.05 were considered statistically significant. The incidence of pneumothorax complicating CT-guided lung biopsy was less in the non-coaxial group (23.2 %, 77 out of 332) than the coaxial group (27 %, 86 out of 318). However, the difference in incidence between both groups was statistically insignificant (p = 0.14). Significant risk factors for the development of pneumothorax in both groups were emphysema (p < 0.001 in both groups), traversing a fissure with the biopsy needle (p value 0.005 in non-coaxial group and 0.001 in coaxial group), small lesion, less than 2 cm in diameter (p value of 0.02 in both groups), location of the lesion in the basal or mid sections of the lung (p = 0.003 and <0.001 in non-coaxial and coaxial groups, respectively), and increased needle track path within the lung tissue of more than 2.5 cm (p = 0.01 in both groups). The incidence of pneumothorax in the non-coaxial group was significantly correlated to the number of specimens obtained (p = 0.006). This factor was statistically insignificant in the coaxial group (p = 0.45). The biopsy yield was more diagnostic and conclusive in the coaxial group in comparison to the non-coaxial group (p = 0.008). Simultaneous incidence of pneumothorax and pulmonary hemorrhage was 27.3 % (21/77) in non-coaxial group and in 30.2 % (26/86) in coaxial group. Conservative management was sufficient for treatment of 91 out of 101 patients of pneumothorax in both groups (90.1 %). Manual evacuation of pneumothorax was efficient in 44/51 patients (86.3 %) in both groups and intercostal chest tube was applied after failure of manual evacuation (7 patients: 13.7 %), from which one patient developed a persistent air leakage necessitating pleurodesis. Pneumothorax complicating CT-guided core biopsy of pulmonary lesions, showed the insignificant difference between coaxial and non-coaxial techniques. However, both techniques have the same significant risk factors including small and basal lesions, increased lesion's depth from pleural surface, and increased length of aerated lung parenchyma crossed by biopsy needle and passing through pulmonary fissures in the needle tract.

Pneumothorax Complicating Coaxial and Non-coaxial CT-Guided Lung Biopsy: Comparative Analysis of Determining Risk Factors and Management of Pneumothorax in a Retrospective Review of 650 Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nour-Eldin, Nour-Eldin A., E-mail: nour410@hotmail.com; Alsubhi, Mohammed, E-mail: mohammedal-subhi@yahoo.com; Emam, Ahmed, E-mail: morgan101002@hotmail.com

PurposeTo assess the scope and determining risk factors related to the development of pneumothorax throughout CT-guided biopsy of pulmonary lesions in coaxial and non-coaxial techniques and the outcome of its management.Materials and MethodsThe study included CT-guided percutaneous lung biopsies in 650 consecutive patients (407 males, 243 females; mean age 54.6 years, SD 5.2) from November 2008 to June 2013 in a retrospective design. Patients were classified according to lung biopsy technique into coaxial group (318 lesions) and non-coaxial group (332 lesions). Exclusion criteria for biopsy were lesions <5 mm in diameter, uncorrectable coagulopathy, positive-pressure ventilation, severe respiratory compromise, pulmonary arterial hypertension, ormore » refusal of the procedure. Risk factors related to the occurrence of pneumothorax were classified into: (a) Technical risk factors, (b) patient-related risk factors, and (c) lesion-associated risk factors. Radiological assessments were performed by two radiologists in consensus. Mann–Whitney U test and Fisher’s exact tests were used for statistical analysis. p values <0.05 were considered statistically significant.ResultsThe incidence of pneumothorax complicating CT-guided lung biopsy was less in the non-coaxial group (23.2 %, 77 out of 332) than the coaxial group (27 %, 86 out of 318). However, the difference in incidence between both groups was statistically insignificant (p = 0.14). Significant risk factors for the development of pneumothorax in both groups were emphysema (p < 0.001 in both groups), traversing a fissure with the biopsy needle (p value 0.005 in non-coaxial group and 0.001 in coaxial group), small lesion, less than 2 cm in diameter (p value of 0.02 in both groups), location of the lesion in the basal or mid sections of the lung (p = 0.003 and <0.001 in non-coaxial and coaxial groups, respectively), and increased needle track path within the lung tissue of more than 2.5 cm (p = 0.01 in both groups). The incidence of pneumothorax in the non-coaxial group was significantly correlated to the number of specimens obtained (p = 0.006). This factor was statistically insignificant in the coaxial group (p = 0.45). The biopsy yield was more diagnostic and conclusive in the coaxial group in comparison to the non-coaxial group (p = 0.008). Simultaneous incidence of pneumothorax and pulmonary hemorrhage was 27.3 % (21/77) in non-coaxial group and in 30.2 % (26/86) in coaxial group. Conservative management was sufficient for treatment of 91 out of 101 patients of pneumothorax in both groups (90.1 %). Manual evacuation of pneumothorax was efficient in 44/51 patients (86.3 %) in both groups and intercostal chest tube was applied after failure of manual evacuation (7 patients: 13.7 %), from which one patient developed a persistent air leakage necessitating pleurodesis.ConclusionPneumothorax complicating CT-guided core biopsy of pulmonary lesions, showed the insignificant difference between coaxial and non-coaxial techniques. However, both techniques have the same significant risk factors including small and basal lesions, increased lesion’s depth from pleural surface, and increased length of aerated lung parenchyma crossed by biopsy needle and passing through pulmonary fissures in the needle tract.« less

Development of the platelet micro-orifice injector. [for liquid propellant rocket engines

NASA Technical Reports Server (NTRS)

La Botz, R. J.

1984-01-01

For some time to come, liquid rocket engines will continue to provide the primary means of propulsion for space transportation. The injector represents a key to the optimization of engine and system performance. The present investigation is concerned with a unique injector design and fabrication process which has demonstrated performance capabilities beyond that achieved with more conventional approaches. This process, which is called the 'platelet process', makes it feasible to fabricate injectors with a pattern an order of magnitude finer than that obtainable by drilling. The fine pattern leads to an achievement of high combustion efficiencies. Platelet injectors have been identified as one of the significant technology advances contributing to the feasibility of advanced dual-fuel booster engines. Platelet injectors are employed in the Space Shuttle Orbit Maneuvering System (OMS) engines. Attention is given to injector design theory as it relates to pattern fineness, a description of platelet injectors, and test data obtained with three different platelet injectors.

Kinematics, partitioning and the relationship between velocity and strain in shear zones

NASA Astrophysics Data System (ADS)

Murphy, Justin James

Granite Point, southeast Washington State, captures older distributed deformation deflected by younger localized deformation. This history agrees with mathematical modeling completed by Watkinson and Patton (2005; 2007 in prep). This model suggests that distributed strain occurs at a lower energy threshold than localized strain and predicts deformation histories similar to Granite Point. Ductile shear zones at Granite Point define a zone of deformation where strain is partitioned and localized into at least ten sub parallel shear zones with sinistral, west side down shear sense. Can the relative movement of the boundaries of this partitioned system be reconstructed? Can partitioning be resolved from a distributed style of deformation? The state of strain and kinematics of actively deforming zones was studied by relating the velocity field to strain. The Aleutian Arc, Alaska and central Walker Lane, Nevada were chosen because they have a wealth of geologic data and are recognized examples of obliquely deforming zones. The graphical construction developed by Declan De Paor is ideally suited for this application because it provides a spatially referenced visualization of the relationship between velocity and strain. The construction of De Paor reproduces the observed orientation of strain in the Aleutian Arc, however, the spatial distribution of GPS stations suggest a component of partitioning. Partitioning does not provide a unique solution and cannot be differentiated from a combination of partitioning and distributed strain. In the central Walker Lane, strain trajectories can be reproduced at the domain scale. Furthermore, the effect of anisotropy from Paleozoic through Cenozoic crustal structure, which breaks the regional strain field into pure shear and simple shear dominated transtension can be detected. Without GPS velocities to document strictly coaxial strain, the strain orientation should not be taken as the velocity orientation. The strain recorded at Granite Point should not be used to reconstruct the relative movement of the boundaries because the strain direction may not be parallel to the velocity orientation. Kinematic reconstructions of obliquely deforming zones that assume a palaeo-velocity orientation equal to the measured orientation of finite strain may not accurately reflect the deviation between velocity and strain.

A LATE BRITTLE COMPONENT OF MOTION WITHIN THE DUCTILE EASTERN SIERRA CREST SHEAR ZONE (ESCSZ) ALONG THE EASTERN BOUNDARY OF THE TOLUMNE BATHOLITH IN THE SADDLEBAG LAKE, CA AREA. WHITESIDES, Andrew1, ENRIQUEZ, Marcus2 , HARDY, Jill1 , EHRET, Philip1, IANNONE, Monika1, CULBERT, Kristan1 GROSS, Ben3, LODEWYK, Jessica3, CAO, Wenrong1 , ZHANG, Tao1, MEMETI, Valbone3, PATERSON, Scott1 SCHMIDT, Keegan4. (1) Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089-0740, awhitesi@usc.edu , (2) Department of Geological Sciences, Cal State L.A., 5151 State University Drive, Los Angeles, CA 90032, (3) Department of Earth and Planetary Sciences, Washington University, Campus Box 1169, 1 Brookings Dr, Saint Louis, MO, 63130, (4) Division of Natural Science and Mathematics, Lewis-Clark State College, 500 8th Ave., Lewiston, ID 83501

NASA Astrophysics Data System (ADS)

Whitesides, A. S.; Enriquez, M.; Hardy, J.; Ehret, P.; Iannone, M.; Culbert, K. N.; Gross, M. B.; Lodewyk, J.; Cao, W.; Zhang, T.; Memeti, V.; Paterson, S. R.; Schmidt, K. L.

2009-12-01

During mapping (by the Undergraduate Team Research program, University of Southern California) in the Saddlebag Lake pendant just along the eastern margin of the Tuolumne batholith we have discovered a brittle slip component in the ESCSZ that juxtaposes largely metasedimentary and metavolcanic rock packages. The metasedimentary package is dominated by bedded sandstones and siltstones and local conglomerates whereas the metavolcanics show a large range of volcanic and volcaniclastic units. All of the units dip steeply and have an average N-NW strike. Dextral oblique ductile shear is distributed in domains in both rock packages with varying width from ~2 km in the South to ~1 km in the North. Shear sense in planes at high angles to a steep to SW plunging mineral lineation include S-C structures, shear bands, asymmetrical folding, sigma and delta clasts, and asymmetrical boudins. Partitioning of shear is common with the metarhyolites and metasediments showing higher non-coaxial strain than in the metaandesite and metadacite units. Map-scale “z-shaped” asymmetrical folds within the shear zone are also consistent with dextral shearing. Folded and sheared dikes of the 88-85 Ma Cathedral Peak phase of the Tuolumne batholith are common in the shear zone. A newly discovered brittle slip surface with breccias, gouge, and local pseudotachylite and large quartz veins was also mapped in the center of the ductile shear zone typically along the contact between the western metasedimentary and eastern metavolcanics (often a metarhyolite at the contact) on the east. Local slickenlines, steps, and offset dikes indicate that the brittle fault also had oblique dextral movement, similar to the ductile shear zone. In the mapped area no dikes originating from the TB cross the brittle fault and some are terminated at the brittle fault surface We interpret these observations to indicate northward displacement of the metasedimentary package by first ductile then brittle faulting during cooling and possibly uplift of this region with the youngest motion post 82 Ma.

Developing the Model of Fuel Injection Process Efficiency Analysis for Injector for Diesel Engines

NASA Astrophysics Data System (ADS)

Anisimov, M. Yu; Kayukov, S. S.; Gorshkalev, A. A.; Belousov, A. V.; Gallyamov, R. E.; Lysenko, Yu D.

2018-01-01

The article proposes an assessment option for analysing the quality of fuel injection by the injector constituting the development of calculation blocks in a common injector model within LMS Imagine.Lab AMESim. The parameters of the injector model in the article correspond to the serial injector Common Rail-type with solenoid. The possibilities of this approach are demonstrated with providing the results using the example of modelling the modified injector. Following the research results, the advantages of the proposed approach to analysing assessing the fuel injection quality were detected.

Plasma injector for a three-phase plasma torch with rail electrodes and some results of its investigation

NASA Astrophysics Data System (ADS)

Dudnik, Yu D.; Borovskoy, A. M.; Shiryaev, V. N.; Safronov, A. A.; Kuznetsov, V. E.; Vasilieva, O. B.; Pavlov, A. V.; Ivanov, D. V.

2018-01-01

Plasma injector made on the basis of the alternating-current plasma torch designed for the three-phase ac plasma torch with 100-500 kWrail electrodes is studied. The construction of the plasma injector is examined. Different materials for manufacture of injector electrodes are investigated. Current-voltage characteristics of the injector are obtained. Investigations of the plasma jet are carried out, and the jet temperature dependence versus the gas flow rate and electric power of the injector is measured.

77 FR 8898 - Certain Coaxial Cable Connectors and Components Thereof and Products Containing Same; Notice of...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-15

... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-650] Certain Coaxial Cable Connectors and... States after importation of certain coaxial cable connectors and components thereof and products... an advisory opinion under Commission Rule 210.79 (19 CFR 210.79) that would declare that its coaxial...

Coaxial cable connector

NASA Technical Reports Server (NTRS)

Caro, Edward R. (Inventor); Bonazza, Walter J. (Inventor)

1987-01-01

A coaxial cable connector is provided, which resists radio frequency breakdown in coaxial cables used in the vacuum of outer space. The connector body surrounds an insulator which includes an easily compressible elastomeric portion. An insulated coaxial cable is prepared so that its insulation projects beyond the outer conductor and compresses the elastomeric portion of the connector insulator.

76 FR 68504 - Advisory Opinion Proceeding; Certain Coaxial Cable Connectors and Components Thereof and Products...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-04

... Coaxial Cable Connectors and Components Thereof and Products Containing Same; Determination To Institute... coaxial cable connectors and components thereof and products containing the same by reason of infringement... under Commission Rule 210.79 (19 CFR 210.79) that would declare that its coaxial cable connectors...

Axially staged combustion system for a gas turbine engine

DOEpatents

Bland, Robert J [Oviedo, FL

2009-12-15

An axially staged combustion system is provided for a gas turbine engine comprising a main body structure having a plurality of first and second injectors. First structure provides fuel to at least one of the first injectors. The fuel provided to the one first injector is adapted to mix with air and ignite to produce a flame such that the flame associated with the one first injector defines a flame front having an average length when measured from a reference surface of the main body structure. Each of the second injectors comprising a section extending from the reference surface of the main body structure through the flame front and having a length greater than the average length of the flame front. Second structure provides fuel to at least one of the second injectors. The fuel passes through the one second injector and exits the one second injector at a location axially spaced from the flame front.

Research on the injectors remanufacturing

NASA Astrophysics Data System (ADS)

Daraba, D.; Alexandrescu, I. M.; Daraba, C.

2017-05-01

During the remanufacturing process, the injector body - after disassembling and cleaning process - should be subjected to some strict control processes, both visually and by an electronic microscope, for evidencing any defects that may occur on the sealing surface of the injector body and the atomizer. In this paper we present the path followed by an injector body in the process of remanufacturing, exemplifying the verification method of roughness and hardness of the sealing surfaces, as well as the microscopic analysis of the sealing surface areas around the inlet. These checks can indicate which path the injector body has to follow during the remanufacturing. The control methodology of the injector body, that is established on the basis of this research, helps preventing some defective injector bodies to enter into the remanufacturing process, thus reducing to a minimum the number of remanufactured injectors to be declared non-conforming after final verification process.

Preparation and characterization of multi-layer biodegradable nanofibers by coaxial electrospinning and their potential for tissue engineering

NASA Astrophysics Data System (ADS)

Liu, Wenwen

As an evolution of conventional electrospinning, coaxial electrospinning became popular soon after its debut as a novel way to develop nanofibers with special structures, such as core-shell and hollow interior. In recent years, there has been an increasing interest in a modified coaxial electrospinning, tri-layer coaxial electrospinning, to develop more complex structures, such as multi-layer and nanowire-in-microtube. Previous studies have primarily concentrated on the fabrication of tri-layered inorganic fibers while studies on tri-layered coaxial polymeric fibers has not been reported until very recently. Our research focuses on the fabrication of core-shell and tri-layer structured biodegradable polymeric nanofibers with coaxial electrospinning. Different characterization methods have been applied to observe the internal structure in single nanofibers and the potential application of tri-layer coaxial electrospinning has been discussed. The material system consists of biodegradable natural polymer gelatin, synthetic polymers poly (epsilon-caprolactone) (PCL) and poly (lactic-co-glycolic acid) (PLGA). A uniquely designed three-needle concentric spinneret is developed to perform tri-layer coaxial electrospinning. Different kinds of core-shell structured nanofibers, including gelatin/PCL, PCL/gelatin, gelatin/PLGA and PCL/PLGA, have been fabricated with a customized coaxial electrospinning apparatus. Two kinds of tri-layer coaxial nanofibers, two-component ABA structured gelatin/PCL/gelatin biodegradable nanofibers and tri-component ABC structured gelatin/PCL/PLGA biodegradable nanofibers, have been developed with the customized three needle coaxial electrospinning setup. The core-shell and tri-layered structures of electrospun nanofibers have been characterized by several commonly used techniques, such as laser scanning confocal microscopy (LSCM) and transmission electron microscopy (TEM). Besides the conventional methods, other newer techniques, including focused ion beam-scanning electron microscopy (FIB-SEM), super-resolution structured illumination microscopy (SR-SIM) and nanoscale-infrared spectroscopy (nano-IR), have been explored to investigate the internal structure in singles fibers. Additionally, the potential application of coaxial electrospinning in the fabrication of bioactive scaffolds for tissue engineering has been studied. Different kinds of coaxial nanofibers were fabricated and studied to determine the potential for BSA and growth factor release and some preliminary results were obtained.

Transverse Injection into Subsonic Crossflow with Various Injector Orifice Geometries

NASA Technical Reports Server (NTRS)

Foster, Lancert E.; Zaman, Khairul B.

2010-01-01

Computational and experimental results are presented for a case study of single injectors employed in 90 deg transverse injection into a non-reacting subsonic flow. Different injector orifice shapes are used (including circular, square, diamond-shaped, and wide rectangular slot), all with constant cross-sectional area, to observe the effects of this variation on injector penetration and mixing. Whereas the circle, square, and diamond injector produce similar jet plumes, the wide rectangular slot produces a plume with less vertical penetration than the others. There is also some evidence that the diamond injector produces slightly faster penetration with less mixing of the injected fluid. In addition, a variety of rectangular injectors were analyzed, with varying length/width ratios. Both experimental and computational data show improved plume penetration with increased streamwise orifice length. 3-D Reynolds-Averaged Navier-Stokes (RANS) results are obtained for the various injector geometries using NCC (National Combustion Code) with the kappa-epsilon turbulence model in multi-species modes on an unstructured grid. Grid sensitivity results are also presented which indicate consistent qualitative trends in the injector performance comparisons with increasing grid refinement.

Reliability and Characterization of High Voltage Power Capacitors

DTIC Science & Technology

2014-03-01

Cable The HVPS cable is a specialized coaxial cable that utilizes a high voltage bayonet connector. The cable itself has a voltage rating in excess...the( LabVIEW(program( GPIB( CABLE ( HVPS( HVPS( COAXIAL ( CABLE ( BNC( COAXIAL ( CABLE ( BNC( COAXIAL ( CABLE ( CAPACITOR(‘C’(DATA( CAPACITOR(‘A’(DATA( Circuit...16   F.   CABLES AND CONNECTORS ...................................................................16

Computations of Torque-Balanced Coaxial Rotor Flows

NASA Technical Reports Server (NTRS)

Yoon, Seokkwan; Chan, William M.; Pulliam, Thomas H.

2017-01-01

Interactional aerodynamics has been studied for counter-rotating coaxial rotors in hover. The effects of torque balancing on the performance of coaxial-rotor systems have been investigated. The three-dimensional unsteady Navier-Stokes equations are solved on overset grids using high-order accurate schemes, dual-time stepping, and a hybrid turbulence model. Computational results for an experimental model are compared to available data. The results for a coaxial quadcopter vehicle with and without torque balancing are discussed. Understanding interactions in coaxial-rotor flows would help improve the design of next-generation autonomous drones.

Coaxial cavity for measuring level of liquid in a container

DOEpatents

Booman, Glenn L.; Phelps, Frank R.

1979-01-01

A method and means for measuring the level of a liquid in a container. A coaxial cavity having a perforated outer conductor is partially submerged in the liquid in the container wherein the liquid enters and terminates the annular region of the coaxial cavity. The fundamental resonant frequency of the portion of the coaxial cavity which does not contain liquid is determined experimentally and is used to calculate the length of the liquid-free portion of the coaxial cavity and thereby the level of liquid in the container.

Structures, microfabrics and textures of the Cordilleran-type Rechnitz metamorphic core complex, Eastern Alps☆

PubMed Central

Cao, Shuyun; Neubauer, Franz; Bernroider, Manfred; Liu, Junlai; Genser, Johann

2013-01-01

Rechnitz window group represents a Cordilleran-style metamorphic core complex, which is almost entirely located within nearly contemporaneous Neogene sediments at the transition zone between the Eastern Alps and the Neogene Pannonian basin. Two tectonic units are distinguished within the Rechnitz metamorphic core complex (RMCC): (1) a lower unit mainly composed of Mesozoic metasediments, and (2) an upper unit mainly composed of ophiolite remnants. Both units are metamorphosed within greenschist facies conditions during earliest Miocene followed by exhumation and cooling. The internal structure of the RMCC is characterized by the following succession of structure-forming events: (1) blueschist relics of Paleocene/Eocene age formed as a result of subduction (D1), (2) ductile nappe stacking (D2) of an ophiolite nappe over a distant passive margin succession (ca. E–W to WNW–ESE oriented stretching lineation), (3) greenschist facies-grade metamorphism annealing dominant in the lower unit, and (4) ductile low-angle normal faulting (D3) (with mainly NE–SW oriented stretching lineation), and (5) ca. E to NE-vergent folding (D4). The microfabrics are related to mostly ductile nappe stacking to ductile low-angle normal faulting. Paleopiezometry in conjunction with P–T estimates yield high strain rates of 10− 11 to 10− 13 s− 1, depending on the temperature (400–350 °C) and choice of piezometer and flow law calibration. Progressive microstructures and texture analysis indicate an overprint of the high-temperature fabrics (D2) by the low-temperature deformation (D3). Phengitic mica from the Paleocene/Eocene high-pressure metamorphism remained stable during D2 ductile deformation as well as preserved within late stages of final sub-greenschist facies shearing. Chlorite geothermometry yields two temperature groups, 376–328 °C, and 306–132 °C. Chlorite is seemingly accessible to late-stage resetting. The RMCC underwent an earlier large-scale coaxial deformation accommodated by a late non-coaxial shear with ductile low-angle normal faulting, resulting in subvertical thinning in the extensional deformation regime. The RMCC was rapidly exhumed during ca. 23–18 Ma. PMID:27065502

Meteoric water circulation and rolling-hinge detachment faulting: Example of the Northern Snake Range core complex, Nevada

NASA Astrophysics Data System (ADS)

Gébelin, Aude; Teyssier, Christian; Heizler, Matthew T.; Andreas, Mulch

2014-05-01

The Northern Snake Range metamorphic core complex developed as a consequence of Oligo-Miocene extension of the Basin and Range Province and is bounded by an arched detachment that separates the cold, brittle upper crust from the ductile middle crust. On the western and eastern limbs of the arch, the detachment footwall displays continuous sections of muscovite-bearing quartzite and schist from which we report new microfabrics, δD values, and 40Ar/39Ar ages. Results indicate that the two limbs record distinct stages of the metamorphic and kinematic Cenozoic events, including Eocene collapse of previously overthickned crust in the west, and one main Oligo-Miocene extensional event in the east. Quartzite from the western part of the range preserves Eocene fabrics (~49-45 Ma) that developed during coaxial deformation in the presence of metamorphic fluids. In contrast, those from the east reveal a large component of non coaxial strain, Oligo-Miocene ages (27-21 Ma) and contain recrystallized muscovite grains indicating that meteoric fluids sourced at high elevation (low-δD) infiltrated the brittle-ductile transition zone during deformation. Percolation of meteoric fluids down to the mylonitic detachment footwall was made possible by the development of an east-dipping rolling-hinge detachment system that controlled the timing and location of active faulting in the brittle upper crust and therefore the pathway of fluids from the surface to the brittle-ductile transition. Oligo-Miocene upper crustal extension was accommodated by a fan-shaped fault pattern that generated shear and tension fractures and channelized surface fluids, while top-to-the-east ductile shearing and advection of hot material in the lower plate allowed the system to be progressively exhumed. As extension proceeded, brittle normal faults active in the wedge of the hanging wall gradually rotated and translated above the detachment fault where, became inactive and precluded the circulation of fluids from the surface to the lower plate. The Eocene section observed on the western limb represents an example of such a tilted block that was rotated and exhumed in the first stages of the rolling-hinge detachment activity.

Study on atomization features of a plain injector in high speed transverse air stream

NASA Astrophysics Data System (ADS)

Wan, Jian; Gu, Shanjian; Yang, Maolin; Xiao, Weihui

1990-04-01

The atomization features of a plain injector in high-speed transverse air stream were investigated by Malvern. In this investigation, air velocity ranged from 50-150m/s, pressure drop of fuel injector, (1.1 - 4.2) x 10 to the 6th Pa, diameter of orifice, 0.5 - 0.9 mm, axial distance between the injector and the survey plane, 50 - 250 mm. Aviation kerosene was used in all experiments. It was found that the atomization features in high pressure drop of fuel injector were greatly differed from the low pressure drop of fuel injector.

Heavy hydrocarbon main injector technology program

NASA Technical Reports Server (NTRS)

Arbit, H. A.; Tuegel, L. M.; Dodd, F. E.

1991-01-01

The Heavy Hydrocarbon Main Injector Program was an analytical, design, and test program to demonstrate an injection concept applicable to an Isolated Combustion Compartment of a full-scale, high pressure, LOX/RP-1 engine. Several injector patterns were tested in a 3.4-in. combustor. Based on these results, features of the most promising injector design were incorporated into a 5.7-in. injector which was then hot-fire tested. In turn, a preliminary design of a 5-compartment 2D combustor was based on this pattern. Also the additional subscale injector testing and analysis was performed with an emphasis on improving analytical techniques and acoustic cavity design methodology. Several of the existing 3.5-in. diameter injectors were hot-fire tested with and without acoustic cavities for spontaneous and dynamic stability characteristics.

Northrop Grumman HEC flight coaxial cryocoolers performance

NASA Astrophysics Data System (ADS)

Nguyen, T.; Russo, J.; Basel, G.; Chi, D.; Abelson, L.

2018-05-01

The Northrop Grumman Aerospace Systems (NGAS) has expanded the cryocooler product line to include a single stage High Efficiency Cryocooler (HEC) cooler with a coaxial pulse tube cold head that operates at temperatures down to 45K. The HEC coaxial pulse tube cooler has been adopted by several customers, and has completed acceptance testing to meet program flight requirements. The NGAS TRL 9 HEC is a pulse tube cryocooler with a flexure bearing compressor which has been delivered for a number of flight payloads that are currently operating in space. To date, NGAS has delivered space cryocoolers in several configurations including single stage with a linear cold head and two stage with both linear and coaxial cold heads. The new HEC coaxial cooler uses the same TRL9 HEC compressor with a passive pulse tube cold head, to maintain the flight heritage of the HEC linear cooler. In this paper, we present the flight acceptance test data of the HEC coaxial cryocooler, which includes thermal performance, launch vibration and thermal cycling. The HEC coaxial cooler has demonstrated excellent performance in family with the flight qualified HEC linear cooler. The HEC coaxial cooler provides users with additional flexibility in selecting the cold head configuration to meet their particular applications.

Economic evaluation of epinephrine auto-injectors for peanut allergy.

PubMed

Shaker, Marcus; Bean, Katherine; Verdi, Marylee

2017-08-01

Three commercial epinephrine auto-injectors were available in the United States in the summer of 2016: EpiPen, Adrenaclick, and epinephrine injection, USP auto-injector. To describe the variation in pharmacy costs among epinephrine auto-injector devices in New England and evaluate the additional expense associated with incremental auto-injector costs. Decision analysis software was used to evaluate costs of the most and least expensive epinephrine auto-injector devices for children with peanut allergy. To evaluate regional variation in epinephrine auto-injector costs, a random sample of New England national and corporate pharmacies was compared with a convenience sample of pharmacies from 10 Canadian provinces. Assuming prescriptions written for 2 double epinephrine packs each year (home and school), the mean costs of food allergy over the 20-year model horizon totaled $58,667 (95% confidence interval [CI] $57,745-$59,588) when EpiPen was prescribed and $45,588 (95% CI $44,873-$46,304) when epinephrine injection, USP auto-injector was prescribed. No effectiveness differences were evident between groups, with 17.19 (95% CI 17.11-17.27) quality-adjusted life years accruing for each subject. The incremental cost per episode of anaphylaxis treated with epinephrine over the model horizon was $12,576 for EpiPen vs epinephrine injection, USP auto-injector. EpiPen costs were lowest at Canadian pharmacies ($96, 95% CI $85-$107). There was price consistency between corporate and independent pharmacies throughout New England by device brand, with the epinephrine injection, USP auto-injector being the most affordable device. Cost differences among epinephrine auto-injectors were significant. More expensive auto-injector brands did not appear to provide incremental benefit. Copyright © 2017 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Unintentional Epinephrine Auto-injector Injuries: A National Poison Center Observational Study.

PubMed

Anshien, Marco; Rose, S Rutherfoord; Wills, Brandon K

2016-11-24

Epinephrine is the only first-line therapeutic agent used to treat life-threatening anaphylaxis. Epinephrine auto-injectors are commonly carried by patients at risk for anaphylaxis, and reported cases of unintentional auto-injector injury have increased over the last decade. Modifications of existing designs and release of a new style of auto-injector are intended to reduce epinephrine auto-injector misuse. The aim of the study was to characterize reported cases of unintentional epinephrine auto-injector exposures from 2013 to 2014 and compare demographics, auto-injector model, and anatomical site of such exposures. The American Association of Poison Control Center's National Poison Data System was searched from January 1, 2013, to December 31, 2014, for cases of unintentional epinephrine auto-injector exposures. Anatomical site data were obtained from all cases reported to the Virginia Poison Center and participating regional poison center for Auvi-Q cases. A total of 6806 cases of unintentional epinephrine auto-injector exposures were reported to US Poison Centers in 2013 and 2014. Of these cases, 3933 occurred with EpiPen, 2829 with EpiPen Jr, 44 with Auvi-Q, and no case reported of Adrenaclick. The most common site of unintentional injection for traditional epinephrine auto-injectors was the digit or thumb, with 58% of cases for EpiPen and 39% of cases with EpiPen Jr. With Auvi-Q, the most common site was the leg (78% of cases). The number of unintentional epinephrine auto-injector cases reported to American Poison Centers in 2013-2014 has increased compared with previous data. Most EpiPen exposures were in the digits, whereas Auvi-Q was most frequently in the leg. Because of the limitations of Poison Center data, more research is needed to identify incidence of unintentional exposures and the effectiveness of epinephrine auto-injector redesign.

Coaxial nanofibers containing TiO2 in the shell for water treatment applications

NASA Astrophysics Data System (ADS)

Kizildag, N.; Geltmeyer, J.; Ucar, N.; De Buysser, K.; De Clerck, K.

2017-10-01

In recent years, the basic electrospinning setup has undergone many modifications carried out to enhance the quality and improve the functionality of the resulting nanofibers. Being one of these modifications, coaxial electrospinning has attracted great attention. It enables to use different materials in nanofiber production and produce multi-layered and functional nanofibers in one step. In this study, TiO2 has been added to the shell layer of coaxial nanofibers to develop functional nanofibers which may be used in water treatment applications. The coaxial nanofibers containing TiO2 in the shell layer are compared to uniaxial nanofibers containing TiO2 in bulk fiber structure, regarding their morphology and photocatalytic activity. Uniform uniaxial and coaxial nanofibers with TiO2 were obtained. The average nanofiber diameter of coaxial nanofibers were higher. Coaxial nanofibers, which contained lower amount of TiO2, displayed similar performance to uniaxial nanofibers with TiO2 in terms of photocatalytic degradation ability against isoproturon.

Designing Liquid Rocket Engine Injectors for Performance, Stability, and Cost

NASA Technical Reports Server (NTRS)

Westra, Douglas G.; West, Jeffrey S.

2014-01-01

NASA is developing the Space Launch System (SLS) for crewed exploration missions beyond low Earth orbit. Marshall Space Flight Center (MSFC) is designing rocket engines for the SLS Advanced Booster (AB) concepts being developed to replace the Shuttle-derived solid rocket boosters. One AB concept uses large, Rocket-Propellant (RP)-fueled engines that pose significant design challenges. The injectors for these engines require high performance and stable operation while still meeting aggressive cost reduction goals for access to space. Historically, combustion stability problems have been a critical issue for such injector designs. Traditional, empirical injector design tools and methodologies, however, lack the ability to reliably predict complex injector dynamics that often lead to combustion stability. Reliance on these tools alone would likely result in an unaffordable test-fail-fix cycle for injector development. Recently at MSFC, a massively parallel computational fluid dynamics (CFD) program was successfully applied in the SLS AB injector design process. High-fidelity reacting flow simulations were conducted for both single-element and seven-element representations of the full-scale injector. Data from the CFD simulations was then used to significantly augment and improve the empirical design tools, resulting in a high-performance, stable injector design.

Effect of the number and position of nozzle holes on in- and near-nozzle dynamic characteristics of diesel injection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moon, Seoksu; Gao, Yuan; Park, Suhan

Despite the fact that all modern diesel engines use multi-hole injectors, single-hole injectors are frequently used to understand the fundamental properties of high-pressure diesel injections due to their axisymmetric design of the injector nozzles. A multi-hole injector accommodates many holes around the nozzle axis to deliver adequate amount of fuel with small orifices. The off-axis arrangement of the multi-hole injectors significantly alters the inter- and near-nozzle flow patterns compared to those of the single-hole injectors. This study compares the transient needle motion and near-nozzle flow characteristics of the single- and multi-hole (3-hole and 6-hole) diesel injectors to understand how themore » difference in hole arrangement and number affects the initial flow development of the diesel injectors. A propagation-based X-ray phase-contrast imaging technique was applied to compare the transient needle motion and near-nozzle flow characteristics of the single- and multi-hole injectors. The comparisons were made by dividing the entire injection process by three sub-stages: opening-transient, quasi-steady and closing-transient. (C) 2015 Elsevier Ltd. All rights reserved.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

NEIL K. MCDOUGALD

Alzeta Corporation has developed surface-stabilized fuel injectors for use with lean premixed combustors which provide extended turndown and ultra-low NOX emission performance. These injectors use a patented technique to form interacting radiant and blue-flame zones immediately above a selectively-perforated porous metal surface. This allows stable operation at low reaction temperatures. This technology is being commercialized under the product name nanoSTAR. Initial tests demonstrated low NOX emissions but, were limited by flashback failure of the injectors. The weld seams required to form cylindrical injectors from flat sheet material were identified as the cause of the failures. The approach for this projectmore » was to first develop new fabrication methods to produce injectors without weld seams, verify similar emissions performance to the original flat sheet material and then develop products for microturbines and small gas turbines along parallel development paths. A 37 month project was completed to develop and test a surface stabilized combustion system for gas turbine applications. New fabrication techniques developed removed a technological barrier to the success of the product by elimination of conductive weld seams from the injector surface. The injectors demonstrated ultra low emissions in rig tests conducted under gas turbine operating conditions. The ability for injectors to share a common combustion chamber allowing for deployment in annular combustion liner was also demonstrated. Some further development is required to resolve integration issues related to specific engine constraints, but the nanoSTAR technology has clearly demonstrated its low emissions potential. The overall project conclusions can be summarized: (1) A wet-laid casting method successfully eliminated weld seams from the injector surface without degrading performance. (2) Gas turbine cycle analysis identified several injector designs and control schemes to start and load engines using nanoSTAR technology. A mechanically simple single zone injector can be used in Solar Turbine's Taurus 60 engine. (3) Rig testing of single monolithic injectors demonstrated sub 3 ppmv NOX and sub 10 ppmv CO and UHC emissions (all corrected to 15% O2) at Taurus 60 full-load pressure and combustion air inlet temperature. (4) Testing of two nanoSTAR injectors in Solar Turbine's sector rig demonstrated the ability for injectors to survive when fired in close proximity at Taurus 60 full load pressure and combustion air inlet temperature. (5) Sector rig tests demonstrated emissions performance and range of operability consistent with single injector rig tests. Alzeta has committed to the commercialization of nanoSTAR injectors and has sufficient production capability to conclude development and meet initial demand.« less

Coaxial cable stripper for confined areas

NASA Technical Reports Server (NTRS)

Brown, J. D.; Lipscomb, W. G.

1968-01-01

Manual coaxial cable stripper quickly and accurately prepares a coaxial cable in a confined area. With this tool, preparation time is greatly reduced, and a completely inexperienced technician can perform the operation.

Coaxial Switch

DTIC Science & Technology

2014-04-23

0005] RF coaxial switches are typically used in environments that are prone to mechanical shocks and vibrations . For example, in military...withstand mechanical shocks and vibrations and to maintain an RF connection throughout a shock or a vibration event. Attorney Docket No. 102139...3 of 16 [0006] It has been found that shocks and vibrations on prior art rotary-type coaxial switches may cause the shaft in the coaxial switch

Administration of the adrenaline auto-injector at the nursery/kindergarten/school in Western Japan.

PubMed

Korematsu, Seigo; Fujitaka, Michiko; Ogata, Mika; Zaitsu, Masafumi; Motomura, Chikako; Kuzume, Kazuyo; Toku, Yuchiro; Ikeda, Masanori; Odajima, Hiroshi

2017-01-01

In view of the increasing prevalence of food allergies, there has been an associated increase in frequency of situations requiring an emergency response for anaphylaxis at the home, childcare facilities and educational institutions. To clarify the situation of adrenaline auto-injector administration in nursery/kindergarten/school, we carried out a questionnaire survey on pediatric physicians in Western Japan. In 2015, self-reported questionnaires were mailed to 421 physicians who are members of the West Japan Research Society Pediatric Clinical Allergy and Shikoku Research Society Pediatric Clinical Allergy. The response rate was 44% (185 physicians) where 160 physicians had a prescription registration for the adrenaline auto-injector. In the past year, 1,330 patients were prescribed the adrenaline auto-injector where 83 patients (6% of the prescribed patients) actually administered the adrenaline auto-injector, of which 14 patients (17% of the administered patients) self-administered the adrenaline auto-injector. "Guardians" at the nursery/kindergarten and elementary school were found to have administered the adrenaline auto-injector the most. Among 117 adrenaline auto-injector prescription-registered physicians, 79% had experienced nonadministration of adrenaline auto-injector at nursery/kindergarten/school when anaphylaxis has occurred. The most frequent reason cited for not administering the adrenaline auto-injector was "hesitation about the timing of administration." If the adrenaline auto-injector was administered after the guardian arrived at the nursery/kindergarten/school, it may lead to delayed treatment of anaphylaxis in which symptoms develop in minutes. Education and cooperation among physicians and nursery/kindergarten/school staff will reduce the number of children suffering unfortunate outcomes due to anaphylaxis.

Alginate Encapsulation of Pluripotent Stem Cells Using a Co-axial Nozzle

PubMed Central

Horiguchi, Ikki; Sakai, Yasuyuki

2015-01-01

Pluripotent stem cells (PS cells) are the focus of intense research due to their role in regenerative medicine and drug screening. However, the development of a mass culture system would be required for using PS cells in these applications. Suspension culture is one promising culture method for the mass production of PS cells, although some issues such as controlling aggregation and limiting shear stress from the culture medium are still unsolved. In order to solve these problems, we developed a method of calcium alginate (Alg-Ca) encapsulation using a co-axial nozzle. This method can control the size of the capsules easily by co-flowing N2 gas. The controllable capsule diameter must be larger than 500 µm because too high a flow rate of N2 gas causes the breakdown of droplets and thus heterogeneous-sized capsules. Moreover, a low concentration of Alg-Na and CaCl2 causes non-spherical capsules. Although an Alg-Ca capsule without a coating of Alg-PLL easily dissolves enabling the collection of cells, they can also potentially leak out from capsules lacking an Alg-PLL coating. Indeed, an alginate-PLL coating can prevent cellular leakage but is also hard to break. This technology can be used to research the stem cell niche as well as the mass production of PS cells because encapsulation can modify the micro-environment surrounding cells including the extracellular matrix and the concentration of secreted factors. PMID:26168084

49 CFR 230.57 - Injectors and feedwater pumps.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Appurtenances Injectors, Feedwater Pumps, and Flue Plugs § 230.57 Injectors and feedwater pumps. (a) Water... water to the boiler, at least one of which is a live steam injector. (b) Maintenance and testing... delivering water to the boiler. Boiler checks, delivery pipes, feed water pipes, tank hose and tank valves...

21 CFR 872.4475 - Spring-powered jet injector.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Spring-powered jet injector. 872.4475 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4475 Spring-powered jet injector. (a) Identification. A spring-powered jet injector is a syringe device intended to administer a local anesthetic. The...

21 CFR 872.4475 - Spring-powered jet injector.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Spring-powered jet injector. 872.4475 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4475 Spring-powered jet injector. (a) Identification. A spring-powered jet injector is a syringe device intended to administer a local anesthetic. The...

21 CFR 872.4475 - Spring-powered jet injector.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Spring-powered jet injector. 872.4475 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4475 Spring-powered jet injector. (a) Identification. A spring-powered jet injector is a syringe device intended to administer a local anesthetic. The...

21 CFR 872.4475 - Spring-powered jet injector.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Spring-powered jet injector. 872.4475 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4475 Spring-powered jet injector. (a) Identification. A spring-powered jet injector is a syringe device intended to administer a local anesthetic. The...

21 CFR 872.4475 - Spring-powered jet injector.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Spring-powered jet injector. 872.4475 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4475 Spring-powered jet injector. (a) Identification. A spring-powered jet injector is a syringe device intended to administer a local anesthetic. The...

Investigation on discharge characteristics of a coaxial dielectric barrier discharge reactor driven by AC and ns power sources

NASA Astrophysics Data System (ADS)

Qian, WANG; Feng, LIU; Chuanrun, MIAO; Bing, YAN; Zhi, FANG

2018-03-01

A coaxial dielectric barrier discharge (DBD) reactor with double layer dielectric barriers has been developed for exhaust gas treatment and excited either by AC power or nanosecond (ns) pulse to generate atmospheric pressure plasma. The comparative study on the discharge characteristics of the discharge uniformity, power deposition, energy efficiency, and operation temperature between AC and ns pulsed coaxial DBD is carried out in terms of optical and electrical characteristics and operation temperature for optimizing the coaxial DBD reactor performance. The voltages across the air gap and dielectric layer and the conduction and displacement currents are extracted from the applied voltages and measured currents of AC and ns pulsed coaxial DBDs for the calculation of the power depositions and energy efficiencies through an equivalent electrical model. The discharge uniformity and operating temperature of the coaxial DBD reactor are monitored and analyzed by optical images and infrared camera. A heat conduction model is used to calculate the temperature of the internal quartz tube. It is found that the ns pulsed coaxial DBD has a much higher instantaneous power deposition in plasma, a lower total power consumption, and a higher energy efficiency compared with that excited by AC power and is more homogeneous and stable. The temperature of the outside wall of the AC and ns pulse excited coaxial DBD reaches 158 °C and 64.3 °C after 900 s operation, respectively. The experimental results on the comparison of the discharge characteristics of coaxial DBDs excited by different powers are significant for understanding of the mechanism of DBDs, reducing energy loss, and optimizing the performance of coaxial DBD in industrial applications.

Advanced Biasing Experiments on the C-2 Field-Reversed Configuration Device

NASA Astrophysics Data System (ADS)

Thompson, Matthew; Korepanov, Sergey; Garate, Eusebio; Yang, Xiaokang; Gota, Hiroshi; Douglass, Jon; Allfrey, Ian; Valentine, Travis; Uchizono, Nolan; TAE Team

2014-10-01

The C-2 experiment seeks to study the evolution, heating and sustainment effects of neutral beam injection on field-reversed configuration (FRC) plasmas. Recently, substantial improvements in plasma performance were achieved through the application of edge biasing with coaxial plasma guns located in the divertors. Edge biasing provides rotation control that reduces instabilities and E × B shear that improves confinement. Typically, the plasma gun arcs are run at ~ 10 MW for the entire shot duration (~ 5 ms), which will become unsustainable as the plasma duration increases. We have conducted several advanced biasing experiments with reduced-average-power plasma gun operating modes and alternative biasing cathodes in an effort to develop an effective biasing scenario applicable to steady state FRC plasmas. Early results show that several techniques can potentially provide effective, long-duration edge biasing.

COAXIAL TUBE COUPLING

DOEpatents

Niemoth, H.R.

1963-02-26

BS>This patent shows a device for quickly coupling coaxial tubes in metal-to-metal fashion, so as to be suitable for use in a nuclear reactor. A threaded coliar urges a tapered metal extension on the outer coaxial tube into a tapered seat in the device and simultaneously exerts pressure through a coaxial helical spring so that a similar extension on the inner tube seats in a similar seat near the other end. (AEC)

Nanoscale devices based on plasmonic coaxial waveguide resonators

NASA Astrophysics Data System (ADS)

Mahigir, A.; Dastmalchi, P.; Shin, W.; Fan, S.; Veronis, G.

2015-02-01

Waveguide-resonator systems are particularly useful for the development of several integrated photonic devices, such as tunable filters, optical switches, channel drop filters, reflectors, and impedance matching elements. In this paper, we introduce nanoscale devices based on plasmonic coaxial waveguide resonators. In particular, we investigate threedimensional nanostructures consisting of plasmonic coaxial stub resonators side-coupled to a plasmonic coaxial waveguide. We use coaxial waveguides with square cross sections, which can be fabricated using lithography-based techniques. The waveguides are placed on top of a silicon substrate, and the space between inner and outer coaxial metals is filled with silica. We use silver as the metal. We investigate structures consisting of a single plasmonic coaxial resonator, which is terminated either in a short or an open circuit, side-coupled to a coaxial waveguide. We show that the incident waveguide mode is almost completely reflected on resonance, while far from the resonance the waveguide mode is almost completely transmitted. We also show that the properties of the waveguide systems can be accurately described using a single-mode scattering matrix theory. The transmission and reflection coefficients at waveguide junctions are either calculated using the concept of the characteristic impedance or are directly numerically extracted using full-wave three-dimensional finite-difference frequency-domain simulations.

Modified coaxial wire method for measurement of transfer impedance of beam position monitors

NASA Astrophysics Data System (ADS)

Kumar, Mukesh; Babbar, L. K.; Deo, R. K.; Puntambekar, T. A.; Senecha, V. K.

2018-05-01

The transfer impedance is a very important parameter of a beam position monitor (BPM) which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables). This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.

A numerical study of candidate transverse fuel injector configurations in the Langley scramjet engine

NASA Technical Reports Server (NTRS)

Drummond, J. P.

1980-01-01

A computer program has been developed that numerically solves the two-dimensional Navier-Stokes and species equations near one or more transverse hydrogen fuel injectors in a scramjet engine. The program currently computes the turbulent mixing and reaction of hydrogen fuel and air, and allows the study of separated regions of the flow immediately preceding and following the injectors. The complex shock-expansion structure produced by the injectors in this region of the engine can also be represented. Results are presented that describe the flow field near two opposing transverse fuel injectors and two opposing staged (multiple) injectors, and comparisons between the two configurations are made to assess their mixing and flameholding qualities.

On the prediction of spray angle of liquid-liquid pintle injectors

NASA Astrophysics Data System (ADS)

Cheng, Peng; Li, Qinglian; Xu, Shun; Kang, Zhongtao

2017-09-01

The pintle injector is famous for its capability of deep throttling and low cost. However, the pintle injector has been seldom investigated. To get a good prediction of the spray angle of liquid-liquid pintle injectors, theoretical analysis, numerical simulations and experiments were conducted. Under the hypothesis of incompressible and inviscid flow, a spray angle formula was deduced from the continuity and momentum equations based on a control volume analysis. The formula was then validated by numerical and experimental data. The results indicates that both geometric and injection parameters affect the total momentum ratio (TMR) and then influence the spray angle formed by liquid-liquid pintle injectors. TMR is the pivotal non-dimensional number that dominates the spray angle. Compared with gas-gas pintle injectors, spray angle formed by liquid-liquid injectors is larger, which benefits from the local high pressure zone near the pintle wall caused by the impingement of radial and axial sheets.

A Versatile Ion Injector at KACST

NASA Astrophysics Data System (ADS)

El Ghazaly, M. O. A.; Behery, S. A.; Almuqhim, A. A.; Papash, A. I.; Welsch, C. P.

2011-10-01

A versatile ion-beam injector is presently being constructed at the National Centre for Mathematics and Physics (NCMP) at the King Abdul-Aziz City for Science and Technology (KACST), Saudi Arabia. This versatile injector will provide an electrostatic storage ring with high-quality ion beams of energies up to 30 keV per charge q. It will also allow for crossed-beams experiments in single-pass setups. The injector has been designed to include beams from two different ion sources, switched by a 90° deflection setup, and to allow for matching of the beam parameters to the Twiss parameters of the ring. The injector is equipped with two crossed beam-lines (inlets), with duplicated beam extraction and acceleration systems. As part of the initial setup, a simple electric discharge ion source has been developed for commissioning of the whole injector. In this paper, we report on the ion optics layout and the design parameters of the injector.

21 CFR 872.4465 - Gas-powered jet injector.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gas-powered jet injector. 872.4465 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4465 Gas-powered jet injector. (a) Identification. A gas-powered jet injector is a syringe device intended to administer a local anesthetic. The syringe is...

21 CFR 872.4465 - Gas-powered jet injector.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gas-powered jet injector. 872.4465 Section 872...) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4465 Gas-powered jet injector. (a) Identification. A gas-powered jet injector is a syringe device intended to administer a local anesthetic. The syringe is...

Scramjet fuel injector design parameters and considerations: Development of a two-dimensional tangential fuel injector with constant pressure at the flame

NASA Technical Reports Server (NTRS)

Agnone, A. M.

1972-01-01

The factors affecting a tangential fuel injector design for scramjet operation are reviewed and their effect on the efficiency of the supersonic combustion process is evaluated using both experimental data and theoretical predictions. A description of the physical problem of supersonic combustion and method of analysis is followed by a presentation and evaluation of some standard and exotic types of fuel injectors. Engineering fuel injector design criteria and hydrogen ignition schemes are presented along with a cursory review of available experimental data. A two-dimensional tangential fuel injector design is developed using analyses as a guide in evaluating the effects on the combustion process of various initial and boundary conditions including splitter plate thickness, injector wall temperature, pressure gradients, etc. The fuel injector wall geometry is shaped so as to maintain approximately constant pressure at the flame as required by a cycle analysis. A viscous characteristics program which accounts for lateral as well as axial pressure variations due to the mixing and combustion process is used in determining the wall geometry.

CFD Based Design of a Filming Injector for N+3 Combustors

NASA Technical Reports Server (NTRS)

Ajmani, Kumud; Mongia, Hukam; Lee, Phil

2016-01-01

An effort was undertaken to perform CFD analysis of fluid flow in Lean-Direct Injection (LDI) combustors with axial swirl-venturi elements for next-generation LDI-3 combustor design. The National Combustion Code (NCC) was used to perform non-reacting and two-phase reacting flow computations for a newly-designed pre-filming type fuel injector LDI-3 injector, in a single-injector and a five-injector array configuration. All computations were performed with a consistent approach of mesh-optimization, spray-modeling, ignition and kinetics-modeling. Computational predictions of the aerodynamics of the single-injector were used to arrive at an optimized main-injector design that meets effective area and fuel-air mixing criteria. Emissions (EINOx) characteristics were predicted for a medium-power engine cycle condition, and will be compared with data when it is made available from experimental measurements. The use of a PDF-like turbulence-chemistry interaction model with NCC's Time-Filtered Navier-Stokes (TFNS) solver is shown to produce a significant impact on the CFD results, when compared with a laminar-chemistry TFNS approach for the five-injector computations.

[Needle-free injection--science fiction or comeback of an almost forgotten drug delivery system?].

PubMed

Ziegler, Andreas

2007-08-01

The first to create a "needle-free injector" was the American anesthetist Robert A. Hingson, 65 year ago. Since that time those devices underwent a changeful history. In 1986 an outbreak of hepatitis B among patients receiving injections from a needle-free multiple-use-nozzle injector was documented and related to the use of the injector device. Due to such risk of transmission of infection with these reusable devices, their application has been restricted. In 1998 the WHO recommended that only conventional needles and syringes should be used for immunization until safe needle-free injectors are identified through independent safety testing. Since needle-free injection has shown numerous advantages in comparison to conventional injection, new systems were developed that combine the advantages of needle-free injection with sufficient safety in mass vaccination programs. As an alternative to this early injector type, the disposable-cartridge injectors were developed. The newest research field in the area of the needle-free injection systems opened with the development of powder injectors, in which the drug preparation is no longer a suspension or solution, but a powdered solid. This injector type using powder formulations shows a number of advantages in comparison with the conventional needle/syringe injection technique as well as towards the liquid jet injectors. Due to this new kind of injectors the comeback of the needle-free injection technique in large-scale vaccination programs of the WHO seems reasonable and within reach.

Influence of Reduced Mass Flow Rate and Chamber Backpressure on Swirl Injector Fluid Mechanics

NASA Technical Reports Server (NTRS)

Kenny, R Jeremy; Hulka, James R.

2008-01-01

Industry interest in variable-thrust liquid rocket engines places a demand on engine injector technology to operate over a wide range of liquid mass flow rates and chamber backpressures. One injection technology of current interest for variable thrust applications is an injector design with swirled fluids. Current swirl injector design methodologies do not take into account how swirl injector design parameters respond to elevated chamber backpressures at less than design mass flow rates. The current work was created to improve state-of-the-art swirl injector design methods in this area. The specific objective was to study the effects of elevated chamber backpressure and off-design mass flow rates on swirl injector fluid mechanics. Using a backpressure chamber with optical access, water was flowed through a swirl injector at various combinations of chamber backpressure and mass flow rates. The film thickness profile down the swirl injector nozzle section was measured through a transparent nozzle section of the injector. High speed video showed measurable increases in the film thickness profile with application of chamber backpressure and mass flow rates less than design. At prescribed combinations of chamber backpressure and injected mass flow rate, a discrete change in the film thickness profile was observed. Measured injector discharge coefficient values showed different trends with increasing chamber backpressure at low mass flow rates as opposed to near-design mass flow rates. Downstream spray angles showed classic changes in morphology as the mass flow rate was decreased below the design value. Increasing chamber backpressure decreased the spray angle at any injection mass flow rate. Experimental measurements and discussion of these results are reported in this paper.

Dynamics and rheology of finitely extensible polymer coils: An overview

NASA Astrophysics Data System (ADS)

Yao, Donggang

2017-05-01

One contemporary research issue in non-Newtonian fluid mechanics is to accurately and effectively model viscoelastic polymer flow of practical relevance. In the past several years, we have been working on the formulation of a finitely extensible coil model for polymer flow, particularly including these elements: (1) decoupled equations for kinematical and dynamical variables, (2) logarithmic relaxation at large deformation, (3) rotational retardation, (4) controllable straining, and (5) finite stretch. In this paper, we provide a constructive overview of this nonlinear coil formulation focusing on integration of these elements in a single, unified constitutive model with a minimal number of model parameters that are linked with corresponding physical processes. We also use this opportunity to share the rationale and thought process in the model development. In one particular implement of the general formulation, three parameters are used to tackle with the principal dynamics of a deforming polymer coil: one for finite stretch dictated by a ceiling stretch of the coil, the second one for rotational recovery/retardation, and the third one for adjusting stretch hardening of the rubbery coil. The new model, even in a single mode, is able to simultaneously predict practical material functions in simple shear and coaxial extension and to fit well to representative experimental data. Particularly in the steady-state (or quasi-steady state) flow case, a nearly closed-form stress to velocity gradient relationship can be derived with which shear thinning and elongational thickening can be simultaneously considered while computational advantages of a classical GNF model is retained. The model also fits reasonably well to representative experimental transient data for both shear and extension.

Behavior of Compact Toroid Injected into C-2U Confinement Vessel

NASA Astrophysics Data System (ADS)

Matsumoto, Tadafumi; Roche, T.; Allrey, I.; Sekiguchi, J.; Asai, T.; Conroy, M.; Gota, H.; Granstedt, E.; Hooper, C.; Kinley, J.; Valentine, T.; Waggoner, W.; Binderbauer, M.; Tajima, T.; the TAE Team

2016-10-01

The compact toroid (CT) injector system has been developed for particle refueling on the C-2U device. A CT is formed by a magnetized coaxial plasma gun (MCPG) and the typical ejected CT/plasmoid parameters are as follows: average velocity 100 km/s, average electron density 1.9 ×1015 cm-3, electron temperature 30-40 eV, mass 12 μg . To refuel particles into FC plasma the CT must penetrate the transverse magnetic field that surrounds the FRC. The kinetic energy density of the CT should be higher than magnetic energy density of the axial magnetic field, i.e., ρv2 / 2 >=B2 / 2μ0 , where ρ, v, and B are mass density, velocity, and surrounded magnetic field, respectively. Also, the penetrated CT's trajectory is deflected by the transverse magnetic field (Bz 1 kG). Thus, we have to estimate CT's energy and track the CT trajectory inside the magnetic field, for which we adopted a fast-framing camera on C-2U: framing rate is up to 1.25 MHz for 120 frames. By employing the camera we clearly captured the CT/plasmoid trajectory. Comparisons between the fast-framing camera and some other diagnostics as well as CT injection results on C-2U will be presented.

Investigation of Combustion Control in a Dump Combustor Using the Feedback Free Fluidic Oscillator

NASA Technical Reports Server (NTRS)

Meier, Eric J.; Casiano, Matthew J.; Anderson, William E.; Heister, Stephen D.

2015-01-01

A feedback free fluidic oscillator was designed and integrated into a single element rocket combustor with the goal of suppressing longitudinal combustion instabilities. The fluidic oscillator uses internal fluid dynamics to create an unsteady outlet jet at a specific frequency. An array of nine fluidic oscillators was tested to mimic modulated secondary oxidizer injection into the combustor dump plane. The combustor has a coaxial injector that uses gaseous methane and decomposed hydrogen peroxide with an overall O/F ratio of 11.7. A sonic choke plate on an actuator arm allows for continuous adjustment of the oxidizer post acoustics enabling the study of a variety of instability magnitudes. The fluidic oscillator unsteady outlet jet performance is compared against equivalent steady jet injection and a baseline design with no secondary oxidizer injection. At the most unstable operating conditions, the unsteady outlet jet saw a 67% reduction in the instability pressure oscillation magnitude when compared to the steady jet and baseline data. Additionally, computational fluid dynamics analysis of the combustor gives insight into the flow field interaction of the fluidic oscillators. The results indicate that open loop high frequency propellant modulation for combustion control can be achieved through fluidic devices that require no moving parts or electrical power to operate.

Combustion characteristics of the LO2/GCH4 fuel-rich preburners for staged combustion cycle rocket engines

NASA Astrophysics Data System (ADS)

Ono, Fumiei; Tamura, Hiroshi; Sakamoto, Hiroshi; Sasaki, Masaki

1991-09-01

The combustion characteristics of Liquid Oxygen (LO2)/Gaseous Methane (GCH4) fuel rich preburners were experimentally studied using subscale hardware. Three types of preburners with coaxial type propellant injection elements were designed and fabricated, and were used for hot fire testing. LO2 was used as oxidizer, and GCH4 at room temperature was used as fuel. The tests were conducted at chamber pressures ranging from 6.7 to 11.9 M Pa, and oxidizer to fuel ratios ranged from 0.16 to 0.42. The test results, which include combustion gas temperature T(sub c), characteristic velocity C(sup *) and soot adhesion data, are presented. The T(sub c) efficiency and the C(sup *) efficiency were found to be a function of oxidizer to fuel ratio and chamber pressure. These efficiencies are correlated by an empirical correlation parameter which accounts for the effects of oxidizer to fuel ratio and chamber pressure. The exhaust plumes were colorless and transparent under all tests conditions. There was some soot adhesion to the chamber wall, but no soot adhesion was observed on the main injector simulator orifices. Higher temperature igniter gas was required to ignite the main propellants of the preburner compared with that of the LO2/Gaseous Hydrogen (GH2) propellants combination.

NASA Tech Briefs, April 2010

NASA Technical Reports Server (NTRS)

2010-01-01

Topics covered include: Active and Passive Hybrid Sensor; Quick-Response Thermal Actuator for Use as a Heat Switch; System for Hydrogen Sensing; Method for Detecting Perlite Compaction in Large Cryogenic Tanks; Using Thin-Film Thermometers as Heaters in Thermal Control Applications; Directional Spherical Cherenkov Detector; AlGaN Ultraviolet Detectors for Dual-Band UV Detection; K-Band Traveling-Wave Tube Amplifier; Simplified Load-Following Control for a Fuel Cell System; Modified Phase-meter for a Heterodyne Laser Interferometer; Loosely Coupled GPS-Aided Inertial Navigation System for Range Safety; Sideband-Separating, Millimeter-Wave Heterodyne Receiver; Coaxial Propellant Injectors With Faceplate Annulus Control; Adaptable Diffraction Gratings With Wavefront Transformation; Optimizing a Laser Process for Making Carbon Nanotubes; Thermogravimetric Analysis of Single-Wall Carbon Nanotubes; Robotic Arm Comprising Two Bending Segments; Magnetostrictive Brake; Low-Friction, Low-Profile, High-Moment Two-Axis Joint; Foil Gas Thrust Bearings for High-Speed Turbomachinery; Miniature Multi-Axis Mechanism for Hand Controllers; Digitally Enhanced Heterodyne Interferometry; Focusing Light Beams To Improve Atomic-Vapor Optical Buffers; Landmark Detection in Orbital Images Using Salience Histograms; Efficient Bit-to-Symbol Likelihood Mappings; Capacity Maximizing Constellations; Natural-Language Parser for PBEM; Policy Process Editor for P(sup 3)BM Software; A Quality System Database; Trajectory Optimization: OTIS 4; and Computer Software Configuration Item-Specific Flight Software Image Transfer Script Generator.

A Pulsed Plasma Thruster Using Dimethyl Ether as Propellant

NASA Astrophysics Data System (ADS)

Masui, Souichi; Okada, Terumasa; Kitatomi, Makoto; Kakami, Akira; Tachibana, Takeshi

The pulsed plasma thruster (PPT), has attracted attention again as a micro-thruster because of its compactness, light weight, and comparatively low power consumption. On the other hand, the propellant utilization efficiency of a conventinal Teflon PPT is relatively low among electric propulsion devices because a propellant that originates from late-time ablation produces negligible thrust. The liquid propellant PPT (LP-PPT), in which water or ethanol is fed with an injector, was proposed to overcome these difficulties. Thrust measurements show that a LP-PPT provides higher specific impulses than a conventional PPT. However, water requires temperature management for propellant storage due to its relatively high freezing point. Moreover, even if ethanol, which has a sufficiently low freezing point, is used as propellant, a pressurant is necessary, as well as water, because the vapor pressures are insufficient for self-pressurization. In this study, we propose to use dimethyl ether (DME) as the propellant. DME, which has a freezing point of 131 K at 1 atm and a vapor pressure of 6 atm at 298 K, can be stored in tanks as a liquid, and requires no feeding pressurant. We designed a DME pulsed plasma thruster to evaluate performance. Thrust measurement yielded a specific impulse of 430 s for a coaxial type at a capacitor-stored energy of 13 J.

Downhole transmission system comprising a coaxial capacitor

DOEpatents

Hall, David R [Provo, UT; Pixton, David S [Lehi, UT; Johnson, Monte L [Orem, UT; Bartholomew, David B [Springville, UT; Hall, Jr., H. Tracy; Rawle, Michael [Springville, UT

2011-05-24

A transmission system in a downhole component comprises a plurality of data transmission elements. A coaxial cable having an inner conductor and an outer conductor is disposed within a passage in the downhole component such that at least one capacitor is disposed in the passage and having a first terminal coupled to the inner conductor and a second terminal coupled to the outer conductor. Preferably the transmission element comprises an electrically conducting coil. Preferably, within the passage a connector is adapted to electrically connect the inner conductor of the coaxial cable and the lead wire. The coaxial capacitor may be disposed between and in electrically communication with the connector and the passage. In another embodiment a connector is adapted to electrical connect a first and a second portion of the inner conductor of the coaxial cable and a coaxial capacitor is in electrical communication with the connector and the passage.

Sound production on a "coaxial saxophone".

PubMed

Doc, J-B; Vergez, C; Guillemain, P; Kergomard, J

2016-11-01

Sound production on a "coaxial saxophone" is investigated experimentally. The coaxial saxophone is a variant of the cylindrical saxophone made up of two tubes mounted in parallel, which can be seen as a low-frequency analogy of a truncated conical resonator with a mouthpiece. Initially developed for the purposes of theoretical analysis, an experimental verification of the analogy between conical and cylindrical saxophones has never been reported. The present paper explains why the volume of the cylindrical saxophone mouthpiece limits the achievement of a good playability. To limit the mouthpiece volume, a coaxial alignment of pipes is proposed and a prototype of coaxial saxophone is built. An impedance model of coaxial resonator is proposed and validated by comparison with experimental data. Sound production is also studied through experiments with a blowing machine. The playability of the prototype is then assessed and proven for several values of the blowing pressure, of the embouchure parameter, and of the instrument's geometrical parameters.

ZaP-HD: High Energy Density Z-Pinch Plasmas using Sheared Flow Stabilization

NASA Astrophysics Data System (ADS)

Golingo, R. P.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Hughes, M. C.; Kim, B.; Ross, M. P.; Weed, J. R.

2015-11-01

The ZaP-HD flow Z-pinch project investigates scaling the flow Z-pinch to High Energy Density Plasma, HEDP, conditions by using sheared flow stabilization. ZaP used a single power supply to produce 100 cm long Z-pinches that were quiescent for many radial Alfven times and axial flow-through times. The flow Z-pinch concept provides an approach to achieve HED plasmas, which are dimensionally large and persist for extended durations. The ZaP-HD device replaces the single power supply from ZaP with two separate power supplies to independently control the plasma flow and current in the Z-pinch. Equilibrium is determined by diagnostic measurements of the density with interferometry and digital holography, the plasma flow and temperature with passive spectroscopy, the magnetic field with surface magnetic probes, and plasma emission with optical imaging. The diagnostics fully characterize the plasma from its initiation in the coaxial accelerator, through the pinch, and exhaust from the assembly region. The plasma evolution is modeled with high resolution codes: Mach2, WARPX, and NIMROD. Experimental results and scaling analyses are presented. This work is supported by grants from the U.S. Department of Energy and the U.S. National Nuclear Security Administration.

Ion heating and characteristics of ST plasma used by double-pulsing CHI on HIST

NASA Astrophysics Data System (ADS)

Hanao, Takafumi; Hirono, Hidetoshi; Hyobu, Takahiro; Ito, Kengo; Matsumoto, Keisuke; Nakayama, Takashi; Oki, Nobuharu; Kikuchi, Yusuke; Fukumoto, Naoyuki; Nagata, Masayoshi

2013-10-01

Multi-pulsing Coaxial Helicity Injection (M-CHI) is an efficient current drive and sustainment method used in spheromak and spherical torus (ST). We have observed plasma current/flux amplification by double pulsing CHI. Poloidal ion temperature measured by Ion Doppler Spectrometer (IDS) has a peak at plasma core region. In this region, radial electric field has a negative peak. At more inboard side that is called separatrix between closed flux region and inner open flux region, poloidal flow has a large shear and radial electric field changes the polarity. After the second CHI pulse, we observed sharp and rapid ion heating at plasma core region and separatrix. In this region, the poloidal ion temperature is selective heating because electron temperature is almost uniform. At this time, flow shear become larger and radial electric field is amplified at separatorix. These effects produce direct heating of ion through the viscous flow damping. Furthermore, we observed decrease of electron density at separatrix. Decreased density makes Hall dynamo electric field as two-fluid effect. When the ion temperature is increasing, dynamo electric field is observed at separatrix. It may have influence with the ion heating. We will discuss characteristic of double pulsing CHI driven ST plasmas and correlation of direct heating of ion with dynamo electric field and any other parameters.

Application of kinematic vorticity techniques for mylonitized Rocks in Al Amar suture, eastern Arabian Shield, Saudi Arabia

NASA Astrophysics Data System (ADS)

Hamimi, Z.; Kassem, O. M. K.; El-Sabrouty, M. N.

2015-09-01

The rotation of rigid objects within a flowing viscous medium is a function of several factors including the degree of non-coaxiality. The relationship between the orientation of such objects and their aspect ratio can be used in vorticity analyses in a variety of geological settings. Method for estimation of vorticity analysis to quantitative of kinematic vorticity number (Wm) has been applied using rotated rigid objects, such as quartz and feldspar objects. The kinematic vorticity number determined for high temperature mylonitic Abt schist in Al Amar area, extreme eastern Arabian Shield, ranges from ˜0.8 to 0.9. Obtained results from vorticity and strain analyses indicate that deformation in the area deviated from simple shear. It is concluded that nappe stacking occurred early during an earlier thrusting event, probably by brittle imbrications. Ductile strain was superimposed on the nappe structure at high-pressure as revealed by a penetrative subhorizontal foliation that is developed subparallel to tectonic contacts versus the underlying and overlying nappes. Accumulation of ductile strain during underplating was not by simple shear but involved a component of vertical shortening, which caused the subhorizontal foliation in the Al Amar area. In most cases, this foliation was formed concurrently with thrust sheets imbrications, indicating that nappe stacking was associated with vertical shortening.

76 FR 79051 - Airworthiness Directives; Lycoming Engines, Fuel Injected Reciprocating Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-21

... models requiring inspections. We are issuing this AD to prevent failure of the fuel injector fuel lines... to prevent failure of the fuel injector fuel lines that would allow fuel to spray into the engine... injector nozzles, and replace as necessary any fuel injector fuel line and clamp that does not meet all...

Vehicle-scale investigation of a fluorine jet-pump liquid hydrogen tank pressurization system

NASA Technical Reports Server (NTRS)

Cady, E. C.; Kendle, D. W.

1972-01-01

A comprehensive analytical and experimental program was performed to evaluate the performance of a fluorine-hydrogen jet-pump injector for main tank injection (MTI) pressurization of a liquid hydrogen (LH2) tank. The injector performance during pressurization and LH2 expulsion was determined by a series of seven tests of a full-scale injector and MTI pressure control system in a 28.3 cu m (1000 cu ft) flight-weight LH2 tank. Although the injector did not effectively jet-pump LH2 continuously, it showed improved pressurization performance compared to straight-pipe injectors tested under the same conditions in a previous program. The MTI computer code was modified to allow performance prediction for the jet-pump injector.

Injector having multiple fuel pegs

DOEpatents

Hadley, Mark Allan; Felling, David Kenton

2013-04-30

A fuel injector is provided, including a fuel injector body, a plurality of fuel vanes, and a plurality of fuel pegs. The injector body includes a manifold and an inlet. The manifold is configured for receiving fuel, and the inlet is configured for receiving air. The fuel vanes are located within the injector body and are positioned in a direction that is generally parallel with a longitudinal axis of the injector body to orient the air flowing from the inlet. The plurality of fuel pegs are fluidly connected to the manifold and are arranged within the plurality of fuel vanes. The plurality of fuel pegs are each spaced at a distance that is about equal between each of the plurality of fuel pegs.

High temperature co-axial winding transformers

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.; Novotny, Donald W.

1993-01-01

The analysis and design of co-axial winding transformers is presented. The design equations are derived and the different design approaches are discussed. One of the most important features of co-axial winding transformers is the fact that the leakage inductance is well controlled and can be made low. This is not the case in conventional winding transformers. In addition, the power density of co-axial winding transformers is higher than conventional ones. Hence, using co-axial winding transformers in a certain converter topology improves the power density of the converter. The design methodology used in meeting the proposed specifications of the co-axial winding transformer specifications are presented and discussed. The final transformer design was constructed in the lab. Co-axial winding transformers proved to be a good choice for high power density and high frequency applications. They have a more predictable performance compared with conventional transformers. In addition, the leakage inductance of the transformer can be controlled easily to suit a specific application. For space applications, one major concern is the extraction of heat from power apparatus to prevent excessive heating and hence damaging of these units. Because of the vacuum environment, the only way to extract heat is by using a cold plate. One advantage of co-axial winding transformers is that the surface area available to extract heat from is very large compared to conventional transformers. This stems from the unique structure of the co-axial transformer where the whole core surface area is exposed and can be utilized for cooling effectively. This is a crucial issue here since most of the losses are core losses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babaei Jandaghi, Ali; Lebady, Mohammadkazem; Zamani, Athar-Alsadat

PurposeTo compare the coaxial and noncoaxial techniques of renal parenchymal core needle biopsy.Materials and MethodsThis is an institutional review board-approved randomised controlled trial comparing 83 patients (male, n = 49) who underwent renal parenchymal core biopsy with coaxial method and 83 patients (male, n = 40) with noncoaxial method. The rate of complications, the number of glomerular profiles, and the procedural time were evaluated in a comparison of the two methods. Correlation between the presence of renal parenchymal disease and the rate of complication was also evaluated.ResultsThe procedural time was significantly shorter in the coaxial technique (coaxial group, 5 ± 1 min; noncoaxial group, 14 ± 2 min; p < 0.001). Themore » rates of complications for the coaxial method was significantly lower than the noncoaxial method (coaxial group, 10.8 %; noncoaxial group, 24.1 %; p = 0.025). There was no significant correlation between gender and the rate of complication. The number of glomerular profiles was significantly higher in patents who underwent renal biopsy with the coaxial method (coaxial group, 18.2 ± 9.1; noncoaxial group, 8.6 ± 5.5; p < 0.001). In the whole study population, the rate of complications was significantly higher in patients with a pathologic renal parenchyma compared to those with a normal parenchyma (19/71 vs. 10/95; p = 0.006).ConclusionsRenal parenchymal biopsy using a coaxial needle is a faster and safer method with a lower rate of complications.« less

Control of critical coupling in a coiled coaxial cable resonator.

PubMed

Huang, Jie; Wei, Tao; Wang, Tao; Fan, Jun; Xiao, Hai

2014-05-01

This paper reports a coiled coaxial cable resonator fabricated by cutting a slot in a spring-like coiled coaxial cable to produce a periodic perturbation. Electromagnetic coupling between two neighboring slots was observed. By manipulating the number of slots, critical coupling of the coiled coaxial cable resonator can be well controlled. An ultrahigh signal-to-noise ratio (over 50 dB) at the resonant frequency band was experimentally achieved from a coiled coaxial cable resonator with 38 turns. A theoretic model is developed to understand the device physics. The proposed device can be potentially used as a high quality and flexibly designed band-stop filter or a sensor in structural health monitoring.

Effect of vorticity on polycrystalline ice deformation

NASA Astrophysics Data System (ADS)

Llorens, Maria-Gema; Griera, Albert; Steinbach, Florian; Bons, Paul D.; Gomez-Rivas, Enrique; Jansen, Daniela; Lebensohn, Ricardo A.; Weikusat, Ilka

2017-04-01

Understanding ice sheet dynamics requires a good knowledge of how dynamic recrystallisation controls ice microstructures and rheology at different boundary conditions. In polar ice sheets, pure shear flattening typically occurs at the top of the sheets, while simple shearing dominates near their base. We present a series of two-dimensional microdynamic numerical simulations that couple ice deformation with dynamic recrystallisation of various intensities, paying special attention to the effect of boundary conditions. The viscoplastic full-field numerical modelling approach (VPFFT) (Lebensohn, 2001) is used to calculate the response of a polycrystalline aggregate that deforms purely by dislocation glide. This code is coupled with the ELLE microstructural modelling platform that includes recrystallisation in the aggregate by intracrystalline recovery, nucleation by polygonisation, as well as grain boundary migration driven by the reduction of surface and strain energies (Llorens et al., 2016a, 2016b, 2017). The results reveal that regardless the amount of DRX and ice flow a single c-axes maximum develops all simulations. This maximum is oriented approximately parallel to the maximum finite shortening direction and rotates in simple shear towards the normal to the shear plane. This leads to a distinctly different behaviour in pure and simple shear. In pure shear, the lattice preferred orientation (LPO) and shape-preferred orientation (SPO) are increasingly unfavourable for deformation, leading to hardening and an increased activity of non-basal slip. The opposite happens in simple shear, where the imposed vorticity causes rotation of the LPO and SPO to a favourable orientation, leading to strain softening. An increase of recrystallisation enhances the activity of the non-basal slip, due to the reduction of deformation localisation. In pure shear conditions, the pyramidal slip activity is thus even more enhanced and can become higher than the basal-slip activity. Our results further show that subgrain boundaries can be developed by the activity of the non-basal slip systems. The implementation of the polygonisation routine reduces grain size and SPO, but does not significantly change the final LPO, because newly nucleated grains approximately keep the c-axis orientations of their parental grains. However, it enables the establishment of an equilibrium grain size, and therefore the differential stress reaches a steady-state. Lebensohn. 2001 N-site modelling of a 3D viscoplastic polycrystal using fast Fourier transform. Acta Materialia, 49(14), 2723-2737. Llorens, et al., 2016a. Dynamic recrystallisation of ice aggregates during co-axial viscoplastic deformation: a numerical approach. Journal of Glaciology, 62(232), 359-377. Llorens, et al., 2016b. Full-field predictions of ice dynamic recrystallisation under simple shear conditions, Earth and Planetary Science Letters, 450, 233-242. Llorens, et al., 2017. Dynamic recrystallisation during deformation of polycrystalline ice: insights from numerical simulations, Philosophical Transactions of the Royal Society A, 375 (2086), 20150346.

On viscoelastic cavitating flows: A numerical study

NASA Astrophysics Data System (ADS)

Naseri, Homa; Koukouvinis, Phoevos; Malgarinos, Ilias; Gavaises, Manolis

2018-03-01

The effect of viscoelasticity on turbulent cavitating flow inside a nozzle is simulated for Phan-Thien-Tanner (PTT) fluids. Two different flow configurations are used to show the effect of viscoelasticity on different cavitation mechanisms, namely, cloud cavitation inside a step nozzle and string cavitation in an injector nozzle. In incipient cavitation condition in the step nozzle, small-scale flow features including cavitating microvortices in the shear layer are suppressed by viscoelasticity. Flow turbulence and mixing are weaker compared to the Newtonian fluid, resulting in suppression of microcavities shedding from the cavitation cloud. Moreover, mass flow rate fluctuations and cavity shedding frequency are reduced by the stabilizing effect of viscoelasticity. Time averaged values of the liquid volume fraction show that cavitation formation is strongly suppressed in the PTT viscoelastic fluid, and the cavity cloud is pushed away from the nozzle wall. In the injector nozzle, a developed cloud cavity covers the nozzle top surface, while a vortex-induced string cavity emerges from the turbulent flow inside the sac volume. Similar to the step nozzle case, viscoelasticity reduces the vapor volume fraction in the cloud region. However, formation of the streamwise string cavity is stimulated as turbulence is suppressed inside the sac volume and the nozzle orifice. Vortical perturbations in the vicinity of the vortex are damped, allowing more vapor to develop in the string cavity region. The results indicate that the effect of viscoelasticity on cavitation depends on the alignment of the cavitating vortices with respect to the main flow direction.

Apparatus for testing high pressure injector elements

NASA Technical Reports Server (NTRS)

Myers, William Neill (Inventor); Scott, Ewell M. (Inventor); Forbes, John C. (Inventor); Shadoan, Michael D. (Inventor)

1995-01-01

An apparatus for testing and evaluating the spray pattern of high pressure fuel injector elements for use in supplying fuel to combustion engines is presented. Prior art fuel injector elements were normally tested by use of low pressure apparatuses which did not provide a purge to prevent mist from obscuring the injector element or to prevent frosting of the view windows; could utilize only one fluid during each test; and had their viewing ports positioned one hundred eighty (180 deg) apart, thus preventing optimum use of laser diagnostics. The high pressure fluid injector test apparatus includes an upper hub, an upper weldment or housing, a first clamp and stud/nut assembly for securing the upper hub to the upper weldment, a standoff assembly within the upper weldment, a pair of window housings having view glasses within the upper weldment, an injector block assembly and purge plate within the upper weldment for holding an injector element to be tested and evaluated, a lower weldment or housing, a second clamp and stud/nut assembly for securing the lower weldment to the upper hub, a third clamp and stud/nut assembly for securing the lower hub to the lower weldment, mechanisms for introducing fluid under high pressure for testing an injector element, and mechanisms for purging the apparatus to prevent frosting of view glasses within the window housings and to permit unobstructed viewing of the injector element.

Apparatus for testing high pressure injector elements

NASA Technical Reports Server (NTRS)

Myers, William Neill (Inventor); Scott, Ewell M. (Inventor); Forbes, John C. (Inventor); Shadoan, Michael D. (Inventor)

1993-01-01

An apparatus for testing and evaluating the spray pattern of high pressure fuel injector elements for use in supplying fuel to combustion engines is presented. Prior art fuel injector elements were normally tested by use of low pressure apparatuses which did not provide a purge to prevent mist from obscuring the injector element or to prevent frosting of the view windows; could utilize only one fluid during each test; and had their viewing ports positioned one hundred eighty (180 deg) apart, thus preventing optimum use of laser diagnostics. The high pressure fluid injector test apparatus includes an upper hub, an upper weldment or housing, a first clamp and stud/nut assembly for securing the upper hub to the upper weldment, a standoff assembly within the upper weldment, a pair of window housings having view glasses within the upper weldment, an injector block assembly and purge plate within the upper weldment for holding an injector element to be tested and evaluated, a lower weldment or housing, a second clamp and stud/nut assembly for securing the lower weldment to the upper weldment, a lower hub, a third clamp and stud/nut assembly for securing the lower hub to the lower weldment, mechanisms for introducing fluid under high pressure for testing an injector element, and mechanisms for purging the apparatus to prevent frosting of view glasses within the window housings and to permit unobstructed viewing of the injector element.

HIT-SI Injector Voltage Measurements Using Injector Langmuir Probes

NASA Astrophysics Data System (ADS)

Aboul Hosn, Rabih; Smith, Roger; Jarboe, Thomas

2006-10-01

A pair of Langmuir probe arrays have been designed and built to measure floating potentials of the plasma at the injector mouth of the HIT-SI device. The Helicity Injected Torus using Steady Inductive Helicity Injection (HIT-SI) [1,2] is a ``bow tie'' spheromak using an electrodeless formation and sustainment concept. HIT-SI is powered by two inductive helicity injectors operated in quadrature to maintain a constant helicity injection rate. The electric probes consist of an array of four floating potential Langmuir probes measuring the voltage distribution in each injector from the shell to midpoint of the injector mouth. The probe measurements combine to determine the part of the injector loop voltage driving the n = 0 spheromak equilibrium region. Preliminary data suggest the spheromak voltage is the loop voltage minus the nearly constant injector voltage of 150-180 volts. These probe data will be used to calculate the helicity decay time of the spheromak. [1] T. R. Jarboe. Steady inductive helicity injection and its application to a high-beta spheromak. Fusion Technology, 36(1):85--91, July 1999. [2] P.E.Sieck et al., ``Demonstration of Steady Inductive Helicity Injection'', Nuc. Fusion, in press (2006).

Experimental evaluation of two premixing-prevaporizing fuel injection concepts for a gas turbine catalytic combustor

NASA Technical Reports Server (NTRS)

Tacina, R.

1976-01-01

A premixing-prevaporizing fuel system to be used with a catalytic combustor was evaluated for possible application in an automotive gas turbine. Spatial fuel distribution and degree of vaporization were measured using jet A fuel. Two types of air blast injectors were tested, a splash groove injector and a multiple jet cross stream injector. Air swirlers with vane angles of 15 deg and 30 deg were used to improve the spatial fuel distribution in a 12 cm diameter tubular rig. Distribution and vaporization measurements were made 35.5 cm downstream of the injector. The spatial fuel distribution was nearly uniform with the multiple jet contrastream injector and the splash-groove injector with a 30 deg air swirler. The vaporization was nearly 100 percent at an inlet air temperature of 600 K, and at 800 K inlet air temperature fuel oxidation reactions were observed. The total pressure loss was less than 0.5 percent of the total pressure for the multiple jet cross stream injector and the splash groove injector (without air swirler) and less than 1 percent for the splash groove with a 30 deg air swirler.

What factors affect the carriage of epinephrine auto-injectors by teenagers?

PubMed

Macadam, Clare; Barnett, Julie; Roberts, Graham; Stiefel, Gary; King, Rosemary; Erlewyn-Lajeunesse, Michel; Holloway, Judith A; Lucas, Jane S

2012-02-02

Teenagers with allergies are at particular risk of severe and fatal reactions, but epinephrine auto-injectors are not always carried as prescribed. We investigated barriers to carriage. Patients aged 12-18 years old under a specialist allergy clinic, who had previously been prescribed an auto-injector were invited to participate. Semi-structured interviews explored the factors that positively or negatively impacted on carriage. Twenty teenagers with food or venom allergies were interviewed. Only two patients had used their auto-injector in the community, although several had been treated for severe reactions in hospital. Most teenagers made complex risk assessments to determine whether to carry the auto-injector. Most but not all decisions were rational and were at least partially informed by knowledge. Factors affecting carriage included location, who else would be present, the attitudes of others and physical features of the auto-injector. Teenagers made frequent risk assessments when deciding whether to carry their auto-injectors, and generally wanted to remain safe. Their decisions were complex, multi-faceted and highly individualised. Rather than aiming for 100% carriage of auto-injectors, which remains an ambitious ideal, personalised education packages should aim to empower teenagers to make and act upon informed risk assessments.

ELM Triggering with the New PPPL Lithium Granular Injector

NASA Astrophysics Data System (ADS)

Mansfield, D. K.; Roquemore, A. L.; Maingi, R.; Hu, J. S.; Liang, Y.; Sun, Z.; Zhang, L.; Zou, G.

2012-10-01

A Li granular injector based on a high-speed rotating impeller has been developed at PPPL. The injector is capable of injecting spherical particles with diameters up to 1.3 mm and velocities of up to 100 m/s and has several possible applications. Primarily, the injector was developed as a tool to induce ELMs for ELM pacing experiments in plasmas operating in the H-mode. It can also operate as a real-time wall conditioning tool or as a method to resupply Li during a discharge to devices where Li is applied to the PFC's prior to a discharge. The injector is also capable of horizontally injecting small dust particles of any variety for plasma-dust transport studies. The first injector has recently been successfully installed on the EAST tokamak in Hefei, China where ELMs were induced with near 100% efficiency when 0.7mm spheres were injected at ˜ 40m/s into the midplane SOL. The injector will be described and supporting data for ELM triggering will be presented.

Focusing electrode and coaxial reflector used for reducing the guiding magnetic field of the Ku-band foilless transit-time oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ling, Junpu; Zhang, Jiande; He, Juntao, E-mail: hejuntao12@163.com

2014-08-15

Based on the theoretical analysis of the intense relativistic electron beam propagation in the coaxial drift-tube, a focusing electrode and a coaxial reflector is proposed to lessen the demand of the coaxial Ku-band foilless transit-time oscillator (TTO) for the guiding magnetic field. Moreover, a Ku-band TTO with the focusing electrode and the coaxial reflector is designed and studied by particle in cell simulation. When the diode voltage is 390 kV, the beam current 7.8 kA, and the guiding magnetic field is only 0.3 T, the device can output 820 MW microwave pulse at 14.25 GHz by means of the simulation.more » However, for the device without them, the output power is only 320 MW. The primary experiments are also carried out. When the guiding magnetic field is 0.3 T, the output power of the device with the focusing electrode and the coaxial reflector is double that of the one without them. The simulation and experimental results prove that the focusing electrode and the coaxial reflector are effective on reducing the guiding magnetic field of the device.« less

Micro injector sample delivery system for charged molecules

DOEpatents

Davidson, James C.; Balch, Joseph W.

1999-11-09

A micro injector sample delivery system for charged molecules. The injector is used for collecting and delivering controlled amounts of charged molecule samples for subsequent analysis. The injector delivery system can be scaled to large numbers (>96) for sample delivery to massively parallel high throughput analysis systems. The essence of the injector system is an electric field controllable loading tip including a section of porous material. By applying the appropriate polarity bias potential to the injector tip, charged molecules will migrate into porous material, and by reversing the polarity bias potential the molecules are ejected or forced away from the tip. The invention has application for uptake of charged biological molecules (e.g. proteins, nucleic acids, polymers, etc.) for delivery to analytical systems, and can be used in automated sample delivery systems.

Effect of broad properties fuel on injector performance in a reverse flow combustor

NASA Technical Reports Server (NTRS)

Raddlebaugh, S. M.; Norgren, C. T.

1983-01-01

The effect of fuel type on the performance of various fuel injectors was investigated in a reverse flow combustor. Combustor performance and emissions are documented for simplex pressure atomizing, spill flow, and airblast fuel injectors using a broad properties fuel and compared with performance using Jet A fuel. Test conditions simulated a range of flight conditions including sea level take off, low and high altitude cruise, as well as a parametric evaluation of the effect of increased combustor loading. The baseline simplex injector produced higher emission levels with corresponding lower combustion efficiency with the broad properties fuel. There was little or not loss in performance by the two advanced concept injectors with the broad properties fuel. The airblast injector proved to be especially insensitive to fuel type.

Visualization of cavitating and flashing flows within a high aspect ratio injector

NASA Astrophysics Data System (ADS)

Thompson, Andrew S.

Thermal management issues necessitate the use of fuel as a heat sink for gas turbine and liquid rocket engines. There are certain benefits to using heated fuels, namely, increased sensible enthalpy, increased combustion efficiency, a decrease in certain emissions, and enhanced vaporization characteristics. However, the thermal and pressure enviornment inside an injector can result in the fuel flashing to vapor. Depending on the injector design, this can have deleterious effects on engine performance. As interest in heated fuels inreases, it is important to understand what occurs in the flow path of an injector under flashing conditions. At the High Pressure Laboratory at Purdue University's Maurice J. Zucrow Laboritories, a test rig was designed and built to give visual access into the flow path of a 2-D slot injector. The rig is capable of pressurizing and heating a liquid to superheated conditions and utilizes a pneumatically actuated piston to pusth the liquid through the slot injector. Methanol was chosen as a surrogate fuel to allow for high levels of superheat at relatively low temperatures. Testing was completed with acrylic and quartz injectors of varying L/DH. Flashing conditions inside the injector flow path were induced via a combination of heating and back pressure adjustments. Volume flow rate, pressure measurements, and temperature measurements were made which allowed the discharge characteristics, the level of superheat, and other parameters to be calculated and compared. To give a basis for comparison the flashing results are compared to the flow through the injector under cavitating conditions. Cavitation and flashing appear to be related phenomena and this relationship is shown. Bubble formation under cavitating or flashing conditions is observed to attenuate the injector's discharge characteristics. High speed videos of the flow field were also collected. Several flow regimes and flow structures, unique to these regimes, were observed. A frequency analysis was also performed on the video files. Bubble formation in the flow field dominates the frequency spectrum, which is confined below 1 kHz. The test campaign was successful. The result is a possible way to predict an injector's performance under flashing conditions without running heated fuel through the injector. These results may be applicable to real world injector design and testing.

Photographic characterization of spark-ignition engine fuel injectors

NASA Technical Reports Server (NTRS)

Evanich, P. L.

1978-01-01

Manifold port fuel injectors suitable for use in general aviation spark-ignition engines were evaluated qualitatively on the basis of fuel spray characteristics. Photographs were taken at various fuel flow rates or pressure levels. Mechanically and electronically operated pintle injectors generally produced the most atomization. The plain-orifice injectors used on most fuel-injected general aviation engines did not atomize the fuel when sprayed into quiescent air.

Potential for cross-contamination from use of a needleless injector.

PubMed

Weintraub, A M; Ponce de Leon, M P

1998-08-01

Medical devices that are used on patients in fields containing potentially infectious body fluids can become contaminated and transmit infectious agents to other sites on the patient or to other patients if the devices are not properly cleaned and decontaminated after use on each patient treatment site. One such device is the needleless or jet injector, which is widely used in medicine and dentistry to deliver local anesthetic in procedures such as bone marrow aspirations, lumbar punctures, and cutaneous and intraoral injections. This study was conducted to determine whether cross-contamination can occur on in vitro reuse of a needleless injector and whether a manufacturer's recommended method of injector decontamination (ie, immersion sterilization) is effective in the prevention of cross-contamination. The study was performed with new autoclaved injectors, fluorescein dye, and Streptococcus crista (the bacteria commonly found in saliva) in the field of use to determine whether these devices can become contaminated during use and carry over the contamination to other sites during immediate reuse. Fluorescein dye and bacteria tests with the needleless injectors showed that contamination or carryover does occur. It appeared to reduced to a minimum when a autoclaved, sterile rubber cap used over the head of the device during injection was replaced between each use, although replacement of the rubber cap alone did not prevent carryover. Immersion of the head of the injector in a 2% glutaraldehyde solution for 30 minutes followed by a sterile water rinse and the replacement of the rubber cap with a sterile cap between uses was shown to curtail bacterial growth and prevent cross-contamination on immediate reuse of the device. This study demonstrated that needleless injectors become contaminated during in vitro use and direct contact with contaminated surfaces and that needless injectors carry over the contamination to subsequent sites of release. The replacement of the injector's rubber cap with a new one after initial discharge or the removal of an exposed rubber cap and immersion of the head of the injector in 2% glutaraldehyde followed by a rinse of the head in sterile water, as recommended by one injector manufacturer, can minimize or eliminate the carryover.

High-Resolution X-Ray and Neutron Computed Tomography of an Engine Combustion Network Spray G Gasoline Injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duke, Daniel J.; Finney, Charles E. A.; Kastengren, Alan

Given the importance of the fuel-injection process on the combustion and emissions performance of gasoline direct injected engines, there has been significant recent interest in understanding the fluid dynamics within the injector, particularly around the needle and through the nozzles. Furthermore, the pressure losses and transients that occur in the flow passages above the needle are also of interest. Simulations of these injectors typically use the nominal design geometry, which does not always match the production geometry. Computed tomography (CT) using x-ray and neutron sources can be used to obtain the real geometry from production injectors, but there are trade-offsmore » in using these techniques. X-ray CT provides high resolution, but cannot penetrate through the thicker parts of the injector. Neutron CT has excellent penetrating power but lower resolution. Here, we present results from a joint effort to characterize a gasoline direct injector representative of the Spray G injector as defined by the Engine Combustion Network. High-resolution (1.2 to 3 µm) x-ray CT measurements from the Advanced Photon Source at Argonne National Laboratory were combined with moderate-resolution (40 µm) neutron CT measurements from the High Flux Isotope Reactor at Oak Ridge National Laboratory to generate a complete internal geometry for the injector. This effort combined the strengths of both facilities’ capabilities, with extremely fine spatially resolved features in the nozzles and injector tips and fine resolution of internal features of the needle along the length of injector. Analysis of the resulting surface model of the internal fluid flow volumes of the injector reveals how the internal cross-sectional area and nozzle hole geometry differs slightly from the design dimensions. A simplified numerical simulation of the internal flow shows how deviations from the design geometry can alter the flow inside the sac and holes. Our results of this study will provide computational modelers with very accurate solid and surface models for use in computational fluid dynamics studies and experimentalists with increased insight into the operating characteristics of their injectors.« less

High-Resolution X-Ray and Neutron Computed Tomography of an Engine Combustion Network Spray G Gasoline Injector

DOE PAGES

Duke, Daniel J.; Finney, Charles E. A.; Kastengren, Alan; ...

2017-03-14

Given the importance of the fuel-injection process on the combustion and emissions performance of gasoline direct injected engines, there has been significant recent interest in understanding the fluid dynamics within the injector, particularly around the needle and through the nozzles. Furthermore, the pressure losses and transients that occur in the flow passages above the needle are also of interest. Simulations of these injectors typically use the nominal design geometry, which does not always match the production geometry. Computed tomography (CT) using x-ray and neutron sources can be used to obtain the real geometry from production injectors, but there are trade-offsmore » in using these techniques. X-ray CT provides high resolution, but cannot penetrate through the thicker parts of the injector. Neutron CT has excellent penetrating power but lower resolution. Here, we present results from a joint effort to characterize a gasoline direct injector representative of the Spray G injector as defined by the Engine Combustion Network. High-resolution (1.2 to 3 µm) x-ray CT measurements from the Advanced Photon Source at Argonne National Laboratory were combined with moderate-resolution (40 µm) neutron CT measurements from the High Flux Isotope Reactor at Oak Ridge National Laboratory to generate a complete internal geometry for the injector. This effort combined the strengths of both facilities’ capabilities, with extremely fine spatially resolved features in the nozzles and injector tips and fine resolution of internal features of the needle along the length of injector. Analysis of the resulting surface model of the internal fluid flow volumes of the injector reveals how the internal cross-sectional area and nozzle hole geometry differs slightly from the design dimensions. A simplified numerical simulation of the internal flow shows how deviations from the design geometry can alter the flow inside the sac and holes. Our results of this study will provide computational modelers with very accurate solid and surface models for use in computational fluid dynamics studies and experimentalists with increased insight into the operating characteristics of their injectors.« less

Generation of radially-polarized terahertz pulses for coupling into coaxial waveguides

PubMed Central

Navarro-Cía, Miguel; Wu, Jiang; Liu, Huiyun; Mitrofanov, Oleg

2016-01-01

Coaxial waveguides exhibit no dispersion and therefore can serve as an ideal channel for transmission of broadband THz pulses. Implementation of THz coaxial waveguide systems however requires THz beams with radially-polarized distribution. We demonstrate the launching of THz pulses into coaxial waveguides using the effect of THz pulse generation at semiconductor surfaces. We find that the radial transient photo-currents produced upon optical excitation of the surface at normal incidence radiate a THz pulse with the field distribution matching the mode of the coaxial waveguide. In this simple scheme, the optical excitation beam diameter controls the spatial profile of the generated radially-polarized THz pulse and allows us to achieve efficient coupling into the TEM waveguide mode in a hollow coaxial THz waveguide. The TEM quasi-single mode THz waveguide excitation and non-dispersive propagation of a short THz pulse is verified experimentally by time-resolved near-field mapping of the THz field at the waveguide output. PMID:27941845

Morphological appearances and photo-controllable coloration of dye-doped cholesteric liquid crystal/polymer coaxial microfibers fabricated by coaxial electrospinning technique.

PubMed

Lin, Jia-De; Chen, Che-Pei; Chen, Lin-Jer; Chuang, Yu-Chou; Huang, Shuan-Yu; Lee, Chia-Rong

2016-02-08

This study systematically investigates the morphological appearance of azo-chiral dye-doped cholesteric liquid crystal (DDCLC)/polymer coaxial microfibers obtained through the coaxial electrospinning technique and examines, for the first time, their photocontrollable reflection characteristics. Experimental results show that the quasi-continuous electrospun microfibers can be successfully fabricated at a high polymer concentration of 17.5 wt% and an optimum ratio of 2 for the feeding rates of sheath to core materials at 25 °C and a high humidity of 50% ± 2% in the spinning chamber. Furthermore, the optical controllability of the reflective features for the electrospun fibers is studied in detail by changing the concentration of the azo-chiral dopant in the core material, the UV irradiation intensity, and the core diameter of the fibers. Relevant mechanisms are addressed to explain the optical-control behaviors of the DDCLC coaxial fibers. Considering the results, optically controllable DDCLC coaxial microfibers present potential applications in UV microsensors and wearable smart textiles or swabs.

CFD-Based Design of a Filming Injector for N+3 Combustors

NASA Technical Reports Server (NTRS)

Ajmani, Kumud; Mongia, Hukam; Lee, Phil

2016-01-01

An effort was undertaken to perform CFD analysis of fluid flow in Lean-Direct Injection (LDI) combustors with axial swirl-venturi elements coupled with a new fuel-filming injector design for next-generation N+3 combustors. The National Combustion Code (NCC) was used to perform non-reacting and two-phase reacting flow computations on a N+3 injector configuration, in a single-element and a five-element injector array. All computations were performed with a consistent approach towards mesh-generation, spray-, ignition- and kinetics-modeling with the NCC. Computational predictions of the aerodynamics of the injector were used to arrive at an optimal injector design that met effective area, aerodynamics, and fuel-air mixing criteria. LDI-3 emissions (EINOx, EICO and UHC) were compared with the previous generation LDI-2 combustor experimental data at representative engine cycle conditions.

Direct Fuel Injector Power Drive System Optimization

DTIC Science & Technology

2014-04-01

solenoid coil to create magnetic field in the stator. Then, the stator pulls the pintle to open the injector nozzle . This pintle movement occurs when the...that typically deal with power strategies to the injector solenoid coil. Numerical simulation codes for diesel injection systems were developed by...Laboratory) for providing the JP-8 test fuel. REFERENCES 1. Digesu, P. and Laforgia D., “ Diesel electro- injector : A numerical simulation code”. Journal of

What factors affect the carriage of epinephrine auto-injectors by teenagers?

PubMed Central

2012-01-01

Background Teenagers with allergies are at particular risk of severe and fatal reactions, but epinephrine auto-injectors are not always carried as prescribed. We investigated barriers to carriage. Methods Patients aged 12-18 years old under a specialist allergy clinic, who had previously been prescribed an auto-injector were invited to participate. Semi-structured interviews explored the factors that positively or negatively impacted on carriage. Results Twenty teenagers with food or venom allergies were interviewed. Only two patients had used their auto-injector in the community, although several had been treated for severe reactions in hospital. Most teenagers made complex risk assessments to determine whether to carry the auto-injector. Most but not all decisions were rational and were at least partially informed by knowledge. Factors affecting carriage included location, who else would be present, the attitudes of others and physical features of the auto-injector. Teenagers made frequent risk assessments when deciding whether to carry their auto-injectors, and generally wanted to remain safe. Their decisions were complex, multi-faceted and highly individualised. Conclusions Rather than aiming for 100% carriage of auto-injectors, which remains an ambitious ideal, personalised education packages should aim to empower teenagers to make and act upon informed risk assessments. PMID:22409884

High performance N2O4/amine elements: Blowapart

NASA Technical Reports Server (NTRS)

Lawver, B. R.

1977-01-01

The mechanisms controlling hypergolic propellant reactive stream separation (RRS) were studied and used to develop design criteria for injectors free from both steady state RSS and cyclic propellant stream separation. This was accomplished through the analysis of single element injectors using N204/MMH propellants; the injectors were representative of the space shuttle orbit maneuvering engine and space tug applications. A gas phase/surface reaction mechanism which controls RSS was identified. Injector design criteria were developed, which defined a critical chamber pressure for those operating conditions above which RSS occurs. It was found that the amount of interfacial surface area at impingement is controlled by injector hydraulics.

Mixing Enhancement in a Lobed Injector

NASA Technical Reports Server (NTRS)

Smith, L. L.; Majamaki, A. J.; Lam, I. T.; Delabroy, O.; Karagozian, A. R.; Marble, F. E.; Smith, O. I.

1997-01-01

An experimental investigation of the non-reactive mixing processes associated with a lobed fuel injector in a coflowing air stream is presented. The lobed fuel injector is a device which generates streamwise vorticity, producing high strain rates which can enhance the mixing of reactants while delaying ignition in a controlled manner. The lobed injectors examined in the present study consist of two corrugated plates between which a fuel surrogate, CO2, is injected into coflowing air. Acetone is seeded in the CO2 supply as a fuel marker. Comparison of two alternative lobed injector geometries is made with a straight fuel injector to determine net differences in mixing and strain fields due to streamwise vorticity generation. Planar laser-induced fluorescence (PLIF) of the seeded acetone yields two-dimensional images of the scalar concentration field at various downstream locations, from which local mixing and scalar dissipation rates are computed. It is found that the lobed injector geometry can enhance molecular mixing and create a highly strained flowfield, and that the strain rates generated by scalar energy dissipation can potentially delay ignition in a reacting flowfield.

Engine Hydraulic Stability. [injector model for analyzing combustion instability

NASA Technical Reports Server (NTRS)

Kesselring, R. C.; Sprouse, K. M.

1977-01-01

An analytical injector model was developed specifically to analyze combustion instability coupling between the injector hydraulics and the combustion process. This digital computer dynamic injector model will, for any imposed chamber of inlet pressure profile with a frequency ranging from 100 to 3000 Hz (minimum) accurately predict/calculate the instantaneous injector flowrates. The injector system is described in terms of which flow segments enter and leave each pressure node. For each flow segment, a resistance, line lengths, and areas are required as inputs (the line lengths and areas are used in determining inertance). For each pressure node, volume and acoustic velocity are required as inputs (volume and acoustic velocity determine capacitance). The geometric criteria for determining inertances of flow segments and capacitance of pressure nodes was set. Also, a technique was developed for analytically determining time averaged steady-state pressure drops and flowrates for every flow segment in an injector when such data is not known. These pressure drops and flowrates are then used in determining the linearized flow resistance for each line segment of flow.

A coaxial cable Fabry-Perot interferometer for sensing applications.

PubMed

Huang, Jie; Wang, Tao; Hua, Lei; Fan, Jun; Xiao, Hai; Luo, Ming

2013-11-07

This paper reports a novel coaxial cable Fabry-Perot interferometer for sensing applications. The sensor is fabricated by drilling two holes half-way into a coaxial cable. The device physics was described. The temperature and strain responses of the sensor were tested. The measurement error was calculated and analyzed.

Low temperature thermal conductivity of alloys used in cryogenic coaxial cables

NASA Astrophysics Data System (ADS)

Kushino, Akihiro; Kasai, Soichi

2014-03-01

We have developed thin seamless coaxial cables applied for readout in low temperature experiments below liquid helium temperature. Stainless steel employed as the center and outer electrical conductors of the coaxial cable has adequately low thermal conductivity compared to pure metals and can be used when heat penetration into low temperature stages through cables should be lowered however it has large electrical resistivity which can disturb sensitive measurements. Superconducting NbTi alloy has good performance with rather low thermal conductivity and high electrical conductivity. Meanwhile coaxial cables using normal conducting copper alloys such as cupro-nickel, brass, beryllium-copper, phosphor-bronze are advantageous with their good electrical, thermal and cost performances. We investigated thermal conductivity of such alloys after the drawing process into coaxial cables, and compared to expected values without drawing.

Electrospun Polyurethane-Core and Gelatin-Shell Coaxial Fibre Coatings for Miniature Implantable Biosensors

PubMed Central

Wang, Ning; Burugapalli, Krishna; Wijesuriya, Shavini; Far, Mahshid Yazdi; Song, Wenhui; Moussy, Francis; Zheng, Yudong; Ma, Yanxuan; Wu, Zhentao; Li, Kang

2014-01-01

The aim of this study was to introduce bioactivity to the electrospun coating for implantable glucose biosensors. Coaxial fibre membranes having polyurethane as the core and gelatin as the shell were produced using a range of polyurethane concentrations (2, 4, 6 & 8% wt/v) while keeping gelatin concentration (10% wt/v) constant in 2,2,2-trifluoroethanol. The gelatin shell was stabilized using glutaraldehyde vapour. The formation of core-shell structure was confirmed using TEM, SEM and FTIR. The coaxial fibre membranes showed uniaxial tensile properties intermediate to that of the pure polyurethane and the gelatin fibre membranes. The gelatin shell increased hydrophilicity and glucose transport flux across the coaxial fibre membranes. The coaxial fibre membranes having small fibre diameter (541 nm) and a thick gelatin shell (52%) did not affect the sensor sensitivity, but decreased sensor’s linearity in the long run. In contrast, thicker coaxial fibre membranes (1133 nm) having a thin gelatin shell (34%) maintained both sensitivity and linearity till 84 days of the study period. To conclude, polyurethane-gelatin co-axial fibre membranes, due to their faster permeability to glucose, tailorable mechanical properties and bioactivity are potential candidates for coatings to favourably modify the host responses to extend the reliable in vivo lifetime of implantable glucose biosensors. PMID:24346001

Instability Analysis of a Low-Density Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Lawson, Anthony Layiwola

2001-01-01

The objective of this study was to determine the effects of buoyancy on the absolute instability of low-density gas jets injected into high-density gas mediums. Most of the existing analyses of low-density gas jets injected into a high-density ambient have been carried out neglecting effects of gravity. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis and a spatio-temporal stability analysis of a low-density round jet injected into a high-density ambient gas were performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. It was found that the presence of variable density within the shear layer resulted in an increase in the temporal amplification rate of the disturbances and an increase in the range of unstable frequencies, accompanied by a reduction in the phase velocities of the disturbances. Also, the temporal growth rates of the disturbances were increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity. The spatio-temporal stability analysis was performed to determine the nature of the absolute instability of the jet. The roles of the density ratio, Froude number, Schmidt number, and the lateral shift between the density and velocity profiles on the jet s absolute instability were determined. Comparisons of the results with previous experimental studies show good agreement when the effects of these variables are combined together. Thus, the combination of these variables determines how absolutely unstable the jet will be. Experiments were carried out to observe the qualitative differences between a round low-density gas jet injected into a high-density gas (helium jet injected into air) and a round constant density jet (air jet injected into air). Flow visualizations and velocity measurements in the near-injector region of the helium jet show more mixing and spreading of the helium jet than the air jet. The vortex structures develop and contribute to the jet spreading causing the helium jet to oscillate.

Evaluation of thermal loading on a methane injector at high pressure and temperature

NASA Technical Reports Server (NTRS)

Harvin, Stephen F.

1990-01-01

Experimental and numerical analyses are conducted to determine the surface temperature on a methane fuel injector used to produce a high enthalpy test stream for a combustion-fed subscale wind tunnel facility. It was found that the ratio of the methane fuel injection velocity to the air stream velocity is a significant factor in the production of high injector surface temperatures which lead to rapid deterioration of the fuel injector structure. The numerical code utilized for the computational analysis was found to be representative of the experimentally measured data since the experimental trends were reproduced by the numerical simulation. The quantitative accuracy of the numerical predictions could not be assessed from the data gathered because of the difficulty of making a noninterfering injector surface temperature measurement. The numerical code can be used for parametric evaluation of combustor parameters and thus will serve as an important tool in the design of such fuel injector systems.

Characterization of typical platelet injector flow configurations. [liquid propellant rocket engines

NASA Technical Reports Server (NTRS)

Hickox, C. E.

1975-01-01

A study to investigate the hydraulic atomization characteristics of several novel injector designs for use in liquid propellant rocket engines is presented. The injectors were manufactured from a series of thin stainless steel platelets through which orifices were very accurately formed by a photoetching process. These individual platelets were stacked together and the orifices aligned so as to produce flow passages of prescribed geometry. After alignment, the platelets were bonded into a single, 'platelet injector', unit by a diffusion bonding process. Because of the complex nature of the flow associated with platelet injectors, it was necessary to use experimental techniques, exclusively, throughout the study. Large scale models of the injectors were constructed from aluminum plates and the appropriate fluids were modeled using a glycerol-water solution. Stop-action photographs of test configurations, using spark-shadowgraph or stroboscopic back-lighting, are shown.

Review on pressure swirl injector in liquid rocket engine

NASA Astrophysics Data System (ADS)

Kang, Zhongtao; Wang, Zhen-guo; Li, Qinglian; Cheng, Peng

2018-04-01

The pressure swirl injector with tangential inlet ports is widely used in liquid rocket engine. Commonly, this type of pressure swirl injector consists of tangential inlet ports, a swirl chamber, a converging spin chamber, and a discharge orifice. The atomization of the liquid propellants includes the formation of liquid film, primary breakup and secondary atomization. And the back pressure and temperature in the combustion chamber could have great influence on the atomization of the injector. What's more, when the combustion instability occurs, the pressure oscillation could further affects the atomization process. This paper reviewed the primary atomization and the performance of the pressure swirl injector, which include the formation of the conical liquid film, the breakup and atomization characteristics of the conical liquid film, the effects of the rocket engine environment, and the response of the injector and atomization on the pressure oscillation.

Experimental Study of Injection Characteristics of a Multi-hole port injector on various Fuel Injection pressures and Temperatures

NASA Astrophysics Data System (ADS)

Movahednejad, E.; Ommi, F.; Nekofar, K.

2013-04-01

The structures of the port injector spray dominates the mixture preparation process and strongly affect the subsequent engine combustion characteristics over a wide range of operating conditions in port-injection gasoline engines. All these spray characteristics are determined by particular injector design and operating conditions. In this paper, an experimental study is made to characterize the breakup mechanism and spray characteristics of a injector with multi-disc nozzle (SAGEM,D2159MA). A comparison was made on injection characteristics of the multi-hole injectors and its effects on various fuel pressure and temperature. The distributions of the droplet size and velocity and volume flux were characterized using phase Doppler anemometry (PDA) technique. Through this work, it was found that the injector produces a finer spray with a wide spray angle in higher fuel pressure and temperature.

Investigation of spray characteristics for flashing injection of fuels containing dissolved air and superheated fuels

NASA Technical Reports Server (NTRS)

Solomon, A. S. P.; Chen, L. D.; Faeth, G. M.

1982-01-01

The flow, atomization and spreading of flashing injector flowing liquids containing dissolved gases (jet/air) as well as superheated liquids (Freon II) were considered. The use of a two stage expansion process separated by an expansion chamber, ws found to be beneficial for flashing injection particularly for dissolved gas systems. Both locally homogeneous and separated flow models provided good predictions of injector flow properties. Conventional correlations for drop sizes from pressure atomized and airblast injectors were successfully modified, using the separated flow model to prescribe injector exit conditions, to correlate drop size measurements. Additional experimental results are provided for spray angle and combustion properties of sprays from flashing injectors.

Method and apparatus for duct sealing using a clog-resistant insertable injector

DOEpatents

Wang, Duo; Modera, Mark P.

2010-12-14

A method for forming a duct access region through one side of a previously installed air duct, wherein the air duct has an air flow with an air flow direction by inserting an aerosol injector into a previously installed air duct through the access region. The aerosol injector includes a liquid tube having a liquid tube orifice for ejecting a liquid to be atomized; and a propellant cap. The method is accomplished by aligning the aerosol injector with the direction of air flow in the duct; activating an air flow within the duct; and spraying a sealant through the aerosol injector to seal the duct in the direction of the air flow.

Noncircular orifice holes and advanced fabrication techniques for liquid rocket injectors. Phase 3: Analytical and cold-flow experimental evaluation of rectangular concentric tube injector elements for gas/liquid application. Phase 4: Analytical and experimental evaluation of noncircular injector elements for gas/liquid and liquid/liquid application

NASA Technical Reports Server (NTRS)

Mchale, R. M.

1974-01-01

Results are presented of a cold-flow and hot-fire experimental study of the mixing and atomization characteristics of injector elements incorporating noncircular orifices. Both liquid/liquid and gas/liquid element types are discussed. Unlike doublet and triplet elements (circular orifices only) were investigated for the liquid/liquid case while concentric tube elements were investigated for the gas/liquid case. It is concluded that noncircular shape can be employed to significant advantage in injector design for liquid rocket engines.

HIV Prevalence and Risk among Heterosexual Methamphetamine Injectors in California

PubMed Central

Kral, Alex H.; Lorvick, Jennifer; Martinez, Alexis; Lewis, Megan A.; Orr, Alexander; Anderson, Rachel; Flynn, Neil; Bluthenthal, Ricky N.

2013-01-01

This CDC-funded study compares HIV prevalence and risk behavior among heterosexual methamphetamine (n=428) and non-methamphetamine (n=878) injectors in California, USA during 2001–2003. While HIV was not highly prevalent among methamphetamine injectors (3%), sexual and injection risk behaviors were highly prevalent (ranging from 21% to 72%). In multivariate analyses, methamphetamine injectors had higher odds than non-methamphetamine injectors of unprotected vaginal intercourse and sex with five or more sexual partners in the past six months, and of distributive and receptive syringe sharing in the past thirty days. There was no significant difference in HIV sero-status by methamphetamine use. Suggestions are made for designing HIV prevention programs. PMID:21391786

A Coaxial Cable Fabry-Perot Interferometer for Sensing Applications

PubMed Central

Huang, Jie; Wang, Tao; Hua, Lei; Fan, Jun; Xiao, Hai; Luo, Ming

2013-01-01

This paper reports a novel coaxial cable Fabry-Perot interferometer for sensing applications. The sensor is fabricated by drilling two holes half-way into a coaxial cable. The device physics was described. The temperature and strain responses of the sensor were tested. The measurement error was calculated and analyzed. PMID:24212121

A Study of Coaxial Rotor Performance and Flow Field Characteristics

DTIC Science & Technology

2016-01-22

and Syal (Ref. 14) developed figure of merit expressions for a coaxial rotor for four different operating conditions; the results are used in the...helicopter rotor,” NACA TN- 2318, March 1951. 14Leishman, J. G. and Syal , M., “Figure of Merit Definition for Coaxial Rotors,” Journal of the American

Development of an NPS Middle Ultraviolet Spectrograph (Mustang) Electronic Interface

DTIC Science & Technology

1991-12-01

connecting coaxial shield ................................ 140 xiii Figure 7-12 Encode Command Signal (top) and Video Data Signal (bottom) after connecting...coaxial shield ................................................ 142 Figure 7-13 Data Ready Signal (top) and Video Data Signal (bottom) after...connecting coaxial shield ....................................................... 142 Figure 7-14 Word Clock (top) and Gated Enable Signal Rising Edge (bottom

Investigation of multipactor breakdown in communication satellite microwave co-axial systems

NASA Astrophysics Data System (ADS)

Nagesh, S. K.; Revannasiddiah, D.; Shastry, S. V. K.

2005-01-01

Multipactor breakdown or multipactor discharge is a form of high frequency discharge that may occur in microwave components operating at very low pressures. Some RF components of multi-channel communication satellites have co-axial geometry and handle high RF power under near-vacuum conditions. The breakdown occurs due to secondary electron resonance, wherein electrons move back and forth in synchronism with the RF voltage across the gap between the inner and outer conductors of the co-axial structure. If the yield of secondary electrons from the walls of the co-axial structure is greater than unity, then the electron density increases with time and eventually leads to the breakdown. In this paper, the current due to the oscillating electrons in the co-axial geometry has been treated as a radially oriented Hertzian dipole. The electric field, due to this dipole, at any point in the coaxial structure, may then be determined by employing the dyadic Green's function technique. This field has been compared with the field that would exist in the absence of multipactor.

Coaxial Tubing Systems Increase Artificial Airway Resistance and Work of Breathing.

PubMed

Wenzel, Christin; Schumann, Stefan; Spaeth, Johannes

2017-09-01

Tubing systems are an essential component of the ventilation circuit, connecting the ventilator to the patient's airways. Coaxial tubing systems incorporate the inspiratory tube within the lumen of the expiratory one. We hypothesized that by design, these tubing systems increase resistance to air flow compared with conventional ones. We investigated the flow-dependent pressure gradient across coaxial, conventional disposable, and conventional reusable tubing systems from 3 different manufacturers. Additionally, the additional work of breathing and perception of resistance during breathing through the different devices were determined in 18 healthy volunteers. The pressure gradient across coaxial tubing systems was up to 6 times higher compared with conventional ones (1.90 ± 0.03 cm H 2 O vs 0.34 ± 0.01 cm H 2 O, P < .001) and was higher during expiration compared with inspiration ( P < .001). Additional work of breathing and perceived breathing resistance were highest in coaxial tubing systems, accordingly. Our findings suggest that the use of coaxial tubing systems should be carefully considered with respect to their increased resistance. Copyright © 2017 by Daedalus Enterprises.

Low energy spread ion source with a coaxial magnetic filter

DOEpatents

Leung, Ka-Ngo; Lee, Yung-Hee Yvette

2000-01-01

Multicusp ion sources are capable of producing ions with low axial energy spread which are necessary in applications such as ion projection lithography (IPL) and radioactive ion beam production. The addition of a radially extending magnetic filter consisting of a pair of permanent magnets to the multicusp source reduces the energy spread considerably due to the improvement in the uniformity of the axial plasma potential distribution in the discharge region. A coaxial multicusp ion source designed to further reduce the energy spread utilizes a cylindrical magnetic filter to achieve a more uniform axial plasma potential distribution. The coaxial magnetic filter divides the source chamber into an outer annular discharge region in which the plasma is produced and a coaxial inner ion extraction region into which the ions radially diffuse but from which ionizing electrons are excluded. The energy spread in the coaxial source has been measured to be 0.6 eV. Unlike other ion sources, the coaxial source has the capability of adjusting the radial plasma potential distribution and therefore the transverse ion temperature (or beam emittance).

Tactical/Combat Engines Cetane Window Evaluation

DTIC Science & Technology

2013-01-31

non-instrumented injector . The leaky instrumented injector was showing some of the combustion characteristics of the diesel fuel and it was...Instrumented HEUI-B Injector -10 0 10 20 30 40 50 60 70 80 90 100 -30 -20 -10 0 10 20 30 40 50 60 J/ CA D CAD HRR Comparison of Different Injectors Diesel ...SUPPLEMENTARY NOTES 14. ABSTRACT The European Stationary Cycle 13 Mode test was performed on a turbocharged inline 6-cylinder diesel engine and a

The use of x-ray radiography for measuring mass distributions of Rocket Injectors

DTIC Science & Technology

2013-06-01

successfully applied to diesel injectors , aerated liquid jets and impinging-jet sprays [7-10]. X-ray radiography can be performed using either a...Rocket Injectors 5a. CONTRACT NUMBER N/A 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) S.A. Schumaker, A.L. Kastengren, M.D.A...measurements for injector design. Unfortunately, the mass flow rates typically encountered in rocket engines create sprays with high optical densities

The Effect of Fuel Injector Nozzle Configuration on JP-8 Sprays at Diesel Engine Conditions

DTIC Science & Technology

2014-10-01

The Effect of Fuel Injector Nozzle Configuration on JP-8 Sprays at Diesel Engine Conditions by Matthew Kurman, Luis Bravo, Chol-Bum Kweon...Fuel Injector Nozzle Configuration on JP-8 Sprays at Diesel Engine Conditions Matthew Kurman, Luis Bravo, and Chol-Bum Kweon Vehicle Technology...March 2014 4. TITLE AND SUBTITLE The Effect of Fuel Injector Nozzle Configuration on JP-8 Sprays at Diesel Engine Conditions 5a. CONTRACT NUMBER 5b

Redirecting by Injector

NASA Technical Reports Server (NTRS)

Filman, Robert E.; Lee, Diana D.; Norvig, Peter (Technical Monitor)

2000-01-01

We describe the Object Infrastructure Framework, a system that seeks to simplify the creation of distributed applications by injecting behavior on the communication paths between components. We touch on some of the ilities and services that can be achieved with injector technology, and then focus on the uses of redirecting injectors, injectors that take requests directed at a particular server and generate requests directed at others. We close by noting that OIF is an Aspect-Oriented Programming system, and comparing OIF to related work.

Using CFD as Rocket Injector Design Tool: Recent Progress at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Tucker, Kevin; West, Jeff; Williams, Robert; Lin, Jeff; Rocker, Marvin; Canabal, Francisco; Robles, Bryan; Garcia, Robert; Chenoweth, James

2003-01-01

The choice of tools used for injector design is in a transitional phase between exclusive reliance on the empirically based correlations and extensive use of computational fluid dynamics (CFD). The Next Generation Launch Technology (NGLT) Program goals emphasizing lower costs and increased reliability have produced a need to enable CFD as an injector design tool in a shorter time frame. This is the primary objective of the Staged Combustor Injector Technology Task currently under way at Marshall Space Flight Center (MSFC). The documentation of this effort begins with a very brief status of current injector design tools. MSFC's vision for use of CFD as a tool for combustion devices design is stated and discussed with emphasis on the injector. The concept of the Simulation Readiness Level (SRL), comprised of solution fidelity, robustness and accuracy, is introduced and discussed. This quantitative measurement is used to establish the gap between the current state of demonstrated capability and that necessary for regular use in the design process. MSFC's view of the validation process is presented and issues associated with obtaining the necessary data are noted and discussed. Three current experimental efforts aimed at generating validation data are presented. The importance of uncertainty analysis to understand the data quality is also demonstrated. First, a brief status of current injector design tools is provided as context for the current effort. Next, the MSFC vision for using CFD as an injector design tool is stated. A generic CFD-based injector design methodology is also outlined and briefly discussed. Three areas where MSFC is using injector CFD analyses for program support will be discussed. These include the Integrated Powerhead Development (IPD) engine which uses hydrogen and oxygen propellants in a full flow staged combustion (FFSC) cycle and the TR-107 and the RS84 engine both of which use RP-1 and oxygen in an ORSC cycle. Finally, an attempt is made to objectively summarize what progress has been made at MSFC in enabling CFD as an injector design tool.

Etude Experimentale du Photo-Injecteur de Fermilab (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carneiro, Jean-Paul

2001-01-01

TESLA (TeV Superconducting Linear Accelerator) is an international collaboration which is studying the feasibility of anmore » $e^+e^-$ collider of energy 0.8 TeV in the center of mass. One of the first goals of this collaboration was to construct a prototype linear accelerator at the DESY Laboratory in Hamburg, the TESLA Test Facility (TTF), in order to establish the technical basis for the collider. Two injectors were developed for TTF: a thermionic injector (developed by LAL-Orsay, IPN-Orsay, and CEA-Saclay) and a photo-injector (developed by Fermilab). The thermionic injector was used from February 1997 to October 1998, and then it was replaced by the photo-injector, which was first operated in December 1998. Another photo-injector, identical to the one delivered to TTF, was installed at Fermilab in the $$A{\\emptyset}$$ Building. The first beam from the latter was produced on 3 March 1999. The photo-injector consists of an RF gun, followed by a superconducting cavity. The RF gun is a 1.625-cell copper cavity with a resonant frequency of 1.3 GHz. The gun contains a cesium telluride ($$C_{s_2}$$Te) photo-cathode, which is illuminated by UV pulses from a Nd:YLF laser. The system can produce trains of 800 bunches of photo-electrons of charge 8 nC per bunch with spacing between bunches of 1$$\\mu$$s and 10 Hz repetition rate. Upon emerging from the RF gun, the beam energy is 4 to 5 MeV; the beam is then rapidly accelerated by the superconducting cavity to an energy of 17 to 20 MeV. Finally, a magnetic chicane, consisting of 4 dipoles, produces longitudinal compression of the electron bunches. This thesis describes the installation of the photo-injector at Fermilab and presents the experimentally-measured characteristics of the injector. The principal measurements were quantum eciency, dark current, transverse emittance, and bunch length. The conclusion from these studies is that the quality of the photo-injector beam fullls the design goals. The photo-injector at Fermilab is presently available for user experiments, including the production of at beams and plasma wake eld acceleration.« less

Low-Power Optical Trapping of Nanoparticles and Proteins with Resonant Coaxial Nanoaperture Using 10 nm Gap.

PubMed

Yoo, Daehan; Gurunatha, Kargal L; Choi, Han-Kyu; Mohr, Daniel A; Ertsgaard, Christopher T; Gordon, Reuven; Oh, Sang-Hyun

2018-06-13

We present optical trapping with a 10 nm gap resonant coaxial nanoaperture in a gold film. Large arrays of 600 resonant plasmonic coaxial nanoaperture traps are produced on a single chip via atomic layer lithography with each aperture tuned to match a 785 nm laser source. We show that these single coaxial apertures can act as efficient nanotweezers with a sharp potential well, capable of trapping 30 nm polystyrene nanoparticles and streptavidin molecules with a laser power as low as 4.7 mW. Furthermore, the resonant coaxial nanoaperture enables real-time label-free detection of the trapping events via simple transmission measurements. Our fabrication technique is scalable and reproducible, since the critical nanogap dimension is defined by atomic layer deposition. Thus our platform shows significant potential to push the limit of optical trapping technologies.

Plasma arc torch with coaxial wire feed

DOEpatents

Hooper, Frederick M

2002-01-01

A plasma arc welding apparatus having a coaxial wire feed. The apparatus includes a plasma arc welding torch, a wire guide disposed coaxially inside of the plasma arc welding torch, and a hollow non-consumable electrode. The coaxial wire guide feeds non-electrified filler wire through the tip of the hollow non-consumable electrode during plasma arc welding. Non-electrified filler wires as small as 0.010 inches can be used. This invention allows precision control of the positioning and feeding of the filler wire during plasma arc welding. Since the non-electrified filler wire is fed coaxially through the center of the plasma arc torch's electrode and nozzle, the wire is automatically aimed at the optimum point in the weld zone. Therefore, there is no need for additional equipment to position and feed the filler wire from the side before or during welding.

An All-Dielectric Coaxial Waveguide.

PubMed

Ibanescu; Fink; Fan; Thomas; Joannopoulos

2000-07-21

An all-dielectric coaxial waveguide that can overcome problems of polarization rotation and pulse broadening in the transmission of optical light is presented here. It consists of a coaxial waveguiding region with a low index of refraction, bounded by two cylindrical, dielectric, multilayer, omnidirectional reflecting mirrors. The waveguide can be designed to support a single mode whose properties are very similar to the unique transverse electromagnetic mode of a traditional metallic coaxial cable. The new mode has radial symmetry and a point of zero dispersion. Moreover, because the light is not confined by total internal reflection, the waveguide can guide light around very sharp corners.

Coaxial-type water load for measuring high voltage, high current and short pulse of a compact Marx system for a high power microwave source

NASA Astrophysics Data System (ADS)

Han, Jaeeun; Kim, Jung-ho; Park, Sang-duck; Yoon, Moohyun; Park, Soo Yong; Choi, Do Won; Shin, Jin Woo; So, Joon Ho

2009-11-01

A coaxial-type water load was used to measure the voltage output from a Marx generator for a high power microwave source. This output had a rise time of 20 ns, a pulse duration of a few hundred ns, and an amplitude up to 500 kV. The design of the coaxial water load showed that it is an ideal resistive divider and can also accurately measure a short pulse. Experiments were performed to test the performance of the Marx generator with the calibrated coaxial water load.

A novel solar bi-ejector refrigeration system and the performance of the added injector with different structures and operation parameters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Fei; Shen, Shengqiang

2009-12-15

A novel solar bi-ejector refrigeration system was investigated, whose difference compared to the traditional system is that the circulation pump is replaced by a thermal injector. The new system works more stably and needs less maintenance work than the old one, and the whole system can more fully utilize the solar energy. The mathematical models for calculating the performance of the injector and the whole solar refrigeration system were established. The pressure rise performance of injector under different structure and operation parameters and the performance of solar bi-ejector refrigeration system were studied with R123. The results show that the dischargedmore » pressure of injector is affected by structure dimensions of injector and operation conditions. With increasing generation temperature, the entrainment ratio of ejector becomes better while that of injector becomes worse and the overall thermal efficiency of the solar bi-ejector refrigeration system first increases and then decreases with an optimum value of 0.132 at generation temperature of 105 C, condensation temperature of 35 C and evaporation temperature of 10 C. (author)« less

Inexpensive high vacuum feedthroughs.

NASA Technical Reports Server (NTRS)

Gerber, S.; Post, D.

1973-01-01

Description of the use of rigid coaxial cable in the construction of high vacuum coaxial and coaxial push-pull rotary motion feedthroughs. This type of feedthroughs is shown to be extremely cheap and simple to make and modify. It can be used for moderately high voltages and provides a continuous, well shielded, low-noise feedthrough cable in any desired configuration.

Coaxial short pulsed laser

DOEpatents

Nelson, M.A.; Davies, T.J.

1975-08-01

This invention relates to a laser system of rugged design suitable for use in a field environment. The laser itself is of coaxial design with a solid potting material filling the space between components. A reservoir is employed to provide a gas lasing medium between an electrode pair, each of which is connected to one of the coaxial conductors. (auth)

Injection characteristics study of high-pressure direct injector for Compressed Natural Gas (CNG) using experimental and analytical method

NASA Astrophysics Data System (ADS)

Taha, Z.; Rahim, MF Abdul; Mamat, R.

2017-10-01

The injection characteristics of direct injector affect the mixture formation and combustion processes. In addition, the injector is converted from gasoline operation for CNG application. Thus measurement of CNG direct injector mass flow rate was done by independently tested a single injector on a test bench. The first case investigated the effect of CNG injection pressure and the second case evaluate the effect of pulse-width of injection duration. An analytical model was also developed to predict the mass flow rate of the injector. The injector was operated in a choked condition in both the experiments and simulation studies. In case 1, it was shown that mass flow rate through the injector is affected by injection pressure linearly. Based on the tested injection pressure of 20 bar to 60 bar, the resultant mass flow rate are in the range of 0.4 g/s to 1.2 g/s which are met with theoretical flow rate required by the engine. However, in Case 2, it was demonstrated that the average mass flow rate at short injection durations is lower than recorded in Case 1. At injection pressure of 50 bar, the average mass flow rate for Case 2 and Case 1 are 0.7 g/s and 1.1 g/s respectively. Also, the measured mass flow rate at short injection duration showing a fluctuating data in the range of 0.2 g/s - 1.3 g/s without any noticeable trends. The injector model able to predict the trend of the mass flow rate at different injection pressure but unable to track the fluctuating trend at short injection duration.

Internal combustion engine with compressed air collection system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, P.W.

1988-08-23

This patent describes an internal combustion engine comprising cylinders respectively including a pressure port, pistons respectively movable in the cylinders through respective compression strokes, fuel injectors respectively connected to the cylinders and operative to supply, from a fuel source to the respective cylinders, a metered quantity of fuel conveyed by compressed gas in response to fuel injector operation during the compression strokes of the respective cylinders, a storage tank for accumulating and storing compressed gas, means for selectively connecting the pressure ports to the storage tank only during the compression strokes of the respective cylinders, and duct means connecting themore » storage tank to the fuel injectors for supplying the fuel injectors with compressed gas in response to fuel injector operation.« less

The subject-fixated coaxially sighted corneal light reflex: a clinical marker for centration of refractive treatments and devices.

PubMed

Chang, Daniel H; Waring, George O

2014-11-01

To describe the inconsistencies in definition, application, and usage of the ocular reference axes (optical axis, visual axis, line of sight, pupillary axis, and topographic axis) and angles (angle kappa, lambda, and alpha) and to propose a precise, reproducible, clinically defined reference marker and axis for centration of refractive treatments and devices. Perspective. Literature review of papers dealing with ocular reference axes, angles, and centration. The inconsistent definitions and usage of the current ocular axes, as derived from eye models, limit their clinical utility. With a clear understanding of Purkinje images and a defined alignment of the observer, light source/fixation target, and subject eye, the subject-fixated coaxially sighted corneal light reflex can be a clinically useful reference marker. The axis formed by connecting the subject-fixated coaxially sighted corneal light reflex and the fixation point, the subject-fixated coaxially sighted corneal light reflex axis, is independent of pupillary dilation and phakic status of the eye. The relationship of the subject-fixated coaxially sighted corneal light reflex axis to a refined definition of the visual axis without reference to nodal points, the foveal-fixation axis, is discussed. The displacement between the subject-fixated coaxially sighted corneal light reflex and pupil center is described not by an angle, but by a chord, here termed chord mu. The application of the subject-fixated coaxially sighted corneal light reflex to the surgical centration of refractive treatments and devices is discussed. As a clinically defined reference marker, the subject-fixated coaxially sighted corneal light reflex avoids the shortcomings of current ocular axes for clinical application and may contribute to better consensus in the literature and improved patient outcomes. Copyright © 2014 Elsevier Inc. All rights reserved.

Mathematical model of a rotational bioreactor for the dynamic cultivation of scaffold-adhered human mesenchymal stem cells for bone regeneration

NASA Astrophysics Data System (ADS)

Ganimedov, V. L.; Papaeva, E. O.; Maslov, N. A.; Larionov, P. M.

2017-09-01

Development of cell-mediated scaffold technologies for the treatment of critical bone defects is very important for the purpose of reparative bone regeneration. Today the properties of the bioreactor for cell-seeded scaffold cultivation are the subject of intensive research. We used the mathematical modeling of rotational reactor and construct computational algorithm with the help of ANSYS software package to develop this new procedure. The solution obtained with the help of the constructed computational algorithm is in good agreement with the analytical solution of Couette for the task of two coaxial cylinders. The series of flow computations for different rotation frequencies (1, 0.75, 0.5, 0.33, 1.125 Hz) was performed for the laminar flow regime approximation with the help of computational algorithm. It was found that Taylor vortices appear in the annular gap between the cylinders in a simulated bioreactor. It was obtained that shear stress in the range of interest (0.002-0.1 Pa) arise on outer surface of inner cylinder when it rotates with the frequency not exceeding 0.8 Hz. So the constructed mathematical model and the created computational algorithm for calculating the flow parameters allow predicting the shear stress and pressure values depending on the rotation frequency and geometric parameters, as well as optimizing the operating mode of the bioreactor.

21 CFR 870.1660 - Indicator injector.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Indicator injector. 870.1660 Section 870.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1660 Indicator injector. (a...

21 CFR 870.1660 - Indicator injector.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Indicator injector. 870.1660 Section 870.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CARDIOVASCULAR DEVICES Cardiovascular Diagnostic Devices § 870.1660 Indicator injector. (a...

Installation and first operation of the International Fusion Materials Irradiation Facility injector at the Rokkasho site

NASA Astrophysics Data System (ADS)

Gobin, Raphael; Bogard, Daniel; Bolzon, Benoit; Bourdelle, Gilles; Chauvin, Nicolas; Chel, Stéphane; Girardot, Patrick; Gomes, Adelino; Guiho, Patrice; Harrault, Francis; Loiseau, Denis; Lussignol, Yves; Misiara, Nicolas; Roger, Arnaud; Senée, Franck; Valette, Matthieu; Cara, Philippe; Duglué, Daniel; Gex, Dominique; Okumura, Yoshikazu; Marcos Ayala, Juan; Knaster, Juan; Marqueta, Alvaro; Kasugai, Atsushi; O'Hira, Shigeru; Shinto, Katsuhiro; Takahashi, Hiroki

2016-02-01

The International Fusion Materials Irradiation Facility (IFMIF) linear IFMIF prototype accelerator injector dedicated to high intensity deuteron beam production has been designed, built, and tested at CEA/Saclay between 2008 and 2012. After the completion of the acceptance tests at Saclay, the injector has been fully sent to Japan. The re-assembly of the injector has been performed between March and May 2014. Then after the check-out phase, the production of the first proton beam occurred in November 2014. Hydrogen and deuteron beam commissioning is now in progress after having proceeded with the final tests on the entire injector equipment including high power diagnostics. This article reports the different phases of the injector installation pointing out the safety and security needs, as well as the first beam production results in Japan and chopper tests. Detailed operation and commissioning results (with H+ and D+ 100 keV beams) are reported in a second article.

Transitions from injecting to non-injecting drug use: potential protection against HCV infection

PubMed Central

Des Jarlais, Don C.; McKnight, Courtney; Arasteh, Kamyar; Feelemyer, Jonathan; Perlman, David C.; Hagan, Holly; Cooper, Hannah L. F.

2013-01-01

Transitions from injecting to non-injecting drug use have been reported from many different areas, particularly in areas with large human immunodeficiency virus (HIV) epidemics. The extent to which such transitions actually protect against HIV and HCV has not been determined. A cross-sectional survey with HIV and hepatitis C (HCV) testing was conducted with 322 former injectors (persons who had injected illicit drugs but permanently transitioned to non-injecting use) and 801 current injectors recruited in New York City between 2007 and 2012. There were no differences in HIV prevalence, while HCV prevalence was significantly lower among former injectors compared to current injectors. Years injecting functioned as a mediating variable linking former injector status to lower HCV prevalence. Transitions have continued well beyond the reduction in the threat of AIDS to injectors in the city. New interventions to support transitions to non-injecting drug use should be developed and supported by both drug treatment and syringe exchange programs. PMID:24161262

An Internal Coaxil Cable Seal System

DOEpatents

Hall, David R.; Hall, Jr., H. Tracy; Pixton, David; Dahlgren, Scott; Sneddon, Cameron; Briscoe, Michael; Fox, Joe

2004-12-23

The invention is a seal system for a coaxial cable more specifically an internal seal system placed within the coaxial cable and its constituent components. A series of seal stacks including flexible rigid rings and elastomeric rings are placed on load bearing members within the coaxial cable. The current invention is adapted to seal the annular space between the coaxial cable and an electrical contact passing there through. The coaxial cable is disposed within drilling components to transmit electrical signals between drilling components within a drill string. During oil and gas exploration, a drill string can see a range of pressures and temperatures thus resulting in multiple combinations of temperature and pressure and increasing the difficulty of creating a robust seal for all combinations. The seal system can be used in a plurality of downhole components, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars.

Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates

NASA Astrophysics Data System (ADS)

Wan, Mimi; Zhao, Wenbo; Peng, Fang; Wang, Qi; Xu, Ping; Mao, Chun; Shen, Jian

2016-08-01

A new kind of high-quality Ag/PS coaxial nanocables can be facilely synthesized by using soft/hard templates method. In order to effectively introduce Ag sources into porous polystyrene (PS) nanotubes which were trapped in porous anodic aluminum oxide (AAO) hard template, Pluronic F127 (F127) was used as guiding agent, soft template and reductant. Meanwhile, ethylene glycol solution was also used as solvent and co-reducing agent to assist in the formation of silver nanowires. The influences of concentration of F127 and reducing reaction time on the formation of Ag/PS coaxial nanocables were discussed. Results indicated that the high-quality Ag/PS coaxial nanocables can be obtained by the mixed mode of soft/hard templates under optimized conditions. This strategy is expected to be extended to design more metal/polymer coaxial nanocables for the benefit of creation of complex and functional nanoarchitectures and components.

Quantification and Patterns of Endothelial Cell Loss Due to Eye Bank Preparation and Injector Method in Descemet Membrane Endothelial Keratoplasty Tissues.

PubMed

Schallhorn, Julie M; Holiman, Jeffrey D; Stoeger, Christopher G; Chamberlain, Winston

2016-03-01

To evaluate endothelial cell damage after eye bank preparation and passage through 1 of 2 different injectors for Descemet membrane endothelial keratoplasty grafts. Eighteen Descemet membrane endothelial keratoplasty grafts were prepared by Lions VisionGift with the standard partial prepeel technique and placement of an S-stamp for orientation. The grafts were randomly assigned to injection with either a glass-modified Jones tube injector (Gunther Weiss Scientific Glass) or a closed-system intraocular lens injector (Viscoject 2.2; Medicel). After injection, the grafts were stained with the vital fluorescent dye Calcein AM and digitally imaged. The percentage of cell loss was calculated by measuring the area of nonfluorescent pixels and dividing it by the total graft area pixels. Grafts injected using the modified Jones tube injector had an overall cell loss of 27% ± 5% [95% confidence interval, 21%-35%]. Grafts injected using the closed-system intraocular lens injector had a cell loss of 32% ± 8% (95% confidence interval, 21%-45%). This difference was not statistically significant (P = 0.3). Several damage patterns including damage due to S-stamp placement were observed, but they did not correlate with injector type. In this in vitro study, there was no difference in the cell loss associated with the injector method. Grafts in both groups sustained significant cell loss and displayed evidence of graft preparation and S-stamp placement. Improvement in graft preparation and injection methods may improve cell retention.

Evaluation of a new soft tipped injector for the implantation of foldable intraocular lenses.

PubMed

Kleinmann, Guy; Apple, David J

2007-08-01

To evaluate the R-INJ-04 soft-tipped injector, a new injector with an integral round nozzle manufactured by Rayner Intraocular Lenses, England. 16 Rayner C-flex intraocular lenses (IOLs; Rayner Intraocular lenses, England) ranging between +10 and +30 D (2 for each power) were tested. An ophthalmic viscoelastic device (Healon, AMO, Santa Ana, California, USA) was applied to the injectors. The IOLs were loaded according to the company injector's instructions for use and were injected into a Petri dish. After the injection, all the IOLs and nozzles were evaluated by gross (macroscopic) and microscopic analyses and photographed under a light microscope. One lens of each power and the cartridge used for the implantation were then sent for further analysis by scanning electron microscopy (SEM). The rest of the IOLs were tested for power and modulation transfer function (MTF). All the injections were successful. No damage to the IOLs or to the injectors was found by gross examination, light microscopy and SEM. No deposits were found on the IOL optical surfaces or haptics. Power and MTF analysis showed a close match with the original measurements. Our results suggest that the R-INJ-04 soft-tipped injector is safe for the implantation of the C-flex IOL with power range from 10 to 30 D. No structural damage to the IOLs or to the injectors was found, and the lens power and light transmission properties were not damaged in any way by the injection process.

Non-Solenoidal Tokamak Startup via Inboard Local Helicity Injection on the Pegasus ST

NASA Astrophysics Data System (ADS)

Perry, J. M.; Barr, J. L.; Bodner, G. M.; Bongard, M. W.; Fonck, R. J.; Pachicano, J. L.; Reusch, J. A.; Rodriguez Sanchez, C.; Richner, N. J.; Schlossberg, D. J.

2016-10-01

Local helicity injection (LHI) is a non-solenoidal startup technique utilizing small injectors at the plasma edge to source current along helical magnetic field lines. Unstable injected current streams relax to a tokamak-like configuration with high toroidal current multiplication. Flexible placement of injectors permits tradeoffs between helicity injection rate, poloidal field induction, and magnetic geometry requirements for initial relaxation. Experiments using a new set of large-area injectors in the lower divertor explore the efficacy of high-field-side (HFS) injection. The increased area (4 cm2) current source is functional up to full Pegasus toroidal field (BT , inj = 0.23 T). However, relaxation to a tokamak state is increasingly frustrated for BT , inj > 0.15 T with uniform vacuum vertical field. Paths to relaxation at increased field include: manipulation of vacuum poloidal field geometry; increased injector current; and plasma initiation with outboard injectors, subsequently transitioning to divertor injector drive. During initial tests of HFS injectors, achieved Vinj was limited to 600 V by plasma-material interactions on the divertor plate, which may be mitigated by increasing injector elevation. In experiments with helicity injection as the dominant current drive Ip 0.13 MA has been attained, with T̲e > 100 eV and ne 1019 m-3. Extrapolation to full BT, longer pulse length, and Vinj 1 kV suggest Ip > 0.25 MA should be attainable in a plasma dominated by helicity drive. Work supported by US DOE Grant DE-FG02-96ER54375.

Plasma Studies in the SPECTOR Experiment as Target Development for MTF

NASA Astrophysics Data System (ADS)

Ivanov, Russ; Young, William; the Fusion Team, General

2016-10-01

General Fusion (GF) is developing a Magnetized Target Fusion (MTF) concept in which magnetized plasmas are adiabatically compressed to fusion conditions by the collapse of a liquid metal vortex. To study and optimize the plasma compression process, GF has a field test program in which subscale plasma targets are rapidly compressed with a moving flux conserver. GF has done many field tests to date on plasmas with sufficient thermal confinement but with a compression geometry that is not nearly self-similar. GF has a new design for our subscale plasma injectors called SPECTOR (for SPhErical Compact TORoid) capable of generating and compressing plasmas with a more spherical form factor. SPECTOR forms spherical tokamak plasmas by coaxial helicity injection into a flux conserver (a = 9 cm, R = 19 cm) with a pre-existing toroidal field created by 0.5 MA current in an axial shaft. The toroidal plasma current of 100 - 300 kA resistively decays over a time period of 1.5 msec. SPECTOR1 has an extensive set of plasma diagnostics including Thomson scattering and polarimetry. MHD stability and lifetime of the plasma was explored in different magnetic configurations with a variable safety factor q(Ψ) . Relatively hot (Te >= 350 eV) and dense ( 1020 m-3) plasmas have achieved energy confinement times τE >= 100 μsec and are now ready for field compression tests. russ.ivanov@generalfusion.com.

NIMROD Simulations of Spheromak Formation, Magnetic Reconnection and Energy Confinement in SSPX

NASA Astrophysics Data System (ADS)

Hooper, E. B.; Sovinec, C. R.

2005-10-01

The SSPX spheromak is formed and driven by a coaxial electrostatic gun that injects current and magnetic flux. Magnetic fluctuations are associated with the conversion of toroidal to poloidal magnetic flux during formation. After formation, fluctuations that break axisymmetry degrade magnetic surfaces, and are anti-correlated with the core temperature and energy confinement time. We report NIMROD simulations extending earlier work^1 supporting the SSPX experiment through predictions of performance and providing insight. The simulations are in fairly good agreement with features observed in SSPX and underscore the importance of current profile control in mitigating magnetic fluctuation amplitudes and improving confinement. The simulations yield insight into magnetic reconnection and the relationship of fluctuations to field line stochasticity. We have added external circuit equations for the new 32 module capacitor bank in SSPX that will add flexibility in shaping the injector current pulses and substantially increase the injected currents and the magnetic energy. New NIMROD simulations of SSPX lead to higher temperature plasmas than in previous simulations. *Work supported by U.S. DOE, under Contr. No. W-7405-ENG-48 at U. Cal. LLNL and under grant FG02-01ER54661 at U. Wisc Madison. ^1C. R. Sovinec, B. I. Cohen, et al., Phys. Rev. Lett. 94, 035003 (2005); B. I. Cohen, E. B. Hooper, et al., Phys. Plasmas 12, 056106 (2005).

The resonant radio-frequency magnetic probe tuned by coaxial cable.

PubMed

Sun, B; Huo, W G; Ding, Z F

2012-08-01

In this paper, the resonant rf magnetic probe is upgraded by replacing the rotary capacitor in the old version with the series-connected coaxial cable. The numerical calculation and the measurement with the prototype probe show that the rf magnetic probe can achieve resonance at a middle length of the series-connected coaxial cable. The good electrical symmetry of the new rf magnetic probe is ensured by both the identity of series-connected coaxial cables and the new structure of the primary winding. Practical measurements conduced on an rf inductively coupled plasma source demonstrate that performances of the new rf magnetic probe are good.

Research on a 170 GHz, 2 MW coaxial cavity gyrotron with inner-outer corrugation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Shenyong, E-mail: houshenyong@sohu.com; Yu, Sheng; Li, Hongfu

2015-03-15

In this paper, a coaxial cavity gyrotron with inner-outer corrugation is researched. The electron kineto-equations and the first order transmission line equations of the gyrotron are derived from Lorentz force equation and the transmission line theory, respectively. And then, a 2 MW, 170 GHz coaxial cavity gyrotron with inner-outer corrugation is designed. By means of numerical calculation, the beam-wave interaction of the coaxial cavity gyrotron with inner-outer corrugation is investigated. Results show that the efficient and the outpower of the gyrotron are 42.3% and 2.38 MW, respectively.

Modified van Vaals-Bergman coaxial cable coil (lambda coil) for high-field imaging.

PubMed

Matsuzawa, H; Nakada, T

1996-03-01

An easily constructed, low-capacitive coupling volume coil based on the van Vaals-Bergman coaxial cable coil for high field imaging is described. The coil (designated "lambda coil") was constructed using two 5/4 length 50 omega coaxial cables matched to a 50 omega transmission line with LC bridge balun. The standing wave on the single 5/4 lambda length coaxial cable provides two points of current maxima in oppositional direction. Therefore, the four current elements necessary for effective B1 field generation can be obtained by two 5/4 lambda length coaxial cables arranged analogous to 1/2 lambda T-antenna. Capacitive coupling between the coil elements and conductive samples (i.e. animals) is minimized by simply retaining the shield of the coaxial cable for the area of voltage maxima. The lambda coil exhibited excellent performance as a volume coil with a high quality factor and highly homogeneous rf fields. Because of its dramatically simple architecture and excellent performance, the lambda coil configuration appears to be an economical alternative to the original van Vaals-Bergman design, especially for research facilities with a high field magnet and limited bore space.

Heat removal capability of divertor coaxial tube assembly

NASA Astrophysics Data System (ADS)

Shibui, Masanao; Nakahira, Masataka; Tada, Eisuke; Takatsu, Hideyuki

1994-05-01

To deal with high power flowing in the divertor region, an advanced divertor concept with gas target has been proposed for use in ITER/EDA. The concept uses a divertor channel to remove the radiated power while allowing neutrals to recirculate. Candidate channel wall designs include a tube array design where many coaxial tubes are arranged in the toroidal direction to make louver. The coaxial tube consists of a Be protection tube encases many supply tubes wound helically around a return tube. V-alloy and hardened Cu-alloy have been proposed for use in the supply and return tubes. Some coolants have also been proposed for the design including pressurized He and liquid metals, because these coolants are consistent with the selection of coolants for the blanket and also meet the requirement of high temperature operation. In the coaxial tube design, the coolant area is restricted and brittle Be material is used under severe thermal cyclings. Thus, to obtain the coaxial tube with sufficient safety margin for the expected fusion power excursion, it is essential to understand its applicability limit. The paper discusses heat removal capability of the coaxial tube and recommends some design modifications.

Computational Study of Flow Interactions in Coaxial Rotors

NASA Technical Reports Server (NTRS)

Yoon, Seokkwan; Lee, Henry C.; Pulliam, Thomas H.

2016-01-01

Although the first idea of coaxial rotors appeared more than 150 years ago, most helicopters have used single main-rotor/tail-rotor combination. Since reactive moments of coaxial rotors are canceled by contra-rotation, no tail rotor is required to counter the torque generated by the main rotor. Unlike the single main rotor design that distributes power to both main and tail rotors, all of the power for coaxial rotors is used for vertical thrust. Thus, no power is wasted for anti-torque or directional control. The saved power helps coaxial rotors reach a higher hover ceiling than single rotor helicopters. Another advantage of coaxial rotors is that the overall rotor diameter can be reduced for a given vehicle gross weight because each rotor provides a maximum contribution to vertical thrust to overcome vehicle weight. However, increased mechanical complexity of the hub has been one of the challenges for manufacturing coaxial rotorcraft. Only the Kamov Design Bureau of Russia had been notably successful in production of coaxial helicopters until Sikorsky built X2, an experimental compound helicopter. Recent developments in unmanned aircraft systems and high-speed rotorcraft have renewed interest in the coaxial configuration. Multi-rotors are frequently used for small electric unmanned rotorcraft partly due to mechanical simplicity. The use of multiple motors provides redundancy as well as cost-efficiency. The multi-rotor concept has rarely been used until recently because of its inherent stability and control problems. However, advances in inexpensive electronic flight control systems have opened the floodgates for small drones using multirotors. Coaxial rotors have started to appear in some multi-rotor configurations. Small coaxial rotors have often been designed using a hundred year old approach that is "sketch, build, fly, and iterate." In that approach, there is no systematic way to explore trade-offs or determine logical next steps. It is neither possible to account for multiple real-world constraints up front in design nor possible to know what performance is possible with a given design. Since unmanned vehicles are sized and optimized for the particular mission, a modern low-fidelity conceptual design and sizing tool that has been used for the design of large helicopters can be used for design of small coaxial rotorcraft. However, unlike most helicopters with single main rotor, the interactions between the upper and lower rotors emerge as an important factor to consider in design because an increase in performance of a multi-rotor system is not proportional to the number of rotors. Interference losses and differences in thrusts between the upper and lower rotors were investigated by theoretical methods as well as a computational fluid dynamics (CFD) method using the Reynolds-Averaged Navier-Stokes (RANS) equations. In this work, hybrid turbulence models are used to investigate the physics of interactions between coaxial rotors and a fuselage that are not well understood. Present study covers not only small-scale drones but also large-scale coaxial rotors for heavy-lifting missions. Considering the recently proposed FAA drone rules that require the flight only in visual line-of-sight, a large multirotor might be used as an airborne carrier for launch and recovery of unmanned aircraft systems with a human operator onboard. For applications to civil operations, their aerodynamic performance and noise levels need to be assessed. Noise is one of the largest limiting factors to rotorcraft operations in urban area. Since the high-frequency noise of multi-rotors may increase the annoyance, noise may turn out to be a key issue that must be addressed for market acceptability. One of the objectives of the present work is to study the effects of inter-rotor spacing and collectives on the performance, efficiency, and acoustics of coaxial rotor systems.

An experimental study of flame stability in a directly-fueled wall cavity with a supersonic free stream

NASA Astrophysics Data System (ADS)

Rasmussen, Chadwick Clifford

An extensive study of flame stability in a cavity-based fuel injector/flameholder has been performed. Flames were stabilized in cavities with two different aft wall configurations and length to depth ratios of 3 and 4. Fuel was injected directly into the cavity using two injector configurations. Fuel injected from the aft wall of the cavity entered directly into the recirculation zone and provided desirable performance near the lean blowout limit. At high fuel flowrates, the cavity became flooded with fuel and rich blowout occurred. When fuel was injected from the floor of the cavity, excess fuel was directed out of the cavity which allowed for flame stabilization at extremely high fuel flowrates; however, this phenomenon also resulted in suboptimal performance near the lean limit where the blowout point was less predictable. Images of planar laser-induced fluorescence (PLIF) of CH, OH, and formaldehyde give insight into the flameholding mechanisms. CH layers in the cavity are thin and continuous and show structure that is comparable to lifted jet flames, while broad CH zones are sometimes observed in the shear layer. OH PLIF images show that hot recirculated products are always present at the location of flame stabilization, whereas images of formaldehyde indicate that partial premixing takes place in the shear layer portion of the flame. Nonreacting measurements of the boundary layer and the free stream velocity profiles were obtained to provide necessary boundary conditions for computational modeling. Mean and instantaneous velocity profiles were determined for the nonreacting flow using particle image velocimetry (PIV). A correlation of the blowout points for a directly-fueled cavity in a supersonic flow was accomplished using a Damkohler number and an equivalence ratio based upon an effective air mass flowrate. The chemical time was formulated using a generic measure of the reaction rate, tauc ˜ alpha/ S2L , which was found to be adequate for correlating lean blowout data from methane, ethylene, acetylene, and hydrogen flames. Blowout data was collected at a number of conditions with varied pressure and temperature and Mach numbers of 2, 2.4, and 3. The effective air mass flowrate was determined using scaling laws for compressible mixing layers, which correctly incorporated the impact of compressibility on air entrainment.

21 CFR 872.4465 - Gas-powered jet injector.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gas-powered jet injector. 872.4465 Section 872.4465 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Surgical Devices § 872.4465 Gas-powered jet injector. (a) Identification. A...

[Development of a novel liquid injection system].

PubMed

Chen, Kai; Lv, Yong-Gui

2009-11-01

A liquid jet injector employs compressed gas or spring to produce a high-velocity stream to deliver liquid drug into human body through skin. There are many clinical jet injection products available, none of which is domestic. A new liquid jet injector is designed based on a comprehensive analysis of the current products. The injector consists of an ejector, trigger and a re-positioning mechanism. The jets characteristics of sample injector are tested, and the results show that the maximum exit pressure is above 15 MPa, a threshold value for penetrating into the skin.

Large Eddy Simulations of Transverse Combustion Instability in a Multi-Element Injector

DTIC Science & Technology

2016-07-27

Instability in a Multi- Element Injector 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Matthew Harvazinski, Yogin...Simulations of Transverse  Combustion Instability in a Multi‐ Element  Injector 2 History Damaged engine injector  faceplate caused by combustion...Clearance #16346 3 Single  Element  Studies Short Post Marginally Stable Intermediate Post Unstable Long Post Stable Long Post Unstable CVRC Experiment

Effectiveness of Additives in Improving Fuel Lubricity and Preventing Pump Failure at High Temperature

DTIC Science & Technology

2013-01-01

after pump calibrations , transfer pump blade measurements, injector nozzle tests, pump parts evaluation, and parts conditions photographs are also... Injectors –0 0.53 5,500 0.257 1 2-15293089 DF2 As Purchased 105 (40) 1,000 1,000 Calibration off spec areas–4 Pump Rating–1.04 Failed Injectors –0 0.53...5,500 0.257 2 1-15382732 DF2 As Purchased 135 (57) 1,000 1,000 Calibration off spec areas–4 Pump Rating–1.13 Failed Injectors –0 0.55

CAM/LIFTER forces and friction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabbey, D.J.; Lee, J.; Patterson, D.J.

1992-02-01

This report details the procedures used to measure the cam/lifter forces and friction. The present effort employed a Cummins LTA-10, and focuses on measurements and dynamic modeling of the injector train. The program was sponsored by the US Department of Energy in support of advanced diesel engine technology. The injector train was instrumented to record the instantaneous roller speed, roller pin friction torque, pushrod force, injector link force and cam speed. These measurements, together with lift profiles for pushrod and injector link displacement, enabled the friction work loss in the injector train to be determined. Other significant design criteria suchmore » as camshaft roller follower slippage and maximum loads on components were also determined. Future efforts will concentrate on the dynamic model, with tests run as required for correlation.« less

Multi-tube arrangement for combustor and method of making the multi-tube arrangement

DOEpatents

Ziminsky, Willy Steve [Simpsonville, SC

2012-07-31

A fuel injector tube includes a one piece, unitary, polygonal tube having an inlet end and an outlet end. The fuel injector tube further includes a fuel passage extending from the inlet end to the outlet end along a longitudinal axis of the polygonal tube, a plurality of air passages extending from the inlet end to the outlet end and surrounding the fuel passage, and a plurality of fuel holes. Each fuel hole connects an air passage with the fuel passage. The inlet end of the polygonal tube is formed into a fuel tube. A fuel injector includes a plurality of fuel injector tubes and a plate. The plurality of fuel tubes are connected to the plate adjacent the inlet ends of the plurality of fuel injector tubes.

LES of cavitating flow inside a Diesel injector including dynamic needle movement

NASA Astrophysics Data System (ADS)

Örley, F.; Hickel, S.; Schmidt, S. J.; Adams, N. A.

2015-12-01

We perform large-eddy simulations (LES) of the turbulent, cavitating flow inside a 9-hole solenoid common-rail injector including jet injection into gas during a full injection cycle. The liquid fuel, vapor, and gas phases are modelled by a homogeneous mixture approach. The cavitation model is based on a thermodynamic equilibrium assumption. The geometry of the injector is represented on a Cartesian grid by a conservative cut-element immersed boundary method. The strategy allows for the simulation of complex, moving geometries with sub-cell resolution. We evaluate the effects of needle movement on the cavitation characteristics in the needle seat and tip region during opening and closing of the injector. Moreover, we study the effect of cavitation inside the injector nozzles on primary jet break-up.

Use of the Keele injector for sample introduction for gas chromatographic analysis of vinclozolin in lettuces.

PubMed

Shim, J H; Lee, Y S; Kim, M R; Lee, C J; Kim, I S

2003-10-10

We examined a Keele injector for sample introduction for gas chromatographic analysis of vinclozolin treated in lettuces. Samples in milligram quantity were introduced into a glass tube in a Keele injector at a gas chromatograph injection port. The glass tube was then crushed to allow the sample to carry onto a capillary column in a normal manner. The standard calibration curve for quantitative detection of vinclozolin was obtained by determining vinclozolin spiked in samples at variable concentrations. The calibration curve showed a linear response to vinclozolin ranging from 0.05 to 1.0 microg/g, giving a slope value of 174.8, the y-intercept value of -2.8146 and the mean r2-value of 0.9994. Limit of quantification for vinclozolin was 0.05 microg/g by this method, comparable to 0.01 microg/g by a normal injector. When samples treated previously with vinclozolin were determined by the Keele injector, vinclozolin was found to be about 30% lower as compared to a normal method, suggesting about 70% recovery of the spiked vinclozolin by the Keele injector. From these results, the Keele injector was suggested to be potential for sample introduction in gas chromatographic analysis of vinclozolin in lettuce samples.

Liquid Methane/Oxygen Injector Study for Mars Ascent Engines

NASA Technical Reports Server (NTRS)

Trinh, Huu Phuoc

1999-01-01

As a part of the advancing technology of the cryogenic propulsion system for the Mars exploration mission, this effort aims at evaluating propellant injection concepts for liquid methane/liquid oxygen (LOX) rocket engines. Split-triplet and unlike impinging injectors were selected for this study. A total of four injector configurations were tested under combustion conditions in a modular combustor test article (MCTA), equipped with optically accessible windows, at MSFC. A series of forty hot-fire tests, which covered a wide range of engine operating conditions with the chamber pressure ranging from 320 to 510 and the mixture ratio from 1.5 to 3.5, were conducted. The test matrix also included a variation in the combustion chamber length for the purpose of investigating its effects on the combustion performance and stability. Initial assessments of the test results showed that the injectors provided stable combustion and there were no injector face overheating problems under all operating conditions. The Raman scattering signal measurement method was successfully demonstrated for the hydrocarbon/oxygen reactive flow field. The near-injector face flow field was visually observed through the use of an infrared camera. Chamber wall temperature, high frequency chamber pressure, and average throat section heat flux were also recorded throughout the test series. Assessments of the injector performance are underway.

Design and Study of a LOX/GH2 Throttleable Swirl Injector for Rocket Applications

NASA Technical Reports Server (NTRS)

Greene, Christopher; Woodward, Roger; Pal, Sibtosh; Santoro, Robert

2002-01-01

A LOX/GH2 swirl injector was designed for a 10:1 propellant throttling range. To accomplish this, a dual LOX manifold was used feeding a single common vortex chamber of the swirl element. Hot-fire experiments were conducted for rocket chamber pressures from 80 to 800 psia at a mixture ratio of nominally 6.0 using steady flow, single-point-per-firing cases as well as dynamic throttling conditions. Low frequency (mean) and high frequency (fluctuating) pressure transducer data, flow meter measurements, and Raman spectroscopy images for mixing information were obtained. The injector design, experimental setup, low frequency pressure data, and injector performance analysis are presented. C* efficiency was very high (approx. 100%) at the middle of the throttleable range with somewhat lower performance at the high and low ends. From the analysis of discreet steady state operating conditions, injector pressure drop was slightly higher than predicted with an inviscid analysis, but otherwise agreed well across the design throttling range. Dynamic throttling of this injector was attempted with marginal success due to the immaturity of the throttling control system. Although the targeted mixture ratio of 6.0 was not maintained throughout the dynamic throttling profile, the injector behaved well over the wide range of conditions.

Efficient GO2/GH2 Injector Design: A NASA, Industry and University Cooperative Effort

NASA Technical Reports Server (NTRS)

Tucker, P. K.; Klem, M. D.; Fisher, S. C.; Santoro, R. J.

1997-01-01

Developing new propulsion components in the face of shrinking budgets presents a significant challenge. The technical, schedule and funding issues common to any design/development program are complicated by the ramifications of the continuing decrease in funding for the aerospace industry. As a result, new working arrangements are evolving in the rocket industry. This paper documents a successful NASA, industry, and university cooperative effort to design efficient high performance GO2/GH2 rocket injector elements in the current budget environment. The NASA Reusable Launch Vehicle (RLV) Program initially consisted of three vehicle/engine concepts targeted at achieving single stage to orbit. One of the Rocketdyne propulsion concepts, the RS 2100 engine, used a full-flow staged-combustion cycle. Therefore, the RS 2100 main injector would combust GO2/GH 2 propellants. Early in the design phase, but after budget levels and contractual arrangements had been set the limitations of the current gas/gas injector database were identified. Most of the relevant information was at least twenty years old. Designing high performance injectors to meet the RS 2100 requirements would require the database to be updated and significantly enhanced. However, there was no funding available to address the need for more data. NASA proposed a teaming arrangement to acquire the updated information without additional funds from the RLV Program. A determination of the types and amounts of data needed was made along with test facilities with capabilities to meet the data requirements, budget constraints, and schedule. After several iterations a program was finalized and a team established to satisfy the program goals. The Gas/Gas Injector Technology (GGIT) Program had the overall goal of increasing the ability of the rocket engine community to design efficient high-performance, durable gas/gas injectors relevant to RLV requirements. First, the program would provide Rocketdyne with data on preliminary gas/gas injector designs which would enable discrimination among candidate injector designs. Secondly, the program would enhance the national gas/gas database by obtaining high-quality data that increases the understanding of gas/gas injector physics and is suitable for computational fluid dynamics (CFD) code validation. The third program objective was to validate CFD codes for future gas/gas injector design in the RLV program.

The Aeroacoustics of Supersonic Coaxial Jets

NASA Technical Reports Server (NTRS)

Dahl, Milo D.

1994-01-01

Instability waves have been established as the dominant source of mixing noise radiating into the downstream arc of a supersonic jet when the waves have phase velocities that are supersonic relative to ambient conditions. Recent theories for supersonic jet noise have used the concepts of growing and decaying linear instability waves for predicting radiated noise. This analysis is extended to the prediction of noise radiation from supersonic coaxial jets. Since the analysis requires a known mean flow and the coaxial jet mean flow is not described easily in terms of analytic functions, a numerical prediction is made for its development. The Reynolds averaged, compressible, boundary layer equations are solved using a mixing length turbulence model. Empirical correlations are developed for the effects of velocity and temperature ratios and Mach number. Both normal and inverted velocity profile coaxial jets are considered. Comparisons with measurements for both single and coaxial jets show good agreement. The results from mean flow and stability calculations are used to predict the noise radiation from coaxial jets with different operating conditions. Comparisons are made between different coaxial jets and a single equivalent jet with the same total thrust, mass flow, and exit area. Results indicate that normal velocity profile jets can have noise reductions compared to the single equivalent jet. No noise reductions are found for inverted velocity profile jets operated at the minimum noise condition compared to the single equivalent jet. However, it is inferred that changes in area ratio may provide noise reduction benefits for inverted velocity profile jets.

Field-emission property of self-purification SiC/SiOx coaxial nanowires synthesized via direct microwave irradiation using iron-containing catalyst

NASA Astrophysics Data System (ADS)

Zhou, Qing; Yu, Yongzhi; Huang, Shan; Meng, Jiang; Wang, Jigang

2017-07-01

SiC/SiOx coaxial nanowires were rapidly synthesized via direct microwave irradiation in low vacuum atmosphere. During the preparation process, only graphite, silicon, silicon dioxide powders were used as raw materials and iron-containing substance was employed as catalyst. Comprehensive characterizations were employed to investigate the microstructure of the products. The results showed that a great quantity of coaxial nanowires with uniform sizes and high aspect ratio had been successfully achieved. The coaxial nanowires consist of a silicon oxide (SiOx) shell and a β-phase silicon carbide (β-SiC) core that exhibited in special tube brush like. In additional, nearly all the products were achieved in the statement of pure SiC/SiOx coaxial nanowires without the existence of metallic catalyst, indicating that the self-removal of iron (Fe) catalyst should be occurred during the synthesis process. Photoluminescence (PL) spectral analysis result indicated that such novel SiC/SiOx coaxial nanowires exhibited significant blue-shift. Besides, the measurement results of field-emission (FE) demonstrated that the SiC/SiOx coaxial nanowires had ultralow turn-on field and threshold field with values of 0.2 and 2.1 V/μm, respectively. The hetero-junction structure formed between SiOx shell and SiC core, lots of emission sites, as well as clear tips of the nanowires were applied to explain the excellent FE properties.[Figure not available: see fulltext.

Fundamental rocket injector/spray programs at the Phillips Laboratory

NASA Astrophysics Data System (ADS)

Talley, D. G.

1993-11-01

The performance and stability of liquid rocket engines is determined to a large degree by atomization, mixing, and combustion processes. Control over these processes is exerted through the design of the injector. Injectors in liquid rocket engines are called upon to perform many functions. They must first of all mix the propellants to provide suitable performance in the shortest possible length. For main injectors, this is driven by the tradeoff between the combustion chamber performance, stability, efficiency, and its weight and cost. In gas generators and preburners, however, it is also driven by the possibility of damage to downstream components, for example piping and turbine blades. This can occur if unburned fuel and oxidant later react to create hot spots. Weight and cost considerations require that the injector design be simple and lightweight. For reusable engines, the injectors must also be durable and easily maintained. Suitable atomization and mixing must be produced with as small a pressure drop as possible, so that the size and weight of pressure vessels and turbomachinery can be minimized. However, the pressure drop must not be so small as to promote feed system coupled instabilities. Another important function of the injectors is to ensure that the injector face plate and the chamber and nozzle walls are not damaged. Typically this requires reducing the heat transfer to an acceptable level and also keeping unburned oxygen from chemically attacking the walls, particularly in reusable engines. Therefore the mixing distribution is often tailored to be fuel-rich near the walls. Wall heat transfer can become catastrophically damaging in the presence of acoustic instabilities, so the injector must prevent these from occurring at all costs. In addition to acoustic stability (but coupled with it), injectors must also be kinetically stable. That is, the flame itself must maintain ignition in the combustion chamber. This is not typically a problem with main injectors, but can be a consideration in preburners, where the desire to keep turbine inlet temperatures as cool as possible can make it advantageous for the preburners to operate as far from stoichiometry as can be tolerated.

Formation of Imploding Plasma Liners for HEDP and MIF Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witherspoon, F. Douglas; Case, Andrew; Brockington, Samuel

Plasma jets with high density and velocity have a number of important applications in fusion energy and elsewhere, including plasma refueling, disruption mitigation in tokamaks, magnetized target fusion, injection of momentum into centrifugally confined mirrors, plasma thrusters, and high energy density plasmas (HEDP). In Magneto-Inertial Fusion (MIF), for example, an imploding material liner is used to compress a magnetized plasma to fusion conditions and to confine the resulting burning plasma inertially to obtain the necessary energy gain. The imploding shell may be solid, liquid, gaseous, or a combination of these states. The presence of the magnetic field in the targetmore » plasma suppresses thermal transport to the plasma shell, thus lowering the imploding power needed to compress the target to fusion conditions. This allows the required imploding momentum flux to be generated electromagnetically using off-the-shelf pulsed power technology. Practical schemes for standoff delivery of the imploding momentum flux are required and are open topics for research. One approach for accomplishing this, called plasma jet driven magneto-inertial fusion (PJMIF), uses a spherical array of pulsed plasma guns to create a spherically imploding shell of very high velocity, high momentum flux plasma. This approach requires development of plasma jet accelerators capable of achieving velocities of 50-200 km/s with very precise timing and density profiles, and with high total mass and density. Low-Z plasma jets would require the higher velocities, whereas very dense high-Z plasma shells could achieve the goal at velocities of only 50-100 km/s. In this report, we describe our work to develop the pulsed plasma gun technology needed for an experimental scientific exploration of the PJMIF concept, and also for the other applications mentioned earlier. The initial goal of a few hundred of hydrogen at 200 km/s was eventually replaced with accelerating 8000 μg of argon or xenon to 50 km/s for the Plasma Liner Experiment (PLX) at Los Alamos National Laboratory (LANL). Initial work used existing computational and analytical tools to develop and refine a specific plasma gun concept having a novel tapered coaxial electromagnetic accelerator contour with an array of symmetric ablative plasma injectors. The profile is designed to suppress the main barrier to success in coaxial guns, namely the blow-by instability in which the arc slips past and outruns the bulk of the plasma mass. Efforts to begin developing a set of annular non-ablative plasma injectors for the coaxial gun, in order to accelerate pure gases, resulted in development of linear parallel-plate MiniRailguns that turned out to work well as plasma guns in their own right and we subsequently chose them for an initial plasma liner experiment on the PLX facility at LANL. This choice was mainly driven by cost and schedule for that particular experiment, while longer term goals still projected use of coaxial guns for reactor-relevant applications for reasons of better symmetry, lower impurities, more compact plasma jet formation, and higher gun efficiency. Our efforts have focused mainly on 1) developing various plasma injection systems for both coax and linear railguns and ensuring they work reliably with the accelerator section, 2) developing a suite of plasma and gun diagnostics, 3) performing computational modeling to design and refine the plasma guns, 4) establishing a research facility dedicated to plasma gun development, and finally, 5) developing plasma guns and associated pulse power systems capable of achieving these goals and installing and testing the first two gun sets on the PLX facility at LANL. During the second funding cycle for this program, HyperV joined in a collaborative effort with LANL, the University of Alabama at Huntsville, and the University of New Mexico to perform a plasma liner experiment (PLX) to investigate the physics and technology of forming spherically imploding plasma liners. HyperV’s tasks focused on developing the plasma guns and associated pulse power systems required for the 30 gun experiment at LANL. Unfortunately, funding for the entire PLX collaborative project was terminated after only two years of the four year project due to program funding realignments which necessitated recompeting the project in midstream. Despite the loss of funding, HyperV installed two Mark1 guns and pulsed power systems on PLX, and jet characterization and merging experiments were subsequently successfully performed at LANL by the PLX Team. In parallel with those PLX experiments, HyperV continued its efforts to develop a plasma gun capable of meeting the PLX goal of 8 mg of argon at 50 km/s. HyperV was ultimately successful in this effort, demonstrating 10.8 mg at 52.8 km/s and 7.5 mg at 62.4 km/s with the Mark2 MiniRailgun.« less

Preliminary investigation of power flow and electrode phenomena in a multi-megawatt coaxial plasma thruster

NASA Technical Reports Server (NTRS)

Schoenberg, Kurt; Gerwin, Richard; Henins, Ivars; Mayo, Robert; Scheuer, Jay; Nurden, Glen

1993-01-01

This paper summarizes preliminary experimental and theoretical research that was directed towards the study of quasisteady-state power flow in a large, un-optimized, multi-megawatt coaxial plasma thruster. The report addresses large coaxial thruster operation and includes evaluation and interpretation of the experimental results with a view to the development of efficient, steady-state megawatt-class magnetoplasmadynamic (MPD) thrusters.

Fabrication, biocompatibility, and tissue engineering substrate analysis of polyvinyl alcohol-gelatin core-shell electrospun nanofibers

NASA Astrophysics Data System (ADS)

Merkle, Valerie Marie

Cardiovascular disease is the leading cause of death in the United States with approximately 49% of the cardiovascular related deaths attributed to coronary heart disease (CHD). CHD is the accumulation of plaque resulting in the narrowing of the vessel lumen and a decrease in blood flow to the downstream heart muscle. In order to restore blood flow, arterial by-pass procedures can be undertaken. However, the patient's own arteries/veins may not be suitable for use as a vessel replacement, and synthetic grafts lack the compliancy and durability needed for these small diameter locations (< 5 mm). Therefore, the goal of this research is to develop a nanofibrous material that can be used in vascular applications such as this. In this study, we fabricate coaxial electrospun nanofibers with gelatin in the shell and polyvinyl alcohol (PVA) in the core using 1 Gelatin: 1 PVA and 3 Gelatin: 1 PVA mass ratios. Gelatin, derived from collagen, is highly bioactive while PVA, a synthetic polymer, has appealing mechanical properties. Therefore, by combining these materials in a core-shell structure, we hypothesize that the resulting nanofibers will have enhanced mechanical properties, cellular growth and migration, as well as minimal platelet deposition and activation compared to scaffolds composed solely of gelatin or PVA. First, the coaxial scaffolds exhibited an enhanced Young's modulus and ultimate strength compared to scaffolds composed of PVA or gelatin alone. Endothelial cells had high proliferation and migration on the coaxial electrospun scaffolds with higher migration seen on the stiffer, coaxial scaffolds. The smooth muscle cells had less proliferation and lower migration rates on the coaxial scaffolds than the endothelial cells. Using a modified prothrombinase assay, the coaxial scaffolds had minimal platelet activation. Lastly, when pre-seeding the coaxial scaffolds with endothelial cells or smooth muscle cells, the platelet deposition decreased in comparison to platelet deposition with no cell pre-seeding. Overall, the 1 Gel: 1 PVA coaxial scaffolds promoted endothelial cell growth and migration, minimized smooth muscle cell growth and migration, and had minimal platelet activation. Therefore, the 1 Gel: 1 PVA coaxial nanofibers are an intriguing material for use in vascular applications.

Direct numerical simulation of incompressible axisymmetric flows

NASA Technical Reports Server (NTRS)

Loulou, Patrick

1994-01-01

In the present work, we propose to conduct direct numerical simulations (DNS) of incompressible turbulent axisymmetric jets and wakes. The objectives of the study are to understand the fundamental behavior of axisymmetric jets and wakes, which are perhaps the most technologically relevant free shear flows (e.g. combuster injectors, propulsion jet). Among the data to be generated are various statistical quantities of importance in turbulence modeling, like the mean velocity, turbulent stresses, and all the terms in the Reynolds-stress balance equations. In addition, we will be interested in the evolution of large-scale structures that are common in free shear flow. The axisymmetric jet or wake is also a good problem in which to try the newly developed b-spline numerical method. Using b-splines as interpolating functions in the non-periodic direction offers many advantages. B-splines have local support, which leads to sparse matrices that can be efficiently stored and solved. Also, they offer spectral-like accuracy that are C(exp O-1) continuous, where O is the order of the spline used; this means that derivatives of the velocity such as the vorticity are smoothly and accurately represented. For purposes of validation against existing results, the present code will also be able to simulate internal flows (ones that require a no-slip boundary condition). Implementation of no-slip boundary condition is trivial in the context of the b-splines.

Linear Temporal Stability Analysis of a Low-Density Round Gas Jet Injected into a High-Density Gas

NASA Technical Reports Server (NTRS)

Lawson, Anthony L.; Parthasarathy, Ramkumar N.

2002-01-01

It has been observed in previous experimental studies that round helium jets injected into air display a repetitive structure for a long distance, somewhat similar to the buoyancy-induced flickering observed in diffusion flames. In order to investigate the influence of gravity on the near-injector development of the flow, a linear temporal stability analysis of a round helium jet injected into air was performed. The flow was assumed to be isothermal and locally parallel; viscous and diffusive effects were ignored. The variables were represented as the sum of the mean value and a normal-mode small disturbance. An ordinary differential equation governing the amplitude of the pressure disturbance was derived. The velocity and density profiles in the shear layer, and the Froude number (signifying the effects of gravity) were the three important parameters in this equation. Together with the boundary conditions, an eigenvalue problem was formulated. Assuming that the velocity and density profiles in the shear layer to be represented by hyperbolic tangent functions, the eigenvalue problem was solved for various values of Froude number. The temporal growth rates and the phase velocity of the disturbances were obtained. The temporal growth rates of the disturbances increased as the Froude number was reduced (i.e. gravitational effects increased), indicating the destabilizing role played by gravity.

Safety assessment of a new single-use small-incision injector for intraocular lens implantation.

PubMed

Satanovsky, Alexandra; Ben-Eliahu, Shmuel; Apple, David J; Kleinmann, Guy

2011-07-01

To evaluate the safety of a new injector, the Raysert R-INJ-04/18, for implantation of the C-flex intraocular lens (IOL). Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel. Experimental study. Sixty IOLs were subdivided into 2 equally sized groups. Group A IOLs were injected using the established R-INJ-04 injector, and those in Group B were injected with the new injector. The IOLs were injected into a Petri dish. Subsequently, all IOLs and injectors were evaluated macroscopically and microscopically and then photographed under light microscopy (LM). Two IOLs in each group were randomly chosen and sent for evaluation by scanning electron microscopy (SEM) and energy dispersive analysis of x-ray. All remaining IOLs were sent for power and modulation transfer function (MTF) analysis. All Group B IOLs were successfully injected without evident signs of scratching, cracks, or deposits on LM and SEM examination. In Group A, findings were confined to a singular incidence of a small deposit detected on the periphery of the posterior optical surface of the IOL, with corresponding findings detected on the injector nozzle. No signs of scratching, cracks, or deposits were found in the rest of the IOLs or injectors. The power and MTF analyses were within the normal range for all IOLs. The new 1.8 mm external diameter soft-tipped injector for 2.4 to 2.2 mm incisions was shown to be safe for the implantation of the C-flex 21.0 diopter IOL. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Usage and Perceptions of Pen Injectors for Diabetes Management: A Survey of Type 2 Diabetes Patients in the United States

PubMed Central

Toscano, Deborah; Brice, Jennifer; Alfaro, Christina

2012-01-01

Background This study was conducted to investigate type 2 diabetes mellitus (T2DM) patient perceptions of their pen injectors and determine which features were deemed most important to overall satisfaction. Methods Frost & Sullivan conducted a Web-based survey of T2DM patients in the United States in November 2010. Survey participants were initially screened prior to full participation. A total of 1002 adult T2DM patients who were using a pen injector on a regular basis to administer their diabetes medication(s) were surveyed. The survey consisted of 24 questions focused on awareness and current usage of pen injectors by type and brand, specific features of pen injectors, and patients' preferences for and satisfaction with pen injectors. Results The majority of surveyed patients were using prefilled pen injectors as compared with durable pens. The LANTUS SoloSTAR (sanofi-aventis) was reported to be the most commonly used pen. The LANTUS SoloSTAR was also ranked highly for overall satisfaction and likelihood of continued usage. Regardless of brand, most surveyed patients reported that they were likely to continue using their current pen. In general, the single most important feature for user satisfaction was an easy push-button injection. Conclusions Ease of self-administration is of highest priority to users of pen injectors. Important features facilitating ease of use, such as an easily depressed push-button injection, are likely to minimize the burden on T2DM patients, thereby improving compliance and clinical outcomes. PMID:22768901

40 CFR 80.176 - Alternative certification test procedures and standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... temperature. At the end of this 48-hour ambient temperature soak, an injector balance test is conducted to... injector balance test. (x) Fuel pressure gauge. A fuel pressure gauge capable of measuring fuel system... conducting the injector balance test. A pressure transducer shall not be used. (xi) Gaskets. The upper intake...

76 FR 8661 - Airworthiness Directives; Lycoming Engines, Fuel Injected Reciprocating Engines

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-15

... engine models requiring inspections. We are proposing this AD to prevent failure of the fuel injector... repetitive inspection compliance time. We issued that AD to prevent failure of the fuel injector fuel lines... engine models requiring inspection. We are issuing this AD to prevent failure of the fuel injector fuel...

Effect of fuel stratification on detonation wave propagation

NASA Astrophysics Data System (ADS)

Masselot, Damien; Fievet, Romain; Raman, Venkat

2016-11-01

Rotating detonation engines (RDEs) form a class of pressure-gain combustion systems of higher efficiency compared to conventional gas turbine engines. One of the key features of the design is the injection system, as reactants need to be continuously provided to the detonation wave to sustain its propagation speed. As inhomogeneities in the reactant mixture can perturb the detonation wave front, premixed fuel jet injectors might seem like the most stable solution. However, this introduces the risk of the detonation wave propagating through the injector, causing catastrophic failure. On the other hand, non-premixed fuel injection will tend to quench the detonation wave near the injectors, reducing the likelihood of such failure. Still, the effects of such non-premixing and flow inhomogeneities ahead of a detonation wave have yet to be fully understood and are the object of this study. A 3D channel filled with O2 diluted in an inert gas with circular H2 injectors is simulated as a detonation wave propagates through the system. The impact of key parameters such as injector spacing, injector size, mixture composition and time variations will be discussed. PhD Candidate.

Effects of Passive Fuel-Air Mixing Control on Burner Emissions Via Lobed Fuel Injectors

NASA Technical Reports Server (NTRS)

Mitchell, M. G.; Smith, O. I.; Karagozian, A. R.

1999-01-01

The present experimental study examines the effects of differing levels of passive fuel-air premixing on flame structures and their associated NO(x) and CO emissions. Four alternative fuel injector geometries were explored, three of which have lobed shapes. These lobed injectors mix fuel and air and strain species inter-faces to differing extents due to streamwise vorticity generation, thus creating different local or core equivalence ratios within flow regions upstream of flame ignition and stabilization. Prior experimental studies of two of these lobed injector flowfields focused on non-reactive mixing characteristics and emissions measurements for the case where air speeds were matched above and below the fuel injector, effectively generating stronger streamwise vorticity than spanwise vorticity. The present studies examine the effects of airstream mismatch (and hence additional spanwise vorticity generation), effects of confinement of the crossflow to reduce the local equivalence ratio, and the effects of altering the geometry and position of the flameholders. NO(x) and CO emissions as well as planar laser-induced fluorescence imaging (PLIF) of seeded acetone are used to characterize injector performance and reactive flow evolution.

Heavy hydrocarbon main injector technology

NASA Technical Reports Server (NTRS)

Fisher, S. C.; Arbit, H. A.

1988-01-01

One of the key components of the Advanced Launch System (ALS) is a large liquid rocket, booster engine. To keep the overall vehicle size and cost down, this engine will probably use liquid oxygen (LOX) and a heavy hydrocarbon, such as RP-1, as propellants and operate at relatively high chamber pressures to increase overall performance. A technology program (Heavy Hydrocarbon Main Injector Technology) is being studied. The main objective of this effort is to develop a logic plan and supporting experimental data base to reduce the risk of developing a large scale (approximately 750,000 lb thrust), high performance main injector system. The overall approach and program plan, from initial analyses to large scale, two dimensional combustor design and test, and the current status of the program are discussed. Progress includes performance and stability analyses, cold flow tests of injector model, design and fabrication of subscale injectors and calorimeter combustors for performance, heat transfer, and dynamic stability tests, and preparation of hot fire test plans. Related, current, high pressure, LOX/RP-1 injector technology efforts are also briefly discussed.

Evolution of quartz microstructure and c-axis crystallographic preferred orientation within ductilely deformed granitoids (Arolla unit, Western Alps)

NASA Astrophysics Data System (ADS)

Menegon, Luca; Pennacchioni, Giorgio; Heilbronner, Renee; Pittarello, Lidia

2008-11-01

We have studied quartz microstructures and the c-axis crystallographic preferred orientations (CPOs) in four granitoid samples representative of increasing ductile shear deformation, from a weakly deformed granitoid (stage 1) to a mylonitic granitoid (stage 4). The quartz c-axis CPO measured in the mylonitic granitoid has been compared with the one observed in a fully recrystallized quartz mylonite from the same area. All the samples belong to the Austroalpine Arolla unit (Western Alps) and were deformed at greenschist facies conditions. The quartz c-axis CPO was analyzed using a U-stage and the optical orientation imaging technique. The magmatic plagioclase, forming more than 50% of the volume of the granitoid, is extensively replaced by a mica-rich aggregate even in weakly deformed samples of stage 1. These aggregates flow to form an interconnected weak matrix with increasing deformation, wrapping relatively less strained quartz grains that undergo dominantly coaxial strain. Recrystallization of quartz ranges from less than 1% in the weakly deformed granitoid to up to 85% in the mylonitic granitoid, with average grain strain of 41% and 64%, respectively. With increasing strain and recrystallization, quartz grains in the granitoids show a sequence of transient microstructures and CPOs. Crystal plastic deformation is initially accomplished by dislocation glide with limited recovery, and at 50% grain strain it results in a CPO consistent with dominantly basal < a> slip. At 60% grain strain, recrystallization is preferentially localized along shear bands, which appear to develop along former intragranular cracks, and the recrystallized grains develop a strong c-axis CPO with maxima orthogonal to the shear band boundaries and independent of the host grain orientation. Within the granitoid mylonite, at an average quartz grain strain of 64%, recrystallization is extensive and the c-axis CPO of new grains displays maxima overlapping the host c-axis orientation and, therefore, unrelated to the bulk sense of shear. The host-controlled CPO is inferred to reflect pervasive recrystallization by progressive subgrain rotation. The switch from 'shear band-control' to 'host-control' on c-axis CPO occurred between 40% and 70% of recrystallization. In the quartz mylonite, the quartz c-axis CPO develops an asymmetric single girdle consistent with the bulk sense of shear and the synkinematic greenschist facies conditions. This study indicates that the CPO evolution of quartz may significantly differ in cases of polymineralic vs. monomineralic rocks under the same deformation conditions, if quartz in the polymineralic rock behaves as a 'strong' phase.

Optical Fuel Injector Patternation Measurements in Advanced Liquid-Fueled, High Pressure, Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Locke, R. J.; Hicks, Y. R.; Anderson, R. C.; Zaller, M. M.

1998-01-01

Planar laser-induced fluorescence (PLIF) imaging and planar Mie scattering are used to examine the fuel distribution pattern (patternation) for advanced fuel injector concepts in kerosene burning, high pressure gas turbine combustors. Three fuel injector concepts for aerospace applications were investigated under a broad range of operating conditions. Fuel PLIF patternation results are contrasted with those obtained by planar Mie scattering. For one injector, further comparison is also made with data obtained through phase Doppler measurements. Differences in spray patterns for diverse conditions and fuel injector configurations are readily discernible. An examination of the data has shown that a direct determination of the fuel spray angle at realistic conditions is also possible. The results obtained in this study demonstrate the applicability and usefulness of these nonintrusive optical techniques for investigating fuel spray patternation under actual combustor conditions.

CAM/LIFTER forces and friction. Final report, September 15, 1988--November 30, 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gabbey, D.J.; Lee, J.; Patterson, D.J.

1992-02-01

This report details the procedures used to measure the cam/lifter forces and friction. The present effort employed a Cummins LTA-10, and focuses on measurements and dynamic modeling of the injector train. The program was sponsored by the US Department of Energy in support of advanced diesel engine technology. The injector train was instrumented to record the instantaneous roller speed, roller pin friction torque, pushrod force, injector link force and cam speed. These measurements, together with lift profiles for pushrod and injector link displacement, enabled the friction work loss in the injector train to be determined. Other significant design criteria suchmore » as camshaft roller follower slippage and maximum loads on components were also determined. Future efforts will concentrate on the dynamic model, with tests run as required for correlation.« less

Numerical analysis and experimental studies on solenoid common rail diesel injector with worn control valve

NASA Astrophysics Data System (ADS)

Krivtsov, S. N.; Yakimov, I. V.; Ozornin, S. P.

2018-03-01

A mathematical model of a solenoid common rail fuel injector was developed. Its difference from existing models is control valve wear simulation. A common rail injector of 0445110376 Series (Cummins ISf 2.8 Diesel engine) produced by Bosch Company was used as a research object. Injector parameters (fuel delivery and back leakage) were determined by calculation and experimental methods. GT-Suite model average R2 is 0.93 which means that it predicts the injection rate shape very accurately (nominal and marginal technical conditions of an injector). Numerical analysis and experimental studies showed that control valve wear increases back leakage and fuel delivery (especially at 160 MPa). The regression models for determining fuel delivery and back leakage effects on fuel pressure and energizing time were developed (for nominal and marginal technical conditions).

Effect of H2O2 injection patterns on catalyst bed characteristics

NASA Astrophysics Data System (ADS)

Kang, Hongjae; Lee, Dahae; Kang, Shinjae; Kwon, Sejin

2017-01-01

The decomposition process of hydrogen peroxide can be applied to a bipropellant thruster, as well as to monopropellant thruster. To provide a framework for the optimal design of the injector and catalyst bed depending on a type of thruster, this research scrutinizes the effect of injection patterns of the propellant on the performance of the catalyst bed. A showerhead injector and impinging jet injector were tested with a 50 N monopropellant thruster. Manganese oxide/γ-alumina catalyst and manganese oxide/lanthanum-doped alumina catalyst were prepared and tested. The showerhead injector provided a fast response time, suitable for pulse mode operation. The impinging jet injector mitigated the performance instability and catalyst attrition that is favorable for large scale bipropellant thrusters. The design of a dual catalyst bed was conceptually proposed based on the data obtained from firing tests.

Investigation of gaseous propellant combustion and associated injector/chamber design guidelines

NASA Technical Reports Server (NTRS)

Calhoon, D. F.; Ito, J. I.; Kors, D. L.

1973-01-01

Injector design criteria are provided for gaseous hydrogen-gaseous oxygen propellants. Design equations and procedures are presented which will allow an injector-chamber designer to a priori estimate of the performance, compatibility and stability characteristics of prototype injectors. The effects of chamber length, element geometry, thrust per element, mixture ratio, impingement angle, and element spacing were evaluated for four element concepts and their derivatives. The data from this series of tests were reduced to a single valued mixing function that describes the mixing potential of the various elements. Performance, heat transfer and stability data were generated for various mixture ratios, propellant temperatures, chamber pressures, contraction ratios, and chamber lengths. Applications of the models resulted in the design of procedures, whereby the performance and chamber heat flux can be calculated directly, and the injector stability estimated in conjunction with existing models.

Quantitative X-ray measurements of high-pressure fuel sprays from a production heavy duty diesel injector

NASA Astrophysics Data System (ADS)

Ramírez, A. I.; Som, S.; Aggarwal, Suresh K.; Kastengren, A. L.; El-Hannouny, E. M.; Longman, D. E.; Powell, C. F.

2009-07-01

A quantitative and time-resolved X-ray radiography technique has been used for detailed measurements of high-pressure fuel sprays in the near-nozzle region of a diesel engine injector. The technique provides high spatial and temporal resolution, especially in the relatively dense core region. A single spray plume from a hydraulically actuated electronically controlled unit injector model 315B injector with a 6-hole nozzle was isolated and studied at engine-like densities for two different injection pressures. Optical spray imaging was also employed to evaluate the effectiveness of the shield used to isolate a single spray plume. The steady state fuel distributions for both injection pressures are similar and show a dense spray region along the axis of the spray, with the on-axis spray density decreasing as the spray progresses downstream. The higher injection pressure case exhibits a larger cone angle and spray broadening at the exit of the nozzle. For some time periods, the near-nozzle penetration speed is lower for the high injection pressure case than the low injection pressure case, which is unexpected, but can be attributed to the needle and flow dynamics inside the injector causing slower pressure build-up for the former case. Rate of injection testing was performed to further understand near-nozzle behavior. Mass distribution data were obtained and used to find mass-averaged velocity of the spray. Comparisons of the radiography data with that from a common rail single-hole light duty injectors under similar injection conditions show several significant differences. The current data show a larger cone angle and lower penetration speed than that from the light-duty injector. Moreover, these data display a Gaussian mass distribution across the spray near the injector, whereas in previous light-duty injector measurements, the mass distribution had steeper sides and a flatter peak. Measurements are also used to examine the spray models in the STAR-CD software.

Coaxial electrospinning for encapsulation and controlled release of fragile water-soluble bioactive agents.

PubMed

Jiang, Hongliang; Wang, Liqun; Zhu, Kangjie

2014-11-10

Coaxial electrospinning is a robust technique for one-step encapsulation of fragile, water-soluble bioactive agents, including growth factors, DNA and even living organisms, into core-shell nanofibers. The coaxial electrospinning process eliminates the damaging effects due to direct contact of the agents with organic solvents or harsh conditions during emulsification. The shell layer serves as a barrier to prevent the premature release of the water-soluble core contents. By varying the structure and composition of the nanofibers, it is possible to precisely modulate the release of the encapsulated agents. Promising work has been done with coaxially electrospun non-woven mats integrated with bioactive agents for use in tissue engineering, in local delivery and in wound healing, etc. This paper reviews the origins of the coaxial electrospinning method, its updated status and potential future developments for controlled release of the class of fragile, water-soluble bioactive agents. Copyright © 2014 Elsevier B.V. All rights reserved.

Facile fabrication of high-quality Ag/PS coaxial nanocables based on the mixed mode of soft/hard templates

PubMed Central

Wan, Mimi; Zhao, Wenbo; Peng, Fang; Wang, Qi; Xu, Ping; Mao, Chun; Shen, Jian

2016-01-01

A new kind of high-quality Ag/PS coaxial nanocables can be facilely synthesized by using soft/hard templates method. In order to effectively introduce Ag sources into porous polystyrene (PS) nanotubes which were trapped in porous anodic aluminum oxide (AAO) hard template, Pluronic F127 (F127) was used as guiding agent, soft template and reductant. Meanwhile, ethylene glycol solution was also used as solvent and co-reducing agent to assist in the formation of silver nanowires. The influences of concentration of F127 and reducing reaction time on the formation of Ag/PS coaxial nanocables were discussed. Results indicated that the high-quality Ag/PS coaxial nanocables can be obtained by the mixed mode of soft/hard templates under optimized conditions. This strategy is expected to be extended to design more metal/polymer coaxial nanocables for the benefit of creation of complex and functional nanoarchitectures and components. PMID:27477888

Leaky coaxial cable signal transmission for remote facilities

NASA Astrophysics Data System (ADS)

Smith, S. F.; Crutcher, R. I.

To develop reliable communications methods to meet the rigorous requirements for nuclear hot cells and similar environments, including control of cranes, transporters, and advanced servomanipulators, the Consolidated Fuel Reprocessing Program (CFRP) at Oak Ridge National Laboratory (ORNL) has conducted extensive tests of numerous technologies to determine their applicability to remote operations. To alleviate the need for large bundles of cables that must accommodate crane/transporter motion relative to the boundaries of the cell, several transmission techniques are available, including slotted-line radio-frequency couplers, infrared beams, fiber-optic cables, free-space microwave, and inductively coupled leaky coaxial cable. This paper discusses the general characteristics, mode of operation, and proposed implementation of leaky coaxial cable technology in a waste-handling facility scheduled to be built in the near future at ORNL. In addition, specific system hardware based around the use of leaky coaxial cable is described in detail. Finally, data from a series of radiation exposure tests conducted by the CFRP on several samples of the basic leaky coaxial cable and associated connectors are presented.

Design of Range Adaptive Wireless Power Transfer System Using Non-coaxial Coils

NASA Astrophysics Data System (ADS)

Yang, Dongsheng; Won, Sokhui; Hong, Huan

2017-05-01

Wireless Power Transfer (WPT) is a remarkable technology because of its convenience and applicability in harsh environment. Particularly, Magnetic Coupling WPT (MC-WPT) is a proper method to midrange power transfer, but the frequency splitting at over-coupling range, which is related with transfer distance, is challenge of transmission efficiency. In order to overcome this phenomenon, recently the range adaptive WPT is proposed. In this paper, we aim to the type with a set of non-coaxial driving coils, so that this may remove the connection wires from PA (Power Amplifier) to driving coil. And, when the radius of driving coil is changed, on the different gaps between driving and TX coils, coupling coefficient between these is computed in both cases of coaxial and non-coaxial configurations. In addition, the designing steps for 4-coil WPT system using non-coaxial coils are described with the example. Finally, the reliability of this topology has been proved and simulated with PSPICE.

Simulation of transient effects in the heavy ion fusion injectors

NASA Astrophysics Data System (ADS)

Chen, Yu-Jiuan; Hewett, D. W.

1993-05-01

We have used the 2-D PIC code, GYMNOS, to study the transient behaviors in the Heavy Ion Fusion (HIF) injectors. GYMNOS simulations accurately provide the steady state Child-Langmuir current and the beam transient behavior within a planar diode. The simulations of the LBL HIF ESAC injector experiments agree well with the experimental data and EGUN steady state results. Simulations of the nominal HIF injectors have revealed the need to design the accelerating electrodes carefully to control the ion beam current, particularly the ion loss at the end of the bunch as the extraction voltage is reduced.

Injector element characterization methodology

NASA Technical Reports Server (NTRS)

Cox, George B., Jr.

1988-01-01

Characterization of liquid rocket engine injector elements is an important part of the development process for rocket engine combustion devices. Modern nonintrusive instrumentation for flow velocity and spray droplet size measurement, and automated, computer-controlled test facilities allow rapid, low-cost evaluation of injector element performance and behavior. Application of these methods in rocket engine development, paralleling their use in gas turbine engine development, will reduce rocket engine development cost and risk. The Alternate Turbopump (ATP) Hot Gas Systems (HGS) preburner injector elements were characterized using such methods, and the methodology and some of the results obtained will be shown.

Mixed Mode Fuel Injector And Injection System

DOEpatents

Stewart, Chris Lee; Tian, Ye; Wang, Lifeng; Shafer, Scott F.

2005-12-27

A fuel injector includes a homogenous charge nozzle outlet set and a conventional nozzle outlet set that are controlled respectively by first and second three way needle control valves. Each fuel injector includes first and second concentric needle valve members. One of the needle valve members moves to an open position for a homogenous charge injection event, while the other needle valve member moves to an open position for a conventional injection event. The fuel injector has the ability to operate in a homogenous charge mode with a homogenous charge spray pattern, a conventional mode with a conventional spray pattern or a mixed mode.

Method for Determining Optimum Injector Inlet Geometry

NASA Technical Reports Server (NTRS)

Myers, W. Neill (Inventor); Trinh, Huu P. (Inventor)

2015-01-01

A method for determining the optimum inlet geometry of a liquid rocket engine swirl injector includes obtaining a throttleable level phase value, volume flow rate, chamber pressure, liquid propellant density, inlet injector pressure, desired target spray angle and desired target optimum delta pressure value between an inlet and a chamber for a plurality of engine stages. The method calculates the tangential inlet area for each throttleable stage. The method also uses correlation between the tangential inlet areas and delta pressure values to calculate the spring displacement and variable inlet geometry of a liquid rocket engine swirl injector.

Systems and methods to reduce reductant consumption in exhaust aftertreament systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Aniket; Cunningham, Michael J.

Systems, apparatus and methods are provided for reducing reductant consumption in an exhaust aftertreatment system that includes a first SCR device and a downstream second SCR device, a first reductant injector upstream of the first SCR device, and a second reductant injector between the first and second SCR devices. NOx conversion occurs with reductant injection by the first reductant injector to the first SCR device in a first temperature range and with reductant injection by the second reductant injector to the second SCR device when the temperature of the first SCR device is above a reductant oxidation conversion threshold.

Fuel Lubricity Impact on Shipboard Engine and Fuel Systems and Sensitivity of U.S. Navy Diesel Engines to Low-Sulfur Diesel Fuel

DTIC Science & Technology

2011-06-30

load fuel and operated with a dummy injector to make sure the system was clean. The rig was de -fueled and a fresh charge of 2000-gram fuel was added...the rocker arm on the injector. The rocker arm contact was repositioned when it was noted it was hitting the injector off-center, and it was felt...going up. Figure B6. DD 149 Unit Injector with Diesel Fuel and Centered Rocker Arm Figure B7. Wear Rate Deviation Attributed to Head

Adrenaline auto-injectors for the treatment of anaphylaxis with and without cardiovascular collapse in the community.

PubMed

Sheikh, Aziz; Simons, F Estelle R; Barbour, Victoria; Worth, Allison

2012-08-15

Anaphylaxis is a serious hypersensitivity reaction that is rapid in onset and may cause death. Adrenaline (epinephrine) auto-injectors are recommended as the initial, potentially life-saving treatment of choice for anaphylaxis in the community, but they are not universally available and have limitations in their use. To assess the effectiveness of adrenaline (epinephrine) auto-injectors in relieving respiratory, cardiovascular, and other symptoms during episodes of anaphylaxis that occur in the community. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE (Ovid SP) (1950 to January 2012), EMBASE (Ovid SP) (1980 to January 2012 ), CINAHL (EBSCO host) (1982 to January 2012 ), AMED (EBSCO host) (1985 to January 2012 ), LILACS, (BIREME) (1980 to January 2012 ), ISI Web of Science (1950 to January 2012 ). We adapted our search terms for other databases. We also searched websites listing on-going trials: the World Health Organization International Clinical Trials Registry Platform, the UK Clinical Research Network Study Portfolio, and the meta Register of Controlled Trials; and contacted pharmaceutical companies who manufacture adrenaline auto-injectors in an attempt to locate unpublished material. Randomized and quasi-randomized controlled trials comparing auto-injector administration of adrenaline with any control including no intervention, placebo, or other adrenergic agonists were eligible for inclusion. Two authors independently assessed articles for inclusion. None of the 1328 studies that were identified satisfied the inclusion criteria. Based on this review, we cannot make any new recommendations on the effectiveness of adrenaline auto-injectors for the treatment of anaphylaxis. Although randomized, double-blind, placebo-controlled clinical trials of high methodological quality are necessary to define the true extent of benefits from the administration of adrenaline in anaphylaxis via an auto-injector, such trials are unlikely to be performed in individuals experiencing anaphylaxis because of ethical concerns associated with randomization to placebo. There is, however, a need to consider trials in which, for example, auto-injectors of different doses of adrenaline and differing devices are compared in order to provide greater clarity on the dose and device of choice. Such trials would be practically challenging to conduct. In the absence of appropriate trials, we recommend that adrenaline administration by auto-injector should still be regarded as the most effective first-line treatment for the management of anaphylaxis in the community. In countries where auto-injectors are not commonly used, it may be possible to conduct trials to compare administration of adrenaline via auto-injector with adrenaline administered by syringe and ampoule, or comparing the effectiveness of two different types of auto-injector.

Frequency Selective Properties of Coaxial Transmission Lines Loaded with Combined Artificial Inclusions

PubMed Central

2014-01-01

The properties of a modified coaxial transmission line by periodic inclusions will be discussed. The introduction of split ring resonators, conductor stubs, air gaps, and combination of these gives rise to new frequency selective properties, such as stopband or passband behavior, observable in planar as well as volumetric metamaterial structures. These results envisage new potential applications and implementation of devices in coaxial transmission line technology. PMID:24587748

Fabrication and application of coaxial polyvinyl alcohol/chitosan nanofiber membranes

NASA Astrophysics Data System (ADS)

Kuo, Ting-Yun; Jhang, Cuei-Fang; Lin, Che-Min; Hsien, Tzu-Yang; Hsieh, Hsyue-Jen

2017-12-01

It is difficult to fabricate chitosan-wrapped coaxial nanofibers, because highly viscous chitosan solutions might hinder the manufacturing process. To overcome this difficulty, our newly developed method, which included the addition of a small amount of gum arabic, was utilized to prepare much less viscous chitosan solutions. In this way, coaxial polyvinyl alcohol (PVA)/chitosan (as core/shell) nanofiber membranes were fabricated successfully by coaxial electrospinning. The core/shell structures were confirmed by TEM, and the existence of PVA and chitosan was also verified using FT-IR and TGA. The tensile strength of the nanofiber membranes was increased from 0.6-0.7 MPa to 0.8-0.9 MPa after being crosslinked with glutaraldehyde. The application potential of the PVA/chitosan nanofiber membranes was tested in drug release experiments by loading the core (PVA) with theophylline as a model drug. The use of the coaxial PVA/chitosan nanofiber membranes in drug release extended the release time of theophylline from 5 minutes to 24 hours. Further, the release mechanisms could be described by the Korsmeyer-Peppas model. In summary, by combining the advantages of PVA and chitosan (good mechanical strength and good biocompatibility respectively), the coaxial PVA/chitosan nanofiber membranes are potential biomaterials for various biomedical applications.

Coaxial Cables for Martian Extreme Temperature Environments

NASA Technical Reports Server (NTRS)

Ramesham, Rajeshuni; Harvey, Wayne L.; Valas, Sam; Tsai, Michael C.

2011-01-01

Work was conducted to validate the use of the rover external flexible coaxial cabling for space under the extreme environments to be encountered during the Mars Science Laboratory (MSL) mission. The antennas must survive all ground operations plus the nominal 670-Martian-day mission that includes summer and winter seasons of the Mars environment. Successful development of processes established coaxial cable hardware fatigue limits, which were well beyond the expected in-flight exposures. In keeping with traditional qualification philosophy, this was accomplished by subjecting flight-representative coaxial cables to temperature cycling of the same depth as expected in-flight, but for three times the expected number of in-flight thermal cycles. Insertion loss and return loss tests were performed on the coaxial cables during the thermal chamber breaks. A vector network analyzer was calibrated and operated over the operational frequency range 7.145 to 8.450 GHz. Even though some of the exposed cables function only at UHF frequencies (approximately 400 MHz), the testing was more sensitive, and extending the test range down to 400 MHz would have cost frequency resolution. The Gore flexible coaxial cables, which were the subject of these tests, proved to be robust and displayed no sign of degradation due to the 3X exposure to the punishing Mars surface operations cycles.

Theoretical analysis to investigate thermal performance of co-axial heat pipe solar collector

NASA Astrophysics Data System (ADS)

Azad, E.

2011-12-01

The thermal performance of co-axial heat pipe solar collector which consist of a collector 15 co-axial heat pipes surrounded by a transparent envelope and which heat a fluid flowing through the condenser tubes have been predicted using heat transfer analytical methods. The analysis considers conductive and convective losses and energy transferred to a fluid flowing through the collector condenser tubes. The thermal performances of co-axial heat pipe solar collector is developed and are used to determine the collector efficiency, which is defined as the ratio of heat taken from the water flowing in the condenser tube and the solar radiation striking the collector absorber. The theoretical water outlet temperature and efficiency are compared with experimental results and it shows good agreement between them. The main advantage of this collector is that inclination of collector does not have influence on performance of co-axial heat pipe solar collector therefore it can be positioned at any angle from horizontal to vertical. In high building where the roof area is not enough the co-axial heat pipe solar collectors can be installed on the roof as well as wall of the building. The other advantage is each heat pipe can be topologically disconnected from the manifold.

Main Chamber Injectors for Advanced Hydrocarbon Booster Engines

NASA Technical Reports Server (NTRS)

Long, Matthew R.; Bazarov, Vladimir G.; Anderson, William E.

2003-01-01

Achieving the highest possible specific impulse has long been a key driver for space launch systems. Recently, more importance has been placed on the need for increased reliability and streamlined launch operations. These general factors along with more specific mission requirements have provided a new focus that is centered on the oxidizer rich staged combustion (ORSC) cycle. Despite a history of use in Russia that extends back to the 1960's, a proven design methodology for ORSC cycle engines does not exist in the West. This lack of design expertise extends to the main chamber injector, a critical subcomponent that largely determines the engine performance and main chamber life. The goals of the effort described here are to establish an empirical knowledge base to provide a fundamental understanding of main chamber injectors and for verification of an injector design methodology for the ORSC cycle. The design of a baseline injector element, derived from information on Russian engines in the open literature, is presented. The baseline injector comprises a gaseous oxidizer core flow and an annular swirling fuel flow. Sets of equations describing the steady-state and the dynamic characteristics of the injector are presented; these equations, which form the basis of the design analysis methodology, will be verified in tests later this year. On-going cold flow studies, using nitrogen and water as simulants, are described which indicate highly atomized and symmetric sprays.

Experimental characterization of gasoline sprays under highly evaporating conditions

NASA Astrophysics Data System (ADS)

Khan, Muhammad Mahabat; Sheikh, Nadeem Ahmed; Khalid, Azfar; Lughmani, Waqas Akbar

2018-05-01

An experimental investigation of multistream gasoline sprays under highly evaporating conditions is carried out in this paper. Temperature increase of fuel and low engine pressure could lead to flash boiling. The spray shape is normally modified significantly under flash boiling conditions. The spray plumes expansion along with reduction in the axial momentum causes the jets to merge and creates a low-pressure area below the injector's nozzle. These effects initiate the collapse of spray cone and lead to the formation of a single jet plume or a big cluster like structure. The collapsing sprays reduces exposed surface and therefore they last longer and subsequently penetrate more. Spray plume momentum increase, jet plume reduction and spray target widening could delay or prevent the closure condition and limit the penetration (delayed formation of the cluster promotes evaporation). These spray characteristics are investigated experimentally using shadowgraphy, for five and six hole injectors, under various boundary conditions. Six hole injectors produce more collapsing sprays in comparison to five hole injector due to enhanced jet to jet interactions. The spray collapse tendency reduces with increase in injection pressure due high axial momentum of spray plumes. The spray evaporation rates of five hole injector are observed to be higher than six hole injectors. Larger spray cone angles of the six hole injectors promote less penetrating and less collapsing sprays.

NASA Multipoint LDI Development

NASA Technical Reports Server (NTRS)

Tacina, Robert

2001-01-01

Multipoint Lean-Direct-Injection (LDI) is a combustor concept in which a large number of fuel injectors and fuel-air mixers are used to quickly and uniformly mix the fuel and air so that ultralow levels of NO, are produced. Each fuel injector has an air swirler associated with it for fuel-air mixing and to establish a small recirculation and burning zone. A concept in which there are 36 fuel injectors in the space of a conventional single fuel injector has been tested in a flame tube. A greater than 80 percent reduction in NO, at high power conditions (400 psia, 1000 "Finlet) was achieved. Alternate concepts with 9,25,36 or 49 fuel injectors are being investigated in flame tube tests for their low NO, potential and with fuel staging to improve the turn-down ratio at low power conditions. A preliminary sector concept of a large engine design has been successfully tested at inlet conditions of 700 psia and 1100 O F . This concept had one half the number of fuel injectors per square inch as the flame tube configuration with 36 fuel injectors, and the NO, reduction was 65 percent of the ICAO standard. Future regional engine size sector tests are planned for the 2nd quarter of FY02 and large engine size sector tests for the 1st quarter of FY03.

Diagnostics for a 1.2 kA, 1 MeV, electron induction injector

NASA Astrophysics Data System (ADS)

Houck, T. L.; Anderson, D. E.; Eylon, S.; Henestroza, E.; Lidia, S. M.; Vanecek, D. L.; Westenskow, G. A.; Yu, S. S.

1998-12-01

We are constructing a 1.2 kA, 1 MeV, electron induction injector as part of the RTA program, a collaborative effort between LLNL and LBNL to develop relativistic klystrons for Two-Beam Accelerator applications. The RTA injector will also be used in the development of a high-gradient, low-emittance, electron source and beam diagnostics for the second axis of the Dual Axis Radiographic Hydrodynamic Test (DARHT) Facility. The electron source will be a 3.5″-diameter, thermionic, flat-surface, m-type cathode with a maximum shroud field stress of approximately 165 kV/cm. Additional design parameters for the injector include a pulse length of over 150 ns flat top (1% energy variation), and a normalized edge emittance of less than 200 π-mm-mr. Precise measurement of the beam parameters is required so that performance of the RTA injector can be confidently scaled to the 4 kA, 3 MeV, and 2-microsecond pulse parameters of the DARHT injector. Planned diagnostics include an isolated cathode with resistive divider for direct measurement of current emission, resistive wall and magnetic probe current monitors for measuring beam current and centroid position, capacitive probes for measuring A-K gap voltage, an energy spectrometer, and a pepperpot emittance diagnostic. Details of the injector, beam line, and diagnostics are presented.

What are the 'ideal' features of an adrenaline (epinephrine) auto-injector in the treatment of anaphylaxis?

PubMed

Frew, A J

2011-01-01

Anaphylaxis is a systemic allergic reaction that often involves respiratory symptoms and cardiovascular collapse, which are potentially life-threatening if not treated promptly with intramuscular adrenaline. Owing to the unpredictable nature of anaphylaxis and accidental exposure to allergens (such as peanuts and shellfish), patients should be prescribed intramuscular adrenaline auto-injectors and carry these with them at all times. Patients also need to be able to use their auto-injectors correctly while under high stress, when an anaphylactic attack occurs. Despite this, an alarming number of patients fail to carry their auto-injectors and many patients, carers of children with known anaphylaxis and healthcare professionals do not know how to use the device correctly, despite having had training. Currently available auto-injector devices have various limitations that may impede their use in the management of anaphylaxis. There is also a lack of validated assessment criteria and regulatory requirements for new devices. This review describes the different delivery systems used in currently available auto-injectors and discusses the key barriers to the use of adrenaline auto-injectors, with the goal of identifying the 'ideal' features/characteristics of such devices in the emergency treatment of anaphylaxis that will ensure ease of use, portability and accurate delivery of a life-saving drug. © 2010 John Wiley & Sons A/S.

Nozzle

DOEpatents

Chen, Alexander G.; Cohen, Jeffrey M.

2009-06-16

A fuel injector has a number of groups of nozzles. The groups are generally concentric with an injector axis. Each nozzle defines a gas flowpath having an outlet for discharging a fuel/air mixture jet. There are means for introducing the fuel to the air. One or more groups of the nozzles are oriented to direct the associated jets skew to the injector axis.

Hot-Fire Test of Liquid Oxygen/Hydrogen Space Launch Mission Injector Applicable to Exploration Upper Stage

NASA Technical Reports Server (NTRS)

Barnett, Greg; Turpin, Jason; Nettles, Mindy

2015-01-01

This task is to hot-fire test an existing Space Launch Mission (SLM) injector that is applicable for all expander cycle engines being considered for the exploration upper stage. The work leverages investment made in FY 2013 that was used to additively manufacture three injectors (fig. 1) all by different vendors..

Evaluation of Future Fuels in a High Pressure Common Rail System. Part 3. John Deere 4.5L Powertech Plus

DTIC Science & Technology

2013-01-01

within the fuel injectors regardless of viscosity or lubricity levels. 15. SUBJECT TERMS Fuel Lubricity, Viscosity, HPCR, Synthetic Jet Fuel, Denso... injectors regardless of viscosity or lubricity levels. UNCLASSIFIED v UNCLASSIFIED FOREWORD/ACKNOWLEDGMENTS The U.S. Army TARDEC...40 3.10 UPPER INJECTOR CONNECTING PIN

Fuel Cell/Reformers Technology Development

NASA Technical Reports Server (NTRS)

2004-01-01

NASA Glenn Research Center is interested in developing Solid Oxide Fuel Cell for use in aerospace applications. Solid oxide fuel cell requires hydrogen rich feed stream by converting commercial aviation jet fuel in a fuel processing process. The grantee's primary research activities center on designing and constructing a test facility for evaluating injector concepts to provide optimum feeds to fuel processor; collecting and analyzing literature information on fuel processing and desulfurization technologies; establishing industry and academic contacts in related areas; providing technical support to in-house SOFC-based system studies. Fuel processing is a chemical reaction process that requires efficient delivery of reactants to reactor beds for optimum performance, i.e., high conversion efficiency and maximum hydrogen production, and reliable continuous operation. Feed delivery and vaporization quality can be improved by applying NASA's expertise in combustor injector design. A 10 KWe injector rig has been designed, procured, and constructed to provide a tool to employ laser diagnostic capability to evaluate various injector concepts for fuel processing reactor feed delivery application. This injector rig facility is now undergoing mechanical and system check-out with an anticipated actual operation in July 2004. Multiple injector concepts including impinging jet, venturi mixing, discrete jet, will be tested and evaluated with actual fuel mixture compatible with reforming catalyst requirement. Research activities from September 2002 to the closing of this collaborative agreement have been in the following areas: compiling literature information on jet fuel reforming; conducting autothermal reforming catalyst screening; establishing contacts with other government agencies for collaborative research in jet fuel reforming and desulfurization; providing process design basis for the build-up of injector rig facility and individual injector design.

Fuel Injector Patternation Evaluation in Advanced Liquid-Fueled, High Pressure, Gas Turbine Combustors, Using Nonintrusive Optical Diagnostic Techniques

NASA Technical Reports Server (NTRS)

Locke, R. J.; Hicks, Y. R.; Anderson, R. C.; Zaller, M. M.

1998-01-01

Planar laser-induced fluorescence (PLIF) imaging and planar Mie scattering are used to examine the fuel distribution pattern (patternation) for advanced fuel injector concepts in kerosene burning, high pressure gas turbine combustors. Three diverse fuel injector concepts for aerospace applications were investigated under a broad range of operating conditions. Fuel PLIF patternation results are contrasted with those obtained by planar Mie scattering. Further comparison is also made for one injector with data obtained through phase Doppler measurements. Differences in spray patterns for diverse conditions and fuel injector configurations are readily discernible. An examination of the data has shown that a direct determination of the fuel spray angle at realistic conditions is also possible. The results obtained in this study demonstrate the applicability and usefulness of these nonintrusive optical techniques for investigating fuel spray patternation under actual combustor conditions.

Injector for the University of Maryland Electron Ring (UMER)

NASA Astrophysics Data System (ADS)

Kehne, D.; Godlove, T.; Haldemann, P.; Bernal, S.; Guharay, S.; Kishek, R.; Li, Y.; O'Shea, P.; Reiser, M.; Yun, V.; Zou, Y.; Haber, I.

2001-05-01

The electron beam injector constructed by FM technologies for the University of Maryland Electron Ring (UMER) program is described. The program will use an electron beam to model space-charge-dominated ion beams in a recirculating linac for heavy ion inertial fusion, as well as for high-current muon colliders. The injector consists of a 10 keV, 100 mA electron gun with 50-100 nsec pulse width and a repetition rate of 120 Hz. The e-gun system includes a 6-mask, rotatable aperture plate, a Rogowski current monitor, an ion pump, and a gate valve. The injector beamline consists of a solenoid, a five-quadrupole matching section, two diagnostic chambers, and a fast current monitor. An independent diagnostic chamber also built for UMER will be used to measure horizontal and vertical emittance, current, energy, energy spread, and the evolution of the beam envelope and profile along the injector beamline.

Integrated numerical modeling of a laser gun injector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, H.; Benson, S.; Bisognano, J.

1993-06-01

CEBAF is planning to incorporate a laser gun injector into the linac front end as a high-charge cw source for a high-power free electron laser and nuclear physics. This injector consists of a DC laser gun, a buncher, a cryounit and a chicane. The performance of the injector is predicted based on integrated numerical modeling using POISSON, SUPERFISH and PARMELA. The point-by-point method incorporated into PARMELA by McDonald is chosen for space charge treatment. The concept of ``conditioning for final bunching`` is employed to vary several crucial parameters of the system for achieving highest peak current while maintaining low emittancemore » and low energy spread. Extensive parameter variation studies show that the design will perform beyond the specifications for FEL operations aimed at industrial applications and fundamental scientific research. The calculation also shows that the injector will perform as an extremely bright cw electron source.« less