Science.gov

Sample records for aerocapture vehicle flowfields

  1. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1994-01-01

    wave precursor ahead of vehicles entering the Earth's atmosphere. (8) Since considerable data exists for radiating nonequilibrium flow behind normal shock waves, a normal shock wave version of the blunt body code was developed. (9) By comparing predictions from the models and codes with available normal shock data and the flight data of Fire II, it is believed that the developed flowfield and nonequilibrium radiation models have been essentially validated for engineering applications.

  2. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1990-01-01

    The primary tasks during January 1990 to June 1990 have been the development and evaluation of various electron and electron-electronic energy equation models, the continued development of improved nonequilibrium radiation models for molecules and atoms, and the continued development and investigation of precursor models and their effects. In addition, work was initiated to develop a vibrational model for the viscous shock layer (VSL) nonequilibrium chemistry blunt body engineering code. Also, an effort was started associated with the effects of including carbon species, say from an ablator, in the flowfield.

  3. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1993-01-01

    The period from Jan. 1993 thru Aug. 1993 is covered. The primary tasks during this period were the development of a single and multi-vibrational temperature preferential vibration-dissociation coupling model, the development of a normal shock nonequilibrium radiation-gasdynamic coupling model based upon the blunt body model, and the comparison of results obtained with these models with experimental data. In addition, an extensive series of computations were conducted using the blunt body model to develop a set of reference results covering a wide range of vehicle sizes, altitudes, and entry velocities.

  4. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 2

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    A technique was developed for predicting the character and magnitude of the shock wave precursor ahead of an entry vehicle and the effect of this precursor on the vehicle flow field was ascertained. A computational method and program were developed to properly model this precursor. Expressions were developed for the mass production rates of each species due to photodissociation and photoionization reactions. Also, consideration was given to the absorption and emission of radiation and how it affects the energy in each of the energy modes of both the atomic and diatomic species. A series of parametric studies were conducted covering a range of entry conditions in order to predict the effects of the precursor on the shock layer and the radiative heat transfer to the body.

  5. Aerocapture vehicle mission design concepts for the inner and outer planets

    NASA Technical Reports Server (NTRS)

    Cruz, M. I.

    1979-01-01

    The paper presents mission design concepts using an aerocapture vehicle for future missions to the inner and outer planets which require substantial payloads in orbit that can not be readily realized using the present Space Transportation System (STS). Aerocapture is a mission design technique that utilizes aerodynamically controlled atmospheric entry to capture payloads into orbit as opposed to a completely propulsive orbit insertion. Results are presented which demonstrate great performance gains and acceptable accuracy using aerocapture. Attention is also given to the potential for aerocapture vehicle system design commonality for different missions, in order to demonstrate the ability of aerocapture as an interplanetary delivery technique to substantially augment the STS performance capabilities.

  6. Aerothermodynamic design feasibility of a Mars aerocapture/aeromaneuver vehicle

    NASA Technical Reports Server (NTRS)

    Florence, D. E.

    1981-01-01

    Lifting aerodynamic configurations have been screened and selected for the Mars aerocapture mission that (1) meet the geometric packaging requirements of the various payloads and the Space Shuttle cargo bay and (2) provide the aerodynamic performance characteristics required to obtain the atmospheric exit steering accuracy and the parachute deployment conditions desired. Hypersonic heat transfer and aerodynamic loads to the vehicle in the CO2 atmosphere are evaluated. Contemporary low density ablative thermal protection materials were selected that meet all the atmospheric entry requirements and provide a minimum mass solution. Results are presented of the aerodynamic configuration and thermal protection materials screening and selection. It is concluded that the aerothermodynamic design of this concept is feasible using state-of-the-art technology.

  7. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    The primary tasks performed are: (1) the development of a second order local thermodynamic nonequilibrium (LTNE) model for atoms; (2) the continued development of vibrational nonequilibrium models; and (3) the development of a new multicomponent diffusion model. In addition, studies comparing these new models with previous models and results were conducted and reported.

  8. Physiological constraints on deceleration during the aerocapture of manned vehicles

    NASA Technical Reports Server (NTRS)

    Lyne, J. E.

    1992-01-01

    The peak deceleration load allowed for aerobraking of manned vehicles is a critical parameter in planning future excursions to Mars. However, considerable variation exists in the limits used by various investigators. The goal of this study was to determine the most appropriate level for this limit. Methods: Since previous U.S. space flights have been limited to 84 days duration, Soviet flight results were examined. Published details of Soviet entry trajectories were not available. However, personal communication with Soviet cosmonauts suggested that peak entry loads of 5-6 G had been encountered upon return from 8 months in orbit. Soyuz entry capsule's characteristics were established and the capsule's entry trajectory was numerically calculated. The results confirm a peak load of 5 to 6 G. Results: Although the Soviet flights were of shorter duration than expected Mars missions, evidence exists that the deceleration experience is applicable. G tolerance has been shown to stabilize after 1 to 3 months in space if adequate countermeasures are used. The calculated Soyuz deceleration histories are graphically compared with those expected for Mars aerobraking. Conclusions: Previous spaceflight experience supports the use of a 5 G limit for the aerocapture of a manned vehicle at Mars.

  9. Aerocapture Technologies

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.

    2006-01-01

    Aeroassist technology development is a vital part of the NASA In-Space Propulsion Technology (ISPT) Program. One of the main focus areas of ISPT is aeroassist technologies through the Aerocapture Technology (AT) Activity. Within the ISPT, the current aeroassist technology development focus is aerocapture. Aerocapture relies on the exchange of momentum with an atmosphere to achieve thrust, in this case a decelerating thrust leading to orbit capture. Without aerocapture, a substantial propulsion system would be needed on the spacecraft to perform the same reduction of velocity. This could cause reductions in the science payload delivered to the destination, increases in the size of the launch vehicle (to carry the additional fuel required for planetary capture) or could simply make the mission impossible due to additional propulsion requirements. The AT is advancing each technology needed for the successful implementation of aerocapture in future missions. The technology development focuses on both rigid aeroshell systems as well as the development of inflatable aerocapture systems, advanced aeroshell performance sensors, lightweight structure and higher temperature adhesives. Inflatable systems such as tethered trailing ballutes ('balloon parachutes'), clamped ballutes, and inflatable aeroshells are also under development. Aerocapture-specific computational tools required to support future aerocapture missions are also an integral part of the ATP. Tools include: engineering reference atmosphere models, guidance and navigation, aerothermodynamic modeling, radiation modeling and flight simulation. Systems analysis plays a key role in the AT development process. The NASA in-house aerocapture systems analysis team has been taken with multiple systems definition and concept studies to complement the technology development tasks. The team derives science requirements, develops guidance and navigation algorithms, as well as engineering reference atmosphere models and

  10. Motion coordination of multiple autonomous vehicles in a spatiotemporal flowfield

    NASA Astrophysics Data System (ADS)

    Peterson, Cameron Kai

    The long-term goal of this research is to provide theoretically justified control strategies to operate autonomous vehicles in spatiotemporal flowfields. The specific objective of this dissertation is to use estimation and nonlinear control techniques to generate decentralized control algorithms that enable motion coordination for multiple autonomous vehicles while operating in a time-varying flowfield. A cooperating team of vehicles can benefit from sharing data and tasking responsibilities. Many existing control algorithms promote collaboration of autonomous vehicles. However, these algorithms often fail to account for the degradation of control performance caused by flowfields. This dissertation presents decentralized multivehicle coordination algorithms designed for operation in a spatially or temporally varying flowfield. Each vehicle is represented using a Newtonian particle traveling in a plane at constant speed relative to the flow and subject to a steering control. Initially, we assume the flowfield is known and describe algorithms that stabilize a circular formation in a time-varying spatially nonuniform flow of moderate intensity. These algorithms are extended by relaxing the assumption that the flow is known: the vehicles dynamically estimate the flow and use that estimate in the control. We propose a distributed estimation and control algorithm comprising a consensus filter to share information gleaned from noisy position measurements, and an information filter to reconstruct a spatially varying flowfield. The theoretical results are illustrated with numerical simulations of circular formation control and validated in outdoor unmanned aerial vehicle (UAV) flight tests.

  11. Assured Crew Return Vehicle flowfield and aerodynamic characteristics

    NASA Technical Reports Server (NTRS)

    Weilmuenster, K. James; Smith, Robert E.; Greene, Francis A.

    1990-01-01

    A lifting body has been proposed as a candidate for the Assured Crew Return Vehicle which will serve as crew rescue vehicle for the Space Station. The focus of this work is on body surface definition, surface and volume grid definition, and the computation of inviscid flowfields about the vehicle at wind-tunnel conditions. Very good agreement is shown between the computed aerodynamic characteristics of the vehicle at a freestream Mach number of 10 and those measured in wind-tunnel tests.

  12. ISP Aerocapture Technology

    NASA Astrophysics Data System (ADS)

    James, B.

    2004-11-01

    Aerocapture technology development is a vital part of the NASA In-Space Propulsion Program (ISP), which is managed by NASA Headquarters and implemented at the NASA Marshall Space Flight Center in Huntsville, Alabama. Aerocapture is a flight maneuver designed to aerodynamically decelerate a spacecraft from hyperbolic approach to a captured orbit during one pass through the atmosphere. Small amounts of propulsive fuel are used for attitude control and periapsis raise only. This technique is very attractive since it permits spacecraft to be launched from Earth at higher verlocities, reducing trip times. The aerocapture technique also significantly reduces the overall mass of the propulsion systems. This allows for more science payload to be added to the mission. Alternatively, a smaller launch vehicle could be used, reducing overall mission cost. Aerocapture can be realized in various ways. It can be accomplished using rigid aeroshells, such as those used in previous mission efforts (like Apollo, the planned Aeroassist Flight Experiment and the Mars Exploration Rovers). Aerocapture can also be achieved with inflatable deceleration systems. This family includes the use of a potentially lighter, inflatable aeroshell or a large, trailing ballute - a combination parachute and balloon made of durable, thin material and stowed behind the vehicle for deployment. Aerocapture utilizing inflatable decelerators is also derived from previous efforts, but will necessitate further research to reach the technology readiness level (TRL) that the rigid aeroshell has achieved. Results of recent Aerocapture Systems analysis studies for small bodies and giant planets show that aerocapture can be enhancing for most missions and absolutely enabling for some mission scenarios. In this way, Aerocapture could open up exciting, new science mission opportunities.

  13. Method and system for control of upstream flowfields of vehicle in supersonic or hypersonic atmospheric flight

    NASA Technical Reports Server (NTRS)

    Daso, Endwell O. (Inventor); Pritchett, II, Victor E. (Inventor); Wang, Ten-See (Inventor); Farr, Rebecca Ann (Inventor)

    2012-01-01

    The upstream flowfield of a vehicle traveling in supersonic or hypersonic atmospheric flight is actively controlled using attribute(s) experienced by the vehicle. Sensed attribute(s) include pressure along the vehicle's outer mold line, temperature along the vehicle's outer mold line, heat flux along the vehicle's outer mold line, and/or local acceleration response of the vehicle. A non-heated, non-plasma-producing gas is injected into an upstream flowfield of the vehicle from at least one surface location along the vehicle's outer mold line. The pressure of the gas so-injected is adjusted based on the attribute(s) so-sensed.

  14. Neptune Aerocapture Systems Analysis

    NASA Technical Reports Server (NTRS)

    Lockwood, Mary Kae

    2004-01-01

    A Neptune Aerocapture Systems Analysis is completed to determine the feasibility, benefit and risk of an aeroshell aerocapture system for Neptune and to identify technology gaps and technology performance goals. The high fidelity systems analysis is completed by a five center NASA team and includes the following disciplines and analyses: science; mission design; aeroshell configuration screening and definition; interplanetary navigation analyses; atmosphere modeling; computational fluid dynamics for aerodynamic performance and database definition; initial stability analyses; guidance development; atmospheric flight simulation; computational fluid dynamics and radiation analyses for aeroheating environment definition; thermal protection system design, concepts and sizing; mass properties; structures; spacecraft design and packaging; and mass sensitivities. Results show that aerocapture can deliver 1.4 times more mass to Neptune orbit than an all-propulsive system for the same launch vehicle. In addition aerocapture results in a 3-4 year reduction in trip time compared to all-propulsive systems. Aerocapture is feasible and performance is adequate for the Neptune aerocapture mission. Monte Carlo simulation results show 100% successful capture for all cases including conservative assumptions on atmosphere and navigation. Enabling technologies for this mission include TPS manufacturing; and aerothermodynamic methods and validation for determining coupled 3-D convection, radiation and ablation aeroheating rates and loads, and the effects on surface recession.

  15. Comparisons of thermochemical nonequilibrium viscous flowfield predictions for AFE vehicle

    NASA Technical Reports Server (NTRS)

    Tam, Luen T.; Li, Chien P.

    1990-01-01

    Numerical solutions for the Aeroassist Flight Experiment vehicle were obtained from three methods at a trajectory point corresponding to the maximum aerodynamic heating. The flow regime and vehicle's speed require a viscous model of laminar flow and finite-rate chemical and thermal modeling. The computational domain covers both forebody and base such that the shock layer and near wake flowfield are included. Because of differences in computational grids, methods of solution, and models of rate equations, the results are generally in poor agreement. Temperature and species concentrations are strongly affected by the physical model equations and associated parameters. The chemistry model based on 11 species is found to yield lower translational temperature profile near stagnation than those from a seven-species model. The vibrational temperature varies according to the modeling details. All solutions indicate that strong neutral and/or molecular dissociation and weak ionization take place at the forebody and vibrational freezing is present in the afterbody expansion region where the vibrational temperature is higher than the translational temperature. Some forms of shear layer emanating from the aerobrake skirt coalesce in the region of reversed flow behind the vehicle.

  16. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 1

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    The following subject areas are covered: the development of detailed nonequilibrium radiation models for molecules along with appropriate models for atoms; the inclusion of nongray radiation gasdynamic coupling in the VSL (Viscous Shock Layer) code; the development and evaluation of various electron-electronic energy models; and an examination of the effects of shock slip.

  17. Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 3

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1991-01-01

    The computer programs developed to calculate the shock wave precursor and the method of using them are described. This method calculated the precursor flow field in a nitrogen gas including the effects of emission and absorption of radiation on the energy and composition of gas. The radiative transfer is calculated including the effects of absorption and emission through the line as well as the continuum process in the shock layer and through the continuum processes only in the precursor. The effects of local thermodynamic nonequilibrium in the shock layer and precursor regions are also included in the radiative transfer calculations. Three computer programs utilized by this computational scheme to calculate the precursor flow field solution for a given shock layer flow field are discussed.

  18. Development of a blended-control, predictor-corrector guidance algorithm for a crewed Mars aerocapture vehicle

    NASA Astrophysics Data System (ADS)

    Jits, Roman Yuryevich

    A robust blended-control guidance system for a crewed Mars aerocapture vehicle is developed. The key features of its guidance algorithm are the use of the both bank-angle and angle-of-attack modulation to control the aerobraking vehicle, and the use of multiple controls (sequenced pairs of bank-angles and angles-of-attack) within its numeric predictor-corrector targeting routine. The guidance algorithm macrologic is based on extensive open loop trajectory analyses, described in the present research, which led to the selection of a blended-control scheme. A heuristic approach to recover from situations where no converged guidance solution could be found by the numeric predictor-corrector is implemented in the guidance algorithm, and has been successfully demonstrated in a large number of test runs. In this research both the outer and inner loop of the guidance and control system employ the POST (Program to Optimize Simulated Trajectories) computer code as the basic simulation module. At each guidance update, the inner loop solves the rigorous three-dimensional equations of motion and computes the control (bank-angle and angle-of-attack) sequence that is required to meet the required atmospheric exit conditions. Throughout the aerocapture trajectory, the guidance algorithm modifies this control sequence computed by the inner loop, and generates commanded controls for the vehicle, which, when implemented by the outer loop, meet an imposed g-load constraint of 5 Earth g's and compensate for unexpected off-nominal conditions. This blended-control, predictor-corrector guidance algorithm has been successfully developed, implemented and tested and has been shown to be capable of meeting the prescribed g-load constraint and guiding the vehicle to the desired exit conditions for a range of off-nominal factors much wider than those which could be accommodated by prior algorithms and bank-angle-only guidance.

  19. Aerocapture Systems Analysis for a Titan Mission

    NASA Technical Reports Server (NTRS)

    Lockwood, Mary K.; Queen, Eric M.; Way, David W.; Powell, Richard W.; Edquist, Karl; Starr, Brett W.; Hollis, Brian R.; Zoby, E. Vincent; Hrinda, Glenn A.; Bailey, Robert W.

    2006-01-01

    Performance projections for aerocapture show a vehicle mass savings of between 40 and 80%, dependent on destination, for an aerocapture vehicle compared to an all-propulsive chemical vehicle. In addition aerocapture is applicable to multiple planetary exploration destinations of interest to NASA. The 2001 NASA In-Space Propulsion Program (ISP) technology prioritization effort identified aerocapture as one of the top three propulsion technologies for solar system exploration missions. An additional finding was that aerocapture needed a better system definition and that supporting technology gaps needed to be identified. Consequently, the ISP program sponsored an aerocapture systems analysis effort that was completed in 2002. The focus of the effort was on aerocapture at Titan with a rigid aeroshell system. Titan was selected as the initial destination for the study due to potential interest in a follow-on mission to Cassini/Huygens. Aerocapture is feasible, and the performance is adequate, for the Titan mission and it can deliver 2.4 times more mass to Titan than an all-propulsive system for the same launch vehicle.

  20. A computational study of the flowfield surrounding the Aeroassist Flight Experiment vehicle

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Greene, Francis A.

    1987-01-01

    A symmetric total variation diminishing (STVD) algorithm has been applied to the solution of the three-dimensional hypersonic flowfield surrounding the Aeroassist Flight Experiment (AFE) vehicle. Both perfect-gas and chemical nonequilibrium models have been used. The perfect-gas flows were computed at two different Reynolds numbers, including a flight trajectory point at maximum dynamic pressure, and on two different grids. Procedures for coupling the solution of the species continuity equations with the Navier-Stokes equations in the presence of chemical nonequilibrium are reviewed and tested on the forebody of the AFE and on the complete flowfield assuming noncatalytic wall and no species diffusion. Problems with the STVD algorithm unique to flows with variable thermodynamic properties (real gas) are identified and algorithm modifications are suggested. A potential heating problem caused by strong flow impingement on the nozzle lip in the near wake at 0-deg angle of attack has been identified.

  1. Nonequilibrium computational flowfield analysis for the design of mars manned entry vehicles

    NASA Astrophysics Data System (ADS)

    Viviani, A.; Pezzella, G.

    2013-06-01

    This paper deals with the aerodynamic exploration analysis of innovative unusual vehicle concepts, suitable for a manned Mars entry, aiming to support design studies of planetary entry systems. In this framework, two lifting body (LB) configurations have been analyzed so far. Several fully three-dimensional (3D) computational fluid dynamics (CFD) analyses, both for a perfect gas model and for a nonequilibrium reacting gas mixture model, have been performed. The flowfield environment past the exploration vehicle for an assigned Mars entry scenario has been addressed. To this end, a wide range of flow conditions, including different angles of attack (AoA), various Mach numbers, and Reynolds numbers, have been investigated. Results reported in the paper are useful for providing numerical data for further understanding the fluid dynamics processes, as those of high enthalpy flow and vehicle shape effects, involved in the design analysis of LB vehicles for the exploration of Mars.

  2. Generic aerocapture atmospheric entry study, volume 1

    NASA Technical Reports Server (NTRS)

    1980-01-01

    An atmospheric entry study to fine a generic aerocapture vehicle capable of missions to Mars, Saturn, and Uranus is reported. A single external geometry was developed through atmospheric entry simulations. Aerocapture is a system design concept which uses an aerodynamically controlled atmospheric entry to provide the necessary velocity depletion to capture payloads into planetary orbit. Design concepts are presented which provide the control accuracy required while giving thermal protection for the mission payload. The system design concepts consist of the following elements: (1) an extendable biconic aerodynamic configuration with lift to drag ratio between 1.0 and 2.0; (2) roll control system concepts to control aerodynamic lift and disturbance torques; (3) aeroshell design concepts capable of meeting dynamic pressure loads during aerocapture; and (4) entry thermal protection system design concepts to meet thermodynamic loads during aerocapture.

  3. Mission Trades for Aerocapture at Neptune

    NASA Technical Reports Server (NTRS)

    Noca, Muriel A.; Bailey, Robert W.

    2004-01-01

    A detailed Neptune aerocapture systems analysis and spacecraft design study was performed to improve our understanding of the techonology requirement for such a hard mission. The primary objective was to engineer a point design based on blunt body aeroshell technology and quantitatively assess feasibility and performance. This paper reviews the launch vehicle, propulsion, and trajectory options to reach Neptune in the 2015-2020 time frame using aerocapture and all-propulsive vehicles. It establishes the range of entry conditions that would be consistent with delivering a - 1900 kg total entry vehicle maximum expected mass to Neptune including a - 790 kg orbiter maximum expected mass to the science orbit. Two Neptune probes would be also be delivered prior to the aerocapture maneuver. Results show that inertial entry velocities in the range of 28 to 30 km/s are to be expected for chemical and solar electric propulsion options with several gravity assists (combinations of Venus, Earth and Jupiter gravity assists). Trip times range from approximately 10-11 years for aerocapture orbiters to 15 years for all-propulsive vehicles. This paper shows that the use of aerocapture enables this mission given the payload to deliver around Neptune compared to an all-propulsive orbit insertion approach. However, an all-propulsive chemical insertion option is possible for lower payload masses than the one needed for this science mission. Both approaches require a Delta IV heavy class launch vehicle.

  4. Outer Planet Mission Studies Neptune Aerocapture

    NASA Technical Reports Server (NTRS)

    Wercinski, Paul F.; Langhoff, Steven R. (Technical Monitor)

    1997-01-01

    Current and previous studies of orbiter missions to the outer planets have clearly identified high-energy aerocapture as a critical and enabling technology. Aerocapture involves the use of aerodynamic lift to fly a trajectory through a planet's atmosphere to sufficiently decelerate an entry vehicle to capture into planetary orbit. In the past, numerous studies of different configurations of lifting entry vehicles were studied for various planetary orbiter missions which identified aerocapture as a feasible concept yet complex and technically challenging. In order to determine the feasibility of high-speed aerocapture at the outer planets, an accurate trajectory simulation of the flight vehicle is the critical first step in the proposed research. Vehicle response to aerodynamic loading must be predicted accurately in the trajectory simulations. For several Neptune orbiter missions currently under study at the Jet Propulsion Laboratory (JPL), entry velocities relative to the rotating atmosphere ranging from 25 to 30 km/sec, are to be expected. Preliminary trajectory analysis has identified the various flow regimes the entry vehicle is expected to fly in the 8 1% H2 and 19% He atmosphere of Neptune. The size and mass of the vehicle are also determined by the launch vehicle constraints and orbiter spacecraft requirements. For a given baseline arrival conditions of an inertial entry velocity of 28 km/sec and an entry mass of 400 kg, a medium lift (L/D = 1), axisymmetric biconic shaped vehicle was selected in order to satisfy entry corridor width requirements expected for Neptune aerocapture. The analysis summarized in this study indicates that a biconic entry vehicle is a feasible concept for a Neptune aerocapture orbiter mission. The preliminary entry trajectory simulations has demonstrated adequate entry corridor control authority. Furthermore, estimates of the stagnation point heating environment has enabled the preliminary selection of candidate lightweight ceramic

  5. CFD flowfield simulation of Delta Launch Vehicles in a power-on configuration

    NASA Astrophysics Data System (ADS)

    Pavish, D. L.; Gielda, T. P.; Soni, B. K.; Deese, J. E.; Agarwal, R. K.

    1993-07-01

    This paper summarizes recent work at McDonnell Douglas Aerospace (MDA) to develop and validate computational fluid dynamic (CFD) simulations of under expanded rocket plume external flowfields for multibody expendable launch vehicles (ELVs). Multi engine reacting gas flowfield predictions of ELV base pressures are needed to define vehicle base drag and base heating rates for sizing external nozzle and base region insulation thicknesses. Previous ELV design programs used expensive multibody power-on wind tunnel tests that employed chamber/nozzle injected high pressure cold or hot-air. Base heating and pressure measurements were belatedly made during the first flights of past ELV's to correct estimates from semi-empirical engineering models or scale model tests. Presently, CFD methods for use in ELV design are being jointly developed at the Space Transportation Division (MDA-STD) and New Aircraft Missiles Division (MDA-NAMD). An explicit three dimensional, zonal, finite-volume, full Navier-Stokes (FNS) solver with finite rate hydrocarbon/air and aluminum combustion kinetics was developed to accurately compute ELV power-on flowfields. Mississippi State University's GENIE++ general purpose interactive grid generation code was chosen to create zonal, finite volume viscous grids. Axisymmetric, time dependent, turbulent CFD simulations of a Delta DSV-2A vehicle with a MB-3 liquid main engine burning RJ-1/LOX were first completed. Hydrocarbon chemical kinetics and a k-epsilon turbulence model were employed and predictions were validated with flight measurements of base pressure and temperature. Zonal internal/external grids were created for a Delta DSV-2C vehicle with a MB-3 and three Castor-1 solid motors burning and a Delta-2 with an RS-27 main engine (LOX/RP-1) and 9 GEM's attached/6 burning. Cold air, time dependent FNS calculations were performed for DSV-2C during 1992. Single phase simulations that employ finite rate hydrocarbon and aluminum (solid fuel) combustion

  6. Mars Aerocapture Systems Study

    NASA Technical Reports Server (NTRS)

    Wright, Henry S.; Oh, David Y.; Westhelle, Carlos H.; Fisher, Jody L.; Dyke, R. Eric; Edquist, Karl T.; Brown, James L.; Justh, Hilary L.; Munk, Michelle M.

    2006-01-01

    Mars Aerocapture Systems Study (MASS) is a detailed study of the application of aerocapture to a large Mars robotic orbiter to assess and identify key technology gaps. This study addressed use of an Opposition class return segment for use in the Mars Sample Return architecture. Study addressed mission architecture issues as well as system design. Key trade studies focused on design of aerocapture aeroshell, spacecraft design and packaging, guidance, navigation and control with simulation, computational fluid dynamics, and thermal protection system sizing. Detailed master equipment lists are included as well as a cursory cost assessment.

  7. Aerocapture Technology Development Needs for Outer Planet Exploration

    NASA Technical Reports Server (NTRS)

    Wercinski, Paul; Munk, Michelle; Powell, Richard; Hall, Jeff; Graves, Claude; Partridge, Harry (Technical Monitor)

    2002-01-01

    The purpose of this white paper is to identify aerocapture technology and system level development needs to enable NASA future mission planning to support Outer Planet Exploration. Aerocapture is a flight maneuver that takes place at very high speeds within a planet's atmosphere that provides a change in velocity using aerodynamic forces (in contrast to propulsive thrust) for orbit insertion. Aerocapture is very much a system level technology where individual disciplines such as system analysis and integrated vehicle design, aerodynamics, aerothermal environments, thermal protection systems (TPS), guidance, navigation and control (GN&C) instrumentation need to be integrated and optimized to meet mission specific requirements. This paper identifies on-going activities, their relevance and potential benefit to outer planet aerocapture that include New Millennium ST7 Aerocapture concept definition study, Mars Exploration Program aeroassist project level support, and FY01 Aeroassist In-Space Guideline tasks. The challenges of performing aerocapture for outer planet missions such as Titan Explorer or Neptune Orbiter require investments to advance the technology readiness of the aerocapture technology disciplines for the unique application of outer planet aerocapture. This white paper will identify critical technology gaps (with emphasis on aeroshell concepts) and strategies for advancement.

  8. Aerocapture Systems Analysis for a Neptune Mission

    NASA Technical Reports Server (NTRS)

    Lockwood, Mary Kae; Edquist, Karl T.; Starr, Brett R.; Hollis, Brian R.; Hrinda, Glenn A.; Bailey, Robert W.; Hall, Jeffery L.; Spilker, Thomas R.; Noca, Muriel A.; O'Kongo, N.

    2006-01-01

    A Systems Analysis was completed to determine the feasibility, benefit and risk of an aeroshell aerocapture system for Neptune and to identify technology gaps and technology performance goals. The systems analysis includes the following disciplines: science; mission design; aeroshell configuration; interplanetary navigation analyses; atmosphere modeling; computational fluid dynamics for aerodynamic performance and aeroheating environment; stability analyses; guidance development; atmospheric flight simulation; thermal protection system design; mass properties; structures; spacecraft design and packaging; and mass sensitivities. Results show that aerocapture is feasible and performance is adequate for the Neptune mission. Aerocapture can deliver 1.4 times more mass to Neptune orbit than an all-propulsive system for the same launch vehicle and results in a 3-4 year reduction in trip time compared to all-propulsive systems. Enabling technologies for this mission include TPS manufacturing; and aerothermodynamic methods for determining coupled 3-D convection, radiation and ablation aeroheating rates and loads.

  9. The Development of a Nonequilibrium Radiative Heat Transfer Computational Model for High Altitude Entry Vehicle Flowfield Methods

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.

    1995-01-01

    This final report will attempt to concisely summarize the activities and accomplishments associated with NASA Grant and to include pertinent documents in an appendix. The project initially had one primary and several secondary objectives. The original primary objective was to couple into the NASA Johnson Space Center (JSC) nonequilibrium chemistry Euler equation entry vehicle flowfield code, INEQ3D, the Texas A&M University (TAMU) local thermodynamic nonequilibrium (LTNE) radiation model. This model had previously been developed and verified under NASA Langley and NASA Johnson sponsorship as part of a viscous shock layer entry vehicle flowfield code. The secondary objectives were: (1) to investigate the necessity of including the radiative flux term in the vibrational-electron-electronic (VEE) energy equation as well as in the global energy equation, (2) to determine the importance of including the small net change in electronic energy between products and reactants which occurs during a chemical reaction, and (3) to study the effect of atom-atom impact ionization reactions on entry vehicle nonequilibrium flowfield chemistry and radiation. For each, of these objectives, it was assumed that the code would be applicable to lunar return entry conditions, i.e. altitude above 75 km, velocity greater, than 11 km/sec, where nonequilibrium chemistry and radiative heating phenomena would be significant. In addition, it was tacitly assumed that as part of the project the code would be applied to a variety of flight conditions and geometries.

  10. Aerocapture Technology to Reduce Trip Time and Cost of Planetary Missions

    NASA Astrophysics Data System (ADS)

    Artis, Gwen R.; James, B.

    2006-12-01

    NASA’s In-Space Propulsion Technology (ISPT) Program is investing in technologies to revolutionize the robotic exploration of deep space. One of these technologies is Aerocapture, the most promising of the “aeroassist” techniques used to maneuver a space vehicle within an atmosphere, using aerodynamic forces in lieu of propellant. (Other aeroassist techniques include aeroentry and aerobraking.) Aerocapture relies on drag atmospheric drag to decelerate an incoming spacecraft and capture it into orbit. This technique is very attractive since it permits spacecraft to be launched from Earth at higher velocities, providing shorter trip times and saving mass and overall cost on future missions. Recent aerocapture systems analysis studies quantify the benefits of aerocapture to future exploration. The 2002 Titan aerocapture study showed that using aerocapture at Titan instead of conventional propulsive capture results in over twice as much payload delivered to Titan. Aerocapture at Venus results in almost twice the payload delivered to Venus as with aerobraking, and over six times more mass delivered into orbit than all-propulsive capture. Aerocapture at Mars shows significant benefits as the payload sizes increase and as missions become more complex. Recent Neptune aerocapture studies show that aerocapture opens up entirely new classes of missions at Neptune. Current aerocapture technology development is advancing the maturity of each sub-system technology needed for successful implementation of aerocapture on future missions. Recent development has focused on both rigid aeroshell and inflatable aerocapture systems. Rigid aeroshell systems development includes new ablative and non-ablative thermal protection systems, advanced aeroshell performance sensors, lightweight structures and higher temperature adhesives. Inflatable systems such as trailing tethered and clamped “ballutes” and inflatable aeroshells are also under development. Computational tools required

  11. Modeling, Simulation and Visualization of Aerocapture

    NASA Astrophysics Data System (ADS)

    leszcynski, Zigmond V.

    1998-12-01

    A vehicle travelling from Earth to another planet on a ballistic trajectory approaches that planet at hyperbolic velocity. Upon arrival, the vehicle must significantly reduce its speed for orbit insertion. Traditionally, this deceleration has been achieved by propulsive capture, which consumes a large amount of propellant. Aerocapture offers a more fuel-efficient alternative by exploiting vehicular drag in the planet's atmosphere. However, this technique generates extreme heat, necessitating a special thermal protection shield (TPS). Performing a trade study between the propellant mass required for propulsive capture and the TPS mass required for aerocapture can help determine which method is more desirable for a particular mission. The research objective of this thesis was to analyze aerocapture dynamics for the advancement of this trade study process. The result was an aerocapture simulation tool (ACAPS) developed in MATLAB with SIMULINK, emphasizing code validation, upgradeability, user-friendliness and trajectory visualization. The current version, ACAPS 1.1, is a three- degrees-of-freedom point mass simulation model that incorporates a look-up table for the Mars atmosphere. ACAPS is expected to supplement the National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) Project Design Center (PDC) toolkit as preliminary design software for the Mars 2005 Sample Return (MSR) Mission, Mars 2007 Mission, Mars Micromissions, Neptune/Triton Mission, and Human Mars Mission.

  12. Aerocapture Guidance Performance for the Neptune Orbiter

    NASA Technical Reports Server (NTRS)

    Masciarelli, James P.; Westhelle, Carlos H.; Graves, Claude A.

    2004-01-01

    A performance evaluation of the Hybrid Predictor corrector Aerocapture Scheme (HYPAS) guidance algorithm for aerocapture at Neptune is presented in this paper for a Mission to Neptune and the Neptune moon Triton'. This mission has several challenges not experienced in previous aerocapture guidance assessments. These challengers are a very high Neptune arrival speed, atmospheric exit into a high energy orbit about Neptune, and a very high ballistic coefficient that results in a low altitude acceleration capability when combined with the aeroshell LD. The evaluation includes a definition of the entry corridor, a comparison to the theoretical optimum performance, and guidance responses to variations in atmospheric density, aerodynamic coefficients and flight path angle for various vehicle configurations (ballistic numbers). The benefits of utilizing angle-of-attack modulation in addition to bank angle modulation to improve flight performance is also discussed. The results show that despite large sensitivities in apoapsis targeting, the algorithm performs within the allocated AV budget for the Neptune mission bank angle only modulation. The addition of angle-of-attack modulation with as little as 5 degrees of amplitude significantly improves the scatter in final orbit apoapsis. Although the angle-of-attack modulation complicates the vehicle design, the performance enhancement reduces aerocapture risk and reduces the propellant consumption needed to reach the high energy target orbit for a conventional propulsion system.

  13. Ballute Aerocapture Trajectories at Neptune

    NASA Technical Reports Server (NTRS)

    Lyons, Daniel T.; Johnson, Wyatt

    2004-01-01

    Using an inflatable ballute system for aerocapture at planets and moons with atmospheres has the potential to provide significant performance benefits compared not only to traditional all propulsive capture, but also to aeroshell based aerocapture technologies. This paper discusses the characteristics of entry trajectories for ballute aerocapture at Neptune. These trajectories are the first steps in a larger systems analysis effort that is underway to characterize and optimize the performance of a ballute aerocapture system for future missions not only at Neptune, but also the other bodies with atmospheres.

  14. Visualization of Flowfield Modification by RCS Jets on a Capsule Entry Vehicle

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Inman, J. A.; Alderfer, D. W.; Buck, G. M.; Schwartz, R.

    2008-01-01

    Nitric oxide planar laser-induced fluorescence (NO PLIF) has been used to visualize the flow on the aft-body of an entry capsule having an activated RCS jet in NASA Langley Research Center's 31-Inch Mach 10 wind tunnel facility. A capsule shape representative of the Apollo command module was tested. These tests were performed to demonstrate the ability of the PLIF method to visualize RCS jet flow while providing some preliminary input to NASA's Orion Vehicle design team. Two different RCS nozzle designs - conical and contoured - were tested. The conical and contoured nozzles had area ratios of 13.4 and 22.5 respectively. The conical nozzle had a half-angle of 10 . Low- and high-Reynolds number cases were investigated by changing the tunnel stagnation pressure from 350 psi to 1300 psi, resulting in freestream Reynolds numbers of 0.56 and 1.8 million per foot respectively. For both of these cases, three different jet plenum pressures were tested (nominally 56, 250 and 500 psi). A single angle-of-attack was investigated (24 degrees). NO PLIF uses an ultraviolet laser sheet to interrogate a slice in the flow containing seeded NO; this UV light excites fluorescence from the NO molecules which is detected by a high-speed digital camera. The system has spatial resolution of about 200 microns (2 pixel blurring) and has flow-stopping time resolution (approximately 1 microsecond). NO was seeded into the flow two different ways. First, the RCS jet fluid was seeded with approximately 1-5% NO, with the balance N2. This allowed observation of the shape, structure and trajectory of the RCS jets. Visualizations of both laminar and turbulent flow jet features were obtained. Visualizations were obtained with the tunnel operating at Mach 10 and also with the test section held at a constant pressure similar to the aftbody static pressure (0.04 psi) obtained during tunnel runs. These two conditions are called "tunnel on" and "tunnel off" respectively. Second, the forebody flow was

  15. Aerocapture navigation at Neptune

    NASA Technical Reports Server (NTRS)

    Haw, Robert J.

    2003-01-01

    A proposed Neptune orbiter Aerocapture mission will use solar electric propulsion to send an orbiter to Neptune. Navigation feasibility of direct-entry aerocapture for orbit insertion at Neptune is shown. The navigation strategy baselines optical imaging and (delta)VLBI measurement in order to satisfy the flight system's atmosphere entry flight path angle, which is targeted to enter Neptune with an entry flight path angle of -11.6 . Error bars on the entry flight path angle of plus/minus0.55 (3(sigma)) are proposed. This requirement can be satisfied with a data cutoff 3.2 days prior to arrival. There is some margin in the arrival template to tighten (i.e. reduce) the entry corridor either by scheduling a data cutoff closer to Neptune or alternatively, reducing uncertainties by increasing the fidelity of the optical navigation camera.

  16. Aerocapture Technology Development Overview

    NASA Technical Reports Server (NTRS)

    Munk, Michelle M.; Moon, Steven A.

    2008-01-01

    This paper will explain the investment strategy, the role of detailed systems analysis, and the hardware and modeling developments that have resulted from the past 5 years of work under NASA's In-Space Propulsion Program (ISPT) Aerocapture investment area. The organizations that have been funded by ISPT over that time period received awards from a 2002 NASA Research Announcement. They are: Lockheed Martin Space Systems, Applied Research Associates, Inc., Ball Aerospace, NASA s Ames Research Center, and NASA s Langley Research Center. Their accomplishments include improved understanding of entry aerothermal environments, particularly at Titan, demonstration of aerocapture guidance algorithm robustness at multiple bodies, manufacture and test of a 2-meter Carbon-Carbon "hot structure," development and test of evolutionary, high-temperature structural systems with efficient ablative materials, and development of aerothermal sensors that will fly on the Mars Science Laboratory in 2009. Due in large part to this sustained ISPT support for Aerocapture, the technology is ready to be validated in flight.

  17. Atmospheric Models for Aerocapture

    NASA Technical Reports Server (NTRS)

    Justus, C. G.; Duvall, Aleta L.; Keller, Vernon W.

    2004-01-01

    There are eight destinations in the solar System with sufficient atmosphere for aerocapture to be a viable aeroassist option - Venus, Earth, Mars, Jupiter, Saturn and its moon Titan, Uranus, and Neptune. Engineering-level atmospheric models for four of these targets (Earth, Mars, Titan, and Neptune) have been developed for NASA to support systems analysis studies of potential future aerocapture missions. Development of a similar atmospheric model for Venus has recently commenced. An important capability of all of these models is their ability to simulate quasi-random density perturbations for Monte Carlo analyses in developing guidance, navigation and control algorithm, and for thermal systems design. Similarities and differences among these atmospheric models are presented, with emphasis on the recently developed Neptune model and on planned characteristics of the Venus model. Example applications for aerocapture are also presented and illustrated. Recent updates to the Titan atmospheric model are discussed, in anticipation of applications for trajectory and atmospheric reconstruct of Huygens Probe entry at Titan.

  18. In-Space Propulsion (ISP) Aerocapture Technology

    NASA Technical Reports Server (NTRS)

    Munk, Michelle M.; James, Bonnie F.; Moon, Steve

    2005-01-01

    A viewgraph presentation is shown to raise awareness of aerocapture technology through in-space propulsion. The topics include: 1) Purpose; 2) In-Space Propulsion Program; 3) Aerocapture Overview; 4) Aerocapture Technology Alternatives; 5) Aerocapture Technology Project Process; 6) Results from 2002 Aerocapture TAG; 7) Bounding Case Requirements; 8) ST9 Flight Demonstration Opportunity; 9) Aerocapture NRA Content: Cycles 1 and 2; 10) Ames Research Center TPS Development; 11) Applied Research Associates TPS Development; 12) LaRC Structures Development; 13) Lockheed Martin Astronautics Aeroshell Development; 14) ELORET/ARC Sensor Development; 15) Ball Aerospace Trailing Ballute Development; 16) Cycle 2 NRA Selections - Aerocapture; and 17) Summary.

  19. Aerocapture Technology Development for Planetary Science - Update

    NASA Technical Reports Server (NTRS)

    Munk, Michelle M.

    2006-01-01

    Within NASA's Science Mission Directorate is a technological program dedicated to improving the cost, mass, and trip time of future scientific missions throughout the Solar System. The In-Space Propulsion Technology (ISPT) Program, established in 2001, is charged with advancing propulsion systems used in space from Technology Readiness Level (TRL) 3 to TRL6, and with planning activities leading to flight readiness. The program's content has changed considerably since inception, as the program has refocused its priorities. One of the technologies that has remained in the ISPT portfolio through these changes is Aerocapture. Aerocapture is the use of a planetary body's atmosphere to slow a vehicle from hyperbolic velocity to a low-energy orbit suitable for science. Prospective use of this technology has repeatedly shown huge mass savings for missions of interest in planetary exploration, at Titan, Neptune, Venus, and Mars. With launch vehicle costs rising, these savings could be the key to mission viability. This paper provides an update on the current state of the Aerocapture technology development effort, summarizes some recent key findings, and highlights hardware developments that are ready for application to Aerocapture vehicles and entry probes alike. Description of Investments: The Aerocapture technology area within the ISPT program has utilized the expertise around NASA to perform Phase A-level studies of future missions, to identify technology gaps that need to be filled to achieve flight readiness. A 2002 study of the Titan Explorer mission concept showed that the combination of Aerocapture and a Solar Electric Propulsion system could deliver a lander and orbiter to Titan in half the time and on a smaller, less expensive launch vehicle, compared to a mission using chemical propulsion for the interplanetary injection and orbit insertion. The study also identified no component technology breakthroughs necessary to implement Aerocapture on such a mission

  20. Overview of a Proposed Flight Validation of Aerocapture System Technology for Planetary Missions

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Hall, Jeffery L.; Oh, David; Munk, Michelle M.

    2006-01-01

    Aerocapture System Technology for Planetary Missions is being proposed to NASA's New Millennium Program for flight aboard the Space Technology 9 (ST9) flight opportunity. The proposed ST9 aerocapture mission is a system-level flight validation of the aerocapture maneuver as performed by an instrumented, high-fidelity flight vehicle within a true in-space and atmospheric environment. Successful validation of the aerocapture maneuver will be enabled through the flight validation of an advanced guidance, navigation, and control system as developed by Ball Aerospace and two advanced Thermal Protection System (TPS) materials, Silicon Refined Ablative Material-20 (SRAM-20) and SRAM-14, as developed by Applied Research Associates (ARA) Ablatives Laboratory. The ST9 aerocapture flight validation will be sufficient for immediate infusion of these technologies into NASA science missions being proposed for flight to a variety of Solar System destinations possessing a significant planetary atmosphere.

  1. Preliminary Assessment of a Neptune Aerocapture Mission Using an Integrated Design Tool

    NASA Technical Reports Server (NTRS)

    Gage, Peter J.; Wercinski, Paul F.

    1998-01-01

    Aerocapture is an efficient orbit insertion technique that uses the planet's atmosphere to decelerate an arriving spacecraft. With current technology and for vehicles of reasonable mass, it is the only technique that might deliver the high delta-V's required for insertion to orbits around the outer planets. Preliminary design studies for outer planet orbital missions must evaluate aerocapture strategies, and must therefore consider the coupling between vehicle geometry, aerodynamics, aerocapture trajectory, heating and thermal protection system mass. The analyses have been linked into an integrated design environment, with the critical parameters grouped in a global database. The designer is free to use single point evaluations, parametric variation, and numerical optimization to evaluate a range of vehicle shapes and insertion trajectories. The application of this design tool to a preliminary study for Neptune aerocapture has implications for the use of such computational environments for any atmospheric entry mission.

  2. Aerocapture Demonstration and Mars Mission Applications

    NASA Astrophysics Data System (ADS)

    Munk, M. M.

    2012-06-01

    Aerocapture is an aeroassist technology that can enable large robotic payloads to be placed into Mars orbit, facilitate access to Phobos and Deimos, and support human Mars exploration. Aerocapture is immediately applicable to near-term Mars missions.

  3. Demonstration of an Aerocapture GN and C System Through Hardware-in-the-Loop Simulations

    NASA Technical Reports Server (NTRS)

    Masciarelli, James; Deppen, Jennifer; Bladt, Jeff; Fleck, Jeff; Lawson, Dave

    2010-01-01

    Aerocapture is an orbit insertion maneuver in which a spacecraft flies through a planetary atmosphere one time using drag force to decelerate and effect a hyperbolic to elliptical orbit change. Aerocapture employs a feedback Guidance, Navigation, and Control (GN&C) system to deliver the spacecraft into a precise postatmospheric orbit despite the uncertainties inherent in planetary atmosphere knowledge, entry targeting and aerodynamic predictions. Only small amounts of propellant are required for attitude control and orbit adjustments, thereby providing mass savings of hundreds to thousands of kilograms over conventional all-propulsive techniques. The Analytic Predictor Corrector (APC) guidance algorithm has been developed to steer the vehicle through the aerocapture maneuver using bank angle control. Through funding provided by NASA's In-Space Propulsion Technology Program, the operation of an aerocapture GN&C system has been demonstrated in high-fidelity simulations that include real-time hardware in the loop, thus increasing the Technology Readiness Level (TRL) of aerocapture GN&C. First, a non-real-time (NRT), 6-DOF trajectory simulation was developed for the aerocapture trajectory. The simulation included vehicle dynamics, gravity model, atmosphere model, aerodynamics model, inertial measurement unit (IMU) model, attitude control thruster torque models, and GN&C algorithms (including the APC aerocapture guidance). The simulation used the vehicle and mission parameters from the ST-9 mission. A 2000 case Monte Carlo simulation was performed and results show an aerocapture success rate of greater than 99.7%, greater than 95% of total delta-V required for orbit insertion is provided by aerodynamic drag, and post-aerocapture orbit plane wedge angle error is less than 0.5 deg (3-sigma). Then a real-time (RT), 6-DOF simulation for the aerocapture trajectory was developed which demonstrated the guidance software executing on a flight-like computer, interfacing with a

  4. Aerocapture Performance Analysis of A Venus Exploration Mission

    NASA Technical Reports Server (NTRS)

    Starr, Brett R.; Westhelle, Carlos H.

    2005-01-01

    A performance analysis of a Discovery Class Venus Exploration Mission in which aerocapture is used to capture a spacecraft into a 300km polar orbit for a two year science mission has been conducted to quantify its performance. A preliminary performance assessment determined that a high heritage 70 sphere-cone rigid aeroshell with a 0.25 lift to drag ratio has adequate control authority to provide an entry flight path angle corridor large enough for the mission s aerocapture maneuver. A 114 kilograms per square meter ballistic coefficient reference vehicle was developed from the science requirements and the preliminary assessment s heating indicators and deceleration loads. Performance analyses were conducted for the reference vehicle and for sensitivity studies on vehicle ballistic coefficient and maximum bank rate. The performance analyses used a high fidelity flight simulation within a Monte Carlo executive to define the aerocapture heating environment and deceleration loads and to determine mission success statistics. The simulation utilized the Program to Optimize Simulated Trajectories (POST) that was modified to include Venus specific atmospheric and planet models, aerodynamic characteristics, and interplanetary trajectory models. In addition to Venus specific models, an autonomous guidance system, HYPAS, and a pseudo flight controller were incorporated in the simulation. The Monte Carlo analyses incorporated a reference set of approach trajectory delivery errors, aerodynamic uncertainties, and atmospheric density variations. The reference performance analysis determined the reference vehicle achieves 100% successful capture and has a 99.87% probability of attaining the science orbit with a 90 meters per second delta V budget for post aerocapture orbital adjustments. A ballistic coefficient trade study conducted with reference uncertainties determined that the 0.25 L/D vehicle can achieve 100% successful capture with a ballistic coefficient of 228 kilograms

  5. Aerocapture Inflatable Decelerator (AID)

    NASA Technical Reports Server (NTRS)

    Reza, Sajjad

    2007-01-01

    Forward Attached Inflatable Decelerators, more commonly known as inflatable aeroshells, provide an effective, cost efficient means of decelerating spacecrafts by using atmospheric drag for aerocapture or planetary entry instead of conventional liquid propulsion deceleration systems. Entry into planetary atmospheres results in significant heating and aerodynamic pressures which stress aeroshell systems to their useful limits. Incorporation of lightweight inflatable decelerator surfaces with increased surface-area footprints provides the opportunity to reduce heat flux and induced temperatures, while increasing the payload mass fraction. Furthermore, inflatable aeroshell decelerators provide the needed deceleration at considerably higher altitudes and Mach numbers when compared with conventional rigid aeroshell entry systems. Inflatable aeroshells also provide for stowage in a compact space, with subsequent deployment of a large-area, lightweight heatshield to survive entry heating. Use of a deployable heatshield decelerator not only enables an increase in the spacecraft payload mass fraction and but may also eliminate the need for a spacecraft backshell and cruise stage. This document is the viewgraph slides for the paper's presentation.

  6. Physiologically constrained aerocapture for manned Mars missions

    NASA Technical Reports Server (NTRS)

    Lyne, James Evans

    1992-01-01

    Aerobraking has been proposed as a critical technology for manned missions to Mars. The variety of mission architectures currently under consideration presents aerobrake designers with an enormous range of potential entry scenarios. Two of the most important considerations in the design of an aerobrake are the required control authority (lift-to-drag ratio) and the aerothermal environment which the vehicle will encounter. Therefore, this study examined the entry corridor width and stagnation-point heating rate and load for the entire range of probable entry velocities, lift-to-drag ratios, and ballistic coefficients for capture at both Earth and Mars. To accomplish this, a peak deceleration limit for the aerocapture maneuvers had to be established. Previous studies had used a variety of load limits without adequate proof of their validity. Existing physiological and space flight data were examined, and it was concluded that a deceleration limit of 5 G was appropriate. When this load limit was applied, numerical studies showed that an aerobrake with an L/D of 0.3 could provide an entry corridor width of at least 1 degree for all Mars aerocaptures considered with entry velocities up to 9 km/s. If 10 km/s entries are required, an L/D of 0.4 to 0.5 would be necessary to maintain a corridor width of at least 1 degree. For Earth return aerocapture, a vehicle with an L/D of 0.4 to 0.5 was found to provide a corridor width of 0.7 degree or more for all entry velocities up to 14.5 km/s. Aerodynamic convective heating calculations were performed assuming a fully catalytic, 'cold' wall; radiative heating was calculated assuming that the shock layer was in thermochemical equilibrium. Heating rates were low enough for selected entries at Mars that a radiatively cooled thermal protection system might be feasible, although an ablative material would be required for most scenarios. Earth return heating rates were generally more severe than those encountered by the Apollo vehicles

  7. Atmospheric Models for Mars Aerocapture

    NASA Technical Reports Server (NTRS)

    Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

    2005-01-01

    level Mars atmospheric model. Applications include systems design, performance analysis, and operations planning for aerobraking, entry descent and landing, and aerocapture. Typical Mars aerocapture periapsis altitudes (for systems with rigid- aeroshell heat shields) are about 50 km. This altitude is above the 0-40 km height range covered by Mars Global Surveyor Thermal Emission Spectrometer (TES) nadir observations. Recently, TES limb sounding data have been made available, spanning more than two Mars years (more than 200,000 data profiles) with altitude coverage up to about 60 km, well within the height range of interest for aerocapture. Results are presented comparing Mars-GRAM atmospheric density with densities from TES nadir and limb sounding observations. A new Mars-GRAM feature is described which allows individual TES nadir or limb profiles to be extracted from the large TES databases, and to be used as an optional replacement for standard Mars-GRAM background (climatology) conditions. For Monte-Carlo applications such as aerocapture guidance and control studies, Mars-GRAM perturbations are available using these TES profile background conditions.

  8. PredGuid+A: Orion Entry Guidance Modified for Aerocapture

    NASA Technical Reports Server (NTRS)

    Lafleur, Jarret

    2013-01-01

    PredGuid+A software was developed to enable a unique numerical predictor-corrector aerocapture guidance capability that builds on heritage Orion entry guidance algorithms. The software can be used for both planetary entry and aerocapture applications. Furthermore, PredGuid+A implements a new Delta-V minimization guidance option that can take the place of traditional targeting guidance and can result in substantial propellant savings. PredGuid+A allows the user to set a mode flag and input a target orbit's apoapsis and periapsis. Using bank angle control, the guidance will then guide the vehicle to the appropriate post-aerocapture orbit using one of two algorithms: Apoapsis Targeting or Delta-V Minimization (as chosen by the user). Recently, the PredGuid guidance algorithm was adapted for use in skip-entry scenarios for NASA's Orion multi-purpose crew vehicle (MPCV). To leverage flight heritage, most of Orion's entry guidance routines are adapted from the Apollo program.

  9. Systems Analysis for a Venus Aerocapture Mission

    NASA Technical Reports Server (NTRS)

    Lockwood, Mary Kae; Starr, Brett R.; Paulson, John W., Jr.; Kontinos, Dean A.; Chen, Y. K.; Laub, Bernard; Olejniczak, Joseph; Wright, Michael J.; Takashima, Naruhisa; Justus, Carl G.

    2006-01-01

    Previous high level analysis has indicated that significant mass savings may be possible for planetary science missions if aerocapture is employed to place a spacecraft in orbit. In 2001 the In-Space Propulsion program identified aerocapture as one of the top three propulsion technologies for planetary exploration but that higher fidelity analysis was required to verify the favorable results and to determine if any supporting technology gaps exist that would enable or enhance aerocapture missions. A series of three studies has been conducted to assess, from an overall system point of view, the merit of using aerocapture at Titan, Neptune and Venus. These were chosen as representative of a moon with an atmosphere, an outer giant gas planet and an inner planet. The Venus mission, based on desirable science from plans for Solar System Exploration and Principal Investigator proposals, to place a spacecraft in a 300km polar orbit was examined and the details of the study are presented in this paper.

  10. Neptune aerocapture mission and spacecraft design overview

    NASA Technical Reports Server (NTRS)

    Bailey, Robert W.; Hall, Jeff L.; Spliker, Tom R.; O'Kongo, Nora

    2004-01-01

    A detailed Neptune aerocapture systems analysis and spacecraft design study was performed as part of NASA's In-Space Propulsion Program. The primary objectives were to assess the feasibility of a spacecraft point design for a Neptune/Triton science mission. That uses aerocapture as the Neptune orbit insertion mechanism. This paper provides an overview of the science, mission and spacecraft design resulting from that study.

  11. AEROELASTIC SIMULATION TOOL FOR INFLATABLE BALLUTE AEROCAPTURE

    NASA Technical Reports Server (NTRS)

    Liever, P. A.; Sheta, E. F.; Habchi, S. D.

    2006-01-01

    A multidisciplinary analysis tool is under development for predicting the impact of aeroelastic effects on the functionality of inflatable ballute aeroassist vehicles in both the continuum and rarefied flow regimes. High-fidelity modules for continuum and rarefied aerodynamics, structural dynamics, heat transfer, and computational grid deformation are coupled in an integrated multi-physics, multi-disciplinary computing environment. This flexible and extensible approach allows the integration of state-of-the-art, stand-alone NASA and industry leading continuum and rarefied flow solvers and structural analysis codes into a computing environment in which the modules can run concurrently with synchronized data transfer. Coupled fluid-structure continuum flow demonstrations were conducted on a clamped ballute configuration. The feasibility of implementing a DSMC flow solver in the simulation framework was demonstrated, and loosely coupled rarefied flow aeroelastic demonstrations were performed. A NASA and industry technology survey identified CFD, DSMC and structural analysis codes capable of modeling non-linear shape and material response of thin-film inflated aeroshells. The simulation technology will find direct and immediate applications with NASA and industry in ongoing aerocapture technology development programs.

  12. Aerocapture and aeromaneuvering at Mars

    NASA Technical Reports Server (NTRS)

    Vijayaraghavan, A.

    1992-01-01

    This paper presents the results of a guidance analysis study for aerocapture and aeromaneuvering at Mars. A 4-state, near-optimal, hybrid guidance algorithm is derived for applications throughout the paper. It is based on the critical assumption that Loh's function remains constant between successive guidance updates. Besides the guidance algorithm, the paper presents a performance evaluation of guidance derived from estimated or 'navigated' spacecraft state, provided by an onboard navigation subsystem for real-time applications on Mars. For the performance evaluation, the spacecraft state is augmented by such parameters as the reference atmospheric density and scale-height, the banking angle and angle of attack for spacecraft control and the accelerometer measurement model errors. Finally, the paper examines also, the influence of random uncertainties in atmospheric density on aeroassisted maneuvers, by a Monte Carlo type of simulation.

  13. Aerocapture Performance Analysis for a Neptune-Triton Exploration Mission

    NASA Technical Reports Server (NTRS)

    Starr, Brett R.; Westhelle, Carlos H.; Masciarelli, James P.

    2004-01-01

    A systems analysis has been conducted for a Neptune-Triton Exploration Mission in which aerocapture is used to capture a spacecraft at Neptune. Aerocapture uses aerodynamic drag instead of propulsion to decelerate from the interplanetary approach trajectory to a captured orbit during a single pass through the atmosphere. After capture, propulsion is used to move the spacecraft from the initial captured orbit to the desired science orbit. A preliminary assessment identified that a spacecraft with a lift to drag ratio of 0.8 was required for aerocapture. Performance analyses of the 0.8 L/D vehicle were performed using a high fidelity flight simulation within a Monte Carlo executive to determine mission success statistics. The simulation was the Program to Optimize Simulated Trajectories (POST) modified to include Neptune specific atmospheric and planet models, spacecraft aerodynamic characteristics, and interplanetary trajectory models. To these were added autonomous guidance and pseudo flight controller models. The Monte Carlo analyses incorporated approach trajectory delivery errors, aerodynamic characteristics uncertainties, and atmospheric density variations. Monte Carlo analyses were performed for a reference set of uncertainties and sets of uncertainties modified to produce increased and reduced atmospheric variability. For the reference uncertainties, the 0.8 L/D flatbottom ellipsled vehicle achieves 100% successful capture and has a 99.87 probability of attaining the science orbit with a 360 m/s V budget for apoapsis and periapsis adjustment. Monte Carlo analyses were also performed for a guidance system that modulates both bank angle and angle of attack with the reference set of uncertainties. An alpha and bank modulation guidance system reduces the 99.87 percentile DELTA V 173 m/s (48%) to 187 m/s for the reference set of uncertainties.

  14. Lunar/Mars earth return aerocapture heating constraint

    NASA Technical Reports Server (NTRS)

    Cuthbert, P. A.; Tigges, M. A.; Bryant, L. E.

    1990-01-01

    Trajectory design issues beyond those under consideration in the Aeroassist Flight Experiment (AFE) program and more in line with the Shuttle design concept are presented. This is deemed necessary as flight regimes encountered in Lunar/Mars aerocapture trajectories at Mars and return-to-earth will provide more stringent requirements on vehicle design than AFE and are not exactly quantifiable at this time. Investigations are conducted of areas where explicit trajectory control is practical and can most directly influence constraints critical to vehicle design for manned and unmanned interplanetary missions. Primary consideration is given to the ability to control vehicle heating during entry, and this particular area of Shuttle entry design is discussed in detail.

  15. Structural Design for a Neptune Aerocapture Mission

    NASA Technical Reports Server (NTRS)

    Dyke, R. Eric; Hrinda, Glenn A.

    2004-01-01

    A multi-center study was conducted in 2003 to assess the feasibility of and technology requirements for using aerocapture to insert a scientific platform into orbit around Neptune. The aerocapture technique offers a potential method of greatly reducing orbiter mass and thus total spacecraft launch mass by minimizing the required propulsion system mass. This study involved the collaborative efforts of personnel from Langley Research Center (LaRC), Johnson Space Flight Center (JSFC), Marshall Space Flight Center (MSFC), Ames Research Center (ARC), and the Jet Propulsion Laboratory (JPL). One aspect of this effort was the structural design of the full spacecraft configuration, including the ellipsled aerocapture orbiter and the in-space solar electric propulsion (SEP) module/cruise stage. This paper will discuss the functional and structural requirements for each of these components, some of the design trades leading to the final configuration, the loading environments, and the analysis methods used to ensure structural integrity. It will also highlight the design and structural challenges faced while trying to integrate all the mission requirements. Component sizes, materials, construction methods and analytical results, including masses and natural frequencies, will be presented, showing the feasibility of the resulting design for use in a Neptune aerocapture mission. Lastly, results of a post-study structural mass optimization effort on the ellipsled will be discussed, showing potential mass savings and their influence on structural strength and stiffness

  16. A Comparative Study of Aerocapture Missions with a Mars Destination

    NASA Technical Reports Server (NTRS)

    Vaughan, Diane; Miller, Heather C.; Griffin, Brand; James, Bonnie F.; Munk, Michelle M.

    2005-01-01

    Conventional interplanetary spacecraft use propulsive systems to decelerate into orbit. Aerocapture is an alternative approach for orbit capture, in which the spacecraft makes a single pass through a target destination's atmosphere. Although this technique has never been performed, studies show there are substantial benefits of using aerocapture for reduction of propellant mass, spacecraft size, and mission cost. The In-Space Propulsion (ISP) Program, part of NASA's Science Mission Directorate, has invested in aerocapture technology development since 2002. Aerocapture investments within ISP are largely driven by mission systems analysis studies, The purpose of this NASA-funded report is to identify and document the fundamental parameters of aerocapture within previous human and robotic Mars mission studies which will assist the community in identifying technology research gaps in human and robotic missions, and provide insight for future technology investments. Upon examination of the final data set, some key attributes within the aerocapture disciplines are identified.

  17. Overview of a Proposed Flight Validation of Aerocapture System Technology

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Hall, Jeffery L.; Oh, David Y.; Munk, Michelle M.

    2006-01-01

    Aerocapture is a very useful capability for NASA that can be used across a wide range of planetary mission sizes and destinations. A substantial mass advantage may be realized through aerocapture maneuver implementation. The mass advantage is enabling for certain outer planet mission profiles. Aerocapture technology provides corollary benefits to the related applications of atmospheric entry and precision landing on worlds with atmospheres through aero/aerothermodynamic model validation, hypersonic guided flight, tps materials, and performance model validation. The ST9 Aerocapture flight validation will be sufficient to immediately infuse aerocapture technology into future NASA science missions. The advanced technologies being flight validated will enable the system level goal of performing an aerocapture maneuver. The advanced technologies include: The GN&C System, TPS materials, plus Advanced recession and heat flux sensors.

  18. Mars Rover Sample Return aerocapture configuration design and packaging constraints

    NASA Technical Reports Server (NTRS)

    Lawson, Shelby J.

    1989-01-01

    This paper discusses the aerodynamics requirements, volume and mass constraints that lead to a biconic aeroshell vehicle design that protects the Mars Rover Sample Return (MRSR) mission elements from launch to Mars landing. The aerodynamic requirements for Mars aerocapture and entry and packaging constraints for the MRSR elements result in a symmetric biconic aeroshell that develops a L/D of 1.0 at 27.0 deg angle of attack. A significant problem in the study is obtaining a cg that provides adequate aerodynamic stability and performance within the mission imposed constraints. Packaging methods that relieve the cg problems include forward placement of aeroshell propellant tanks and incorporating aeroshell structure as lander structure. The MRSR missions developed during the pre-phase A study are discussed with dimensional and mass data included. Further study is needed for some missions to minimize MRSR element volume so that launch mass constraints can be met.

  19. Flowfield computation of entry vehicles

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.

    1990-01-01

    The equations governing the multidimensional flow of a reacting mixture of thermally perfect gasses were derived. The modeling procedures for the various terms of the conservation laws are discussed. A numerical algorithm, based on the finite-volume approach, to solve these conservation equations was developed. The advantages and disadvantages of the present numerical scheme are discussed from the point of view of accuracy, computer time, and memory requirements. A simple one-dimensional model problem was solved to prove the feasibility and accuracy of the algorithm. A computer code implementing the above algorithm was developed and is presently being applied to simple geometries and conditions. Once the code is completely debugged and validated, it will be used to compute the complete unsteady flow field around the Aeroassist Flight Experiment (AFE) body.

  20. Flowfield computer graphics

    NASA Technical Reports Server (NTRS)

    Desautel, Richard

    1993-01-01

    The objectives of this research include supporting the Aerothermodynamics Branch's research by developing graphical visualization tools for both the branch's adaptive grid code and flow field ray tracing code. The completed research for the reporting period includes development of a graphical user interface (GUI) and its implementation into the NAS Flowfield Analysis Software Tool kit (FAST), for both the adaptive grid code (SAGE) and the flow field ray tracing code (CISS).

  1. Rectangular subsonic jet flowfield study

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Tatterson, Gary B.; Swan, David H.

    1987-01-01

    The flowfield of a rectangular jet with 2:1 aspect ratio was studied at an axial Reynolds number of 127,000, using a three-dimensional laser anemometer. The flowfield surveys resulted in mean velocity vector field plots and contour plots of the Reynolds stress tensor components for the major and minor axes. These data contribute substantially to currently available data of jet flowfields.

  2. The Stakes of the Aerocapture for Missions to Mars

    NASA Astrophysics Data System (ADS)

    Cledassou, R.; Lam-Trong, Th.; Charbonnier, J. M.

    2000-07-01

    The Hohmann transfer trajectory is an economical way to go from Earth to Mars but a spacecraft has to reduce its speed very significantly upon arrival in order to be inserted into a Mars orbit. The aerocapture is a way to do that, by using the Martian atmosphere to produce sufficient aerodynamic drag force on a heatshield and achieve the required deceleration. This presentation will address the major stake of the aerocapture which is twofold: a) We will list the different technologies and areas of knowledge related to the aerocapture, identify the risks associated with each of them and finally demonstrate that aerocapture is not as risky as it is said to be; b) Aerocapture saves a huge amount of propellant and so allows to improve dramatically the dollar/kg ratio for any payload at Mars by using this mass savings for payloads and by decreasing the launch cost. This benefit is particularly evident for a return mission because of the amplification factor of the propellant mass for the escape of Mars ("snow ball" effect). We will have a quantitative analysis of some typical cases of spacecraft vs. launcher performance . We will conclude that aerocapture is interesting for the present robotic missions and certainly a good investment for the future manned missions to Mars.

  3. Trailing Ballute Aerocapture: Concept and Feasibility Assessment

    NASA Technical Reports Server (NTRS)

    Miller, Kevin L.; Gulick, Doug; Lewis, Jake; Trochman, Bill; Stein, Jim; Lyons, Daniel T.; Wilmoth, Richard G.

    2003-01-01

    Trailing Ballute Aerocapture offers the potential to obtain orbit insertion around a planetary body at a fraction of the mass of traditional methods. This allows for lower costs for launch, faster flight times and additional mass available for science payloads. The technique involves an inflated ballute (balloon-parachute) that provides aerodynamic drag area for use in the atmosphere of a planetary body to provide for orbit insertion in a relatively benign heating environment. To account for atmospheric, navigation and other uncertainties, the ballute is oversized and detached once the desired velocity change (Delta V) has been achieved. Analysis and trades have been performed for the purpose of assessing the feasibility of the technique including aerophysics, material assessments, inflation system and deployment sequence and dynamics, configuration trades, ballute separation and trajectory analysis. Outlined is the technology development required for advancing the technique to a level that would allow it to be viable for use in space exploration missions.

  4. Aerocapture Inflatable Decelerator for Planetary Entry

    NASA Technical Reports Server (NTRS)

    Reza, Sajjad; Hund, Richard; Kustas, Frank; Willcockson, William; Songer, Jarvis; Brown, Glen

    2007-01-01

    Forward Attached Inflatable Decelerators, more commonly known as inflatable aeroshells, provide an effective, cost efficient means of decelerating spacecrafts by using atmospheric drag for aerocapture or planetary entry instead of conventional liquid propulsion deceleration systems. Entry into planetary atmospheres results in significant heating and aerodynamic pressures which stress aeroshell systems to their useful limits. Incorporation of lightweight inflatable decelerator surfaces with increased surface-area footprints provides the opportunity to reduce heat flux and induced temperatures, while increasing the payload mass fraction. Furthermore, inflatable aeroshell decelerators provide the needed deceleration at considerably higher altitudes and Mach numbers when compared with conventional rigid aeroshell entry systems. Inflatable aeroshells also provide for stowage in a compact space, with subsequent deployment of a large-area, lightweight heatshield to survive entry heating. Use of a deployable heatshield decelerator enables an increase in the spacecraft payload mass fraction and may eliminate the need for a spacecraft backshell.

  5. Mars Aerocapture Analysis For MESUR/Mars-Pathfinder Aeroshells Using Un-modulated Control in Low L/D Configurations

    NASA Technical Reports Server (NTRS)

    Wercinski, Paul F.; Edwards, Thomas A. (Technical Monitor)

    1994-01-01

    Aerocapture scenarios are examined to determine the feasibility of using MESUR/Mars Pathfinder aeroshell designs to capture spacecraft aerodynamically into Mars orbit. Using lift over drag (L/D) ratios up to 0.3, entry trajectories were simulated over a range of entry vehicle masses and entry velocities. Entry corridor widths were calculated for undershoot and overshoot trajectories yielding Mars parking orbits having periods from 2 to 20 hours. For entries with L/D = 0.3, entry corridor widths of about 1.2 degrees are possible over entry velocities from 5.5 to 9.0 km/sec. The design constraints for an aeroshell used for orbital aerocapture are less severe than a ballistic entry for a surface lander mission such as Mars Pathfinder, because the aerothermodynamic heating and deceleration loads are smaller. The mass savings from aerocapture orbit insertion versus propulsive insertion into Mars orbit could result in significantly reducing program costs and increasing mission capabilities.

  6. An onboard navigation system which fulfills Mars aerocapture guidance requirements

    NASA Technical Reports Server (NTRS)

    Brand, Timothy J.; Fuhry, Douglas P.; Shepperd, Stanley W.

    1989-01-01

    The development of a candidate autonomous onboard Mars approach navigation scheme capable of supporting aerocapture into Mars orbit is discussed. An aerocapture guidance and navigation system which can run independently of the preaerocapture navigation was used to define a preliminary set of accuracy requirements at entry interface. These requirements are used to evaluate the proposed preaerocapture navigation scheme. This scheme uses optical sightings on Deimos with a star tracker and an inertial measurement unit for instrumentation as a source for navigation nformation. Preliminary results suggest that the approach will adequately support aerocaputre into Mars orbit.

  7. Aerocapture guidance and navigation for the Rosetta Comet Nucleus Sample Return Mission

    NASA Astrophysics Data System (ADS)

    Serrano-Martinez, J. B.; Hechler, M.

    The aerocapture/reentry phase of the Comet Nucleus Sample Return Mission Rosetta when returning from the Comet back to earth is discussed. The guidance and navigation process for a guided atmospheric entry to ground from an entry velocity of over 15 km/s has been simulated and the feasibility of such an entry at an entry angle of -10.5 deg, using an Apollo shape vehicle and guidance methods similar to those used for Apollo and the Shuttle Orbiter, has been demonstrated. Landing precision of less than 10 km at accelerations below 20 g can be reached. Critical areas of system design like the center of gravity location of the entry vehicle are addressed.

  8. Numerical study of external burning flowfields

    NASA Technical Reports Server (NTRS)

    Bittner, Robert D.; Mcclinton, Charles R.

    1991-01-01

    This paper demonstrates the successful application of CFD to modeling an external burning flowfield. The study used the 2D, 3D, and PNS versions of the SPARK code. Various grids, boundary conditions, and ignition methodologies have been employed. Flameholding was achieved through the use of a subsonic outflow condition and a hot block located behind the step to ignite the fuel. Since the resulting burning produces a large subsonic region downstream of the cowl, this entire surface can be pressurized to the level of the back pressure. An evaluation of interactions between the ramjet exhaust and the external burning products demonstrate the complexity of this design issue. Ths code is now capable of evaluating the external burning effectiveness for flight vehicles using simple injector schemes, and the methodology can be readily applied to other external burning designs.

  9. A CFD study of tilt rotor flowfields

    NASA Technical Reports Server (NTRS)

    Fejtek, Ian; Roberts, Leonard

    1989-01-01

    The download on the wing produced by the rotor wake of a tilt rotor vehicle in hover is of major concern because of its severe impact on payload-carrying capability. In a concerted effort to understand the fundamental fluid dynamics that cause this download, and to help find ways to reduce it, computational fluid dynamics (CFD) is employed to study this problem. The thin-layer Navier-Stokes equations are used to describe the flow, and an implicit, finite difference numerical algorithm is the method of solution. The methodology is developed to analyze the tilt rotor flowfield. Included are discussions of computations of an airfoil and wing in freestream flows at -90 degrees, a rotor alone, and wing/rotor interaction in two and three dimensions. Preliminary results demonstrate the feasibility and great potential of the present approach. Recommendations are made for both near-term and far-term improvements to the method.

  10. Outstanding Science at Neptune: Aerocapture Implementation of NASA's "Neptune Orbiter With Probes" Vision Mission

    NASA Astrophysics Data System (ADS)

    Spilker, T. R.; Ingersoll, A. P.

    2004-12-01

    After successfully proposing to NASA's "Vision Missions Studies" NRA (NRA-03-OSS-01-VM) the authors are studying an implementation option for the "Neptune Orbiter With Probes" mission that performs Cassini-level science without fission-based electric power or propulsion. Our Study Team includes a Science Team composed of experienced planetary scientists, many of whom helped draft the Neptune discussions in the Solar System Exploration Decadal Survey, and an Implementation Team with experienced engineers and technologists from multiple NASA Centers and JPL. The key characteristics of our mission concept are a mix of Solar Electric Propulsion and gravity assists to reach Neptune in 12 years or less, aerocapture into an eccentric Neptune orbit for a Triton-driven orbital tour, and a well designed set of science objectives guiding a very capable science payload including multiple Neptune entry probes. Significant pathfinding work done in 2002-03 by NASA's Aerocapture Systems Analysis Team allowed focusing quickly on principal issues. By the end of May 2004 the Science Team had drafted a thorough and coherent set of science objectives, leading to our first series of design sessions with JPL's "Team X" in early June. The initial design options studied in those sessions produced flight system designs that all fit easily on soon-to-be-operational launch vehicles. Since then, students working in Caltech's Laboratory for Space Mission Design have studied the potential benefits of incorporating new technologies into those initial designs. Later this year another series of Team X sessions will incorporate the most beneficial technologies into the best design options. The poster will discuss the mission's science objectives, and summarize study results to date. This work was performed at the Jet Propulsion Laboratory and its parent institution, the California Institute of Technology, under contract to NASA's Office of Space Science.

  11. Outstanding Science in the Neptune System From an Aerocaptured Vision Mission

    NASA Astrophysics Data System (ADS)

    Spilker, T. R.; Ingersoll, A. P.

    2004-11-01

    In 2003 the authors successfully proposed to NASA's ``Vision Missions Studies" NRA (NRA-03-OSS-01-VM) to study an implementation option for the ``Neptune Orbiter with Probes" mission that does Cassini-level science without fission-based electric power or propulsion. Our Study Team includes a Science Team composed of experienced planetary scientists, many of whom helped draft the Neptune discussions in the Solar System Exploration Decadal Survey, and an Implementation Team with experienced engineers and technologists from multiple NASA Centers and JPL. The key characteristics of our mission concept are a mix of Solar Electric Propulsion and gravity assists to reach Neptune in 12 years or less, aerocapture into an eccentric Neptune orbit for a Triton-driven orbital tour, and a well designed set of science objectives guiding a very capable science payload that includes multiple Neptune entry probes. We leveraged the significant pathfinding work done in 2002-03 by NASA's Aerocapture Systems Analysis Team to focus quickly on principal issues. By the end of May 2004 the Science Team had drafted a thorough and coherent set of science objectives, leading to our first series of design sessions with JPL's ``Team X" in early June. The initial design options studied in those sessions produced flight system designs that all fit easily on soon-to-be-operational launch vehicles. Since then, students working in Caltech's Laboratory for Space Mission Design have studied the potential benefits of incorporating new technologies into those initial designs. Later this year another series of Team X sessions will incorporate the most beneficial technologies into the best design options. The poster will discuss the mission's science objectives, and summarize study results to date. This work was done at multiple NASA Centers and the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA's Office of Space Science.

  12. A Design Study of Onboard Navigation and Guidance During Aerocapture at Mars. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Fuhry, Douglas Paul

    1988-01-01

    The navigation and guidance of a high lift-to-drag ratio sample return vehicle during aerocapture at Mars are investigated. Emphasis is placed on integrated systems design, with guidance algorithm synthesis and analysis based on vehicle state and atmospheric density uncertainty estimates provided by the navigation system. The latter utilizes a Kalman filter for state vector estimation, with useful update information obtained through radar altimeter measurements and density altitude measurements based on IMU-measured drag acceleration. A three-phase guidance algorithm, featuring constant bank numeric predictor/corrector atmospheric capture and exit phases and an extended constant altitude cruise phase, is developed to provide controlled capture and depletion of orbital energy, orbital plane control, and exit apoapsis control. Integrated navigation and guidance systems performance are analyzed using a four degree-of-freedom computer simulation. The simulation environment includes an atmospheric density model with spatially correlated perturbations to provide realistic variations over the vehicle trajectory. Navigation filter initial conditions for the analysis are based on planetary approach optical navigation results. Results from a selection of test cases are presented to give insight into systems performance.

  13. Control of jet flowfield dynamics

    NASA Astrophysics Data System (ADS)

    Kibens, V.; Wlezien, R. W.

    1984-02-01

    Passive control of shear layer turbulence was investigated experimentally for low subsonic velocity jets from circular nozzles by studying effects of modifying nozzle exit geometry. Indeterminate origin (I.O.) nozzles used, including slanted, stepped and crenelated exit geometries, were so designated because streamwise location of the nozzle lip varies with azimuthal position, unlike standard nozzles for which the entire termination is at the same streamwise location. Flow visualization and detailed hot-wire measurements were used to observe development and interaction of large-scale turbulent structures in shear layers originating from various sectors of the I.O. nozzles, to determine the influence of instability wave patterns on ensuing flowfield characteristics and to relate observed evolution of three-dimensional large-scale turbulent structures to global properties of the jet flowfield such as velocity profiles and shear layer spreading rates as a function of streamwise distance and azimuthal angle. Results showed pronounced asymmetries in shear layer growth rates, which could be controlled by varying nozzle parameters. The asymmetries were also confirmed by measurements of azimuthal variation of shear layer turbulent energy as well as mean-velocity profiles. Detailed features of energy transfer from the mean flow into successively larger flow structures were traced by spectral mapping techniques and by mapping energy levels contained in subharmonics of the shear-layer instability frequency at various azimuthal flow sectors.

  14. Computational and experimental investigation of cavity flowfields

    NASA Technical Reports Server (NTRS)

    Baysal, O.; Stallings, R. L., Jr.

    1987-01-01

    This paper presents a computational and experimental investigation of supersonic flow past a cavity in a flat plate. The source of the particular interest in this problem is the ongoing study of the aerodynamic interference effects between a separating store and its bay in the parent body. An upwind relaxation scheme, utilizing flux vector splitting and line-Gauss-Seidel iterations, is used to solve Reynolds-averaged Navier-Stokes equations. Spatial discretizations of this two-dimensional analysis are based on implicit and finite-volume methods. Turbulence is modeled and shocks are captured. The flowfield of the symmetry plane at the half-width is computationally visualized and all flow properties are computed. Experimental tests are conducted in the Langley Unitary Plan Wind Tunnel to measure wall pressures and to capture schlieren photographs. Qualitative as well as quantitative data of computations and experiments agree very well. These two vehicles of investigation are merged to show open, closed and transitional cavity flow behaviors.

  15. Images constructed from computed flowfields

    NASA Technical Reports Server (NTRS)

    Yates, Leslie A.

    1992-01-01

    A method for constructing interferograms, schlieren, and shadowgraphs from ideal- and real-gas, two- and three-dimensional computed flowfileds is described. The computational grids can be structured or unstructured, and multiple grids are an option. The constructed images are compared to experimental images for several types of flow, including a ramp, a blunt-body, a nozzle, and a reacting flow. The constructed images simulate the features observed in the experimental images. They are sensitive to errors in the flowfield solutions and can be used to identify solution errors. In addition, techniques for obtaining phase shifts from experimental finite-fringe interferograms and for removing experimentally induced phase-shift errors are discussed. Both the constructed images and calculated phase shifts can be used for validation of computational fluid dynamics (CFD) codes.

  16. Enhancement of the Natural Earth Satellite Population Through Meteoroid Aerocapture

    NASA Technical Reports Server (NTRS)

    Moorhead, Althea V.; Cooke, William J.

    2014-01-01

    The vast majority of meteoroids either fall to the ground as meteorites or ablate completely in the atmosphere. However, large meteoroids have been observed to pass through the atmosphere and reenter space in a few instances. These atmosphere-grazing meteoroids have been characterized using ground-based observation and satellite-based infrared detection. As these methods become more sensitive, smaller atmospheregrazing meteoroids will likely be detected. In anticipation of this increased detection rate, we compute the frequency with which centimeter-sized meteoroids graze and exit Earth's atmosphere. We characterize the post-atmosphere orbital characteristics of these bodies and conduct numerical simulations of their orbital evolution under the perturbing influence of the Sun and Moon. We find that a small subset of aerocaptured meteoroids are perturbed away from immediate atmospheric reentry and become temporary natural Earth satellites.

  17. Advanced Space Propulsion System Flowfield Modeling

    NASA Technical Reports Server (NTRS)

    Smith, Sheldon

    1998-01-01

    Solar thermal upper stage propulsion systems currently under development utilize small low chamber pressure/high area ratio nozzles. Consequently, the resulting flow in the nozzle is highly viscous, with the boundary layer flow comprising a significant fraction of the total nozzle flow area. Conventional uncoupled flow methods which treat the nozzle boundary layer and inviscid flowfield separately by combining the two calculations via the influence of the boundary layer displacement thickness on the inviscid flowfield are not accurate enough to adequately treat highly viscous nozzles. Navier Stokes models such as VNAP2 can treat these flowfields but cannot perform a vacuum plume expansion for applications where the exhaust plume produces induced environments on adjacent structures. This study is built upon recently developed artificial intelligence methods and user interface methodologies to couple the VNAP2 model for treating viscous nozzle flowfields with a vacuum plume flowfield model (RAMP2) that is currently a part of the Plume Environment Prediction (PEP) Model. This study integrated the VNAP2 code into the PEP model to produce an accurate, practical and user friendly tool for calculating highly viscous nozzle and exhaust plume flowfields.

  18. Aerocapture Guidance and Performance at Mars for High-Mass Systems

    NASA Technical Reports Server (NTRS)

    Zumwalt, Carlie H.; Sostaric, Ronald r.; Westhelle, Carlos H.

    2009-01-01

    The Mars Entry, Descent, and Landing System Analysis (EDL-SA) project has been tasked with performing systems analysis to identify the optimal technologies required to land a 20-50 MT Exploration-class mission on Mars. It has been shown that it is not possible to safely land these large systems using heritage Mars EDL systems, or analogous Earth or Moon EDL systems. In 2007, NASA conducted a Mars Exploration Architecture Study which included an in depth review of the science motivations and engineering technology requirements for a human Mars mission campaign. This study resulted in an update to the Mars Design Reference Architecture (DRA 5.0). Among the primary findings and recommendations was the conclusion that landing of large payloads (greater than 1 MT) on the surface of Mars remains a key architectural challenge. Additionally, research and system studies of fundamental EDL technologies were highly recommended. The EDL-SA project identified the candidate technologies and assembled them into full capture and EDL sequences so that simulations could be developed to evaluate them. The chosen architectures combine the various technologies of interest in eight different ways. For aerocapture, only two scenarios were considered. The first is a rigid mid-L/D aeroshell (AS), which is represented in architectures 1, 4, 5, and 7. This scenario calls for a vehicle that flies at a 55-degree angle of attack, resulting in ballistic coefficient and L/D values of 490 kg/m 2 and 0.43, respectively. The second is a lifting hypersonic inflatable aerodynamic decelerator (HIAD), which is represented in architectures 2, 6, and 8. This scenario requires the vehicle to fly at a 22.2- degree angle of attack, which correlates to an L/D of 0.3 and was sized to provide a ballistic coefficient of 165 kg/m 2 . Architecture 3 is an all-propulsive sequence, and is not considered in this study.

  19. Flowfield analysis of an arcjet thruster

    NASA Astrophysics Data System (ADS)

    Uda, Nobuki; Tahara, Hirokazu; Onoe, Ken-Ichi; Yoshikawa, Takao

    Flowfields of a medium-power (10-kW class) direct-current (dc) arcjet were numerically analyzed using a quasi-one dimensional core-flow model to understand the arc features in the discharge chamber. The flowfield calculations showed that the arc radii for Ar gradually increased downstream in the constrictor and that the arcs attached to the constrictor wall though the arcs for N2 passed through the constrictor. The difference of the arc attachment characteristics between molecular and atomic gases is due to whether there is dissociation process. The flowfields in the expansion nozzle were also found to be early frozen flows, as the heavy species temperatures drastically decreased downstream compared with the electron temperatures.

  20. Aerocapture Technology Developments from NASA's In-Space Propulsion Technology Program

    NASA Technical Reports Server (NTRS)

    Munk, Michelle M.; Moon, Steven A.

    2007-01-01

    This paper will explain the investment strategy, the role of detailed systems analysis, and the hardware and modeling developments that have resulted from the past 5 years of work under NASA's In-Space Propulsion Program (ISPT) Aerocapture investment area. The organizations that have been funded by ISPT over that time period received awards from a 2002 NASA Research Announcement. They are: Lockheed Martin Space Systems, Applied Research Associates, Inc., Ball Aerospace, NASA's Ames Research Center, and NASA's Langley Research Center. Their accomplishments include improved understanding of entry aerothermal environments, particularly at Titan, demonstration of aerocapture guidance algorithm robustness at multiple bodies, manufacture and test of a 2-meter Carbon-Carbon "hot structure," development and test of evolutionary, high-temperature structural systems with efficient ablative materials, and development of aerothermal sensors that will fly on the Mars Science Laboratory in 2009. Due in large part to this sustained ISPT support for Aerocapture, the technology is ready to be validated in flight.

  1. Angle-of-Attack-Modulated Terminal Point Control for Neptune Aerocapture

    NASA Technical Reports Server (NTRS)

    Queen, Eric M.

    2004-01-01

    An aerocapture guidance algorithm based on a calculus of variations approach is developed, using angle of attack as the primary control variable. Bank angle is used as a secondary control to alleviate angle of attack extremes and to control inclination. The guidance equations are derived in detail. The controller has very small onboard computational requirements and is robust to atmospheric and aerodynamic dispersions. The algorithm is applied to aerocapture at Neptune. Three versions of the controller are considered with varying angle of attack authority. The three versions of the controller are evaluated using Monte Carlo simulations with expected dispersions.

  2. Lag Model Predictions for UFAST SBLI Flowfield

    NASA Technical Reports Server (NTRS)

    Olsen, Mike; Lillard, Randy; Oliver, Brandon; Blaisdell, Gregory

    2010-01-01

    Presentation for Shock Boundary Layer Interaction Workshop. Shows results for Lag turbulence model on one of the international workshop test cases the UFAST 8 degree test case. Comparison with PIV velocity measurements as well as computed tunnel wall flowfields are shown, emphasizing that the interaction is a 3D phenomena, and is reasonably well predicted.

  3. Planar laser-induced fluorescence (PLIF) investigation of hypersonic flowfields in a Mach 10 wind tunnel

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Wilkes, Jennifer A.; Aderfer, David W.; Jones, Stephen B.; Robbins, Anthony W.; Pantry, Danny P.; Schwartz, Richard J.

    2006-01-01

    Planar laser-induced fluorescence (PLIF) of nitric oxide (NO) was used to visualize four different hypersonic flowfields in the NASA Langley Research Center 31-Inch Mach 10 Air wind tunnel. The four configurations were: (1) the wake flowfield of a fuselage-only X-33 lifting body, (2) flow over a flat plate containing a rectangular cavity, (3) flow over a 70deg blunted cone with a cylindrical afterbody, formerly studied by an AGARD working group, and (4) an Apollo-geometry entry capsule - relevant to the Crew Exploration Vehicle currently being developed by NASA. In all cases, NO was seeded into the flowfield through tubes inside or attached to the model sting and strut. PLIF was used to visualize the NO in the flowfield. In some cases pure NO was seeded into the flow while in other cases a 5% NO, 95% N2 mix was injected. Several parameters were varied including seeding method and location, seeding mass flow rate, model angle of attack and tunnel stagnation pressure, which varies the unit Reynolds number. The location of the laser sheet was as also varied to provide three dimensional flow information. Virtual Diagnostics Interface (ViDI) technology developed at NASA Langley was used to visualize the data sets in post processing. The measurements demonstrate some of the capabilities of the PLIF method for studying hypersonic flows.

  4. Observability-based sampling and estimation of flowfields using multi-sensor systems

    NASA Astrophysics Data System (ADS)

    DeVries, Levi D.

    The long-term goal of this research is to optimize estimation of an unknown flowfield using an autonomous multi-vehicle or multi-sensor system. The specific research objective is to provide theoretically justified, nonlinear control, estimation, and optimization techniques enabling a group of sensors to coordinate their motion to target measurements that improve observability of the surrounding environment, even when the environment is unknown. Measures of observability provide an optimization metric for multi-agent control algorithms that avoid spatial regions of the domain prone to degraded or ill-conditioned estimation performance, thereby improving closed-loop control performance when estimated quantities are used in feedback control. The control, estimation, and optimization framework is applied to three applications of multi-agent flowfield sensing including (1) environmental sampling of strong flowfields using multiple autonomous unmanned vehicles, (2) wake sensing and observability-based optimal control for two-aircraft formation flight, and (3) bio-inspired flow sensing and control of an autonomous unmanned underwater vehicle. For environmental sampling, this dissertation presents an adaptive sampling algorithm steering a multi-vehicle system to sampling formations that improve flowfield observability while simultaneously estimating the flow for use in feedback control, even in strong flows where vehicle motion is hindered. The resulting closed-loop trajectories provide more informative measurements, improving estimation performance. For formation flight, this dissertation uses lifting-line theory to represent a two-aircraft formation and derives optimal control strategies steering the follower aircraft to a desired position relative to the leader while simultaneously optimizing the observability of the leader's relative position. The control algorithms guide the follower aircraft to a desired final position along trajectories that maintain adequate

  5. Mars Aerocapture and Validation of Mars-GRAM with TES Data

    NASA Technical Reports Server (NTRS)

    Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

    2005-01-01

    Mars Global Reference Atmospheric Model (Mars-GRAM) is a widely-used engineering- level Mars atmospheric model. Applications include systems design, performance analysis, and operations planning for aerobraking, entry descent and landing, and aerocapture. Typical Mars aerocapture periapsis altitudes (for systems with rigid-aeroshell heat shields) are about 50 km. This altitude is above the 0-40 km height range covered by Mars Global Surveyor Thermal Emission Spectrometer (TES) nadir observations. Recently, TES limb sounding data have been made available, spanning more than two Mars years (more than 200,000 data profiles) with altitude coverage up to about 60 km, well within the height range of interest for aerocapture. Results are presented comparing Mars-GRAM atmospheric density with densities from TES nadir and limb sounding observations. A new Mars-GRAM feature is described which allows individual TES nadir or limb profiles to be extracted from the large TES databases, and to be used as an optional replacement for standard Mars-GRAM background (climatology) conditions. For Monte-Carlo applications such as aerocapture guidance and control studies, Mars-GRAM perturbations are available using these TES profile background conditions.

  6. Supercomputer applications in gas turbine flowfield simulation

    NASA Technical Reports Server (NTRS)

    Madavan, Nateri K.; Kelaita, Paul; Gavali, Sharad

    1990-01-01

    The numerical simulation of the unsteady three-dimensional viscous flow in a gas turbine stage is considered. Results from a three-dimensional time-accurate Navier-Stokes simulation of rotor-stator interaction in an axial turbine stage are presented. The present study uses a fine grid in the spanwise direction to better resolve the complex three-dimensional flowfield, and complements earlier reported coarse-grid calculations. Several different features of the flowfield are analyzed and compared to earlier calculations and to experimental data whenever possible. Computer animation techniques are used to visualize various unsteady three-dimensional features of the flow. The results demonstrate the capabilities of current computing hardware in obtaining accurate simulations of unsteady flows in turbomachines.

  7. Turbulent transport models for scramjet flowfields

    NASA Technical Reports Server (NTRS)

    Sindir, M. M.; Harsha, P. T.

    1984-01-01

    Turbulence modeling approaches were examined from the standpoint of their capability to predict the complex flowfield features observed in scramjet combustions. Thus, for example, the accuracy of each turbulence model, with respect to the prediction of recirculating flows, was examined. It was observed that for large diameter ratio axisymmetric sudden expansion flows, a choice of turbulence model was not critical because of the domination of their flowfields by pressure forces. For low diameter ratio axisymmetric sudden expansions and planar backward-facing steps flows, where turbulent shear stresses are of greater significance, the algebraic Reynolds stress approach, modified to increase its sensitivity to streamline curvature, was found to provide the best results. Results of the study also showed that strongly swirling flows provide a stringent test of turbulence model assumptions. Thus, although flows with very high swirl are not of great practical interest, they are useful for turbulence model development. Finally, it was also noted that numerical flowfields solution techniques have a strong interrelation with turbulence models, particularly with the turbulent transport models which involve source-dominated transport equations.

  8. Experimental and computational surface and flow-field results for an all-body hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Lockman, William K.; Lawrence, Scott L.; Cleary, Joseph W.

    1990-01-01

    Personnel from NASA Ames Research Center presented a paper on establishing a benchmark experimental data base for generic hypersonic vehicle shape for validation and/or calibration of advanced computational fluid dynamics computer codes. The need for this capability is based on a requirement for extensive hypersonic data to fully validate CFD codes to be used for NASP and other hypersonic vehicles. The use of wind tunnel models in the Ames 3.5-ft Hypersonic Wind Tunnel to obtain pertinent surface and flow-field data over a broad range of test conditions is described.

  9. Comparison of vibration dissociation coupling and radiative heat transfer models for AOTV/AFE flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.; Bobskill, Glenn J.; Greendyke, Robert B.

    1988-01-01

    A series of detailed studies comparing various vibration dissociation coupling models, reaction systems and rates, and radiative heating models has been conducted for the nonequilibrium stagnation region of an AFE/AOTV vehicle. Atomic and molecular nonequilibrium radiation correction factors have been developed and applied to various absorption coefficient step models, and a modified vibration dissociation coupling model has been shown to yield good vibration/electronic temperature and concentration profiles. While results indicate sensitivity to the choice of vibration dissociation coupling model and to the nitrogen electron impact ionization rate, by proper combinations accurate flowfield and radiative heating results can be obtained. These results indicate that nonequilibrium effects significantly affect the flowfield and the radiative heat transfer. However, additional work is needed in ionization chemistry and absorption coefficient modeling.

  10. Co-Optimization of Blunt Body Shapes for Moving Vehicles

    NASA Technical Reports Server (NTRS)

    Brown, James L. (Inventor); Garcia, Joseph A (Inventor); Kinney, David J. (Inventor); Bowles, Jeffrey V (Inventor); Mansour, Nagi N (Inventor)

    2014-01-01

    A method and associated system for multi-disciplinary optimization of various parameters associated with a space vehicle that experiences aerocapture and atmospheric entry in a specified atmosphere. In one embodiment, simultaneous maximization of a ratio of landed payload to vehicle atmospheric entry mass, maximization of fluid flow distance before flow separation from vehicle, and minimization of heat transfer to the vehicle are performed with respect to vehicle surface geometric parameters, and aerostructure and aerothermal vehicle response for the vehicle moving along a specified trajectory. A Pareto Optimal set of superior performance parameters is identified.

  11. Three-dimensional turbopump flowfield analysis

    NASA Technical Reports Server (NTRS)

    Sharma, O. P.; Belford, K. A.; Ni, R. H.

    1992-01-01

    A program was conducted to develop a flow prediction method applicable to rocket turbopumps. The complex nature of a flowfield in turbopumps is described and examples of flowfields are discussed to illustrate that physics based models and analytical calculation procedures based on computational fluid dynamics (CFD) are needed to develop reliable design procedures for turbopumps. A CFD code developed at NASA ARC was used as the base code. The turbulence model and boundary conditions in the base code were modified, respectively, to: (1) compute transitional flows and account for extra rates of strain, e.g., rotation; and (2) compute surface heat transfer coefficients and allow computation through multistage turbomachines. Benchmark quality data from two and three-dimensional cascades were used to verify the code. The predictive capabilities of the present CFD code were demonstrated by computing the flow through a radial impeller and a multistage axial flow turbine. Results of the program indicate that the present code operated in a two-dimensional mode is a cost effective alternative to full three-dimensional calculations, and that it permits realistic predictions of unsteady loadings and losses for multistage machines.

  12. Flap effectiveness appraisal for winged re-entry vehicles

    NASA Astrophysics Data System (ADS)

    de Rosa, Donato; Pezzella, Giuseppe; Donelli, Raffaele S.; Viviani, Antonio

    2016-05-01

    The interactions between shock waves and boundary layer are commonplace in hypersonic aerodynamics. They represent a very challenging design issue for hypersonic vehicle. A typical example of shock wave boundary layer interaction is the flowfield past aerodynamic surfaces during control. As a consequence, such flow interaction phenomena influence both vehicle aerodynamics and aerothermodynamics. In this framework, the present research effort describes the numerical activity performed to simulate the flowfield past a deflected flap in hypersonic flowfield conditions for a winged re-entry vehicle.

  13. Nonequilibrium chemical and radiation coupling phenomena in AOTV flowfields

    NASA Technical Reports Server (NTRS)

    Carlson, Leland A.; Gally, Thomas A.

    1991-01-01

    A flowfield model for the nonequilibrium stagnation region of high altitude entry vehicles which includes nonequilibrium chemistry, multitemperature, viscous, conduction, and diffusion effects is presented. It contains coupled nongray nonequilibrium radiative transfer for atoms and molecules and local thermodynamic nonequilibrium phenomena. Comparison with Fire 2 flight data verifies that the model is reasonably accurate; and it has been applied to two AFE trajectory points, a high speed return from Mars, a series of points at 80 km for 12 to 16 km/sec, and three altitudes at 16 km/sec. Based on these results shock slip is significant, radiation cooling/coupling is minor at AFE conditions but important by 14 km/sec and dominant at 16 km/sec, radiation for the AFE is small but important and primarily molecular, above 12 km/sec atomic radiation is a significant or dominant portion of the total heating, and local thermodynamic nonequilibrium is important and should be included in all models.

  14. Support of Integrated Health Management (IHM) through Automated Analyses of Flowfield-Derived Spectrographic Data

    NASA Technical Reports Server (NTRS)

    Patrick, Marshall C.; Cooper, Anita E.; Powers, W. T.

    2003-01-01

    Flow-field analysis techniques under continuing development at NASA's Marshall Space Flight Center are the foundation for a new type of health monitoring instrumentation for propulsion systems and a vast range of other applications. Physics, spectroscopy, mechanics, optics, and cutting-edge computer sciences merge to make recent developments in such instrumentation possible. Issues encountered in adaptation of such a system to future space vehicles, or retrofit in existing hardware, are central to the work. This paper is an overview of the collaborative efforts results, current efforts, and future plans.

  15. Experimental and computational surface and flow-field results for an all-body hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Lockman, William K.; Lawrence, Scott L.; Cleary, Joseph W.

    1990-01-01

    The objective of the present investigation is to establish a benchmark experimental data base for a generic hypersonic vehicle shape for validation and/or calibration of advanced computational fluid dynamics computer codes. This paper includes results from the comprehensive test program conducted in the NASA/Ames 3.5-foot Hypersonic Wind Tunnel for a generic all-body hypersonic aircraft model. Experimental and computational results on flow visualization, surface pressures, surface convective heat transfer, and pitot-pressure flow-field surveys are presented. Comparisons of the experimental results with computational results from an upwind parabolized Navier-Stokes code developed at Ames demonstrate the capabilities of this code.

  16. Careful numerical study of flowfields about asymmetric external conical corners

    NASA Technical Reports Server (NTRS)

    Salas, M. D.

    1980-01-01

    A numerical study of the flowfield about asymmetrical external axial corners formed by the juncture of swept compressive wedges is presented. The geometrical configuration allows a unified treatment of external corners typical of delta wings and rectangular inlets. The study investigates how the flow transitions from a symmetrical flowfield with a cross-flow stagnation point at the corner to an asymmetrical flowfield for which the flow spills over the corner. The effects of leading-edge sweep, wedge compression, and corner radius are investigated.

  17. Advanced orbit transfer vehicle propulsion system study

    NASA Technical Reports Server (NTRS)

    Cathcart, J. A.; Cooper, T. W.; Corringrato, R. M.; Cronau, S. T.; Forgie, S. C.; Harder, M. J.; Mcallister, J. G.; Rudman, T. J.; Stoneback, V. W.

    1985-01-01

    A reuseable orbit transfer vehicle concept was defined and subsequent recommendations for the design criteria of an advanced LO2/LH2 engine were presented. The major characteristics of the vehicle preliminary design include a low lift to drag aerocapture capability, main propulsion system failure criteria of fail operational/fail safe, and either two main engines with an attitude control system for backup or three main engines to meet the failure criteria. A maintenance and servicing approach was also established for the advanced vehicle and engine concepts. Design tradeoff study conclusions were based on the consideration of reliability, performance, life cycle costs, and mission flexibility.

  18. Numerical Simulation of a Flap-Edge Flowfield

    NASA Technical Reports Server (NTRS)

    Streett, C. L.

    1998-01-01

    In this paper we develop an approximate computational framework for simulation of the fluctuating flowfield associated with the complex vortex system seen at the side edge of a flap in a multielement high-lift airfoil system. The eventual goal of these simulations is to provide an estimate of the spectral content of these fluctuations, in order that the spectrum of the noise generated by such flowfields may be estimated. Results from simulations utilizing this computational framework are shown.

  19. CFD analyses of coolant channel flowfields

    NASA Technical Reports Server (NTRS)

    Yagley, Jennifer A.; Feng, Jinzhang; Merkle, Charles L.

    1993-01-01

    The flowfield characteristics in rocket engine coolant channels are analyzed by means of a numerical model. The channels are characterized by large length to diameter ratios, high Reynolds numbers, and asymmetrical heating. At representative flow conditions, the channel length is approximately twice the hydraulic entrance length so that fully developed conditions would be reached for a constant property fluid. For the supercritical hydrogen that is used as the coolant, the strong property variations create significant secondary flows in the cross-plane which have a major influence on the flow and the resulting heat transfer. Comparison of constant and variable property solutions show substantial differences. In addition, the property variations prevent fully developed flow. The density variation accelerates the fluid in the channels increasing the pressure drop without an accompanying increase in heat flux. Analyses of the inlet configuration suggest that side entry from a manifold can affect the development of the velocity profile because of vortices generated as the flow enters the channel. Current work is focused on studying the effects of channel bifurcation on the flow field and the heat transfer characteristics.

  20. Flowfield characteristics of an aerodynamic acoustic levitator

    NASA Astrophysics Data System (ADS)

    Yarin, A. L.; Brenn, G.; Keller, J.; Pfaffenlehner, M.; Ryssel, E.; Tropea, C.

    1997-11-01

    A droplet held in a single-axis ultrasonic levitator will principally sustain a certain external blowing along the levitation axis, which introduces the possibility of investigating heat and/or mass transfer from the droplet under conditions which are not too remote from those in spray systems. The focus of the present work is on the influence of the acoustic field on the external flow. More specifically, an axisymmetric submerged gas jet in an axial standing acoustic wave is examined, both in the absence and presence of a liquid droplet. Flow visualization is first presented to illustrate the global flow effects and the operating windows of jet velocities and acoustic powers which are suitable for further study. An analytic and numeric solution, based on the parabolic boundary layer equations are then given for the case of no levitated droplet, providing quantitative estimates of the acoustic field/flow interaction. Detailed velocity measurements using a laser Doppler anemometer verify the analytic results and extend these to the case of a levitated droplet. Some unresolved discrepancy remains in predicting the maximum velocity attainable before the droplet is blown out of the levitator. Two methods are developed to estimate the sound pressure level in the levitator by comparing flowfield patterns with analytic results. These results and observations are used to estimate to what extent acoustic aerodynamic levitators can be used in the future for investigating transport properties of individual droplets.

  1. SparkJet characterizations in quiescent and supersonic flowfields

    NASA Astrophysics Data System (ADS)

    Emerick, T.; Ali, M. Y.; Foster, C.; Alvi, F. S.; Popkin, S.

    2014-12-01

    The aerodynamic community has studied active flow control actuators for some time, and developments have led to a wide variety of devices with various features and operating mechanisms. The design requirements for a practical actuator used for active flow control include reliable operation, requisite frequency and amplitude modulation capabilities, and a reasonable lifespan while maintaining minimal cost and design complexity. An active flow control device called the SparkJet actuator has been developed for high-speed flight control and incorporates no mechanical/moving parts, zero net mass flux capabilities and the ability to tune the operating frequency and momentum throughput. This actuator utilizes electrical power to deliver high-momentum flow with a very fast response time. The SparkJet actuator was characterized on the benchtop using a laser-based microschlieren visualization technique and maximum blast wave and jet front velocities of ~400 and ~310 m/s were, respectively, measured in the flowfield. An increase in jet front velocity from 240 to 310 m/s during subatmospheric (60 kPa) testing reveals that the actuator may have greater control authority at lower ambient pressures, which correspond to high-altitude flight conditions for air vehicles. A SparkJet array was integrated into a flat plate and tested in a Mach 1.5 crossflow. Phase-conditioned shadowgraph results revealed a maximum flow deflection angle of 5° created by the SparkJet 275 µs after the actuator was triggered in single-shot mode. Burst mode operation of frequencies up to 700 Hz revealed similar results during wind tunnel testing. Following these tests, the actuator trigger mechanism was improved and the ability of the actuator to be discharged in burst mode at a frequency of 1 kHz was achieved.

  2. Aerocapture Guidance and Performance at Mars for High-Mass Systems

    NASA Technical Reports Server (NTRS)

    Zumwalt, Carlie H.; Sostaric, Ronald r.; Westhelle, Carlos H.; Cianciolo, Alicia Dwyer

    2010-01-01

    The objective of this study is to understand the performance associated with using the aerocapture maneuver to slow high-mass systems from an Earth-approach trajectory into orbit around Mars. This work is done in conjunction with the Mars Entry Descent and Landing Systems Analysis (EDL-SA) task to explore candidate technologies necessary for development in order to land large-scale payloads on the surface of Mars. Among the technologies considered include hypersonic inflatable aerodynamic decelerators (HIADs) and rigid mid-lift to drag (L/D) aeroshells. Nominal aerocapture trajectories were developed for the mid-L/D aeroshell and two sizes of HIADs, and Monte Carlo analysis was completed to understand sensitivities to dispersions. Additionally, a study was completed in order to determine the size of the larger of the two HIADs which would maintain design constraints on peak heat rate and diameter. Results show that each of the three aeroshell designs studied is a viable option for landing high-mass payloads as none of the three exceed performance requirements.

  3. Preliminary Convective-Radiative Heating Environments for a Neptune Aerocapture Mission

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Wright, Michael J.; Olejniczak, Joseph; Takashima, Naruhisa; Sutton, Kenneth; Prabhu, Dinesh

    2004-01-01

    Convective and radiative heating environments have been computed for a three-dimensional ellipsled configuration which would perform an aerocapture maneuver at Neptune. This work was performed as part of a one-year Neptune aerocapture spacecraft systems study that also included analyses of trajectories, atmospheric modeling, aerodynamics, structural design, and other disciplines. Complementary heating analyses were conducted by separate teams using independent sets of aerothermodynamic modeling tools (i.e. Navier-Stokes and radiation transport codes). Environments were generated for a large 5.50 m length ellipsled and a small 2.88 m length ellipsled. Radiative heating was found to contribute up to 80% of the total heating rate at the ellipsled nose depending on the trajectory point. Good agreement between convective heating predictions from the two Navier-Stokes solvers was obtained. However, the radiation analysis revealed several uncertainties in the computational models employed in both sets of codes, as well as large differences between the predicted radiative heating rates.

  4. Numerical Analysis of Base Flowfield for a Four-Engine Clustered Nozzle Configuration

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See

    1995-01-01

    Excessive base heating has been a problem for many launch vehicles. For certain designs such as the direct dump of turbine exhaust inside and at the lip of the nozzle, the potential burning of the turbine exhaust in the base region can be of great concern. Accurate prediction of the base environment at altitudes is therefore very important during the vehicle design phase. Otherwise, undesirable consequences may occur. In this study, the turbulent base flowfield of a cold flow experimental investigation for a four-engine clustered nozzle was numerically benchmarked using a pressure-based computational fluid dynamics (CFD) method. This is a necessary step before the benchmarking of hot flow and combustion flow tests can be considered. Since the medium was unheated air, reasonable prediction of the base pressure distribution at high altitude was the main goal. Several physical phenomena pertaining to the multiengine clustered nozzle base flow physics were deduced from the analysis.

  5. Shock Tunnel Studies of the Hypersonic Flowfield around the Hypervelocity Ballistic Models with Aerospikes

    NASA Astrophysics Data System (ADS)

    Balakalyani, G.; Saravanan, S.; Jagadeesh, G.

    Reduced drag and aerodynamic heating are the two basic design requirements for any hypersonic vehicle [1]. The flowfield around an axisymmetric blunt body is characterized by a bow shockwave standing ahead of its nose. The pressure and temperature behind this shock wave are very high. This increased pressure and temperature are responsible for the high levels of drag and aerodynamic heating over the body. In the past, there have been many investigations on the use of aerospikes as a drag reduction tool. These studies on spiked bodies aim at reducing both the drag and aerodynamic heating by modifying the hypersonic flowfield ahead of the nose of the body [2]. However, most of them used very simple configurations to experimentally study the drag reduction using spikes at hypersonic speeds [3] and therefore very little experimental data is available for a realistic geometric configuration. In the present study, the standard AGARD Hypervelocity Ballistic model 1 is used as the test model. The addition of the spike to the blunt body significantly alters the flowfield ahead of the nose, leading to the formation of a low pressure conical recirculation region, thus causing a reduction in drag and wall heat flux [4]. In the present investigation, aerodynamic drag force is measured over the Hypervelocity Ballistic model-1, with and without spike, at a flow enthalpy of 1.7 MJ/kg. The experiments are carried out at a Mach number of 8 and at zero angle of attack. An internally mountable accelerometer based 3-component force balance system is used to measure the aerodynamic forces on the model. Also computational studies are carried out to complement the experiments.

  6. Laser diagnostics for flowfields, combustion, and MHD applications

    SciTech Connect

    Lederman, S.; Sacks, S.

    1984-02-01

    Among the most extensively investigated light scattering processes considered for the analysis of flowfields, combustion systems and MHD phenomena have been such elastic scattering types as the Rayleigh and Mie, and inelastic scattering processes such as Raman, near-resonant Raman, and fluorescence. Additional techniques for combustion and flowfield diagnostics are the absorption optical processes of coherent anti-Stokes Raman and stimulated Raman scattering. The Mie scattering phenomenon has been used in laser Doppler velocimetry, and can provide nonintrusive measurements of velocity, turbulent intensity, and particle size distribution in flowfields. It is noted that the equivalent scattering cross section of coherent anti-Stokes Raman spectroscopy, in conjunction with the coherence of the radiation, yields signals 5-6 order of magnitude higher than the spontaneous Raman effect.

  7. Investigations of flowfields found in typical combustor geometries

    NASA Technical Reports Server (NTRS)

    Lilley, D. G.

    1982-01-01

    Measurements and computations are being applied to an axisymmetric swirling flow, emerging from swirl vanes at angle phi, entering a large chamber test section via a sudden expansion of various side-wall angles alpha. New features are: the turbulence measurements are being performed on swirling as well as nonswirling flow; and all measurements and computations are also being performed on a confined jet flowfield with realistic downstream blockage. Recent activity falls into three categories: (1) Time-mean flowfield characterization by five-hole pitot probe measurements and by flow visualization; (2) Turbulence measurements by a variety of single- and multi-wire hot-wire probe techniques; and (3) Flowfield computations using the computer code developed during the previous year's research program.

  8. Post-aerocapture orbit selection and maintenance for the Aerofast mission to Mars

    NASA Astrophysics Data System (ADS)

    Pontani, Mauro; Teofilatto, Paolo

    2012-10-01

    Aerofast is the abbreviation of “aerocapture for future space transportation” and represents a project aimed at developing aerocapture techniques with regard to an interplanetary mission to Mars, in the context of the 7th Framework Program, with the financial support of the European Union. This paper describes the fundamental characteristics of the operational orbit after aerocapture for the mission of interest, as well as the related maintenance strategy. The final orbit selection depends on the desired lighting conditions, maximum revisit time of specific target regions, and feasibility of the orbit maintenance strategy. A sunsynchronous, frozen, repeating-ground-track orbit is chosen. First, the period of repetition is such that adjacent ascending node crossings (over the Mars surface) have a separation compatible with the swath of the optical payload. Secondly, the sunsynchronism condition ensures that a given latitude is periodically visited at the same local time, which condition is essential for comparing images of the same region at different epochs. Lastly, the fulfillment of the frozen condition guarantees improved orbit stability with respect to perturbations due to the zonal harmonics of Mars gravitational field. These three fundamental features of the operational orbit lead to determining its mean orbital elements. The evaluation of short and long period effects (e.g., those due to the sectorial harmonics of the gravitational field or to the aerodynamic drag) requires the determination of the osculating orbital elements at an initial reference time. This research describes a simple and accurate approach that leads to numerically determining these initial values, without employing complicated analytical developments. Numerical simulations demonstrate the long-period stability of the orbit when a significant number of harmonics of the gravitational field are taken into account. However, aerodynamic drag produces a relatively slow orbital decay at the

  9. A Comparison of Computed and Experimental Flowfields of the RAH-66 Helicopter

    NASA Technical Reports Server (NTRS)

    vanDam, C. P.; Budge, A. M.; Duque, E. P. N.

    1996-01-01

    This paper compares and evaluates numerical and experimental flowfields of the RAH-66 Comanche helicopter. The numerical predictions were obtained by solving the Thin-Layer Navier-Stokes equations. The computations use actuator disks to investigate the main and tail rotor effects upon the fuselage flowfield. The wind tunnel experiment was performed in the 14 x 22 foot facility located at NASA Langley. A suite of flow conditions, rotor thrusts and fuselage-rotor-tail configurations were tested. In addition, the tunnel model and the computational geometry were based upon the same CAD definition. Computations were performed for an isolated fuselage configuration and for a rotor on configuration. Comparisons between the measured and computed surface pressures show areas of correlation and some discrepancies. Local areas of poor computational grid-quality and local areas of geometry differences account for the differences. These calculations demonstrate the use of advanced computational fluid dynamic methodologies towards a flight vehicle currently under development. It serves as an important verification for future computed results.

  10. Investigations of flowfields found in typical combustor geometries

    NASA Technical Reports Server (NTRS)

    Lilley, D. G.; Mclaughlin, D. K.

    1981-01-01

    The flowfields of gas turbine combustion chambers were investigated. Six flowfield configurations with sidewall angles alpha = 90 and 45 deg. and swirl vane angles phi = 0, 45 and 70 deg. are characterized. Photography of neutrally-buoyant helium-filled soap bubbles, tufts, and injected smoke helps to characterize the time-mean streamlines, recirculation zones and regions of highly turbulent flow. Five-hole pitot probe pressure measurements allow the determination of time-mean velocities u, v and w. An advanced computer code equipped with a standard two-equation kappa-epsilon turbulence model was used to predict corresponding flow situations and to compare results with the experimental data.

  11. Gas composition measurements in arc heated flowfields via mass spectrometry

    NASA Astrophysics Data System (ADS)

    Willey, Ronald J.; Blake, David J.

    1991-06-01

    Gas compositions for an arc heated flowfield were determined by mass spectrometry on gas samples drawn from the flowfield through a sample probe. Surveys were made across the freestream flow using sample probes made of copper and quartz. Oxygen atoms reaching the mass spectrometer ranged from 6 to 9.4 percent and was a direct function of arc heater current and resultant stream enthalpy. Likewise, mole percents of nitrogen atoms ranged from 13.5 to 19 for total enthalpies of 7.0 to 18.4 MJ/kg. Species gradients existed in both the radial and axial directions. Atomic concentrations were highest near the centerline and at the nozzle exit. A species survey was completed around a shock that was established by a copper blunt body placed in the flowfield. The results showed strong species gradients following the shock edge, with atom mole fractions highest along the shock edge. Overall, the results provide insight into gas composition by point measurements in arc heated flowfields. The results suggest that nitrogen may begin dissociating before all of the oxygen dissociates, and that past assumptions based on frozen chemistry models may be faulty.

  12. Validation of two-equation turbulence models for propulsion flowfields

    NASA Technical Reports Server (NTRS)

    Deshpande, Manish; Venkateswaran, S.; Merkle, Charles L.

    1994-01-01

    The objective of the study is to assess the capability of two-equation turbulence models for simulating propulsion-related flowfields. The standard kappa-epsilon model with Chien's low Reynolds number formulation for near-wall effects is used as the baseline turbulence model. Several experimental test cases, representative of rocket combustor internal flowfields, are used to catalog the performance of the baseline model. Specific flowfields considered here include recirculating flow behind a backstep, mixing between coaxial jets and planar shear layers. Since turbulence solutions are notoriously dependent on grid and numerical methodology, the effects of grid refinement and artificial dissipation on numerical accuracy are studied. In the latter instance, computational results obtained with several central-differenced and upwind-based formulations are compared. Based on these results, improved turbulence modes such as enhanced kappa-epsilon models as well as other two-equation formulations (e.g., kappa-omega) are being studied. In addition, validation of swirling and reacting flowfields are also currently underway.

  13. Experimental Characterization of Gas/Gas Injector Flowfields

    NASA Technical Reports Server (NTRS)

    Marshall, William M.; Cramer, John M.; Pal, Sibtosh; Santoro, Robert J.; Turner, Jim (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on activities pertaining to the experimental characterization of gas/gas injector flowfields. An experimental testbed for uni-element gas/gas injector studies at realistic conditions has been fabricated and verified. Experiments for characterizing mixing/combustion of gas/gas injectors with raman spectroscopy have been initiated.

  14. Aeroassisted-vehicle design studies for a manned Mars mission

    NASA Technical Reports Server (NTRS)

    Menees, Gene P.

    1987-01-01

    An aerobrake design that has matured over several years of development accounting for all of the important flow phenomenology which are characteristic of aerobraking vehicles is proposed as the mission baseline. Flight regimes and aerothermal environments for both Mars and Earth entry are calculated using advanced methods to account for real-gas, thermochemical, relaxation effects. The results are correlated with thermal-protection and structural requirements and mission performance capability. The importance of nonequilibrium radiative heating for Earth aerocapture is demonstrated. It is suggested that two aerobrakes of different sizes will produce optimal performance for the three phases of the mission (i.e., one aerobrake for Mars aerocapture and descent of the surface lander and another for Earth return).

  15. Liquid Booster Module (LBM) plume flowfield model

    NASA Technical Reports Server (NTRS)

    Smith, S. D.

    1981-01-01

    A complete definition of the LBM plume is important for many Shuttle design criteria. The exhaust plume shape has a significant effect on the vehicle base pressure. The LBM definition is also important to the Shuttle base heating, aerodynamics and the influence of the exhaust plume on the launch stand and environment. For these reasons a knowledge of the LBM plume characteristics is necessary. A definition of the sea level LBM plume as well as at several points along the Shuttle trajectory to LBM, burnout is presented.

  16. Aerodynamic Performance and Flow-Field Characteristics of Two Waverider-Derived Hypersonic Cruise Configurations

    NASA Technical Reports Server (NTRS)

    Cockrell, Charles E., Jr.; Huebner, Lawrence D.; Finley, Dennis B.

    1995-01-01

    The component integration of a class of hypersonic high-lift configurations known as waveriders into hypersonic cruise vehicles was evaluated. A wind-tunnel model was developed which integrates realistic vehicle components with two waverider shapes, referred to as the straight-wing and cranked-wing shapes. Both shapes were conical-flow-derived waveriders for a design Mach number of 4.0. Experimental data and limited computational fluid dynamics (CFD) predictions were obtained over a Mach number range of 1.6 to 4.63 at a Reynolds number of 2.0 x 10(exp 6) per foot. The CFD predictions and flow visualization data confirmed the shock attachment characteristics of the baseline waverider shapes and illustrated the waverider flow-field properties. Experimental data showed that no significant performance degradations, in terms of maximum lift-to-drag ratios, occur at off-design Mach numbers for the waverider shapes and the integrated configurations. A comparison of the fully-integrated waverider vehicles to the baseline shapes showed that the performance was significantly degraded when all of the components were added to the waveriders, with the most significant degradation resulting from aftbody closure and the addition of control surfaces. Both fully-integrated configurations were longitudinally unstable over the Mach number range studied with the selected center of gravity location and for unpowered conditions. The cranked-wing configuration provided better lateral-directional stability characteristics than the straight-wing configuration.

  17. Experimental Flow Models for SSME Flowfield Characterization

    NASA Technical Reports Server (NTRS)

    Abel, L. C.; Ramsey, P. E.

    1989-01-01

    Full scale flow models with extensive instrumentation were designed and manufactured to provide data necessary for flow field characterization in rocket engines of the Space Shuttle Main Engine (SSME) type. These models include accurate flow path geometries from the pre-burner outlet through the throat of the main combustion chamber. The turbines are simulated with static models designed to provide the correct pressure drop and swirl for specific power levels. The correct turbopump-hot gas manifold interfaces were designed into the flow models to permit parametric/integration studies for new turbine designs. These experimental flow models provide a vehicle for understanding the fluid dynamics associated with specific engine issues and also fill the more general need for establishing a more detailed fluid dynamic base to support development and verification of advanced math models.

  18. Application of OVERFLOW to Hypersonic Perfect Gas Flowfields

    NASA Technical Reports Server (NTRS)

    Olsen, M. E.; Prabhu, D. K.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    A validation of the matrix dissipation option in OVERFLOW was completed, and a single set of constants was found which yield good inviscid shock capturing, viscous heat and skin friction predictions, and work over a wide Mach and Reynolds number range. This scheme works well with multigrid, and produces fast convergence to steady state for 2 and 3 dimensional problems, with accuracy comparable to Roe upwinding, and without 'carbuncle' problems for the blunt body flowfields.

  19. Flowfield Characterization in a LOX/GH2 Propellant Rocket

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    The objective of the current work is to experimentally characterize the flowfield associated with an uni-element shear coaxial injector burning liquid oxygen/gaseous hydrogen (LOX/GH2) propellants. These experiments were carried out in an optically-accessible rocket chamber operating at a high pressure (approximately 400 psia). Quantitative measurements of drop size and velocity were obtained along with qualitative measurements of the disintegrating jet.

  20. Unified CFD Methods Via Flowfield-Dependent Variation Theory

    NASA Technical Reports Server (NTRS)

    Chung, T. J.; Schunk, Greg; Canabal, Francisco; Heard, Gary

    1999-01-01

    This paper addresses the flowfield-dependent variation (FDV) methods in which complex physical phenomena are taken into account in the final form of partial differential equations to be solved so that finite difference methods (FDM) or finite element methods (FEM) themselves will not dictate the physics, but rather are no more than simply the options how to discretize between adjacent nodal points or within an element. The variation parameters introduced in the formulation are calculated from the current flowfield based on changes of Mach numbers, Reynolds numbers, Peclet numbers, and Damkohler numbers between adjacent nodal points, which play many significant roles such as adjusting the governing equations (hyperbolic, parabolic, and/or e!liptic), resolving various physical phenomena, and controlling the accuracy and stability of the numerical solution. The theory is verified by a number of example problems addressing the physical implications of the variation parameters which resemble the flowfield itself, shock capturing mechanism, transitions and interactions between inviscid/viscous, compressibility/incompressibility, and laminar/turbulent flows.

  1. Investigation of flowfields found in typical combustor geometries

    NASA Technical Reports Server (NTRS)

    Lilley, D. G.

    1985-01-01

    Activities undertaken during the entire course of research are summarized. Studies were concerned with experimental and theoretical research on 2-D axisymmetric geometries under low speed nonreacting, turbulent, swirling flow conditions typical of gas turbine and ramjet combustion chambers. They included recirculation zone characterization, time-mean and turbulence simulation in swirling recirculating flow, sudden and gradual expansion flowfields, and furher complexities and parameter influences. The study included the investigation of: a complete range of swirl strengths; swirler performance; downstream contraction nozzle sizes and locations; expansion ratios; and inlet side-wall angles. Their individual and combined effects on the test section flowfield were observed, measured and characterized. Experimental methods included flow visualization (with smoke and neutrally-buoyant helium-filled soap bubbles), five-hole pitot probe time-mean velocity field measurements, and single-, double-, and triple-wire hot-wire anemometry measurements of time-mean velocities, normal and shear Reynolds sresses. Computational methods included development of the STARPIC code from the primitive-variable TEACH computer code, and its use in flowfield prediction and turbulence model development.

  2. Testing of Flexible Ballutes in Hypersonic Wind Tunnels for Planetary Aerocapture

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.

    2007-01-01

    Studies were conducted for the In-Space Propulsion (ISP) Ultralightweight Ballute Technology Development Program to increase the technical readiness level of inflatable decelerator systems for planetary aerocapture. The present experimental study was conducted to develop the capability for testing lightweight, flexible materials in hypersonic facilities. The primary objectives were to evaluate advanced polymer film materials in a high-temperature, high-speed flow environment and provide experimental data for comparisons with fluid-structure interaction modeling tools. Experimental testing was conducted in the Langley Aerothermodynamics Laboratory 20-Inch Hypersonic CF4 and 31-Inch Mach 10 Air blowdown wind tunnels. Quantitative flexure measurements were made for 60 degree half angle afterbody-attached ballutes, in which polyimide films (1-mil and 3- mil thick) were clamped between a 1/2-inch diameter disk and a base ring (4-inch and 6-inch diameters). Deflection measurements were made using a parallel light silhouette of the film surface through an existing schlieren optical system. The purpose of this paper is to discuss these results as well as free-flying testing techniques being developed for both an afterbody-attached and trailing toroidal ballute configuration to determine dynamic fluid-structural stability. Methods for measuring polymer film temperature were also explored using both temperature sensitive paints (for up to 370 C) and laser-etched thin-film gages.

  3. Testing of Flexible Ballutes in Hypersonic Wind Tunnels for Planetary Aerocapture

    NASA Technical Reports Server (NTRS)

    Buck, Gregory M.

    2006-01-01

    Studies were conducted for the In-Space Propulsion (ISP) Ultralightweight Ballute Technology Development Program to increase the technical readiness level of inflatable decelerator systems for planetary aerocapture. The present experimental study was conducted to develop the capability for testing lightweight, flexible materials in hypersonic facilities. The primary objectives were to evaluate advanced polymer film materials in a high-temperature, high-speed flow environment and provide experimental data for comparisons with fluid-structure interaction modeling tools. Experimental testing was conducted in the Langley Aerothermodynamics Laboratory 20-Inch Hypersonic CF4 and 31-Inch Mach 10 Air blowdown wind tunnels. Quantitative flexure measurements were made for 60 degree half angle afterbody-attached ballutes, in which polyimide films (1-mil and 3-mil thick) were clamped between a 1/2-inch diameter disk and a base ring (4-inch and 6-inch diameters). Deflection measurements were made using a parallel light silhouette of the film surface through an existing schlieren optical system. The purpose of this paper is to discuss these results as well as free-flying testing techniques being developed for both an afterbody-attached and trailing toroidal ballute configuration to determine dynamic fluid-structural stability. Methods for measuring polymer film temperature were also explored using both temperature sensitive paints (for up to 370 C) and laser-etched thin-film gages.

  4. Aerocapture and aeroassisted orbital transfer - A high performance leverage space technology

    NASA Technical Reports Server (NTRS)

    Cruz, M. I.

    1983-01-01

    Single pass aerocapture and aeroassisted orbital transfer designs are discussed for modifying spacecraft orbits using planetary atmospheres. Aerodynamic drag can be used to shift a hyperbolic flyby trajectory to a planetary orbit by having the spacecraft altering its in-plane L/D ratio to maintain constant drag until the desired velocity is attained. The spacecraft would then move out of the atmosphere, sometimes with a small propulsive assist. Sample missions to Uranus, Jupiter, and Titan are mentioned, with mission scenarios commencing with a Shuttle launch. Biconic-shaped spacecraft are cited as having the best L/D for insertion accuracy, a low hypersonic ballistic coefficient, and volumeric efficiency. Aeroassisted orbital transfer involves atmospheric braking in order to shed velocity on a return trip from higher orbits. No decision has yet been made as to the spacecraft shape, but calculations indicate that aeroassist braking before return to LEO for rendezvous with the Shuttle has the potential for the lowest cost/mass to GEO of any delivery system currently under consideration.

  5. Trajectory Guidance for Mars Robotic Precursors: Aerocapture, Entry, Descent, and Landing

    NASA Technical Reports Server (NTRS)

    Sostaric, Ronald R.; Zumwalt, Carlie; Garcia-Llama, Eduardo; Powell, Richard; Shidner, Jeremy

    2011-01-01

    Future crewed missions to Mars require improvements in landed mass capability beyond that which is possible using state-of-the-art Mars Entry, Descent, and Landing (EDL) systems. Current systems are capable of an estimated maximum landed mass of 1-1.5 metric tons (MT), while human Mars studies require 20-40 MT. A set of technologies were investigated by the EDL Systems Analysis (SA) project to assess the performance of candidate EDL architectures. A single architecture was selected for the design of a robotic precursor mission, entitled Exploration Feed Forward (EFF), whose objective is to demonstrate these technologies. In particular, inflatable aerodynamic decelerators (IADs) and supersonic retro-propulsion (SRP) have been shown to have the greatest mass benefit and extensibility to future exploration missions. In order to evaluate these technologies and develop the mission, candidate guidance algorithms have been coded into the simulation for the purposes of studying system performance. These guidance algorithms include aerocapture, entry, and powered descent. The performance of the algorithms for each of these phases in the presence of dispersions has been assessed using a Monte Carlo technique.

  6. Numerical Roll Reversal Predictor Corrector Aerocapture and Precision Landing Guidance Algorithms for the Mars Surveyor Program 2001 Missions

    NASA Technical Reports Server (NTRS)

    Powell, Richard W.

    1998-01-01

    This paper describes the development and evaluation of a numerical roll reversal predictor-corrector guidance algorithm for the atmospheric flight portion of the Mars Surveyor Program 2001 Orbiter and Lander missions. The Lander mission utilizes direct entry and has a demanding requirement to deploy its parachute within 10 km of the target deployment point. The Orbiter mission utilizes aerocapture to achieve a precise captured orbit with a single atmospheric pass. Detailed descriptions of these predictor-corrector algorithms are given. Also, results of three and six degree-of-freedom Monte Carlo simulations which include navigation, aerodynamics, mass properties and atmospheric density uncertainties are presented.

  7. Global Flowfield About the V-22 Tiltrotor Aircraft

    NASA Technical Reports Server (NTRS)

    Meakin, Robert L.

    1996-01-01

    This final report includes five publications that resulted from the studies of the global flowfield about the V-22 Tiltrotor Aircraft. The first of the five is 'The Chimera Method of Simulation for Unsteady Three-Dimensional Viscous Flow', as presented in 'Computational Fluid Dynamics Review 1995.' The remaining papers, all presented at AIAA conferences, are 'Unsteady Simulation of the Viscous Flow About a V-22 Rotor and Wing in Hover', 'An Efficient Means of Adaptive Refinement Within Systems of Overset Grids', 'On the Spatial and Temporal Accuracy of Overset Grid Methods for MOving Body Problems', and 'Moving Body Overset Grid Methods for Complete Aircraft Tiltrotor Simulations.'

  8. Flowfield in the plane of symmetry below a delta wing

    NASA Technical Reports Server (NTRS)

    Cramer, M. S.; George, A. R.; Seebass, A. R.

    1976-01-01

    The flowfield in the plane of symmetry of a thin lifting delta wing with supersonic leading edges is examined for wings with apex angles that are comparable to the Mach angle, as well as for the limiting case of a straight leading edge. For these two cases, a simplified treatment of the interaction between the plane expansion wave emanating from the trailing edge and the three-dimensional bow shock is presented. In the region unaffected by the wing tips, the shock decays inversely with distance from the wing.

  9. Computation of reacting flowfield with radiation interaction in chemical lasers

    SciTech Connect

    Quan, V.; Persselin, S.F.; Yang, T.T.

    1982-01-01

    A numerical procedure has been developed to provide a rapid and stable solution of the reacting and radiating flowfield in chemical laser cavities. A marching technique, implicit in both fluid mechanics and chemistry, is employed in solving the two-dimensional mixing layer equations. The aerokinetics and radiation interaction is calculated iteratively by solving the aerokinetic equations for the gain distribution and the propagation equations for the radiation field. In the iterative solution, a linearization method which leads to enhanced numerical efficiency is employed.

  10. Planar Imaging of Mach 3 Hypermixer Flowfields with Varying Geometry

    NASA Astrophysics Data System (ADS)

    Burns, Ross; Clemens, Noel

    2012-11-01

    At the high Mach number associated with hypersonic flight, potentially excessive pressure loads and changes in air chemistry necessitate supersonic flow within a scramjet combustor. A form of mixing enhancement is therefore required to enable proper mixing of the fuel and air streams and maintain efficient combustion. Hypermixers have shown promise as an effective mixing enhancement strategy, utilizing streamwise vorticity to enhance large scale transport and micromixing rather than relying solely on turbulence. An experimental investigation of several strut-based Mach 3 hypermixing flowfields is being conducted, concentrating on the effect of geometric variations (ramp angle and spacing) on the flowfield mixing characteristics. Global flow features are examined through the use of planar laser scattering (PLS) and two-component particle image velocimetry (PIV). The evolution of streamwise vortical structures is observed at different streamwise locations using stereoscopic PIV. Finally, the interaction of these vorticies with an injected scalar is studied by combining the use of two- and three-component PIV with planar laser-induced fluorescence (PLIF). This work was supported by NASA Fundamental Aeronautics Program.

  11. Analysis of supersonic plug nozzle flowfield and heat transfer

    NASA Technical Reports Server (NTRS)

    Murthy, S. N. B.; Sheu, W. H.

    1988-01-01

    A number of problems pertaining to the flowfield in a plug nozzle, designed as a supersonic thruster nozzle, with provision for cooling the plug with a coolant stream admitted parallel to the plug wall surface, were studied. First, an analysis was performed of the inviscid, nonturbulent, gas dynamic interaction between the primary hot stream and the secondary coolant stream. A numerical prediction code for establishing the resulting flowfield with a dividing surface between the two streams, for various combinations of stagnation and static properties of the two streams, was utilized for illustrating the nature of interactions. Secondly, skin friction coefficient, heat transfer coefficient and heat flux to the plug wall were analyzed under smooth flow conditions (without shocks or separation) for various coolant flow conditions. A numerical code was suitably modified and utilized for the determination of heat transfer parameters in a number of cases for which data are available. Thirdly, an analysis was initiated for modeling turbulence processes in transonic shock-boundary layer interaction without the appearance of flow separation.

  12. Flowfield and acoustic characteristics of telescope cavity in SOFIA platform

    NASA Technical Reports Server (NTRS)

    Srinivasan, G. R.

    1995-01-01

    Unsteady three-dimensional flowfields are calculated for the Stratospheric Observatory For Infrared Astronomy (SOFIA) at both free-flight cruise and wind tunnel conditions with a view to help in the design process of an acoustically quiet telescope cavity and to understand the flow physics of a three dimensional cavity. The calculation method is based on the numerical solution of thin layer Navier-Stokes equations on a Chimera overset grid system. The Boeing 747-200 aircraft is examined as one option for the SOFIA platform. The flowfield domain is composed of 45 grids consisting of over 4.1 million points. Numerical simulations are performed for both wind tunnel and free-flight cruise conditions at one freestream condition of M(infinity) = 0.85, alpha = 2.5 deg. Comparison of results from wind tunnel simulation show good agreement with experimental data for time-averaged surface pressures, drag for the empennage, and sound pressure levels and power spectra at various locations within the cavity and on the telescope. The presence of the open cavity induces an incremental drag increase, an increased acoustic radiation, and an increase in unsteady pressure loads on the telescope. Its impact on the effectiveness of aircraft control surfaces appears minimal.

  13. Fuel cell with metal screen flow-field

    DOEpatents

    Wilson, M.S.; Zawodzinski, C.

    1998-08-25

    A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field there between for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells. 11 figs.

  14. Fuel cell with metal screen flow-field

    DOEpatents

    Wilson, Mahlon S.; Zawodzinski, Christine

    2001-01-01

    A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field therebetween for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells.

  15. Fuel cell with metal screen flow-field

    DOEpatents

    Wilson, Mahlon S.; Zawodzinski, Christine

    1998-01-01

    A polymer electrolyte membrane (PEM) fuel cell is provided with electrodes supplied with a reactant on each side of a catalyzed membrane assembly (CMA). The fuel cell includes a metal mesh defining a rectangular flow-field pattern having an inlet at a first corner and an outlet at a second corner located on a diagonal from the first corner, wherein all flow paths from the inlet to the outlet through the square flow field pattern are equivalent to uniformly distribute the reactant over the CMA. In a preferred form of metal mesh, a square weave screen forms the flow-field pattern. In a particular characterization of the present invention, a bipolar plate electrically connects adjacent fuel cells, where the bipolar plate includes a thin metal foil having an anode side and a cathode side; a first metal mesh on the anode side of the thin metal foil; and a second metal mesh on the cathode side of the thin metal foil. In another characterization of the present invention, a cooling plate assembly cools adjacent fuel cells, where the cooling plate assembly includes an anode electrode and a cathode electrode formed of thin conducting foils; and a metal mesh flow field therebetween for distributing cooling water flow over the electrodes to remove heat generated by the fuel cells.

  16. Flowfield Measurements Inside a Boundary-Layer Bleed Slot

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Willis, B. P.; Hingst, W. R.

    1996-01-01

    An experimental investigation was conducted to determine the flowfield inside a bleed slot used to control an oblique shock-wave and turbulent boundary-layer interaction. The slot was oriented normal to the primary flow direction and had a width of 1.0 cm (primary flow direction) and a length of 2.54 cm and spanned 16.5 cm. The approach boundary layer upstream of the interaction was nominally 3.0 cm thick. Two operating conditions were studied: M = 1.98 with a shock generator deflection angle of 6 deg and M = 2.46 with a shock generator deflection angle of 8 deg. Measurements include surface and flowfield static pressure, pitot pressure, and total mass flow through the slot. The results show that despite an initially two-dimensional interaction for the zero-bleed-flow case, the slot does not remove mass uniformly in the spanwise direction. Inside the slot, the flow is characterized bv two separation regions, which significantly reduce the effective flow area. The upper separation region acts as an aerodynamic throat, resulting in supersonic flow through much of the slot.

  17. Effects of Canard on the Flowfield over a Wing

    NASA Astrophysics Data System (ADS)

    Nayebzadeh, Arash

    2015-11-01

    Surface and flowfield pressure measurements have been done over delta wing/canard configuration in a variety of canard vertical and horizontal locations and angles of attack. The experimental model consisted of wing, canard and a body to accommodate pressure tubing and canard rotation mechanism. All the tests have been performed at subsonic velocities and the effect of canard were analyzed through comparison between surface and flowfield pressure distributions. It was found that vortex flow pattern over the wing is dominated mainly by canard vertical position and in some cases, by merging of canard and wing vortices. In addition, the pressure loss induced by canard vortex on the wing surface moves the wing vortex toward the leading edge. In the mid canard configuration, canard and wing vortices merge at x/c greater than 0.5 and as a result of this phenomenon, abrupt pressure loss induces more stable vortex flow over the wing. It is also shown that canard plays a vital role in vortex break down over the wing.

  18. Nonequilibrium radiative heating prediction method for aeroassist flowfields with coupling to flowfield solvers. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Hartung, Lin C.

    1991-01-01

    A method for predicting radiation adsorption and emission coefficients in thermochemical nonequilibrium flows is developed. The method is called the Langley optimized radiative nonequilibrium code (LORAN). It applies the smeared band approximation for molecular radiation to produce moderately detailed results and is intended to fill the gap between detailed but costly prediction methods and very fast but highly approximate methods. The optimization of the method to provide efficient solutions allowing coupling to flowfield solvers is discussed. Representative results are obtained and compared to previous nonequilibrium radiation methods, as well as to ground- and flight-measured data. Reasonable agreement is found in all cases. A multidimensional radiative transport method is also developed for axisymmetric flows. Its predictions for wall radiative flux are 20 to 25 percent lower than those of the tangent slab transport method, as expected, though additional investigation of the symmetry and outflow boundary conditions is indicated. The method was applied to the peak heating condition of the aeroassist flight experiment (AFE) trajectory, with results comparable to predictions from other methods. The LORAN method was also applied in conjunction with the computational fluid dynamics (CFD) code LAURA to study the sensitivity of the radiative heating prediction to various models used in nonequilibrium CFD. This study suggests that radiation measurements can provide diagnostic information about the detailed processes occurring in a nonequilibrium flowfield because radiation phenomena are very sensitive to these processes.

  19. Numerical Analysis of the Trailblazer Inlet Flowfield for Hypersonic Mach Numbers

    NASA Technical Reports Server (NTRS)

    Steffen, C. J., Jr.; DeBonis, J. R.

    1999-01-01

    A study of the Trailblazer vehicle inlet was conducted using the Global Air Sampling Program (GASP) code for flight Mach numbers ranging from 4-12. Both perfect gas and finite rate chemical analysis were performed with the intention of making detailed comparisons between the two results. Inlet performance was assessed using total pressure recovery and kinetic energy efficiency. These assessments were based upon a one-dimensional stream-thrust-average of the axisymmetric flowfield. Flow visualization utilized to examine the detailed shock structures internal to this mixed-compression inlet. Kinetic energy efficiency appeared to be the least sensitive to differences between the perfect gas and finite rate chemistry results. Total pressure recovery appeared to be the most sensitive discriminator between the perfect gas and finite rate chemistry results for flight Mach numbers above Mach 6. Adiabatic wall temperature was consistently overpredicted by the perfect gas model for flight Mach numbers above Mach 4. The predicted shock structures were noticeably different for Mach numbers from 6-12. At Mach 4, the perfect gas and finite rate chemistry models collapse to the same result.

  20. On computations of the integrated space shuttle flowfield using overset grids

    NASA Technical Reports Server (NTRS)

    Chiu, I-T.; Pletcher, R. H.; Steger, J. L.

    1990-01-01

    Numerical simulations using the thin-layer Navier-Stokes equations and chimera (overset) grid approach were carried out for flows around the integrated space shuttle vehicle over a range of Mach numbers. Body-conforming grids were used for all the component grids. Testcases include a three-component overset grid - the external tank (ET), the solid rocket booster (SRB) and the orbiter (ORB), and a five-component overset grid - the ET, SRB, ORB, forward and aft attach hardware, configurations. The results were compared with the wind tunnel and flight data. In addition, a Poisson solution procedure (a special case of the vorticity-velocity formulation) using primitive variables was developed to solve three-dimensional, irrotational, inviscid flows for single as well as overset grids. The solutions were validated by comparisons with other analytical or numerical solution, and/or experimental results for various geometries. The Poisson solution was also used as an initial guess for the thin-layer Navier-Stokes solution procedure to improve the efficiency of the numerical flow simulations. It was found that this approach resulted in roughly a 30 percent CPU time savings as compared with the procedure solving the thin-layer Navier-Stokes equations from a uniform free stream flowfield.

  1. The development of an explicit thermochemical nonequilibrium algorithm and its application to compute three dimensional AFE flowfields

    NASA Technical Reports Server (NTRS)

    Palmer, Grant

    1989-01-01

    This study presents a three-dimensional explicit, finite-difference, shock-capturing numerical algorithm applied to viscous hypersonic flows in thermochemical nonequilibrium. The algorithm employs a two-temperature physical model. Equations governing the finite-rate chemical reactions are fully-coupled to the gas dynamic equations using a novel coupling technique. The new coupling method maintains stability in the explicit, finite-rate formulation while allowing relatively large global time steps. The code uses flux-vector accuracy. Comparisons with experimental data and other numerical computations verify the accuracy of the present method. The code is used to compute the three-dimensional flowfield over the Aeroassist Flight Experiment (AFE) vehicle at one of its trajectory points.

  2. Upgrade of PARC2D to include real gas effects. [computer program for flowfield surrounding aeroassist flight experiment

    NASA Technical Reports Server (NTRS)

    Saladino, Anthony; Praharaj, Sarat C.; Collins, Frank G.; Seaford, C. Mark

    1990-01-01

    This paper presents a description of the changes and additions to the perfect gas PARC2D code to include chemical equilibrium effects, resulting in a code called PARCEQ2D. The work developed out of a need to have the capability of more accurately representing the flowfield surrounding the aeroassist flight experiment (AFE) vehicle. Use is made of the partition function of statistical mechanics in the evaluation of the thermochemical properties. This approach will allow the PARC code to be extended to thermal nonequilibrium when this task is undertaken in the future. The transport properties follow from formulae from the kinetic theory of gases. Results are presented for a two-dimensional AFE that compare perfect gas and real gas solutions at flight conditions, showing vast differences between the two cases.

  3. Numerical Simulation of Three-Dimensional Boattail Afterbody Flowfields

    NASA Technical Reports Server (NTRS)

    Deiwert, G. S.

    1981-01-01

    The thin shear-layer approximations of the three-dimensional, compressible Navier-Stokes equations are solved for subsonic, transonic, and supersonic now over axisymmetric boattail bodies at moderate angles of attack. The plume is simulated by a solid body configuration identical to those used In experimental tests. An implicit algorithm of second-order accuracy is used to solve the equations on the ILLIAC 4 computer. The turbulence is expressed by an algebraic model applicable to three-dimensional flowfields with moderate separation. The formulation used is attractive in its independence of boundary-layer parameters. Such a simple model, however, is incapable of supporting detailed quantitative descriptions of complex shear flows. Never-the-less, good qualitative comparisons are found with three different sets of experimental date. Quantitative improvement will depend on improved turbulence transport descriptions.

  4. Fuel cell with interdigitated porous flow-field

    DOEpatents

    Wilson, Mahlon S.

    1997-01-01

    A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers.

  5. Numerical Simulation of the Aircraft Wake Vortex Flowfield

    NASA Technical Reports Server (NTRS)

    Ahmad, Nashat N.; Proctor, Fred H.; Perry, R. Brad

    2013-01-01

    The near wake vortex flowfield from a NACA0012 half-wing was simulated using a fully unstructured Navier-Stokes flow solver in three dimensions at a chord Reynolds number of 4.6 million and a Mach number of approximately 0.15. Several simulations were performed to examine the effect of boundary conditions, mesh resolution and turbulence scheme on the formation of wingtip vortex and its downstream propagation. The standard Spalart-Allmaras turbulence model was compared with the Dacles-Mariani and Spalart-Shur corrections for rotation and curvature effects. The simulation results were evaluated using the data from experiment performed at NASA Ames' 32in x 48in low speed wind tunnel.

  6. Mean flowfields in axisymmetric combustor geometries with swirl

    SciTech Connect

    Rhode, D.L.; Lilley, D.G.

    1982-01-01

    Six flowfield configurations are investigated with sidewall angles of 90 and 45/sup 0/, and swirl vane angles of 0, 45, and 70/sup 0/. It is found that central recirculation zones occur for the swirling flow cases investigated, which extend from the inlet to x/D 1.7, where x is the axial polar coordinate, and D is the test section diameter. Five-hole pitot probe pressure measurements are used to determine time-mean velocities, and corresponding flow situations are predicted and compared to results of experimental data. Excellent agreement is found for the nonswirling flow, although poor agreement is found for swirling flow cases, especially near the inlet. The discrepancy is attributed to the lack of realism in the turbulence model, and/or to inaccurate specification of time-mean velocity and turbulence energy distributions at the inlet.

  7. Fuel cell with interdigitated porous flow-field

    DOEpatents

    Wilson, M.S.

    1997-06-24

    A polymer electrolyte membrane (PEM) fuel cell is formed with an improved system for distributing gaseous reactants to the membrane surface. A PEM fuel cell has an ionic transport membrane with opposed catalytic surfaces formed thereon and separates gaseous reactants that undergo reactions at the catalytic surfaces of the membrane. The fuel cell may also include a thin gas diffusion layer having first and second sides with a first side contacting at least one of the catalytic surfaces. A macroporous flow-field with interdigitated inlet and outlet reactant channels contacts the second side of the thin gas diffusion layer for distributing one of the gaseous reactants over the thin gas diffusion layer for transport to an adjacent one of the catalytic surfaces of the membrane. The porous flow field may be formed from a hydrophilic material and provides uniform support across the backside of the electrode assembly to facilitate the use of thin backing layers. 9 figs.

  8. Computational fluid dynamic analysis of hybrid rocket combustor flowfields

    NASA Technical Reports Server (NTRS)

    Venkateswaran, S.; Merkle, C. L.

    1995-01-01

    Computational fluid dynamic analyses of the Navier-Stokes equations coupled with solid-phase pyrolysis, gas-phase combustion, turbulence and radiation are performed to study hybrid rocket combustor flowfields. The computational study is closely co-ordinated with a companion experimental program using a planar slab burner configuration with HTPB as fuel and gaseous oxygen. Computational predictions agree reasonably well with measurement data of fuel regression rates and surface temperatures. Additionally, most of the parametric trends predicted by the model are in general agreement with experimental trends. The computational model is applied to extend the results from the lab-scale to a full-scale axisymmetric configuration. The numerical predictions indicate that the full-scale configuration burns at a slower rate than the lab-scale combustor under identical specific flow rate conditions. The results demonstrate that detailed CFD analyses can play a useful role in the design of hybrid combustors.

  9. Non-Intrusive Optical Diagnostic Methods for Flowfield Characterization

    NASA Technical Reports Server (NTRS)

    Tabibi, Bagher M.; Terrell, Charles A.; Spraggins, Darrell; Lee, Ja. H.; Weinstein, Leonard M.

    1997-01-01

    Non-intrusive optical diagnostic techniques such as Electron Beam Fluorescence (EBF), Laser-Induced Fluorescence (LIF), and Focusing Schlieren (FS) have been setup for high-speed flow characterization and large flowfield visualization, respectively. Fluorescence emission from the First Negative band of N2(+) with the (0,0) vibration transition (at lambda =391.44 nm) was obtained using the EBF technique and a quenching rate of N2(+)* molecules by argon gas was reported. A very high sensitivity FS system was built and applied in the High-Speed Flow Generator (HFG) at NASA LaRC. A LIF system is available at the Advanced Propulsion Laboratory (APL) on campus and a plume exhaust velocity measurement, measuring the Doppler shift from lambda = 728.7 nm of argon gas, is under way.

  10. Quantitative characterization of a nonreacting, supersonic combustor flowfield using unified, laser-induced iodine fluorescence

    NASA Technical Reports Server (NTRS)

    Fletcher, D. G.; Mcdaniel, J. C.

    1989-01-01

    A calibrated, nonintrusive optical technique, laser-induced iodine fluorescence (LIIF) was used to quantify the steady, compressible flowfield of a nonreacting, supersonic combustor. The combustor was configured with single and staged, transverse-air injection into a supersonic-air freestream behind a rearward-facing step. Pressure, temperature, two-velocity components, and injectant mole fraction were measured with high spatial resolution in the three-dimensional flowfields. These experimental results provide a benchmark set of data for validation of computational fluid dynamic (CFD) codes being developed to model supersonic combustor flowfields.

  11. Viscous flowfields induced by three-dimensional lift jets in ground effect

    NASA Astrophysics Data System (ADS)

    Bower, W. W.

    1982-01-01

    The turbulent flowfields associated with single and multiple jets impinging on a ground plane are relevant to the aerodynamics of VTOL aircraft in ground effect. These flowfields are computed using the Reynolds equations and a two-equation turbulence model to describe an isolated jet and two interacting jets with fountain formation. Coordinate transformations are employed to apply the boundary conditions for the governing equations in the far field, and a third-order-accurate upwind-difference scheme is used to discretize the resulting system. Flowfield properties calculated for these impinging-jet configurations are presented and compared with experimental data.

  12. Experimental investigation of the flowfield of an oscillating airfoil

    NASA Technical Reports Server (NTRS)

    Panda, J.; Zaman, K. B. M. Q.

    1992-01-01

    The flowfield of an airfoil oscillated periodically over a wide range of reduced frequencies, 0 less than or = k less than or = 1.6 is studied experimentally at chord Reynolds numbers of R sub c = 22,000 and 44,000. The NACA0012 airfoil is pitched sinusoidally about one quarter chord between angles of attack (alpha) of 5 and 25 degrees. Detailed flow visualization and phase averaged vorticity measurements are carried out for k = 0.2 to document the evolution and the shedding of the dynamic stall vortex (DSV). In addition to the DSV, an intense vortex of opposite sign originates from the trailing edge just when the DSV is shed. After being shed into the wake, the two together take the shape of a large 'mushroom' while being convected away from the airfoil. The unsteady circulation around the airfoil and, therefore, the time varying component of the lift is estimated in a novel way from the shed vorticity flux and is found to be in good agreement with the lift variation reported by others. The delay in the shedding of the DSV with increasing k, as observed by previous researchers, is documented for the full range of k. The DSV, for example, is shed nearly at the maximum alpha of 25 degrees at k = 0.2, but is shed at the minimum alpha of 5 degrees at k = 0.8. At low k, the flowfield appears quasi-steady and the bluff body shedding corresponding to the maximum alpha (25 degrees) dominates the unsteady fluctuations in the wake.

  13. Fuel Plume Image Mixing Analysis Formulation With Proper Treatment of Non-Constant Velocity Flowfields

    NASA Technical Reports Server (NTRS)

    Mekkes, Gregory L.

    2000-01-01

    A previously developed technique allows an estimate of integral mixing to be obtained from an image of laser scattered light from particle seeded fuel in the hypervelocity flow through a scramjet combustor. This previous mixing analysis formulation contains an assumption of a constant velocity flowfield across the plane of the fuel plume image. For high-speed scramjet combustors, the velocity flowfield is quite uniform and an assumption of constant velocity works well. Applying this same mixing analysis technique to fuel plume images obtained from a mid-speed scramjet combustor makes it desirable to remove the constant velocity assumption. This is due to the non-uniform velocity flowfields present in mid-speed scramjet combustors. A new formulation of the mixing analysis methodology is developed and presented so that the technique can be applied to a mid-speed scramjet combustor without the need to assume a constant velocity flowfield.

  14. Development of a nonequilibrium radiative heating prediction method for coupled flowfield solutions

    NASA Technical Reports Server (NTRS)

    Hartung, Lin C.

    1991-01-01

    A method for predicting radiation in thermochemical nonequilibrium flows has been developed. A summary of the development is presented, with emphasis on its unique features. The optimization of the method to provide efficient solutions allowing coupling to flowfield solvers is discussed. Representative results are obtained and compared to previous solutions and flight data. The method is found to be a useful tool for studies of nonequilibrium flowfields.

  15. Navier-Stokes solutions of flowfield characteristics produced by ice accretion

    NASA Technical Reports Server (NTRS)

    Scott, J. N.; Gielda, T. P.; Hankey, W. L.

    1988-01-01

    The flowfield and resultant heat transfer rates over a series of ice accretion shapes have been obtained through numerical solutions of the Navier-Stokes equations. The influence of roughness is modeled by including blockage, form drag and stagnation heating effects as source terms in the governing equations. Using the flowfield information obtained from the Navier-Stokes equations the droplet impingement efficiencies are computed using a PNS-type solving scheme. Good agreement is achieved between the numerical results and experimental data.

  16. Design and Calibration of a Flowfield Survey Rake for Inlet Flight Research

    NASA Technical Reports Server (NTRS)

    Flynn, Darin C.; Ratnayake, Nalin A.; Frederick, Michael

    2009-01-01

    Flowfield rake was designed to quantify the flowfield for inlet research underneath NASA DFRC s F-15B airplane. Detailed loads and stress analysis performed using CFD and empirical methods to assure structural integrity. Calibration data were generated through wind tunnel testing of the rake. Calibration algorithm was developed to determine the local Mach and flow angularity at each probe. RAGE was flown November, 2008. Data is currently being analyzed.

  17. Detailed flow-field measurements over a 75 deg swept delta wing

    NASA Technical Reports Server (NTRS)

    Kjelgaard, Scott O.; Sellers, William L., III

    1990-01-01

    Results from an experimental investigation documenting the flowfield over a 75 deg swept delta wing at an angle-of-attack of 20.5 deg are presented. Results obtained include surface flow visualization, off-body flow visualization, and detailed flowfield surveys for various Reynolds numbers. Flowfield surveys at Reynolds numbers of 0.5, 1.0, and 1.5 million based on the root chord were conducted with both a Pitot pressure probe and a 5-hole pressure probe; and 3-component laser velocimeter surveys were conducted at a Reynolds number of 1.0 million. The Pitot pressure surveys were obtained at 5 chordwise stations, the 5-hole probe surveys were obtained at 3 chordwise stations and the laser velocimeter surveys were obtained at one station. The results confirm the classical roll up of the flow into a pair of primary vortices over the delta wing. The velocity measurements indicate that Reynolds number has little effect on the global structure of the flowfield for the Reynolds number range investigated. Measurements of the non-dimensional axial velocity in the core of the vortex indicate a jet like flow with values greater than twice freestream. Comparisons between velocity measurements from the 5-hole pressure probe and the laser velocimeter indicate that the pressure probe does a reasonable job of measuring the flowfield quantities where the velocity gradients in the flowfield are low.

  18. Navier-Stokes simulations of WECS airfoil flowfields

    SciTech Connect

    Homicz, G.F.

    1994-06-01

    Sandia National Laboratories has initiated an effort to apply Computational Fluid Dynamics (CFD) to the study of WECS aerodynamics. Preliminary calculations are presented for the flow past a SAND 0018/50 airfoil. The flow solver used is F3D, an implicitly, finite-difference code which solves the Thin-Layer Navier-airfoil. The flow solver used is F3D, an implicit, finite-difference code which solves the Thin-Layer Navier-Stokes equations. 2D steady-state calculations are presented at various angles of attack, {alpha}. Sectional lift and drag coefficient, as well as surface pressure distributions, are compared with wind tunnel data, and exhibit reasonable agreement at low to moderate angles of attack. At high {alpha}, where the airfoil is stalled, a converged solution to the steady-state equations could not be obtained. The flowfield continued to change with successive iterations, which is consistent with the fact that the actual flow is inherently transient, and requires the solution of the full unsteady form of the equations.

  19. Improved Flow-Field Structures for Direct Methanol Fuel Cells

    SciTech Connect

    Gurau, Bogdan

    2013-05-31

    The direct methanol fuel cell (DMFC) is ideal if high energy-density liquid fuels are required. Liquid fuels have advantages over compressed hydrogen including higher energy density and ease of handling. Although state-of-the-art DMFCs exhibit manageable degradation rates, excessive fuel crossover diminishes system energy and power density. Although use of dilute methanol mitigates crossover, the concomitant lowering of the gross fuel energy density (GFED) demands a complex balance-of-plant (BOP) that includes higher flow rates, external exhaust recirculation, etc. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol. NuVant Systems Inc. (NuVant) will maximize the GFED by design and assembly of a DMFC that uses near neat methanol. The approach is to tune the diffusion of highly concentrated methanol (to the anode catalytic layer) to the back-diffusion of water formed at the cathode (i.e. in situ generation of dilute methanol at the anode layer). Crossover will be minimized without compromising the GFED by innovative integration of the anode flow-field and the diffusion layer. The integrated flow-field-diffusion-layers (IFDLs) will widen the current and potential DMFC operating ranges and enable the use of cathodes optimized for hydrogen-air fuel cells.

  20. Computational Relativistic Astrophysics Using the Flowfield-Dependent Variation Theory

    NASA Technical Reports Server (NTRS)

    Richardson, G. A.; Chung, T. J.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Theoretical models, observations and measurements have preoccupied astrophysicists for many centuries. Only in recent years, has the theory of relativity as applied to astrophysical flows met the challenges of how the governing equations can be solved numerically with accuracy and efficiency. Even without the effects of relativity, the physics of magnetohydrodynamic flow instability, turbulence, radiation, and enhanced transport in accretion disks has not been completely resolved. Relativistic effects become pronounced in such cases as jet formation from black hole magnetized accretion disks and also in the study of Gamma-Ray bursts (GRB). Thus, our concern in this paper is to reexamine existing numerical simulation tools as to the accuracy and efficiency of computations and introduce a new approach known as the flowfield-dependent variation (FDV) method. The main feature of the FDV method consists of accommodating discontinuities of shock waves and high gradients of flow variables such as occur in turbulence and unstable motions. In this paper, the physics involved in the solution of relativistic hydrodynamics and solution strategies of the FDV theory are elaborated. The general relativistic astrophysical flow and shock solver (GRAFSS) is introduced, and some simple example problems for Computational Relativistic Astrophysics (CRA) are demonstrated.

  1. Development of a 3-D upwind PNS code for chemically reacting hypersonic flowfields

    NASA Technical Reports Server (NTRS)

    Tannehill, J. C.; Wadawadigi, G.

    1992-01-01

    Two new parabolized Navier-Stokes (PNS) codes were developed to compute the three-dimensional, viscous, chemically reacting flow of air around hypersonic vehicles such as the National Aero-Space Plane (NASP). The first code (TONIC) solves the gas dynamic and species conservation equations in a fully coupled manner using an implicit, approximately-factored, central-difference algorithm. This code was upgraded to include shock fitting and the capability of computing the flow around complex body shapes. The revised TONIC code was validated by computing the chemically-reacting (M(sub infinity) = 25.3) flow around a 10 deg half-angle cone at various angles of attack and the Ames All-Body model at 0 deg angle of attack. The results of these calculations were in good agreement with the results from the UPS code. One of the major drawbacks of the TONIC code is that the central-differencing of fluxes across interior flowfield discontinuities tends to introduce errors into the solution in the form of local flow property oscillations. The second code (UPS), originally developed for a perfect gas, has been extended to permit either perfect gas, equilibrium air, or nonequilibrium air computations. The code solves the PNS equations using a finite-volume, upwind TVD method based on Roe's approximate Riemann solver that was modified to account for real gas effects. The dissipation term associated with this algorithm is sufficiently adaptive to flow conditions that, even when attempting to capture very strong shock waves, no additional smoothing is required. For nonequilibrium calculations, the code solves the fluid dynamic and species continuity equations in a loosely-coupled manner. This code was used to calculate the hypersonic, laminar flow of chemically reacting air over cones at various angles of attack. In addition, the flow around the McDonnel Douglas generic option blended-wing-body was computed and comparisons were made between the perfect gas, equilibrium air, and the

  2. A six-degree-of-freedom guidance and control analysis of Mars aerocapture

    NASA Astrophysics Data System (ADS)

    Powell, Richard W.; Braun, Robert D.

    1992-01-01

    A six-degree-of-freedom (6DOF) simulation is developed to investigate the control and guidance issues of a Mars aerobraking vehicle. The guidance algorithm used is a predictor-corrector guidance formulation designed to control the exit orbital apoapsis and wedge angle using bank-angle modulation. Major features of this predictor-corrector guidance algorithm include: (1) integration of the 3DOF equations of motion within an inner-loop simulation; (2) load-relief logic; (3) finite roll rates; and (4) an aerodynamic feedback multiplier. The algorithm is capable of successfully guiding the vehicle through combinations of atmospheric density dispersions, aerodynamic mispredictions, and off-nominal atmospheric interface conditions. This study demonstrated that the addition of vehicle dynamics to the Mars aerobraking simulation does not significantly impact mission feasibility. That is, a robust control system design coupled with an adaptive guidance algorithm can assure mission success in the presence of numerous off-nominal conditions.

  3. Flowfield-Dependent Mixed Explicit-Implicit (FDMEL) Algorithm for Computational Fluid Dynamics

    NASA Technical Reports Server (NTRS)

    Garcia, S. M.; Chung, T. J.

    1997-01-01

    Despite significant achievements in computational fluid dynamics, there still remain many fluid flow phenomena not well understood. For example, the prediction of temperature distributions is inaccurate when temperature gradients are high, particularly in shock wave turbulent boundary layer interactions close to the wall. Complexities of fluid flow phenomena include transition to turbulence, relaminarization separated flows, transition between viscous and inviscid incompressible and compressible flows, among others, in all speed regimes. The purpose of this paper is to introduce a new approach, called the Flowfield-Dependent Mixed Explicit-Implicit (FDMEI) method, in an attempt to resolve these difficult issues in Computational Fluid Dynamics (CFD). In this process, a total of six implicitness parameters characteristic of the current flowfield are introduced. They are calculated from the current flowfield or changes of Mach numbers, Reynolds numbers, Peclet numbers, and Damkoehler numbers (if reacting) at each nodal point and time step. This implies that every nodal point or element is provided with different or unique numerical scheme according to their current flowfield situations, whether compressible, incompressible, viscous, inviscid, laminar, turbulent, reacting, or nonreacting. In this procedure, discontinuities or fluctuations of an variables between adjacent nodal points are determined accurately. If these implicitness parameters are fixed to certain numbers instead of being calculated from the flowfield information, then practically all currently available schemes of finite differences or finite elements arise as special cases. Some benchmark problems to be presented in this paper will show the validity, accuracy, and efficiency of the proposed methodology.

  4. Navier-Stokes Flowfield Simulation of Boeing 747-200 as Platform for SOFIA

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.R.

    1994-01-01

    Steady and unsteady viscous, three-dimensional flowfields are calculated using a thin layer approximation of Navier-Stokes equations in conjunction with Chimera overset grids. The finite-difference numerical scheme uses structured grids and a pentadiagonal flow solver called "OVERFLOW". The configuration of Boeing 747-200 has been chosen as one of configurations to be used as a platform for the SOFIA (Stratospheric Observatory For Infrared Astronomy). Initially, the steady flowfield of the full aircraft is calculated for the clean configuration (without a cavity to house telescope). This solution is then used to start the unsteady flowfield of a configuration containing cavity housing the observation telescope and its peripheral units. Analysis of unsteady flowfield in the cavity and its influence on the tail empennage, as well as the noise due to turbulence and optical quality of the flow are the main focus of this study. For the configuration considered here, the telescope housing cavity is located slightly downstream of the portwing. The entire flow-field is carefully constructed using 45 overset grids and consists of nearly 4 million grid points. All the computations axe done at one freestream flow condition of M(sub infinity) = 0.85, alpha = 2.5deg, and a Reynolds of Re = 1.85x10deg

  5. Decoding complex flow-field patterns in visual working memory.

    PubMed

    Christophel, Thomas B; Haynes, John-Dylan

    2014-05-01

    There has been a long history of research on visual working memory. Whereas early studies have focused on the role of lateral prefrontal cortex in the storage of sensory information, this has been challenged by research in humans that has directly assessed the encoding of perceptual contents, pointing towards a role of visual and parietal regions during storage. In a previous study we used pattern classification to investigate the storage of complex visual color patterns across delay periods. This revealed coding of such contents in early visual and parietal brain regions. Here we aim to investigate whether the involvement of visual and parietal cortex is also observable for other types of complex, visuo-spatial pattern stimuli. Specifically, we used a combination of fMRI and multivariate classification to investigate the retention of complex flow-field stimuli defined by the spatial patterning of motion trajectories of random dots. Subjects were trained to memorize the precise spatial layout of these stimuli and to retain this information during an extended delay. We used a multivariate decoding approach to identify brain regions where spatial patterns of activity encoded the memorized stimuli. Content-specific memory signals were observable in motion sensitive visual area MT+ and in posterior parietal cortex that might encode spatial information in a modality independent manner. Interestingly, we also found information about the memorized visual stimulus in somatosensory cortex, suggesting a potential crossmodal contribution to memory. Our findings thus indicate that working memory storage of visual percepts might be distributed across unimodal, multimodal and even crossmodal brain regions.

  6. Experimental investigation of the flowfield of an oscillating airfoil

    NASA Technical Reports Server (NTRS)

    Panda, J.; Zaman, K. B. M. Q.

    1992-01-01

    The flow field of an airfoil oscillated periodically over a wide range of reduced frequencies, 0 less than k less than 1.6, is studied experimentally at chord Reynolds numbers of R sub c = 22,000 and 44,000. The NACA0012 airfoil is pitched sinusoidally about one quarter chord between alpha of 5 deg and 25 deg. Detailed flow visualization and phase averaged vorticity measurements are carried out for k = 0.2 to document the evolution and the shedding of the dynamic stall vortex (DSV). In addition to the DSV, an intense vortex of opposite sign originates from the trailing edge just when the DSV is shed. After being shed into the wake, the two together take the shape of a large 'mushroom' while being convected away from the airfoil. The unsteady circulation around the airfoil and, therefore, the time varying component of the lift is estimated in a novel way from the shed vorticity flux and is found to be in good agreement with the lift variation reported by others. The delay in the shedding of the DSV with increasing k, as observed by previous researchers, is documented for the full range of k. The DSV, for example, is shed nearly at the maximum alpha of 25 deg at k = 0.2, but is shed at the minimum alpha of 5 deg at k = 0.8. At low k, the flowfield appears quasi-steady and the bluff body shedding corresponding to the maximum alpha (25 deg) dominates the unsteady fluctuations in the wake.

  7. Flowfield characterization of a piloted lean premixed injector by particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Berdanier, Catherine G. P.

    Limiting atmospheric pollution, especially nitrous oxides, is an important endeavor for aviation technology companies. Technology-driving regulations from the International Civil Aviation Organization's (ICAO) Committee of Aviation Environmental Protection (CAEP) standards spur the combustion research and development community to find innovative engine technologies to decrease emissions in the coming years. As engine technologies are developed, testing is necessary to verify combustion models and expected flow patterns. Optical diagnostics provide a unique opportunity to visualize flowfields in complex practical combustor systems. For this thesis, Particle Image Velocimetry (PIV) was employed to characterize the flowfield in a piloted lean premixed injector under non-combusting conditions. Planes of PIV data were acquired at five spanwise locations and two streamwise locations, at two different pressure conditions in order to characterize the flowfields and structures throughout the optically accessible flowpath. Average velocity maps and time-resolved vector fields at these planes were analyzed for this thesis.

  8. Detailed flowfield measurements over a 75 deg swept delta wing for code validation

    NASA Technical Reports Server (NTRS)

    Kjelgaard, Scott O.; Sellers, William L., III

    1988-01-01

    Selected results from an experimental investigation documenting the flowfield over 75 deg swept delta wing at an angle-of-attack of 20.5 deg are presented. Results obtained in the investigation include surface flow visualization, off-body flow visualization, and detailed flowfield surveys for various Reynolds numbers. Flowfield surveys at Reynolds numbers of 0.5, 1.0 and 1.5 million were conducted with both a pitot pressure probe and a 5-hole pressure probe; and 3-component laser Doppler velocimeter surveys were conducted at a Reynolds number of 1.0 million. The pitot pressure surveys were obtained at 5 longitudinal stations, the 5-hole probe surveys were obtained at 3 longitudinal stations and the laser Doppler velocimeter surveys were obtained at one station. The accuracy of each instrumentation system is discussed, as well as, discrepancies in the calculation of vorticity using various algorithms.

  9. A Computer Program for the Calculation of Three-Dimensional Transonic Nacelle/Inlet Flowfields

    NASA Technical Reports Server (NTRS)

    Vadyak, J.; Atta, E. H.

    1983-01-01

    A highly efficient computer analysis was developed for predicting transonic nacelle/inlet flowfields. This algorithm can compute the three dimensional transonic flowfield about axisymmetric (or asymmetric) nacelle/inlet configurations at zero or nonzero incidence. The flowfield is determined by solving the full-potential equation in conservative form on a body-fitted curvilinear computational mesh. The difference equations are solved using the AF2 approximate factorization scheme. This report presents a discussion of the computational methods used to both generate the body-fitted curvilinear mesh and to obtain the inviscid flow solution. Computed results and correlations with existing methods and experiment are presented. Also presented are discussions on the organization of the grid generation (NGRIDA) computer program and the flow solution (NACELLE) computer program, descriptions of the respective subroutines, definitions of the required input parameters for both algorithms, a brief discussion on interpretation of the output, and sample cases to illustrate application of the analysis.

  10. A knowledge-based approach to automated flow-field zoning for computational fluid dynamics

    NASA Technical Reports Server (NTRS)

    Vogel, Alison Andrews

    1989-01-01

    An automated three-dimensional zonal grid generation capability for computational fluid dynamics is shown through the development of a demonstration computer program capable of automatically zoning the flow field of representative two-dimensional (2-D) aerodynamic configurations. The applicability of a knowledge-based programming approach to the domain of flow-field zoning is examined. Several aspects of flow-field zoning make the application of knowledge-based techniques challenging: the need for perceptual information, the role of individual bias in the design and evaluation of zonings, and the fact that the zoning process is modeled as a constructive, design-type task (for which there are relatively few examples of successful knowledge-based systems in any domain). Engineering solutions to the problems arising from these aspects are developed, and a demonstration system is implemented which can design, generate, and output flow-field zonings for representative 2-D aerodynamic configurations.

  11. Laser-velocimeter flow-field measurements of an advanced turboprop

    NASA Technical Reports Server (NTRS)

    Serafini, J. S.; Sullivan, J. P.; Neumann, H. E.

    1981-01-01

    Non-intrusive measurements of velocity about a spinner-propeller-nacelle configuration at a Mach number of 0.8 were performed. A laser velocimeter, specifically developed for these measurements in the NASA Lewis 8-foot by 6-foot Supersonic Wind Tunnel, was used to measure the flow-field of the advanced swept SR-3 turboprop. The laser velocimeter uses an argon ion laser and a 2-color optics system to allow simultaneous measurements of 2-components of velocity. The axisymmetric nature of the propeller-nacelle flow-field permits two separate 2 dimensonal measurements to be combined into 3 dimensional velocity data. Presented are data ahead of and behind the prop blades and also a limited set in between the blades. Aspects of the observed flow-field such as the tip vortex are discussed.

  12. Design optimization for a space based, reusable orbit transfer vehicle

    NASA Technical Reports Server (NTRS)

    Redd, L.

    1985-01-01

    Future NASA and DOD missions will benefit from high performance, reusable orbit transfer vehicles. With the advent of a space station, advanced engine technology, and various new vehicle concepts, reusable orbit transfer vehicles that provide significant economic benefits and mission capability improvements will be realized. Engine and vehicle design criteria previously have lacked definition with regard to issues such as space basing and servicing, man-rating and reliability, performance, mission flexibility, and life cycle cost for a reusable vehicle. The design study described here has resulted in the definition of a reusable orbit transfer vehicle concept and subsequent recommendations for the design criteria of an advanced LO2/LH2 engine. These design criteria include number of engines per vehicle, nozzle design, etc. The major characteristics of the vehicle preliminary design include low lift to drag aerocapture capability, a main propulsion system failure criteria of fail operational/fail safe, and either two main engines with a high performance attitude control system for back-up or three main engines with which to meet this failure criteria. In addition, a maintenance approach has been established for the advanced vehicle concept.

  13. Burning of a spherical fuel droplet in a uniform subsonic flowfield

    SciTech Connect

    Madooglu, K.; Karagozian, A.R.

    1989-12-31

    An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill`s spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet`s effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.

  14. Burning of a spherical fuel droplet in a uniform subsonic flowfield

    SciTech Connect

    Madooglu, K.; Karagozian, A.R.

    1989-01-01

    An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill's spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet's effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.

  15. Laser imaging of chemistry-flowfield interactions: Enhanced soot formation in time-varying diffusion flames

    SciTech Connect

    Harrington, J.E.; Shaddix, C.R.; Smyth, K.C.

    1994-12-31

    Models of detailed flame chemistry and soot formation are based upon experimental results obtained in steady, laminar flames. For successful application of these descriptions to turbulent combustion, it is instructive to test predictions against measurements in time-varying flowfields. This paper reports the use of optical methods to examine soot production and oxidation processes in a co-flowing, axisymmetric CH{sub 4}/air diffusion flame in which the fuel flow rate is acoustically forced to create a time-varying flowfield. For a particular forcing condition in which tip clipping occurs (0.75 V loudspeaker excitation), elastic scattering of vertically polarized light from the soot particles increases by nearly an order of magnitude with respect to that observed for a steady flame with the same mean fuel flow rate. The visible flame luminosity and laser-induced fluorescence attributed to polycyclic aromatic hydrocarbons (PAH) are also enhanced. Peak soot volume fractions, as measured by time-resolved laser extinction/tomography at 632.8 and 454.5 nm and calibrated laser-induced incandescence (LII), show a factor of 4--5 enhancement in this flickering flame. The LII method is found to track the soot volume fraction closely and to give better signal-to-noise than the extinction measurements in both the steady and time-varying flowfields. A Mie analysis suggests that most of the enhanced soot production results from the formation of larger particles in the time-varying flowfield.

  16. Plume flowfield analysis of the shuttle primary Reaction Control System (RCS) rocket engine

    NASA Technical Reports Server (NTRS)

    Hueser, J. E.; Brock, F. J.

    1990-01-01

    A solution was generated for the physical properties of the Shuttle RCS 4000 N (900 lb) rocket engine exhaust plume flowfield. The modeled exhaust gas consists of the five most abundant molecular species, H2, N2, H2O, CO, and CO2. The solution is for a bare RCS engine firing into a vacuum; the only additional hardware surface in the flowfield is a cylinder (=engine mount) which coincides with the nozzle lip outer corner at X = 0, extends to the flowfield outer boundary at X = -137 m and is coaxial with the negative symmetry axis. Continuum gas dynamic methods and the Direct Simulation Monte Carlo (DSMC) method were combined in an iterative procedure to produce a selfconsistent solution. Continuum methods were used in the RCS nozzle and in the plume as far as the P = 0.03 breakdown contour; the DSMC method was used downstream of this continuum flow boundary. The DSMC flowfield extends beyond 100 m from the nozzle exit and thus the solution includes the farfield flow properties, but substantial information is developed on lip flow dynamics and thus results are also presented for the flow properties in the vicinity of the nozzle lip.

  17. High performance Solid Rocket Motor (SRM) submerged nozzle/combustion cavity flowfield assessment

    NASA Technical Reports Server (NTRS)

    Freeman, J. A.; Chan, J. S.; Murph, J. E.; Xiques, K. E.

    1987-01-01

    Two and three dimensional internal flowfield solutions for critical points in the Space Shuttle solid rocket booster burn time were developed using the Lockheed Huntsville GIM/PAID Navier-Stokes solvers. These perfect gas, viscous solutions for the high performance motor characterize the flow in the aft segment and nozzle of the booster. Two dimensional axisymmetric solutions were developed at t = 20 and t = 85 sec motor burn times. The t = 85 sec solution indicates that the aft segment forward inhibitor stub produces vortices with are shed and convected downwards. A three dimensional 3.5 deg gimbaled nozzle flowfield solution was developed for the aft segment and nozzle at t = 9 sec motor burn time. This perfect gas, viscous analysis, provided a steady state solution for the core region and the flow through the nozzle, but indicated that unsteady flow exists in the region under the nozzle nose and near the flexible boot and nozzle/case joint. The flow in the nozzle/case joint region is characterized by low magnitude pressure waves which travel in the circumferential direction. From the two and three dimensional flowfield calculations presented it can be concluded that there is no evidence from these results that steady state gas dynamics is the primary mechanism resulting in the nozzle pocketing erosion experienced on SRM nozzles 8A or 17B. The steady state flowfield results indicate pocketing erosion is not directly initiated by a steady state gas dynamics phenomenon.

  18. Navier-Stokes calculations of scramjet-nozzle-afterbody flowfields

    NASA Astrophysics Data System (ADS)

    Baysal, Oktay

    1991-07-01

    A comprehensive computational fluid dynamics effort was conducted from 1987 to 1990 to properly design a nozzle and lower aft end of a generic hypersonic vehicle powered by a scramjet engine. The interference of the exhaust on the control surfaces of the vehicle can have adverse effects on its stability. Two-dimensional Navier-Stokes computations were performed, where the exhaust gas was assumed to be air behaving as a perfect gas. Then the exhaust was simulated by a mixture of Freon-12 and argon, which required solving the Navier-Stokes equations for four species: (nitrogen, oxygen, Freon-12, and argon). This allowed gamma to be a field variable during the mixing of the multispecies gases. Two different mixing models were used and comparisons between them as well as the perfect gas air calculations were made to assess their relative merits. Finally, the three dimensional Navier-Stokes computations were made for the full-span scramjet nozzle afterbody module.

  19. Interferograms, schlieren, and shadowgraphs constructed from real- and ideal-gas, two- and three-dimensional computed flowfields

    NASA Technical Reports Server (NTRS)

    Yates, Leslie A.

    1993-01-01

    The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method of constructing these images from both ideal- and real-gas, two and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, th sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.

  20. Interferograms, Schlieren, and Shadowgraphs Constructed from Real- and Ideal-Gas, Two- and Three-Dimensional Computed Flowfields

    NASA Technical Reports Server (NTRS)

    Yates, Leslie A.

    1992-01-01

    The construction of interferograms, schlieren, and shadowgraphs from computed flowfield solutions permits one-to-one comparisons of computed and experimental results. A method for constructing these images from both ideal- and real-gas, two- and three-dimensional computed flowfields is described. The computational grids can be structured or unstructured, and multiple grids are an option. Constructed images are shown for several types of computed flows including nozzle, wake, and reacting flows; comparisons to experimental images are also shown. In addition, the sensitivity of these images to errors in the flowfield solution is demonstrated, and the constructed images can be used to identify problem areas in the computations.

  1. Plume impingement study for reaction control system of the Orbital Maneuvering Vehicle

    NASA Technical Reports Server (NTRS)

    Mcgregor, R. D.; Lohn, P. D.; Haflinger, D. E.

    1990-01-01

    A study has been performed to assess plume impingement effects from the reaction control system of NASA's OMV. A key aspect of this modeling effort has been the use of the direct Monte Carlo method as an integral part of the nozzle/plume flowfield modeling and to compute the impingement effects for configurations in which vehicle structure or multiple plumes resulted in highly three-dimensional rarefied plume flowfields. The calculation of the flowfield for a pair of interacting thruster plumes has shown that backflow in the region between the thrusters is greatly enhanced by the interaction of the two plumes. Although the present analyses have focussed on impingement force and heating effects, this methodology would also be valuable for contamination assessments since it properly accounts for the species separation effects that are inherent in the nonequilibrium nature of rarefied gas flows.

  2. Computational Fluid Dynamic Modeling of Rocket Based Combined Cycle Engine Flowfields

    NASA Technical Reports Server (NTRS)

    Daines, Russell L.; Merkle, Charles L.

    1994-01-01

    Computational Fluid Dynamic techniques are used to study the flowfield of a fixed geometry Rocket Based Combined Cycle engine operating in rocket ejector mode. Heat addition resulting from the combustion of injected fuel causes the subsonic engine flow to choke and go supersonic in the slightly divergent combustor-mixer section. Reacting flow computations are undertaken to predict the characteristics of solutions where the heat addition is determined by the flowfield. Here, adaptive gridding is used to improve resolution in the shear layers. Results show that the sonic speed is reached in the unheated portions of the flow first, while the heated portions become supersonic later. Comparison with results from another code show reasonable agreement. The coupled solutions show that the character of the combustion-based thermal choking phenomenon can be controlled reasonably well such that there is opportunity to optimize the length and expansion ratio of the combustor-mixer.

  3. Navier-Stokes simulation of rotor-body flowfield in hover using overset grids

    NASA Technical Reports Server (NTRS)

    Srinivasan, G. R.; Ahmad, J. U.

    1993-01-01

    A free-wake Navier-Stokes numerical scheme and multiple Chimera overset grids have been utilized for calculating the quasi-steady hovering flowfield of a Boeing-360 rotor mounted on an axisymmetric whirl-tower. The entire geometry of this rotor-body configuration is gridded-up with eleven different overset grids. The composite grid has 1.3 million grid points for the entire flow domain. The numerical results, obtained using coarse grids and a rigid rotor assumption, show a thrust value that is within 5% of the experimental value at a flow condition of M(sub tip) = 0.63, Theta(sub c) = 8 deg, and Re = 2.5 x 10(exp 6). The numerical method thus demonstrates the feasibility of using a multi-block scheme for calculating the flowfields of complex configurations consisting of rotating and non-rotating components.

  4. Rotor Hover Performance and Flowfield Measurements with Untwisted and Highly-Twisted Blades

    NASA Technical Reports Server (NTRS)

    Ramasamy, Manikandan; Gold, Nili P.; Bhagwat, Mahendra J.

    2010-01-01

    The flowfield and performance characteristics of highly-twisted blades were analyzed at various thrust conditions to improve the fundamental understanding relating the wake effects on rotor performance. Similar measurements made using untwisted blades served as the baseline case. Twisted blades are known to give better hover performance than untwisted blades at high thrust coefficients typical of those found in full-scale rotors. However, the present experiments were conducted at sufficiently low thrust (beginning from zero thrust), where the untwisted blades showed identical, if not better, performance when compared with the highly-twisted blades. The flowfield measurements showed some key wake differences between the two rotors, as well. These observations when combined with simple blade element momentum theory (also called annular disk momentum theory) helped further the understanding of rotor performance characteristics.

  5. Predictions and measurements of isothermal flowfields in axisymmetric combustor geometries. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Rhodes, D. L.; Lilley, D. G.

    1985-01-01

    Numerical predictions, flow visualization experiments and time-mean velocity measurements were obtained for six basic nonreacting flowfields (with inlet swirl vane angles of 0 (swirler removed), 45 and 70 degrees and sidewall expansion angles of 90 and 45 degrees) in an idealized axisymmetric combustor geometry. A flowfield prediction computer program was developed which solves appropriate finite difference equations including a conventional two equation k-epsilon eddy viscosity turbulence model. The wall functions employed were derived from previous swirling flow measurements, and the stairstep approximation was employed to represent the sloping wall at the inlet to the test chamber. Recirculation region boundaries have been sketched from the entire flow visualization photograph collection. Tufts, smoke, and neutrally buoyant helium filled soap bubbles were employed as flow tracers. A five hole pitot probe was utilized to measure the axial, radial, and swirl time mean velocity components.

  6. Swept shock/boundary-layer interactions: Scaling laws, flowfield structure, and experimental methods

    NASA Technical Reports Server (NTRS)

    Settles, Gary S.

    1993-01-01

    A general review is given of several decades of research on the scaling laws and flowfield structures of swept shock wave/turbulent boundary layer interactions. Attention is further restricted to the experimental study and physical understanding of the steady-state aspects of these flows. The interaction produced by a sharp, upright fin mounted on a flat plate is taken as an archetype. An overall framework of quasiconical symmetry describing such interactions is first developed. Boundary-layer separation, the interaction footprint, Mach number scaling, and Reynolds number scaling are then considered, followed by a discussion of the quasiconical similarity of interactions produced by geometrically-dissimilar shock generators. The detailed structure of these interaction flowfields is next reviewed, and is illustrated by both qualitative visualizations and quantitative flow images in the quasiconical framework. Finally, the experimental techniques used to investigate such flows are reviewed, with emphasis on modern non-intrusive optical flow diagnostics.

  7. Reentry-F Flowfield Solutions at 80,000 ft.

    NASA Technical Reports Server (NTRS)

    Wood, William A.; Riley, Christopher J.; Cheatwood, F. McNeil

    1997-01-01

    Three equilibrium-air numerical solutions are presented for the Reentry-F flight-test vehicle at Mach 20, 80,000 Ft. conditions, including turbulent flow predictions. The three solutions are from a thin-layer Navier-Stokes code, coupled thin-layer and parabolized Navier-Stokes codes, and an approximate viscous shock-layer code. Boundary-layer and shock-layer profiles are presented and compared between the three solutions, revealing close agreement between the three solution methods. Notable exceptions to the close agreement, with 7-10 percent discrepancies, occur in the density profiles at the boundary-layer edge, in the boundary-layer velocity profiles, and in the shock-layer profiles in regions influenced by the nose bluntness.

  8. Trajectory and Aeroheating Environment Development and Sensitivity Analysis for Capsule-shaped Vehicles

    NASA Technical Reports Server (NTRS)

    Robinson, Jeffrey S.; Wurster, Kathryn E.

    2006-01-01

    Recently, NASA's Exploration Systems Research and Technology Project funded several tasks that endeavored to develop and evaluate various thermal protection systems and high temperature material concepts for potential use on the crew exploration vehicle. In support of these tasks, NASA Langley's Vehicle Analysis Branch generated trajectory information and associated aeroheating environments for more than 60 unique entry cases. Using the Apollo Command Module as the baseline entry system because of its relevance to the favored crew exploration vehicle design, trajectories for a range of lunar and Mars return, direct and aerocapture Earth-entry scenarios were developed. For direct entry, a matrix of cases was created that reflects reasonably expected minimum and maximum values of vehicle ballistic coefficient, inertial velocity at entry interface, and inertial flight path angle at entry interface. For aerocapture, trajectories were generated for a range of values of initial velocity and ballistic coefficient that, when combined with proper initial flight path angles, resulted in achieving a low Earth orbit either by employing a full lift vector up or full lift vector down attitude. For each trajectory generated, aeroheating environments were generated which were intended to bound the thermal protection system requirements for likely crew exploration vehicle concepts. The trades examined clearly pointed to a range of missions / concepts that will require ablative systems as well as a range for which reusable systems may be feasible. In addition, the results clearly indicated those entry conditions and modes suitable for manned flight, considering vehicle deceleration levels experienced during entry. This paper presents an overview of the analysis performed, including the assumptions, methods, and general approach used, as well as a summary of the trajectory and aerothermal environment information that was generated.

  9. Turbofan forced mixer-nozzle internal flowfield. Volume 2: Computational fluid dynamic predictions

    NASA Technical Reports Server (NTRS)

    Werle, M. J.; Vasta, V. N.

    1982-01-01

    A general program was conducted to develop and assess a computational method for predicting the flow properties in a turbofan forced mixed duct. The detail assessment of the resulting computer code is presented. It was found that the code provided excellent predictions of the kinematics of the mixing process throughout the entire length of the mixer nozzle. The thermal mixing process between the hot core and cold fan flows was found to be well represented in the low speed portion of the flowfield.

  10. An investigation of vortical flowfields due to single and multiple surface perturbations at the forebody

    NASA Astrophysics Data System (ADS)

    Hamilton, Howard Hugh

    Vortical flowfields produced by one and two cylindrical surface perturbations at the apex of a blunted conical forebody were investigated as a function of geometric parameters that defined the perturbation: axial position, perturbation height, and circumferential position. Static side force and yaw moment measurements, smoke- and oil-flow visualizations and flowfield mappings were used to correlate changes in the flow physics with the aerodynamic loads. The flow physics at the perturbation were dominated by the presence of a horseshoe vortex at the base of the surface perturbation and three-dimensional wake shedding along its height. These phenomena created a region of high Reynolds shear stresses and fluctuation velocities that deformed locally the separation and reattachment lines and increased the strength of the secondary vortex. Nonlinear regressions of the aerodynamic loads as a function of the geometric parameters revealed a fractional power-law dependence of the decay rate of the loads on the perturbation height and a stronger power-law dependence of the growth rate on the axial position. A discrete vortex simulation of the flowfield in which the effect of the perturbations was simulated as a shift in shed vortex particles confirmed these dependencies. A pair of perturbations of equal height located at the same axial position but on opposite sides of the forebody manipulated the separation lines and the related vortices independently of each other. Perturbations placed on the same side of the forebody created flowfields that were dependent of the angular spacing between the pair and the circumferential position of the perturbations. It was concluded that although the presence of single and multiple surface perturbations was sufficient to deform the local surface skin-friction lines, they were not sufficient to change the global topological structure of the mean skin-friction patterns. This change in the topological structure is postulated to be sufficient

  11. Numerical simulations of the flowfields of industrial ventilation systems and solar rocket plume

    SciTech Connect

    Yu, Shengtao.

    1989-01-01

    The motivation for this research is to incorporate modern numerical methods in modeling the flowfields of two systems: (1) industrial ventilation systems and (2) solar rocket plume. For both systems, calculations of the velocity, temperature, turbulence properties, and species concentration of flowfields were performed. Brief discussions of the two topics follow: (1) Industrial ventilation systems. An open vessel equipped with a push-pull ventilation system to control toxic vapor and a flanged suction inlet to control grinding particles and welding fumes has been analyzed. The computational method involves solving the two-dimensional turbulent flow equations for the conservation of mass, momentum, energy, turbulence properties, and chemical species in finite form. The method provides information needed by engineers to assess the effectiveness of their designs. In order to verify the accuracy of the theoretical analysis, a two-dimensional push-pull system prototype was set up and color schlieren photography and hot wire anemometry were performed. Favorable agreement was found between the experimental data and calculated results. (2) Solar rocket plume. The interaction of the solar rocket plume and the solar concentrator is studied by flow-field analysis. Such interaction can adversely affect the collector performance through fouling, excessive heat, or pressure loading. The geometrical shape of the concentrator is such that only the flow from the nozzle boundary layer can reach it, but the thrust levels of interest lead to very thick boundary layers. A time-marching Parabolized Navier-Stokes (PNS) scheme is developed to calculate the flowfields inside nozzles. The Method of Characteristics (MOC) is used to simulate the flow of rocket plume. Results show that both pressure and heat transfer effects are low, but that they increase as the chamber pressure or the thrust level size is reduced.

  12. Flowfield measurements in a model scramjet combustion using laser-induced iodine fluorescence

    NASA Technical Reports Server (NTRS)

    Mcdaniel, J. C., Jr.

    1984-01-01

    Preliminary designs were completed for an iodine mixing chamber and the optical setup to be used with a modified wind tunnel in obtaining accurate, spatially resolved measurements of variables in the flowfield of a model nonreacting scramjet combustor. Schematics of the iodine-seeded wind tunnel and a sketch of the charcoal filter for removing the iodine are included along with a cutaway section of the laboratory.

  13. Computations of two-dimensional airfoil-vortex interactions. [helicopter rotor flowfields

    NASA Technical Reports Server (NTRS)

    Srinivasan, G. R.

    1985-01-01

    A procedure for calculating the interaction of a vortex with a two dimensional airfoil in a uniform free stream is presented along with results for several test cases. A Lamb like anaytical vortex having a finite core and convect in a uniform free stream interacts with the flowfield of NACA 0012 or NACA 64A006 airfoil in transonic and subsonic flow. Euler and thin layer Navier-Stokes solutions are computed and the results are compared with the results from transonic small disturbance code and available experimental results. For interactions within the limits of transonic small disturbance assumptions, the three methods gave qualitatively similar results of a two bladed helicopter rotor and suggest that the time lag effects of the free stream velocity approaching the blade may be important and should be considered in the analysis. In general, the results show a tremendous influence of the interacting vortex on the flowfield around the airfoil. This is particularly true when the vortex is stationary. For a convecting vortex, the most dramatic changes in the flowfield seem to occur when the vortex is within one chord of the airfoil.

  14. On Flowfield Periodicity in the NASA Transonic Flutter Cascade. Part 1; Experimental Study

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; McFarland, E. R.; Chima, R. V.; Wood, J. R.

    2000-01-01

    An extensive study to improve flow uniformity and periodicity in the NASA Transonic Flutter Cascade is presented here. The results are reported in two independent parts dealing with the experimental approach and the analytical approach. The first part, the Experimental Study, focuses first on the data sets acquired in this facility in the past and explains several discrepancies, particularly the questions of actual flow incidence and cascade back pressure levels. Next, available means for control and modifications of the cascade flowfield, boundary layer bleed and tailboard settings are presented in detail. This is followed by experimental data sets acquired in modified test facility configurations that were based on analytical predictions of the cascade flowfield. Finally, several important conclusions about improving the cascade flowfield uniformity and blade load periodicity are summarized. The important conclusions are: (1) boundary layer bleed does not improve the cascade flow periodicity; (2) tunnel wall contours must be carefully matched to the expected shape of cascade streamlines; (3) actual flow incidence for each cascade configuration rather must be measured instead of relying on the tunnel geometry; and (4) the current cascade configuration exhibits a very high blade load uniformity over six blades from blade #2 to blade #7, and the facility is now ready for unsteady pressure data acquisition.

  15. A high-performance flow-field structured iron-chromium redox flow battery

    NASA Astrophysics Data System (ADS)

    Zeng, Y. K.; Zhou, X. L.; An, L.; Wei, L.; Zhao, T. S.

    2016-08-01

    Unlike conventional iron-chromium redox flow batteries (ICRFBs) with a flow-through cell structure, in this work a high-performance ICRFB featuring a flow-field cell structure is developed. It is found that the present flow-field structured ICRFB reaches an energy efficiency of 76.3% with a current density of 120 mA cm-2 at 25 °C. The energy efficiency can be as high as 79.6% with an elevated current density of 200 mA cm-2 at 65 °C, a record performance of the ICRFB in the existing literature. In addition, it is demonstrated that the energy efficiency of the battery is stable during the cycle test, and that the capacity decay rate of the battery is 0.6% per cycle. More excitingly, the high performance of the flow-field structured battery significantly lowers the capital cost at 137.6 kWh-1, which is 28.2% lower than that of the conventional ICRFB for 8-h energy storage.

  16. Sting-free Unsteady Flowfield, Base Pressure and Force Measurements on Axisymmetric Bluff-Body

    NASA Astrophysics Data System (ADS)

    Higuchi, Hiroshi; Sawada, Hideo; Kato, Hiroyuki; Kunimasu, Tetsuya

    2006-11-01

    To avoid interference of model support, flowfields as well as aerodynamic force and base pressure on blunt short cylinders in axial flow were measured at Re=100,000 with the JAXA 60cm magnetic suspension and balance system. The fineness ratio ranged from 1.27 to 1.79. A digital telemeter system was developed for the base pressure measurement, and the velocity field was obtained using a PIV system. Vortices along separating shear layer and shear layer flappings with or without reattachment on the wall were observed. Downstream the cylinder in the azimuthal plane, PIV snapshots showed large-scale motion of longitudinal vortices. These instantaneous flowfields presented excellent axisymmetry when they were ensemble-averaged. Mean base pressure agreed with the drag variation at different fineness ratios. The present magnetic suspension and balance system allowed evaluation of low frequency unsteady aerodynamic force vector from feedback current to the coils and the detected small model movement. Base pressure fluctuations were compared with the drag fluctuations and discussed in light of overall flowfield phenomena.

  17. A high-performance flow-field structured iron-chromium redox flow battery

    NASA Astrophysics Data System (ADS)

    Zeng, Y. K.; Zhou, X. L.; An, L.; Wei, L.; Zhao, T. S.

    2016-08-01

    Unlike conventional iron-chromium redox flow batteries (ICRFBs) with a flow-through cell structure, in this work a high-performance ICRFB featuring a flow-field cell structure is developed. It is found that the present flow-field structured ICRFB reaches an energy efficiency of 76.3% with a current density of 120 mA cm-2 at 25 °C. The energy efficiency can be as high as 79.6% with an elevated current density of 200 mA cm-2 at 65 °C, a record performance of the ICRFB in the existing literature. In addition, it is demonstrated that the energy efficiency of the battery is stable during the cycle test, and that the capacity decay rate of the battery is 0.6% per cycle. More excitingly, the high performance of the flow-field structured battery significantly lowers the capital cost at 137.6 kWh-1, which is 28.2% lower than that of the conventional ICRFB for 8-h energy storage.

  18. Inflatable Re-entry Vehicle Experiment (IRVE-4) Overview

    NASA Technical Reports Server (NTRS)

    Litton, Daniel K.; Bose, David M.; Cheatwood, F. McNeil; Hughes, Stephen; Wright, Henry S.; Lindell, Michael C.; Derry, Stephen D.; Olds, Aaron

    2011-01-01

    The suite of Inflatable Re-Entry Vehicle Experiments (IRVE) is designed to further our knowledge and understanding of Hypersonic Inflatable Aerodynamic Decelerators (HIADs). Before infusion into a future mission, three challenges need to be addressed: surviving the heat pulse during re-entry, demonstrating system performance at relevant scales, and demonstrating controllability in the atmosphere. IRVE-4 will contribute to a better understanding of controllability by characterizing how a HIAD responds to a set of controlled inputs. The ability to control a HIAD is vital for missions that are g-limited, require precision targeting and guidance for aerocapture or entry, descent, and landing. The IRVE-4 flight test will focus on taking a first look into controlling a HIAD. This paper will give an overview of the IRVE-4 mission including the control response portion of the flight test sequence, and will provide a review of the mission s development.

  19. Aerothermodynamic Heating Analysis of Aerobraking and Aeromaneuvering Orbital Transfer Vehicles

    NASA Technical Reports Server (NTRS)

    Menees, Gene P.; Davies, Carol B.; Wilson, John F.; Brown, Kevin G.

    1985-01-01

    The thermal-protection requirements of two aeroassisted orbital transfer vehicles (AOTVS) are analyzed for return missions between the geosynchronous and Shuttle orbits. One of the designs is a specialized version of a previously proposed generic aerobraking vehicle that Is capable of only delivery-type operations. The other Is a high-lift aeromaneuvering vehicle that is optimized for low Earth orbit sortie missions involving large, multiple plane-inclination changes. The aerothermal environment of the aerobraking vehicle is analyzed using state-of-the-art methods for nonequilibrium-radiative and convective heating that incorporate refinements unique to the configuration. The heating analysis of the aeromaneuvering vehicle required the development of a flowfield model for rarefied-hypersonic flow over a lifting surface at incidence. The predicted aerothermodynamic heating characteristics for both vehicles are correlated with thermal-control

  20. DSMC Grid Methodologies for Computing Low-Density, Hypersonic Flows About Reusable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Wilmoth, Richard G.; LeBeau, Gerald J.; Carlson, Ann B.

    1996-01-01

    Two different grid methodologies are studied for application to DSMC simulations about reusable launch vehicles. One method uses an unstructured, tetrahedral grid while the other uses a structured, variable-resolution Cartesian grid. The relative merits of each method are discussed in terms of accuracy, computational efficiency, and overall ease of use. Both methods are applied to the computation of a low-density, hypersonic flow about a winged single-stage-to-orbit reusable launch vehicle concept at conditions corresponding to an altitude of 120 km. Both methods are shown to give comparable results for both surface and flowfield quantities as well as for the overall aerodynamic behavior. For the conditions simulated, the flowfield about the vehicle is very rarefied but the DSMC simulations show significant departure from free-molecular predictions for the surface friction and heat transfer as well as certain aerodynamic quantities.

  1. Method and System for Weakening Shock Wave Strength at Leading Edge Surfaces of Vehicle in Supersonic Atmospheric Flight

    NASA Technical Reports Server (NTRS)

    Daso, Endwell O. (Inventor); Pritchett, Victor E., II (Inventor); Wang, Ten-See (Inventor); Farr, Rebecca Ann (Inventor); Auslender, Aaron Howard (Inventor); Blankson, Isaiah M. (Inventor); Plotkin, Kenneth J. (Inventor)

    2015-01-01

    A method and system are provided to weaken shock wave strength at leading edge surfaces of a vehicle in atmospheric flight. One or more flight-related attribute sensed along a vehicle's outer mold line are used to control the injection of a non-heated, non-plasma-producing gas into a local external flowfield of the vehicle from at least one leading-edge surface location along the vehicle's outer mold line. Pressure and/or mass flow rate of the gas so-injected is adjusted in order to cause a Rankine-Hugoniot Jump Condition along the vehicle's outer mold line to be violated.

  2. Automating Structural Analysis of Spacecraft Vehicles

    NASA Technical Reports Server (NTRS)

    Hrinda, Glenn A.

    2004-01-01

    A major effort within NASA's vehicle analysis discipline has been to automate structural analysis and sizing optimization during conceptual design studies of advanced spacecraft. Traditional spacecraft structural sizing has involved detailed finite element analysis (FEA) requiring large degree-of-freedom (DOF) finite element models (FEM). Creation and analysis of these models can be time consuming and limit model size during conceptual designs. The goal is to find an optimal design that meets the mission requirements but produces the lightest structure. A structural sizing tool called HyperSizer has been successfully used in the conceptual design phase of a reusable launch vehicle and planetary exploration spacecraft. The program couples with FEA to enable system level performance assessments and weight predictions including design optimization of material selections and sizing of spacecraft members. The software's analysis capabilities are based on established aerospace structural methods for strength, stability and stiffness that produce adequately sized members and reliable structural weight estimates. The software also helps to identify potential structural deficiencies early in the conceptual design so changes can be made without wasted time. HyperSizer's automated analysis and sizing optimization increases productivity and brings standardization to a systems study. These benefits will be illustrated in examining two different types of conceptual spacecraft designed using the software. A hypersonic air breathing, single stage to orbit (SSTO), reusable launch vehicle (RLV) will be highlighted as well as an aeroshell for a planetary exploration vehicle used for aerocapture at Mars. By showing the two different types of vehicles, the software's flexibility will be demonstrated with an emphasis on reducing aeroshell structural weight. Member sizes, concepts and material selections will be discussed as well as analysis methods used in optimizing the structure

  3. Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

    NASA Technical Reports Server (NTRS)

    Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

    2006-01-01

    As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

  4. Advanced Multi-phase Flow CFD Model Development for Solid Rocket Motor Flowfield Analysis

    NASA Technical Reports Server (NTRS)

    Liaw, Paul; Chen, Yen-Sen

    1995-01-01

    A Navier-Stokes code, finite difference Navier-Stokes (FDNS), is used to analyze the complicated internal flowfield of the SRM (solid rocket motor) to explore the impacts due to the effects of chemical reaction, particle dynamics, and slag accumulation on the solid rocket motor (SRM). The particulate multi-phase flowfield with chemical reaction, particle evaporation, combustion, breakup, and agglomeration models are included in present study to obtain a better understanding of the SRM design. Finite rate chemistry model is applied to simulate the chemical reaction effects. Hermsen correlation model is used for the combustion simulation. The evaporation model introduced by Spalding is utilized to include the heat transfer from the particulate phase to the gase phase due to the evaporation of the particles. A correlation of the minimum particle size for breakup expressed in terms of the Al/Al2O3 surface tension and shear force was employed to simulate the breakup of particles. It is assumed that the breakup occurs when the Weber number exceeds 6. A simple L agglomeration model is used to investigate the particle agglomeration. However, due to the large computer memory requirements for the agglomeration model, only 2D cases are tested with the agglomeration model. The VOF (Volume of Fluid) method is employed to simulate the slag buildup in the aft-end cavity of the redesigned solid rocket motor (RSRM). Monte Carlo method is employed to calculate the turbulent dispersion effect of the particles. The flowfield analysis obtained using the FDNS code in the present research with finite rate chemical reaction, particle evaporation, combustion, breakup, agglomeration, and VOG models will provide a design guide for the potential improvement of the SRM including the use of materials and the shape of nozzle geometry such that a better performance of the SRM can be achieved. The simulation of the slag buildup in the aft-end cavity can assist the designer to improve the design of

  5. Investigation of the iced flowfield characteristics related to the stall margin instrumentation used in icing conditions

    NASA Astrophysics Data System (ADS)

    Pederson, Erik Thomas

    The purpose of this dissertation is to investigate the relationship between the flowfield surrounding an iced airfoil and the stall margin instrumentation developed for use in icing conditions. The stall margin system indicates to the pilot the change in available lift due to ice accretions on the leading edge of an airfoil. This system displays the change in the form of a normalized lift coefficient. Four pressure ports are chosen to specifically maintain a constant calibration curve, for pressure versus normalized lift coefficient, regardless of ice shape. This allows these pressures to be used to determine the change in maximum lift coefficient. The instrumentation currently maintains an accuracy of +/-10%. There was a need to investigate the relationship between the flowfield and the port locations, and the airfoil shape and the port locations. This allowed further understanding of the placement of these ports. Through this investigation, better port locations have been determined and the accuracy and usefulness of the instrumentation has been increased. This investigation was conducted using wind tunnel testing techniques. A 2-D NACA 23012 pressure model and a 2-D NACA 23012 force model were constructed and tested to determine initial port locations for the stall margin instrumentation. Simulated ice shapes were produced using the LEWICE software from NASA Glenn. The flowfield around the airfoil was mapped using smoke wire flow visualization and hotwire anemometry. A single wire system was used to determine a 2-D profile of the turbulence intensity levels surrounding the ice covered wing. The movement of the separation region behind the ice shape, with change in angle of attack, was also investigated. The relationship between this movement and the port locations was documented and its significance determined. Through these observations, better port locations for the stall margin instrumentation were determined thus allowing accuracy of the instrumentation to

  6. Advanced multi-phase flow CFD model development for solid rocket motor flowfield analysis

    NASA Astrophysics Data System (ADS)

    Liaw, Paul; Chen, Yen-Sen

    1995-03-01

    A Navier-Stokes code, finite difference Navier-Stokes (FDNS), is used to analyze the complicated internal flowfield of the SRM (solid rocket motor) to explore the impacts due to the effects of chemical reaction, particle dynamics, and slag accumulation on the solid rocket motor (SRM). The particulate multi-phase flowfield with chemical reaction, particle evaporation, combustion, breakup, and agglomeration models are included in present study to obtain a better understanding of the SRM design. Finite rate chemistry model is applied to simulate the chemical reaction effects. Hermsen correlation model is used for the combustion simulation. The evaporation model introduced by Spalding is utilized to include the heat transfer from the particulate phase to the gase phase due to the evaporation of the particles. A correlation of the minimum particle size for breakup expressed in terms of the Al/Al2O3 surface tension and shear force was employed to simulate the breakup of particles. It is assumed that the breakup occurs when the Weber number exceeds 6. A simple L agglomeration model is used to investigate the particle agglomeration. However, due to the large computer memory requirements for the agglomeration model, only 2D cases are tested with the agglomeration model. The VOF (Volume of Fluid) method is employed to simulate the slag buildup in the aft-end cavity of the redesigned solid rocket motor (RSRM). Monte Carlo method is employed to calculate the turbulent dispersion effect of the particles. The flowfield analysis obtained using the FDNS code in the present research with finite rate chemical reaction, particle evaporation, combustion, breakup, agglomeration, and VOG models will provide a design guide for the potential improvement of the SRM including the use of materials and the shape of nozzle geometry such that a better performance of the SRM can be achieved. The simulation of the slag buildup in the aft-end cavity can assist the designer to improve the design of

  7. Flow-Field Measurement of Device-Induced Embedded Streamwise Vortex on a Flat Plate

    NASA Technical Reports Server (NTRS)

    Yao, Chung-Sheng; Lin, John C.; Allan, Brian G.

    2002-01-01

    Detailed flow-field measurements were performed downstream of a single vortex generator (VG) using an advanced Stereo Digital Particle Image Velocimetry system. Thc passive flow-control devices examined consisted of a low-profile VG with a device height, h, approximately equal to 20 percent of the boundary-layer thickness, sigma, and a conventional VG with h is approximately sigma. Flow-field data were taken at twelve cross-flow planes downstream of the VG to document and quantify the evolution of embedded streamwise vortex. The effects of device angle of attack on vortex development downstream were compared between the low-profile VG and the conventional VG. Key parameters including vorticity, circulation, trajectory, and half-life radius - describing concentration, strength, path, and size, respectively--of the device-induced streamwise vortex were extracted from the flow-field data. The magnitude of maximum vorticity increases as angle of attack increases for the low-profile VG, but the trend is reversed for the conventional VG, probably due to flow stalling around the larger device at higher angles of attack. Peak vorticity and circulation for the low-profile VG decays exponentially and inversely proportional to the distance downstream from the device. The device-height normalized vortex trajectories for the low-profile VG, especially in the lateral direction, follow the general trends of the conventional VG. The experimental database was used to validate the predictive capability of computational fluid dynamics (CFD). CFD accurately predicts the vortex circulation and path; however, improvements are needed for predicting the vorticity strength and vortex size.

  8. 2-D and 3-D numerical simulation of a supersonic inlet flowfield

    NASA Astrophysics Data System (ADS)

    Enomoto, Shunji; Arakawa, Chuichi

    The 2-D and 3-D steady, Reynolds-averaged Navier-Stokes equations were numerically solved for the flowfields in an experimentally tested inlet model with bleed through a cavity. In the 2-D analysis, a normal shock was located at diffuser inlet instead of the position below the cavity. The normal shock in the middle of the diffuser caused a massive separation of the boundary layer and a large total pressure loss. In the 3-D analysis, the shock wave was distorted by the side wall boundary layer separation, and the complex flow structure was established. The result of the 3-D analysis agreed well with the experiment.

  9. Application of Chimera Grid Scheme to Combustor Flowfields at all Speeds

    NASA Technical Reports Server (NTRS)

    Yungster, Shaye; Chen, Kuo-Huey

    1997-01-01

    A CFD method for solving combustor flowfields at all speeds on complex configurations is presented. The approach is based on the ALLSPD-3D code which uses the compressible formulation of the flow equations including real gas effects, nonequilibrium chemistry and spray combustion. To facilitate the analysis of complex geometries, the chimera grid method is utilized. To the best of our knowledge, this is the first application of the chimera scheme to reacting flows. In order to evaluate the effectiveness of this numerical approach, several benchmark calculations of subsonic flows are presented. These include steady and unsteady flows, and bluff-body stabilized spray and premixed combustion flames.

  10. Propulsion-related flowfields using the preconditioned Navier-Stokes equations

    NASA Technical Reports Server (NTRS)

    Venkateswaran, S.; Weiss, J. M.; Merkle, C. L.; Choi, Y.-H.

    1992-01-01

    A previous time-derivative preconditioning procedure for solving the Navier-Stokes is extended to the chemical species equations. The scheme is implemented using both the implicit ADI and the explicit Runge-Kutta algorithms. A new definition for time-step is proposed to enable grid-independent convergence. Several examples of both reacting and non-reacting propulsion-related flowfields are considered. In all cases, convergence that is superior to conventional methods is demonstrated. Accuracy is verified using the example of a backward facing step. These results demonstrate that preconditioning can enhance the capability of density-based methods over a wide range of Mach and Reynolds numbers.

  11. Complete analysis of steady and transient missile aerodynamic/propulsive/plume flowfield interactions

    NASA Astrophysics Data System (ADS)

    York, B. J.; Sinha, N.; Dash, S. M.; Hosangadi, A.; Kenzakowski, D. C.; Lee, R. A.

    1992-07-01

    The analysis of steady and transient aerodynamic/propulsive/plume flowfield interactions utilizing several state-of-the-art computer codes (PARCH, CRAFT, and SCHAFT) is discussed. These codes have been extended to include advanced turbulence models, generalized thermochemistry, and multiphase nonequilibrium capabilities. Several specialized versions of these codes have been developed for specific applications. This paper presents a brief overview of these codes followed by selected cases demonstrating steady and transient analyses of conventional as well as advanced missile systems. Areas requiring upgrades include turbulence modeling in a highly compressible environment and the treatment of particulates in general. Recent progress in these areas are highlighted.

  12. Two-dimensional calculation of chemical species and electrical properties in rocket plume flowfields

    NASA Astrophysics Data System (ADS)

    Zhang, Ping; Cui, Jisong; Liu, Qingyun

    1993-08-01

    A computational modeling technique and prediction method are presented for calculating two-dimensional profiles of chemical species mole fraction and electrical properties of rocket exhaust plumes. A comprehensive computer code has been programmed. The chemical reactions and radar attenuation which occur in a rocket plume can be predicted more truly by using this code. It is suitable to calculating parameters of rocket plumes under a near complete-expansion condition and for smokeless (or reduced smoke) propellant application. The calculation results indicate that evident errors will occur for prediction of chemical and electrical parameters in the plume flowfield if the chemical reactions in the plume are ignored.

  13. Thin graphite bipolar plate with associated gaskets and carbon cloth flow-field for use in an ionomer membrane fuel cell

    DOEpatents

    Marchetti, George A.

    2003-01-03

    The present invention comprises a thin graphite plate with associated gaskets and pieces of carbon cloth that comprise a flow-field. The plate, gaskets and flow-field comprise a "plate and gasket assembly" for use in an ionomer membrane fuel cell, fuel cell stack or battery.

  14. A three-dimensional upwind PNS code for chemically reacting scramjet flowfields. [Parabolized Navier Stokes

    SciTech Connect

    Wadawadigi, G.; Tannehill, J.C.; Buelow, P.E.; Lawrence, S.L. NASA, Ames Research Center, Moffett Field, CA )

    1992-07-01

    A new upwind, parabolized Navier-Stokes (PNS) code has been developed to compute the three-dimensional (3D) chemically reacting flow in scramjet (supersonic combustion ramjet) engines. The code is a modification of the 3D upwind PNS (UPS) airflow code which has been extended in the present study to permit internal flow calculations with hydrogen-air chemistry. With these additions, the new code has the capability of computing aerodynamic and propulsive flowfields simultaneously. The algorithm solves the PNS equations using a finite-volume, upwind TVD method based on Roe's approximate Riemann solver that has been modified to account for 'real gas' effects. The fluid medium is assumed to be a chemically reacting mixture of thermally perfect (but calorically imperfect) gases in thermal equilibrium. The new code has been applied to two test cases. These include the Burrows-Kurkov supersonic combustion experiment and a generic 3D scramjet flowfield. The computed results compare favorably with the available experimental data. 38 refs.

  15. Wind Code Application to External Forebody Flowfields with Comparisons to Experimental Results

    NASA Technical Reports Server (NTRS)

    Frate, F. C.; Kim, H. D.

    2001-01-01

    The WIND Code, a general purpose Navier-Stokes solver, has been utilized to obtain supersonic external flowfield Computational Fluid Dynamics (CFD) solutions over an axisymmetric, parabolic forebody with comparisons made to wind tunnel experimental results. Various cases have been investigated at supersonic freestream conditions ranging from Mach 2.0 to 3.5, at 0 deg and 3 deg angles-of-attack, and with either a sharp-nose or blunt-nose forebody configuration. Both a turbulent (Baldwin-Lomax algebraic turbulence model) and a laminar model have been implemented in the CFD. Obtaining the solutions involved utilizing either the parabolized- or full-Navier-Stokes analyses supplied in WIND. Comparisons have been made with static pressure measurements, with boundary-layer rake and flowfield rake pitot pressure measurements, and with temperature sensitive paint experimental results. Using WIND's parabolized Navier-Stokes capability, grid sequencing, and the Baldwin-Lomax algebraic turbulence model allowed for significant reductions in computational time while still providing good agreement with experiment. Given that CFD and experiment compare well, WIND is found to be a good computational platform for solving this type of forebody problem, and the grids developed in conjunction with it will be used in the future to investigate varying freestream conditions not tested experimentally.

  16. Design of a Scaled Model for Experimental Flowfield Studies of Louvered Plate Fins.

    NASA Astrophysics Data System (ADS)

    Springer, Marlow E.; Thole, Karen A.

    1997-11-01

    The optimization of compact heat exchangers maximizing heat transfer while minimizing pressure drop is important for many industrial applications. Because the dominant thermal resistance for most air-and-water or air-and-oil heat exchangers occurs on the air side, an understanding of the flowfield on the air side is needed to further optimize the heat exchanger. Louvered plate fin heat exchangers are used not only to increase the convective heat transfer surface area, but also to initiate the growth of multiple boundary layers. There is also evidence that vortex shedding occurs from the trailing edge of the louvers, which would increase heat transfer. Computational fluid dynamics models have been used to design a scaled up model of a louvered plate fin geometry representative of what would occur in a compact heat exchanger. The current model has a louver angle of 27^circ and a louver-to-fin pitch ratio of 1.31. The same technique can be used to design models for other geometries. Critical issues in the design include endwall spacings to maintain a straight inlet flow, and the required number of louver rows to capture the periodic nature of a heat exchanger with perhaps hundreds of rows. Within the louver passages, measurements of mean and time-resolved velocities to characterize the mean flowfield and vortex shedding have been obtained using laser Doppler velocimetry.

  17. Evaporation and burning of a spherical fuel droplet in a uniform convective flowfield

    SciTech Connect

    Madooglu, K.

    1992-01-01

    An analytical/numerical model is developed for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential-flow solution, while the internal flowfield of the droplet is represented by the classical Hill's spherical vortex. This allows a numerical solution for the external boundary layer, from which the droplet's effective drag coefficent, rate of mass loss, size, and the shape of the diffusion flame with infinitely fast chemical reaction kinetics are determined. Subsequently, the quasi-steady model with uniform liquid temperature is extended to examine the effects of the transient heating of the droplet interior. Time-dependent calculations are performed with updated droplet Reynolds numbers and updated surface temperatures. Comparisons of model predictions with experimental data are made. To examine the effects of finite-rate chemical reaction kinetics, a one-step formulation of the combustion mechanism is integrated into the gaseous boundary layer equations. Simplifying assumptions for the variation of gas properties commonly used in combustion calculations, are subjected to an examination as to their degree of accuracy. For this purpose, the droplet model is extended to account for the variation of gas properties with temperature and gas composition within the boundary layer. Comparisons are made between the predictions obtained from the different models developed in this study, as well as with existing experimental data.

  18. Computational models for the analysis of three-dimensional internal and exhaust plume flowfields

    NASA Technical Reports Server (NTRS)

    Dash, S. M.; Delguidice, P. D.

    1977-01-01

    This paper describes computational procedures developed for the analysis of three-dimensional supersonic ducted flows and multinozzle exhaust plume flowfields. The models/codes embodying these procedures cater to a broad spectrum of geometric situations via the use of multiple reference plane grid networks in several coordinate systems. Shock capturing techniques are employed to trace the propagation and interaction of multiple shock surfaces while the plume interface, separating the exhaust and external flows, and the plume external shock are discretely analyzed. The computational grid within the reference planes follows the trace of streamlines to facilitate the incorporation of finite-rate chemistry and viscous computational capabilities. Exhaust gas properties consist of combustion products in chemical equilibrium. The computational accuracy of the models/codes is assessed via comparisons with exact solutions, results of other codes and experimental data. Results are presented for the flows in two-dimensional convergent and divergent ducts, expansive and compressive corner flows, flow in a rectangular nozzle and the plume flowfields for exhausts issuing out of single and multiple rectangular nozzles.

  19. Flowfield And Download Measurements And Computation of a Tiltrotor Aircraft In Hover

    NASA Technical Reports Server (NTRS)

    Brand, Albert G.; Peryea, Martin A.; Wood, Tom L.; Meakin, Robert L.

    2001-01-01

    A multipart study of the V-22 hover flowfield was conducted. Testing involved a 0.15-scale semispan model with multiple independent force balance systems. The velocity flowfield surrounding the airframe was measured using a robotic positioning system and anemometer. Both time averaged and cycle-averaged results are reported. It is shown that the fuselage download in hover can be significantly reduced using a small download reduction device. Measurements indicate that the success of the device is attributed to the substantial elimination of tiltrotor fountain flow. As part of.the study, an unsteady CFD prediction is time-averaged, and shown to have excellent agreement in predicting the baseline configuration fountain flow. Some discrepancies at the outboard edge of the rotor are discussed. An &&sessment of an advanced tip shape rotor comp"'Ietes the study. Derived from a nonrotating study, the advanced tip shape rotor was developed and tested on the Bell 0.15 scale semi-span V-22 model. The tip shape was intended to diffuse the tip vortex and reduce BVI noise. Rotor wake vorticity is extracted from the measured velocity dam to show that the advanced tip shape produces a tip vortex that is only slightly more diffuse than the baseline tip blade. The results indicate that nonrotating tests may overpredict the amount of tip vortex diffusion achieved by tip shape design in a rotating environment.

  20. Flow-Field Measurement of a Hybrid Wing Body Model with Blown Flaps

    NASA Technical Reports Server (NTRS)

    Lin, John C.; Jones, Gregory S.; Allan, Brian G.; Westra, Bryan W.; Collins, Scott W.; Zeune, Cal H.

    2008-01-01

    In this paper we describe flow-field measurements obtained in the wake of a full-span Hybrid Wing Body model with internally blown flaps. The test was performed at the NASA Langley 14 x 22 Foot Subsonic Tunnel at low speeds. Off-body measurements were obtained with a 7-hole probe rake survey system. Three model configurations were investigated. At 0deg angle of attack the surveys were completed with 0deg and 60deg flap deflections. At 10deg angle of attack the wake surveys were completed with a slat and a 60deg flap deflection. The 7-hole probe results further quantified two known swirling regions (downstream of the outboard flap edge and the inboard/outboard flap juncture) for the 60deg flap cases with blowing. Flow-field results and the general trends are very similar for the two blowing cases at nozzle pressure ratios of 1.37 and 1.56. High downwash velocities correlated with the enhanced lift for the 60deg flap cases with blowing. Jet-induced effects are the largest at the most inboard station for all (three) velocity components due in part to the larger inboard slot height. The experimental data are being used to improve computational tools for high-lift wings with integrated powered-lift technologies.

  1. Time dependent heat transfer rates in high Reynolds number hypersonic flowfields

    NASA Technical Reports Server (NTRS)

    Flanagan, Michael J.

    1992-01-01

    Time dependent heat transfer rates have been calculated from time dependent temperature measurements in the vicinity of shock-wave boundary-layer interactions due to conical compression ramps on an axisymmetric body. The basic model is a cylindrical body with a 10 degree conical nose. Four conical ramps, 20, 25, 30, and 35 degrees serve as shock wave generators. Flowfield surveys have been made in the vicinity of the conical ramp vertex, the separation point, and the reattachment point. A significant effort was made to characterize the natural frequencies and relative powers of the resulting fluctuations in heat transfer rates. This research effort, sponsored jointly by NASA and the Air Force, was conducted in the Air Force Flight Dynamics Directorate High Reynolds Facility. The nominal freestream Mach number was 6, and the freestream Reynolds numbers ranged from 2.2 million/ft to 30.0 million/ft. Experimental results quantify temperature response and the resulting heat transfer rates as a function of ramp angle and Reynolds number. The temperature response within the flowfield appears to be steady-state for all compression ramp angles and all Reynolds numbers, and hence, the heat transfer rates appear to be steady-state.

  2. Flowfield Measurements in a Slot-Bled Oblique Shock Wave and Turbulent Boundary-Layer Interaction

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Willis, B. P.; Hingst, W. R.

    1998-01-01

    An experimental investigation was conducted to determine the flowfield inside a bleed slot used to control an oblique shock-wave and turbulent boundary-layer interaction. The slot was oriented normal to the primary flow direction and had a width of 1.0 cm (primary flow direction), a length of 2.54 cm, and spanned 16.5 cm. The approach boundary layer upstream of the interaction was nominally 3.0 cm thick. Two operating conditions were studied: M = 1.98 with a shock generator deflection angle of 6 deg and M= 2.46 with a shock generator deflection angle of 8 deg. Measurements include surface and flowfield static pressure, Pitot pressure, and total mass-flow through the slot. The results show that despite an initially two-dimensional interaction for the zero bleed-flow case, the slot does not remove mass uniformly in the spanwise direction. Inside the slot, the flow is characterized by two separation regions which significantly reduce the effective flow area. The upper separation region acts as an aerodynamic throat resulting in supersonic flow through much of the slot.

  3. Effects of a Forward-swept Front Rotor on the Flowfield of a Counterrotation Propeller

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Podboy, Gary G.

    1994-01-01

    The effects of a forward-swept front rotor on the flowfield of a counterrotation model propeller at takeoff conditions at zero degree angle of attack are studied by solving the unsteady three-dimensional Euler equations. The configuration considered is an uneven blade count counterrotation model with twelve forward-swept blades on the fore rotor and ten aft-swept blades on the aft rotor. The flowfield is compared with that of a reference aft-swept counterrotation geometry and Laser Doppler Velocimeter (LDV) measurements. At the operating conditions considered, the forward-swept blade experiences a higher tip loading and produces a stronger tip vortex compared to the aft-swept blade, consistent with the LDV and acoustic measurements. Neither the solution nor the LDV data indicated the formation of a leading edge vortex. The predicted radial distribution of the circumferentially averaged axial velocity at the measurement station agreed very closely with LDV data, while crossflow velocities showed poor agreement. The discrepancy between prediction and LDV data of tangential and radial velocities is due in part to the insufficient mesh resolution in the region between the rotors and in the tip region to track the tip vortex. The vortex is diffused by the time it arrives at the measurement station. The uneven blade count configuration requires the solution to be carried out for six blade passages of the fore rotor and five passages of the aft rotor, thus making grid refinement prohibitive.

  4. Three-Dimensional Numerical Analysis for Posture Stability of Laser Propulsion Vehicle

    NASA Astrophysics Data System (ADS)

    Takahashi, Masayuki; Ohnishi, Naofumi

    2011-11-01

    We have developed a three-dimensional hydrodynamics code coupling equation of motion of a rigid body for analyzing posture stability of laser propulsion vehicle through numerical simulations of flowfield interacting with unsteady motion of the vehicle. Asymmetric energy distribution is initially added around the focal spot (ring) in order to examine posture stability against an asymmetric blast wave resulting from a laser offset for a lightcraft-type vehicle. The vehicle moves to cancel out the offset from initial offset. However, the Euler angle grows and never returns to zero in a time scale of laser pulse. Also, we found that the vehicle moves to cancel tipping angle when the laser is irradiated to the vehicle with initial tipping angle over the wide angle range, through the vehicle cannot get sufficient restoring force in particular angle, and the tipping angle does not decrease from the initial value for that case.

  5. GEOPHYSICS, ASTRONOMY AND ASTROPHYSICS: Scaling of the flowfield in a combustion chamber with a gas-gas injector

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

    The scaling of the flowfield in a gas-gas combustion chamber is investigated theoretically, numerically and experimentally. To obtain the scaling criterion of the gas-gas combustion flowfield, formulation analysis of the three-dimensional (3D) Navier-Stokes equations for a gaseous multi-component mixing reaction flow is conducted and dimensional analysis on the gas-gas combustion phenomena is also carried out. The criterion implies that the size and the pressure of the gas-gas combustion chamber can be changed. Based on the criterion, multi-element injector chambers with different geometric sizes and at different chamber pressures ranging from 3 MPa to 20 MPa are numerically simulated. A multi-element injector chamber is designed and hot-fire tested at five chamber pressures from 1.64 MPa to 3.68 MPa. Wall temperature measurements are used to understand the similarity of combustion flowfields in the tests. The results have verified the similarities between combustion flowfields under different chamber pressures and geometries, with the criterion applied.

  6. Advanced Optical Diagnostic Methods for Describing Fuel Injection and Combustion Flowfield Phenomena

    NASA Technical Reports Server (NTRS)

    Locke, Randy J.; Hicks, Yolanda R.; Anderson, Robert C.

    2004-01-01

    Over the past decade advanced optical diagnostic techniques have evolved and matured to a point where they are now widely applied in the interrogation of high pressure combusting flows. At NASA Glenn Research Center (GRC), imaging techniques have been used successfully in on-going work to develop the next generation of commercial aircraft gas turbine combustors. This work has centered on providing a means by which researchers and designers can obtain direct visual observation and measurements of the fuel injection/mixing/combustion processes and combustor flowfield in two- and three-dimensional views at actual operational conditions. Obtaining a thorough understanding of the chemical and physical processes at the extreme operating conditions of the next generation of combustors is critical to reducing emissions and increasing fuel efficiency. To accomplish this and other tasks, the diagnostic team at GRC has designed and constructed optically accessible, high pressurer high temperature flame tubes and sectar rigs capable of optically probing the 20-60 atm flowfields of these aero-combustors. Among the techniques employed at GRC are planar laser-induced fluorescence (PLIF) for imaging molecular species as well as liquid and gaseous fuel; planar light scattering (PLS) for imaging fuel sprays and droplets; and spontaneous Raman scattering for species and temperature measurement. Using these techniques, optical measurements never before possible have been made in the actual environments of liquid fueled gas turbines. 2-D mapping of such parameters as species (e.g. OH-, NO and kerosene-based jet fuel) distribution, injector spray angle, and fuel/air distribution are just some of the measurements that are now routinely made. Optical imaging has also provided prompt feedback to researchers regarding the effects of changes in the fuel injector configuration on both combustor performance and flowfield character. Several injector design modifications and improvements have

  7. Dynamics of the flame flowfields in a low-swirl burner

    SciTech Connect

    Cheng, Robert; Johnson, Matthew R.; Cheng, Robert K.

    2003-07-01

    The concept of using low swirl to stabilize lean premixed turbulent flame was introduced in 1992. Since then, the low-swirl burner (LSB) has become a useful laboratory tool for the study of detailed flame structures as well as turbulent burning speeds. Its main attribute is that the flame is freely propagating and is locally normal to the turbulent approach flow (Figure 1). Therefore, the turbulent flame brush is not influence by physical boundaries. The capability of LSB to support very lean flames and very turbulent flames [1, 2] was further exploited in recent studies to test the validity of the flame regime concept. Using 2D imaging diagnostics (e.g. planar laser induced fluorescence, PLIF, and planar laser induced Rayleigh scattering) our analysis showed that the wrinkled flame regime to be valid at a turbulence intensity level much higher than previously thought [3-5]. This provided experimental verification of a new 'thin reaction zone' regime for the Kalovitz number range of 1 < Ka < 10 (Ka = (u{prime}/s{sub L}){sup 3/2} (l{sub x}/d{sub L}){sup 1/2}) proposed by Peters. Due to its freely propagating nature, modeling and simulations of LSB flames are non-trivial. The flame position cannot be specified a priori because it is coupled to the turbulent flowfield and the turbulent flame speed may be required as input. This has not been a significant issue when treating the LSB flame as a close approximation to a 1D premixed turbulent flame. However, to support the development of more robust 3D simulation methods, accurate information on the flowfield dynamics in particular those at the burner exit and the interactions between the core and swirl air flows becomes important. In the past, velocity measurements in LSB have concentrated on collecting information along the centerline. The objective of this investigation is to conduct a detailed study using particle image velocimetry (PIV) to provide the flowfield information that are more suited to support 3D

  8. Development of a Nonequilibrium Radiative Heating Prediction Method for Coupled Flowfield Solutions

    NASA Technical Reports Server (NTRS)

    Hartung, Lin C.

    1991-01-01

    A method for predicting radiative heating and coupling effects in nonequilibrium flow-fields has been developed. The method resolves atomic lines with a minimum number of spectral points, and treats molecular radiation using the smeared band approximation. To further minimize computational time, the calculation is performed on an optimized spectrum, which is computed for each flow condition to enhance spectral resolution. Additional time savings are obtained by performing the radiation calculation on a subgrid optimally selected for accuracy. Representative results from the new method are compared to previous work to demonstrate that the speedup does not cause a loss of accuracy and is sufficient to make coupled solutions practical. The method is found to be a useful tool for studies of nonequilibrium flows.

  9. On the prediction of swirling flowfields found in axisymmetric combustor geometries

    NASA Technical Reports Server (NTRS)

    Rhode, D. L.; Lilley, D. G.; Mclaughlin, D. K.

    1981-01-01

    The paper reports research restricted to steady turbulence flow in axisymmetric geometries under low speed and nonreacting conditions. Numerical computations are performed for a basic two-dimensional axisymmetrical flow field similar to that found in a conventional gas turbine combustor. Calculations include a stairstep boundary representation of the expansion flow, a conventional k-epsilon turbulence model and realistic accomodation of swirl effects. A preliminary evaluation of the accuracy of computed flowfields is accomplished by comparisons with flow visualizations using neutrally-buoyant helium-filled soap bubbles as tracer particles. Comparisons of calculated results show good agreement, and it is found that a problem in swirling flows is the accuracy with which the sizes and shapes of the recirculation zones may be predicted, which may be attributed to the quality of the turbulence model.

  10. Navier-Stokes calculation of solid-propellant rocket motor internal flowfields

    NASA Technical Reports Server (NTRS)

    Hsieh, Kwang-Chung; Yang, Vigor; Tseng, Jesse I. S.

    1988-01-01

    A comprehensive numerical analysis has been carried out to study the detailed physical and chemical processes involved in the combustion of homogeneous propellant in a rocket motor. The formulation is based on the time-dependent full Navier-Stokes equations, with special attention devoted to the chemical reactions in both gas and condensed phases. The turbulence closure is achieved using both the Baldwin-Lomax algebraic model and a modified k-epsilon two-equation scheme with a low Reynolds number and near-wall treatment. The effects of variable thermodynamic and transport properties are also included. The system of governing equations are solved using a multi-stage Runge-Kutta shceme with the source terms treated implicitly. Preliminary results clearly demonstrate the presence of various combustion regimes in the vicinity of propellant surface. The effects of propellant combustion on the motor internal flowfields are investigated in detail.

  11. Wind-tunnel research of flowfields within naturally ventilated rooms of simple geometry

    SciTech Connect

    Poreh, M.; Cermak, J.E.; Peterka, J.A.

    1982-09-01

    The study described consisted of wind-tunnel experiments to determine the flowfield created within a box-like structure containing two windows. Three configurations of the structure were investigated. The pressure distributions on the closed windows and the pressure at the same locations with open windows were measured and related to the approach flow. The mean air speed and the turbulence intensities near the windows and at various locations inside the rooms were measured using an omni-directional hot-film probe and a vertical, cylindrical hot-film probe. The air speed inside the room and at the windows was related to the approach flow and the pressures on the closed windows. Flow visualization using smoke and cotton tufts was used to study the flow patterns and the direction of the air flow at various locations inside each structure. Black and white photographs showing the basic features of the flow are presented.

  12. Supersonic-nitrogen flow-field measurements with the resonant Doppler velocimeter

    NASA Technical Reports Server (NTRS)

    Cheng, S.; Zimmermann, M.; Miles, R. B.

    1983-01-01

    The application of the resonant Doppler velocimeter (RDV) for obtaining the mean velocity, temperature, and pressure measurements and flow-field visualization in a supersonic free nitrogen jet is reported. This method utilizes laser-induced fluorescence to determine the spectral absorption of an atomic or molecular species seeded into the flow. A narrow linewidth tunable laser is directed into the flow and the total fluorescence from any point is obtained as the laser is tuned. The velocity of the flow is obtained from the Doppler shifted absorption frequency, and the temperature and pressure of the gas are determined from line broadening measurements. Results are presented for the use of this technique to determine the velocity, temperature, and pressure of the flow of sodium atoms seeded into a supersonic nitrogen jet. It is concluded that the visible signal is sufficiently intense for spatially resolved flow visualization purposes.

  13. Computational analysis of the flowfield of a two-dimensional ejector nozzle

    NASA Technical Reports Server (NTRS)

    Choi, Y. H.; Soh, W. Y.

    1990-01-01

    A time-iterative full Navier-Stokes code, PARC, is used to analyze the flowfield of a two-dimensional ejector nozzle system. A parametric study was performed for two controlling parameters, duct to nozzle area ratio and nozzle pressure ratio. Results show that there is an optimum area ratio for the efficient pumping of secondary flow. At high area ratios, a freestream flow passes directly through the mixing duct without giving adequate pumping. At low area ratios, the jet boundary blocks the incoming flow. The nozzle pressure ratio variation shows that the pumping rate increases as the pressure ratio increases, provided there is no interaction between the shroud wall and the shock cell structure.

  14. A careful numerical study of flowfields about external conical corners. I - Symmetric configurations

    NASA Technical Reports Server (NTRS)

    Salas, M. D.

    1979-01-01

    A numerical study of the flowfield about symmetrical external axial corners formed by the juncture of swept compressive wedges is presented. The geometrical configuration under investigation allows a unified treatment of external corners typical of delta wings and of rectangular inlets. Comparisons are made with other numerical results. For the delta wing configuration, the occurrence of an anomalous shock behavior predicted by Gonor is discussed. A parametric study shows the singular behavior of the pressure at the corner as a function of the external corner angle, and a second parametric study shows the effect of finite corner radius on the location of the crossflow stagnation point. Previous theoretical predictions of certain flow features typical of corner flows agree well with present numerical results.

  15. Effects of Buoyancy on the Flowfields of Lean Premixed Turbulent V-Flames

    NASA Technical Reports Server (NTRS)

    Cheng, R. K.; Bedat, B.; Yegian, D. T.; Greenberg, P.

    1999-01-01

    Open laboratory turbulent flames used for investigating fundamental flame turbulence interactions are greatly affected by buoyancy. Though much of our current knowledge is based on observations made in open flames, buoyancy effects are usually not considered in data interpretation, numerical analysis or theories. This inconsistency remains an obstacle to merging experimental observations and theoretical predictions. To better understanding the effects of buoyancy, our research focuses on steady lean premixed flames propagating in fully developed turbulence. We hypothesize that the most significant role of buoyancy forces on these flames is to influence their flowfields through a coupling with the mean and the fluctuating pressure fields. This coupling relates to the elliptical problem that emphasizes the importance of the upstream, wall and downstream boundary conditions in determining all aspects of flame propagation. Therefore, buoyancy has the same significance as other parameters such as flow configuration, and flame geometry.

  16. Effect of geometry on the nose-region flow-field of shuttle entry-configurations

    NASA Technical Reports Server (NTRS)

    Bertin, J. J.; Faria, H. T.

    1973-01-01

    In order to determine the convective heat-transfer distribution for the nose region of the space shuttle entry configurations, a three-dimensional flow-field is described which may include extensive regions of separated flow. Because of the complexity of the flow field for the nose region, experimental data are needed to define the relation between the nose geometry and the resultant flow field. According to theoretical solutions of the three-dimensional boundary layer, the boundary layer separates from the leeward generator of a blunted cone at an alpha equal to the cone half-angle. Separation results from the transverse pressure gradient, i.e., the velocity derivative due to crossflow. The boundary layer limiting streamlines converge toward the singular point of sep aration. The separated region is bounded by an ordinary line of separation.

  17. Experimental flowfield visualization of a high alpha wing at Mach 1.62

    NASA Technical Reports Server (NTRS)

    Pittman, James L.

    1987-01-01

    Experimental oil-flow and tuft patterns and vapor-screen flow-visualization data were obtained on a cambered wing model at Mach = 1.62 for an angle-of attack range of 0-14 deg. These data were used as flow diagnostic tools along with surface-pressure and force data and full-potential theory calculations. A large separation bubble was found on the lower wing surface at low angle of attack. The high-angle-of-attack flowfield was characterized by a large attached-flow leading-edge expansion followed by a crossflow shock. At alpha = 14 deg the crossflow shock apparently induced discrete regions of streamwise separated flow, which were clearly indicated in the vapor-screen and oil-flow photographs.

  18. Experimental flowfield visualization of a high alpha wing at Mach 1.62

    NASA Technical Reports Server (NTRS)

    Pittman, James L.

    1987-01-01

    Experimental oil-flow and tuft patterns and vapor-screen flow-visualization data were obtained on a cambered wing model at Mach 1.62 for an angle-of-attack range of 0 to 14 deg. These data were used as flow diagnostic tools along with surface-pressure and force data and full-potential theory calculations. A large separation bubble was found on the lower wing surface at low angle of attack. The high-angle-of-attack flowfield was characterized by a large attached-flow leading-edge expansion followed by a cross-flow shock. At 14 deg, the cross-flow shock apparently induced discrete regions of streamwise separated flow which were clearly indicated in the vapor-screen and oil-flow photographs.

  19. A Grid-resolved Analysis of Base Flowfield for a Four-Engine Clustered Nozzle Configuration

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See

    1993-01-01

    The objective of this study is to propose a computational methodology that can effectively anchor the base flowfield of a four-engine clustered nozzle configuration. This computational methodology is based on a three-dimensional, viscous flow, pressure-based computational fluid dynamics (CFD) formulation. For efficient CFD calculation, a Prandtl-Meyer solution treatment is applied to the algebraic grid lines for initial plume expansion resolution. As the solution evolves, the computational grid is adapted to the pertinent flow gradients. The CFD model employs an upwind scheme in which second- and fourth-order central differencing schemes with artificial dissipation are used. The computed quantitative base flow properties such as the radial base pressure distributions, model centerline static pressure, Mach number and impact pressure variations, and base pressure characteristic curve agreed reasonably well with those of the measurement.

  20. Plasma Flowfields Around Low Earth Orbit Objects: Aerodynamics to Underpin Orbit Predictions

    NASA Astrophysics Data System (ADS)

    Capon, Christopher; Boyce, Russell; Brown, Melrose

    2016-07-01

    Interactions between orbiting bodies and the charged space environment are complex. The large variation in passive body parameters e.g. size, geometry and materials, makes the plasma-body interaction in Low Earth Orbit (LEO) a region rich in fundamental physical phenomena. The aerodynamic interaction of LEO orbiting bodies with the neutral environment constitutes the largest non-conservative force on the body. However in general, study of the LEO plasma-body interaction has not been concerned with external flow physics, but rather with the effects on surface charging. The impact of ionospheric flow physics on the forces on space debris (and active objects) is not well understood. The work presented here investigates the contribution that plasma-body interactions have on the flow structure and hence on the total atmospheric force vector experienced by a polar orbiting LEO body. This work applies a hybrid Particle-in-Cell (PIC) - Direct Simulation Monte Carlo (DSMC) code, pdFoam, to self-consistently model the electrostatic flowfield about a cylinder with a uniform, fixed surface potential. Flow conditions are representative of the mean conditions experienced by the Earth Observing Satellite (EOS) based on the International Reference Ionosphere model (IRI-86). The electron distribution function is represented by a non-linear Boltzmann electron fluid and ion gas-surface interactions are assumed to be that of a neutralising, conducting, thermally accommodating solid wall with diffuse reflections. The variation in flowfield and aerodynamic properties with surface potential at a fixed flow condition is investigated, and insight into the relative contributions of charged and neutral species to the flow physics experienced by a LEO orbiting body is provided. This in turn is intended to help improve the fidelity of physics-based orbit predictions for space debris and other near-Earth space objects.

  1. Study on numerical simulation of flowfield in afterburner for ducted rocket

    NASA Astrophysics Data System (ADS)

    Ding, Xiaoyu; Jin, Xing; Zhang, Peng

    2015-03-01

    Ducted rocket has been widely concerned on account of its high specific impulse, combustion stability and convenient maintenance which mixes the exhaust from a fuel gas generator with air from air inlet, and burns to produce thrust. It is necessary to establish two-dimensional or three-dimensional numerical models based on computational fluid dynamics to study on the flowfield in afterburner which is the key of ducted rocket because of expensive experiments, which is aimed at providing theoretical foundation for ducted rocket's development. In this paper, the gas-phase turbulent combustion process in afterburner with dual inlet three-dimensional mode was simulated numerically by solving Favre-averaged compressible turbulent N-S equations, the renormalization group (RNG) k-ɛ turbulence model was applied to simulate the turbulent flow, and Eddy-Dissipation Model (EDM) was applied to simulate gas combustion. Through simulation, situation analysis of flowfield in afterburner was done, and the influence of mixing combustion on afterburner was studied by taking air inlet angles and air-fuel ratio into account respectively. The results indicate that the distribution of temperature in afterburner is nonuniform, the backflow and axial swirl produced by gas mixing have an important influence on afterburner combustion. As air inlet angle is increased, the intensity of gas mixing is enhanced which is beneficial for afterburner combustion. That increasing air-fuel ratio is able to strength contact of oxygen with fuel gas, so that more fuel gas is consumed in the same location which is more beneficial for afterburner combustion.

  2. Migration of the Cratering Flow-Field Center with Implications for Scaling Oblique Impacts

    NASA Technical Reports Server (NTRS)

    Anderson, J. L. B.; Schultz, P. H.; Heineck, J. T.

    2004-01-01

    Crater-scaling relationships are used to predict many cratering phenomena such as final crater diameter and ejection speeds. Such nondimensional relationships are commonly determined from experimental impact and explosion data. Almost without exception, these crater-scaling relationships have used data from vertical impacts (90 deg. to the horizontal). The majority of impact craters, however, form by impacts at angles near 45 deg. to the horizontal. While even low impact angles result in relatively circular craters in sand targets, the effects of impact angle have been shown to extend well into the excavation stage of crater growth. Thus, the scaling of oblique impacts needs to be investigated more thoroughly in order to quantify fully how impact angle affects ejection speed and angle. In this study, ejection parameters from vertical (90 deg.) and 30 deg. oblique impacts are measured using three-dimensional particle image velocimetry (3D PIV) at the NASA Ames Vertical Gun Range (AVGR). The primary goal is to determine the horizontal migration of the cratering flow-field center (FFC). The location of the FFC at the time of ejection controls the scaling of oblique impacts. For vertical impacts the FFC coincides with the impact point (IP) and the crater center (CC). Oblique impacts reflect a more complex, horizontally migrating flow-field. A single, stationary point-source model cannot be used accurately to describe the evolution of the ejection angles from oblique impacts. The ejection speeds for oblique impacts also do not follow standard scaling relationships. The migration of the FFC needs to be understood and incorporated into any revised scaling relationships.

  3. The effects of shock wave precursors ahead of hypersonic entry vehicles

    NASA Technical Reports Server (NTRS)

    Stanley, Scott A.; Carlson, Leland A.

    1991-01-01

    A model has been developed to predict the magnitude and characteristics of the shock wave precursor ahead of a hypervelocity vehicle. This model includes both chemical and thermal nonequilibrium, utilizes detailed mass production rates for the photodissociation and photoionization reactions, and accounts for the effects of radiative absorption and emission on the individual internal energy modes of both atomic and diatomic species. Comparison of the present results with shock tube data indicates that the model is reasonably accurate. A series of test cases representing earth aerocapture return from Mars indicate that there is significant production of atoms, ions and electrons ahead of the shock front due to radiative absorption and that the precursor is characterized by an enhanced electron/electronic temperature and molecular ionization. However, the precursor has a negligible effect on the shock layer flow field.

  4. Computer-controlled multi-parameter mapping of 3D compressible flowfields using planar laser-induced iodine fluorescence

    NASA Technical Reports Server (NTRS)

    Donohue, James M.; Victor, Kenneth G.; Mcdaniel, James C., Jr.

    1993-01-01

    A computer-controlled technique, using planar laser-induced iodine fluorescence, for measuring complex compressible flowfields is presented. A new laser permits the use of a planar two-line temperature technique so that all parameters can be measured with the laser operated narrowband. Pressure and temperature measurements in a step flowfield show agreement within 10 percent of a CFD model except in regions close to walls. Deviation of near wall temperature measurements from the model was decreased from 21 percent to 12 percent compared to broadband planar temperature measurements. Computer-control of the experiment has been implemented, except for the frequency tuning of the laser. Image data storage and processing has been improved by integrating a workstation into the experimental setup reducing the data reduction time by a factor of 50.

  5. Aerodynamic requirements of a manned Mars aerobraking transfer vehicle

    NASA Technical Reports Server (NTRS)

    Braun, Robert D.; Powell, Richard W.

    1990-01-01

    In this investigation, entry corridor analyses are performed to identify the aerodynamic requirements of a manned Mars aerobraking transfer vehicle. The major emphasis is on identifying the required aerobrake hypersonic L/D to insure a successful aerocapture. Aerobraking entry requirements are also imposed on a set of interplanetary mission opportunities to demonstrate their effect on mission flexibility. Based on the requirements of a 1 deg corridor width, deceleration into a parking orbit witn an apoapsis altitude of 32,972 km, and a 5-g deceleration limit, a manned Mars aerobrake characterized by an L/D of at least 1.5 is required for entry velocities as high as 10.0 km/sec. Limiting the Mars entry velocity to values below 8.5 km/sec is shown to induce a minor restriction on mission flexibility while alleviating aerothermodynamic and vehicle packaging concerns; hence, Mars entry velocities in the range of 6.0-8.5 km/sec are suggested, and a manned Mars aerobrake characterized by an L/D between 0.3 and 0.5 is recommended.

  6. An approximate method for calculating heating rates on three-dimensional vehicles

    NASA Technical Reports Server (NTRS)

    Hamilton, H. H., II; Greene, Francis A.; Dejarnette, Fred R.

    1993-01-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body fitted coordinate system. Edge conditions for the boundary layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used the method is applicable to any blunt body geometry for which a inviscid flowfield solution can be obtained. It is validated by comparing with experimental heating data and with Navier-Stokes calculations on the Shuttle orbiter at both wind tunnel and flight conditions and with Navier-Stokes calculations on the HL-20 at wind tunnel conditions.

  7. Approximate method for calculating heating rates on three-dimensional vehicles

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris; Greene, Francis A.; Dejarnette, F. R.

    1994-01-01

    An approximate method for calculating heating rates on three-dimensional vehicles at angle of attack is presented. The method is based on the axisymmetric analog for three-dimensional boundary layers and uses a generalized body-fitted coordinate system. Edge conditions for the boundary-layer solution are obtained from an inviscid flowfield solution, and because of the coordinate system used, the method is applicable to any blunt body geometry for which an inviscid flowfield solution can be obtained. The method is validated by comparing with experimental heating data and with thin-layer Navier-Stokes calculations on the shuttle orbiter at both wind-tunnel and flight conditions and with thin-layer Navier-Stokes calculations on the HL-20 at wind-tunnel conditions.

  8. Flame trench analysis of NLS vehicles

    NASA Technical Reports Server (NTRS)

    Zeytinoglu, Nuri

    1993-01-01

    The present study takes the initial steps of establishing a better flame trench design criteria for future National Launch System vehicles. A three-dimensional finite element computer model for predicting the transient thermal and structural behavior of the flame trench walls was developed using both I-DEAS and MSC/NASTRAN software packages. The results of JANNAF Standardized Plume flowfield calculations of sea-level exhaust plume of the Space Shuttle Main Engine (SSME), Space Transportation Main Engine (STME), and Advanced Solid Rocket Motors (ASRM) were analyzed for different axial distances. The results of sample calculations, using the developed finite element model, are included. The further suggestions are also reported for enhancing the overall analysis of the flame trench model.

  9. Comparison of NO and OH planar fluorescence temperature measurements in scramjet model flowfields

    SciTech Connect

    Mcmillin, B.K.; Seitzman, J.M.; Hanson, R.K.

    1994-10-01

    The use of nitric oxide (NO) and the hydroxyl radical (OH) as temperature tracers, in a two-line planar laser-induced fluorescence technique, is examined in the context of a supersonic mixing and combustion flowfield. The temperature measurements were based on the sequential excitation of two transitions, either in the A implied by X (0,0) band of NO near 226 nm or the A implied by X (1,0) band of OH near 283 nm. The measurements were obtained for each species through the use of two lasers and two cameras, with each camera integrating signal induced from only one of the lasers. Both temporally resolved and frame-averaged temperature measurements of each species are presented. Additional results include simultaneous NO and OH visualizations, in which seeded NO marks the fuel jet fluid and nascent OH marks the reaction zones and convected combustion gases. A detailed temperature comparison shows good agreement in the common measurement regions and indicates that shot noise is the largest source of uncertainty. The comparison also illustrates the importance of a careful interpretation of the measurements, since, depending on the origin of the tracer and the degree of mixing, the measurements may be biased toward the fuel, freestream, or reaction zone temperatures. 33 refs.

  10. Design and Calibration of a Flowfield Survey Rake for Inlet Flight Research

    NASA Technical Reports Server (NTRS)

    Flynn, Darin C.; Ratnayake, Nalin A.; Frederick, Michael

    2009-01-01

    The Propulsion Flight Test Fixture at the NASA Dryden Flight Research Center is a unique test platform available for use on NASA's F-15B aircraft, tail number 836, as a modular host for a variety of aerodynamics and propulsion research. For future flight data from this platform to be valid, more information must be gathered concerning the quality of the airflow underneath the body of the F-15B at various flight conditions, especially supersonic conditions. The flow angularity and Mach number must be known at multiple locations on any test article interface plane for measurement data at these locations to be valid. To determine this prerequisite information, flight data will be gathered in the Rake Airflow Gauge Experiment using a custom-designed flowfield rake to probe the airflow underneath the F-15B at the desired flight conditions. This paper addresses the design considerations of the rake and probe assembly, including the loads and stress analysis using analytical methods, computational fluid dynamics, and finite element analysis. It also details the flow calibration procedure, including the completed wind-tunnel test and posttest data reduction, calibration verification, and preparation for flight-testing.

  11. Numerical Calculations of Flowfields around a Rotor Flying over Near-Ground at Low Speed

    NASA Astrophysics Data System (ADS)

    Itoga, Noriaki; Nagashima, Tomoari; Yoshizawa, Yoshimasa

    It is known that when a rotor is flying over the ground at low speed, a ground vortex may appear in front of the rotor. The ground vortex, which can be formed by the interaction between the rotor downwash and the incoming flow in close proximity to the ground, will change the performance of the rotor. The flow environment becomes much more complex compared with that of O.G.E. flight. It is clearly necessary to investigate the basic physical phenomenon of the ground vortex and its effect on the aerodynamic characteristics of the rotor. Therefore, numerical study of the flowfields around a rotor in forward flight near the ground at low speed are carried out by solving the CFD code based on unsteady 3D compressible Euler equations with a moving grid system. In this paper, we present typical numerical results with respect to the formation of ground vortex, the induced velocity distribution on the rotor disc, and describe the effect of the rotor height and advanced ratio on the rotor thrust.

  12. Flowfield Comparisons from Three Navier-Stokes Solvers for an Axisymmetric Separate Flow Jet

    NASA Technical Reports Server (NTRS)

    Koch, L. Danielle; Bridges, James; Khavaran, Abbas

    2002-01-01

    To meet new noise reduction goals, many concepts to enhance mixing in the exhaust jets of turbofan engines are being studied. Accurate steady state flowfield predictions from state-of-the-art computational fluid dynamics (CFD) solvers are needed as input to the latest noise prediction codes. The main intent of this paper was to ascertain that similar Navier-Stokes solvers run at different sites would yield comparable results for an axisymmetric two-stream nozzle case. Predictions from the WIND and the NPARC codes are compared to previously reported experimental data and results from the CRAFT Navier-Stokes solver. Similar k-epsilon turbulence models were employed in each solver, and identical computational grids were used. Agreement between experimental data and predictions from each code was generally good for mean values. All three codes underpredict the maximum value of turbulent kinetic energy. The predicted locations of the maximum turbulent kinetic energy were farther downstream than seen in the data. A grid study was conducted using the WIND code, and comments about convergence criteria and grid requirements for CFD solutions to be used as input for noise prediction computations are given. Additionally, noise predictions from the MGBK code, using the CFD results from the CRAFT code, NPARC, and WIND as input are compared to data.

  13. Effects of Buoyancy on the Flowfields of Lean Premixed Turbulent V-Flames

    NASA Technical Reports Server (NTRS)

    Cheng, R. K.; Greenberg, P.; Bedat, B.; Yegian, D. T.

    1999-01-01

    Open laboratory turbulent flames used for investigating fundament flame turbulence interactions are greatly affected by buoyancy. Though much of our current knowledge is based on observations made in these open flames, the effects of buoyancy are usually not included in data interpretation, numerical analysis or theories. This inconsistency remains an obstacle to merging experimental observations and theoretical predictions. To better understanding the effects of buoyancy, our research focuses on steady lean premixed flames propagating in fully developed turbulence. We hypothesize that the most significant role of buoyancy forces on these flames is to influence their flowfields through a coupling with mean and fluctuating pressure fields. Changes in flow pattern alter the mean aerodynamic stretch and in turn affect turbulence fluctuation intensities both upstream and downstream of the flame zone. Consequently, flame stabilization, reaction rates, and turbulent flame processes are all affected. This coupling relates to the elliptical problem that emphasizes the importance of the upstream, wall and downstream boundary conditions in determining all aspects of flame propagation. Therefore, buoyancy has the same significance as other parameters such as flow configuration, flame geometry, means of flame stabilization, flame shape, enclosure size, mixture conditions, and flow conditions.

  14. Quick reproduction of blast-wave flow-field properties of nuclear, TNT, and ANFO explosions

    NASA Astrophysics Data System (ADS)

    Groth, C. P. T.

    1986-04-01

    In many instances, extensive blast-wave flow-field properties are required in gasdynamics research studies of blast-wave loading and structure response, and in evaluating the effects of explosions on their environment. This report provides a very useful computer code, which can be used in conjunction with the DNA Nuclear Blast Standard subroutines and code, to quickly reconstruct complete and fairly accurate blast-wave data for almost any free-air (spherical) and surface-burst (hemispherical) nuclear, trinitrotoluene (TNT), or ammonium nitrate-fuel oil (ANFO) explosion. This code is capable of computing all of the main flow properties as functions of radius and time, as well as providing additional information regarding air viscosity, reflected shock-wave properties, and the initial decay of the flow properties just behind the shock front. Both spatial and temporal distributions of the major blast-wave flow properties are also made readily available. Finally, provisions are also included in the code to provide additional information regarding the peak or shock-front flow properties over a range of radii, for a specific explosion of interest.

  15. Flow-Field Survey in the Test Region of the SR-71 Aircraft Test Bed Configuration

    NASA Technical Reports Server (NTRS)

    Mizukami, Masashi; Jones, Daniel; Weinstock, Vladimir D.

    2000-01-01

    A flat plate and faired pod have been mounted on a NASA SR-71A aircraft for use as a supersonic flight experiment test bed. A test article can be placed on the flat plate; the pod can contain supporting systems. A series of test flights has been conducted to validate this test bed configuration. Flight speeds to a maximum of Mach 3.0 have been attained. Steady-state sideslip maneuvers to a maximum of 2 deg have been conducted, and the flow field in the test region has been surveyed. Two total-pressure rakes, each with two flow-angle probes, have been placed in the expected vicinity of an experiment. Static-pressure measurements have been made on the flat plate. At subsonic and low supersonic speeds with no sideslip, the flow in the surveyed region is quite uniform. During sideslip maneuvers, localized flow distortions impinge on the test region. Aircraft sideslip does not produce a uniform sidewash over the test region. At speeds faster than Mach 1.5, variable-pressure distortions were observed in the test region. Boundary-layer thickness on the flat plate at the rake was less than 2.1 in. For future experiments, a more focused and detailed flow-field survey than this one would be desirable.

  16. Computational/experimental study of the flowfield on a body of revolution at incidence

    NASA Technical Reports Server (NTRS)

    Zilliac, G. G.

    1989-01-01

    A joint computational-experimental study of the vortical flowfield on a pointed body of revolution is undertaken. The incompressible Navier-Stokes equations are solved numerically for steady flow around an ogive-cylinder at angle of attack. The three-dimensional vortical flow is investigated, with emphasis on the tip and the near-wake region. Comparisons of computational results with results of a companion towing-tank experiment are presented at Re(L) = 1000. Results of a wind tunnel experiment at Re(L) = 820,000, featuring use of a seven-hole pressure probe, also are presented. It was observed that at the low Reynolds number of the towing tank study, the leeside flow was symmetric at the angles of attack considered. For the same configuration at the higher Reynolds number of the wind tunnel study, the flow was asymmetric under equivalenat conditions for some of the angles of attack studied. The topology of the flow is discussed and conclusions are drawn concerning the growth and stability of the primary vortices.

  17. Effects of buoyancy on the flowfields of lean premixed turbulentv-flames

    SciTech Connect

    Cheng, R.K.; Bedat, B.; Yegian, D.T.; Greenberg, P.

    2001-03-01

    Open laboratory turbulent flames used for investigating fundament flame turbulence interactions are greatly affected by buoyancy. Though much of our current knowledge is based on observations made in these open flames, the effects of buoyancy are usually not included in data interpretation, numerical analysis or theories. This inconsistency remains an obstacle to merging experimental observations and theoretical predictions. To better understanding the effects of buoyancy, our research focuses on steady lean premixed flames propagating in fully developed turbulence. We hypothesize that the most significant role of buoyancy forces on these flames is to influence their flowfields through a coupling with mean and fluctuating pressure fields. Changes in flow pattern alter the mean aerodynamic stretch and in turn affect turbulence fluctuation intensities both upstream and downstream of the flame zone. Consequently, flame stabilization, reaction rates, and turbulent flame processes are all affected. This coupling relates to the elliptical problem that emphasizes the importance of the upstream, wall and downstream boundary conditions in determining all aspects of flame propagation. Therefore, buoyancy has the same significance as other parameters such as flow configuration, flame geometry, means of flame stabilization, flame shape, enclosure size, mixture conditions, and flow conditions.

  18. Analytical and experimental heat transfer and flow-field prediction on a rectangular reentry module

    SciTech Connect

    Laganelli, A.L.

    1980-02-05

    A General Purpose Heat Source (GPHS) has been designed for the purpose of supplying power to a radioisotope thermal generator intended for interplanetary missions. The baseline configuration, nominally 2 in. x 4 in. x 4 in. with sharp edges and corners, is required to survive accidental earth reentry as well as terminal impact velocities. Several problems have been identified relative to survival criteria during reentry. This paper is concerned with the flow field and reentry heating for a broad face-on or side-on reentry orientation. Moreover, the analysis considers convective heat transfer in the absence of roughness or ablation effects during the supersonic/hypersonic regime of reentry. The anaytical results are compared with wind tunnel data. From these studies it was concluded that heat transfer distributions for non-circular shapes ca be obtained for reentry conditions using wind tunnel data for the surface distributions and a stagnation value based on a reference sphere condition. The distributions obtained at a fixed Mach number (M > 1) appear valid over an extended range of Mach numbers. The above required definition of a proper velocity gradient, and definition of an area aspect ratio. Flowfield predictions (inviscid) using the CM2DT program provide a proper definition of pressure and shock characteristics for non-similar (viscous) solutions. (LCL)

  19. An interactive approach to surface-fitting complex geometries for flowfield applications

    NASA Technical Reports Server (NTRS)

    Dejarnette, Fred R.; Hamilton, H. Harris, II; Cheatwood, F. Mcneil

    1987-01-01

    Numerical flowfield methods require a geometry subprogram which can calculate body coordinates, slopes, and radii of curvature for typical aircraft and spacecraft configurations. The objective of this paper is to develop a new surface-fitting technique which addresses two major problems with existing geometry packages: computer storage requirements and the time required of the user for the initial set-up of the geometry model. In the present method, coordinates of cross sections are fit in a least-squares sense using segments of general conic sections. After fitting each cross section, the next step is to blend the cross-sectional curve-fits in the longitudinal direction using general conics to fit specific meridional half-planes. For the initial setup of the geometry model, an interactive, completely menu-driven computer code has been developed to allow the user to make modifications to the initial fit for a given cross section or meridional cut. Graphic displays are provided to assist the user in the visualization of the effect of each modification. The completed model may be viewed from any angle using the code's three-dimensional graphics package. Geometry results for the modeling of the Space Shuttle and a proposed Aeroassist Flight Experiment (AFE) geometry are presented, in addition to calculated heat-transfer rates based on these models.

  20. Pulsed laser Rayleigh scattering diagnostic for hydrogen/oxygen rocket exit plane flowfield velocimetry

    NASA Technical Reports Server (NTRS)

    Zupanc, Frank J.

    1993-01-01

    A Doppler-resolved, pulsed laser Rayleigh scattering diagnostic has been developed to obtain local flowfield velocity measurements at the exit plane of a low thrust hydrogen/oxygen rocket engine operating in a high-altitude test facility. Fiberoptic signal collection was employed to obtain the forescatter and backscatter Doppler shifts necessary to resolve the axial and radial velocity components. A radial profile was obtained by traversing the collection probes along the beam path at the nozzle exit. The results are compared with theoretical predictions from a full Navier-Stokes model (RK/RPLUS). Significant discrepancies between the measured and predicted axial velocity profiles are observed, in terms of both magnitude and character. Radial velocity measurements exhibit excellent agreement with predictions near the centerline but show some departure off-axis. The discrepancies between theory and experiment are potentially the result of enhanced mixing between the core and fuel-film region beyond that predicted, and/or flow stratification between the hydrogen and oxygen injected into the central core region.

  1. Orbiter BLT Flight Experiment Wind Tunnel Simulations: Nearfield Flowfield Imaging and Surface Thermography

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Ivey, Christoper B.; Barthel, Brett F.; Inman, Jennifer A.; Jones, Stephen B.; Watkins, Anthony N.; Goodman, Kyle Z.; McCrea, Andrew C.; Leighty, Bradley D.; Lipford, William K.; Jiang, N.; Webster, M.; Lempert, Walter; Miller, J.; Meyer, T.

    2010-01-01

    This paper reports a series of wind tunnel tests simulating the near-field behavior of the Space Shuttle Orbiter Boundary Layer Transition Detailed Test Objective (BLT DTO) flight experiment. Hypersonic flow over a flat plate with an attached BLT DTO-shaped trip was tested in a Mach 10 wind tunnel. The sharp-leading-edge flat plate was oriented at an angle of 20 degrees with respect to the freestream flow, resulting in post-shock edge Mach number of approximately 4. The flowfield was visualized using nitric oxide (NO) planar laser-induced fluorescence (PLIF). Flow visualizations were performed at 10 Hz using a wide-field of view and high-resolution NO PLIF system. A lower spatial resolution and smaller field of view NO PLIF system visualized the flow at 500 kHz, which was fast enough to resolve unsteady flow features. At the lowest Reynolds number studied, the flow was observed to be laminar and mostly steady. At the highest Reynolds number, flow visualizations showed streak instabilities generated immediately downstream of the trip. These instabilities transitioned to unsteady periodic and spatially irregular structures downstream. Quantitative surface heating imagery was obtained using the Temperature Sensitive Paint (TSP) technique. Comparisons between the PLIF flow visualizations and TSP heating measurements show a strong correlation between flow patterns and surface heating trends.

  2. Dynamic simulations of under-rib convection-driven flow-field configurations and comparison with experiment in polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Duy, Vinh Nguyen; Lee, Jungkoo; Kim, Kyungcheol; Ahn, Jiwoong; Park, Seongho; Kim, Taeeun; Kim, Hyung-Man

    2015-10-01

    The under-rib convection-driven flow-field design for the uniform distribution of reacting gas and the generation of produced water generates broad scientific interest, especially among those who study the performance of polymer electrolyte membrane fuel cells (PEMFCs). In this study, we simulate the effects of an under-rib convection-driven serpentine flow-field with sub-channel and by-pass (SFFSB) and a conventional advanced serpentine flow-field (CASFF) on single cell performance, and we compare the simulation results with experimental measurements. In the under-rib convection-driven flow-field configuration with SFFSB, the pressure drop is decreased because of the greater cross-sectional area for gas flow, and the decreased pressure drop results in the reduction of the parasitic loss. The anode liquid water mass fraction increases with increasing channel height because of increased back diffusion, while the cathode liquid water mass fraction does not depend upon the sub-channels but is ascribed mainly to the electro-osmotic drag. Simulation results verify that the maximum current and the power densities of the SFFSB are increased by 18.85% and 23.74%, respectively, due to the promotion of under-rib convection. The findings in this work may enable the optimization of the design of under-rib convection-driven flow-fields for efficient PEMFCs.

  3. Effects of the reacting flowfield on combustion processes in a Stagnation Point Reverse Flow combustor

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Priya

    The performance of dry, low NOx gas turbines, which employ lean premixed (or partially premixed) combustors, is often limited by static and dynamic combustor stability, and they require complicated mixing hardware. To overcome these issues, a novel design, referred to as a Stagnation Point Reverse Flow (SPRF) combustor, has been recently demonstrated. The SPRF combustor has been shown to operate with ultra low NOx emissions in premixed and nonpremixed modes with gaseous and liquid fuels. The objective of this thesis is to elucidate the interactions between the flowfield and combustion processes in this novel combustor for gas- and liquid-fueled operation. This is achieved with experimental measurements employing various optical diagnostic techniques, which include Particle Image Velocimetry (PIV), chemiluminescence imaging, Planar Laser-Induced Fluorescence (PLIF) of OH radicals and elastic laser scattering from liquid droplets. The velocity measurements obtained during gas-fueled operation show that both nonreacting and reacting flows exhibit a "stagnation" region with low mean velocity and high RMS fluctuations. In nonreacting flow, it has been shown that the decay rate of the jet can be modeled as a combination of a free jet and a jet in a uniform opposed flow. The high shear between the forward and reverse flows causes significant recirculation, resulting in enhanced entrainment and mixing of the returning hot product gases into the incoming reactant jet for the reacting flow cases, which enables stable operation of the combustor at very lean equivalence ratios. Nonpremixed operation produces a flowfield similar to that of the premixed case except in the near-field region. The coaxial injector design results in high turbulence intensities close to the injector exit leading to significant fuel-air premixing before combustion occurs. The operation of the SPRF combustor fueled with liquid Jet-A is also experimentally investigated. The results indicate that while

  4. Unsteady Flowfield Around Tandem Cylinders as Prototype for Component Interaction in Airframe Noise

    NASA Technical Reports Server (NTRS)

    Khorrami, Meldi R.; Choudhari, Meelan M.; Jenkins, Luther N.; McGinley, Catherine B.

    2005-01-01

    Synergistic application of experiments and numerical simulations is crucial to understanding the underlying physics of airframe noise sources. The current effort is aimed at characterizing the details of the flow interaction between two cylinders in a tandem configuration. This setup is viewed to be representative of several component-level flow interactions that occur when air flows over the main landing gear of large civil transports. Interactions of this type are likely to have a significant impact on the noise radiation associated with the aircraft undercarriage. The paper is focused on two-dimensional, time-accurate flow simulations for the tandem cylinder configuration. Results of the unsteady Reynolds Averaged Navier-Stokes (URANS) computations with a two-equation turbulence model, at a Reynolds number of 0.166 million and a Mach number of 0.166, are presented. The experimental measurements of the same flow field are discussed in a separate paper by Jenkins, Khorrami, Choudhari, and McGinley (2005). Two distinct flow regimes of interest, associated with short and intermediate separation distances between the two cylinders, are considered. Emphasis is placed on understanding both time averaged and unsteady flow features between the two cylinders and in the wake of the rear cylinder. Predicted mean flow quantities and vortex shedding frequencies show reasonable agreement with the measured data for both cylinder spacings. Computations for short separation distance indicate decay of flow unsteadiness with time, which is not unphysical; however, the predicted sensitivity of mean lift coefficient to small angles of attack explains the asymmetric flowfield observed during the experiments.

  5. Novel, Miniature Multi-Hole Probes and High-Accuracy Calibration Algorithms for their use in Compressible Flowfields

    NASA Technical Reports Server (NTRS)

    Rediniotis, Othon K.

    1999-01-01

    Two new calibration algorithms were developed for the calibration of non-nulling multi-hole probes in compressible, subsonic flowfields. The reduction algorithms are robust and able to reduce data from any multi-hole probe inserted into any subsonic flowfield to generate very accurate predictions of the velocity vector, flow direction, total pressure and static pressure. One of the algorithms PROBENET is based on the theory of neural networks, while the other is of a more conventional nature (polynomial approximation technique) and introduces a novel idea of local least-squares fits. Both algorithms have been developed to complete, user-friendly software packages. New technology was developed for the fabrication of miniature multi-hole probes, with probe tip diameters all the way down to 0.035". Several miniature 5- and 7-hole probes, with different probe tip geometries (hemispherical, conical, faceted) and different overall shapes (straight, cobra, elbow probes) were fabricated, calibrated and tested. Emphasis was placed on the development of four stainless-steel conical 7-hole probes, 1/16" in diameter calibrated at NASA Langley for the entire subsonic regime. The developed calibration algorithms were extensively tested with these probes demonstrating excellent prediction capabilities. The probes were used in the "trap wing" wind tunnel tests in the 14'x22' wind tunnel at NASA Langley, providing valuable information on the flowfield over the wing. This report is organized in the following fashion. It consists of a "Technical Achievements" section that summarizes the major achievements, followed by an assembly of journal articles that were produced from this project and ends with two manuals for the two probe calibration algorithms developed.

  6. Analysis of the dynamic response of a supersonic inlet to flow-field perturbations upstream of the normal shock

    NASA Technical Reports Server (NTRS)

    Cole, G. L.; Willoh, R. G.

    1975-01-01

    A linearized mathematical analysis is presented for determining the response of normal shock position and subsonic duct pressures to flow-field perturbations upstream of the normal shock in mixed-compression supersonic inlets. The inlet duct cross-sectional area variation is approximated by constant-area sections; this approximation results in one-dimensional wave equations. A movable normal shock separates the supersonic and subsonic flow regions, and a choked exit is assumed for the inlet exit condition. The analysis leads to a closed-form matrix solution for the shock position and pressure transfer functions. Analytical frequency response results are compared with experimental data and a method of characteristics solution.

  7. Electric vehicles

    SciTech Connect

    Not Available

    1990-03-01

    Quiet, clean, and efficient, electric vehicles (EVs) may someday become a practical mode of transportation for the general public. Electric vehicles can provide many advantages for the nation's environment and energy supply because they run on electricity, which can be produced from many sources of energy such as coal, natural gas, uranium, and hydropower. These vehicles offer fuel versatility to the transportation sector, which depends almost solely on oil for its energy needs. Electric vehicles are any mode of transportation operated by a motor that receives electricity from a battery or fuel cell. EVs come in all shapes and sizes and may be used for different tasks. Some EVs are small and simple, such as golf carts and electric wheel chairs. Others are larger and more complex, such as automobile and vans. Some EVs, such as fork lifts, are used in industries. In this fact sheet, we will discuss mostly automobiles and vans. There are also variations on electric vehicles, such as hybrid vehicles and solar-powered vehicles. Hybrid vehicles use electricity as their primary source of energy, however, they also use a backup source of energy, such as gasoline, methanol or ethanol. Solar-powered vehicles are electric vehicles that use photovoltaic cells (cells that convert solar energy to electricity) rather than utility-supplied electricity to recharge the batteries. This paper discusses these concepts.

  8. Grid generation and flow computation about a Martian entry vehicle

    NASA Technical Reports Server (NTRS)

    Stewart, J. E.; Tiwari, S. N.

    1990-01-01

    A number of vehicles are currently being proposed for a manned mission to Mars. One of these vehicles has a modified blunt-nosed cone configuration. Experimental results were obtained for this vehicle in 1968. They show lift-over-drag ratios comparable to those needed for Mars entry. Computations are performed to verify the earlier results and to further describe the flight characteristics of this vehicle. An analytical method is used to define the surface of this vehicle. A single-block volume grid is generated around the vehicle using the algebraic Two-Boundary Grid Generation algorithm (TBGG) and transfinite interpolation. Euler solutions are then obtained from a Langley Aerodynamic Upward Relaxation Algorithm (LAURA) at Mach 6.0 and angles of attack of 0, 6, and 12 deg. The lift coefficient determined from the LAURA code agree very well with the experimental results. The drag and pitching moment coefficients, however, are underestimated by the code since viscous effects are not considered. Contour plots of the flowfield show no evidence of separation for angles of attack up to 12 deg.

  9. Advanced Multi-Phase Flow CFD Model Development for Solid Rocket Motor Flowfield Analysis

    NASA Technical Reports Server (NTRS)

    Liaw, Paul; Chen, Y. S.; Shang, H. M.; Doran, Denise

    1993-01-01

    It is known that the simulations of solid rocket motor internal flow field with AL-based propellants require complex multi-phase turbulent flow model. The objective of this study is to develop an advanced particulate multi-phase flow model which includes the effects of particle dynamics, chemical reaction and hot gas flow turbulence. The inclusion of particle agglomeration, particle/gas reaction and mass transfer, particle collision, coalescence and breakup mechanisms in modeling the particle dynamics will allow the proposed model to realistically simulate the flowfield inside a solid rocket motor. The Finite Difference Navier-Stokes numerical code FDNS is used to simulate the steady-state multi-phase particulate flow field for a 3-zone 2-D axisymmetric ASRM model and a 6-zone 3-D ASRM model at launch conditions. The 2-D model includes aft-end cavity and submerged nozzle. The 3-D model represents the whole ASRM geometry, including additional grain port area in the gas cavity and two inhibitors. FDNS is a pressure based finite difference Navier-Stokes flow solver with time-accurate adaptive second-order upwind schemes, standard and extended k-epsilon models with compressibility corrections, multi zone body-fitted formulations, and turbulence particle interaction model. Eulerian/Lagrangian multi-phase solution method is applied for multi-zone mesh. To simulate the chemical reaction, penalty function corrected efficient finite-rate chemistry integration method is used in FDNS. For the AL particle combustion rate, the Hermsen correlation is employed. To simulate the turbulent dispersion of particles, the Gaussian probability distribution with standard deviation equal to (2k/3)(exp 1/2) is used for the random turbulent velocity components. The computational results reveal that the flow field near the juncture of aft-end cavity and the submerged nozzle is very complex. The effects of the turbulent particles affect the flow field significantly and provide better

  10. Reynolds-Averaged Turbulence Model Assessment for a Highly Back-Pressured Isolator Flowfield

    NASA Technical Reports Server (NTRS)

    Baurle, Robert A.; Middleton, Troy F.; Wilson, L. G.

    2012-01-01

    The use of computational fluid dynamics in scramjet engine component development is widespread in the existing literature. Unfortunately, the quantification of model-form uncertainties is rarely addressed with anything other than sensitivity studies, requiring that the computational results be intimately tied to and calibrated against existing test data. This practice must be replaced with a formal uncertainty quantification process for computational fluid dynamics to play an expanded role in the system design, development, and flight certification process. Due to ground test facility limitations, this expanded role is believed to be a requirement by some in the test and evaluation community if scramjet engines are to be given serious consideration as a viable propulsion device. An effort has been initiated at the NASA Langley Research Center to validate several turbulence closure models used for Reynolds-averaged simulations of scramjet isolator flows. The turbulence models considered were the Menter BSL, Menter SST, Wilcox 1998, Wilcox 2006, and the Gatski-Speziale explicit algebraic Reynolds stress models. The simulations were carried out using the VULCAN computational fluid dynamics package developed at the NASA Langley Research Center. A procedure to quantify the numerical errors was developed to account for discretization errors in the validation process. This procedure utilized the grid convergence index defined by Roache as a bounding estimate for the numerical error. The validation data was collected from a mechanically back-pressured constant area (1 2 inch) isolator model with an isolator entrance Mach number of 2.5. As expected, the model-form uncertainty was substantial for the shock-dominated, massively separated flowfield within the isolator as evidenced by a 6 duct height variation in shock train length depending on the turbulence model employed. Generally speaking, the turbulence models that did not include an explicit stress limiter more closely

  11. Detailed near-wake flowfield surveys with comparison to an Euler method of an aspect ratio 4 rectangular wing

    NASA Technical Reports Server (NTRS)

    Klinge, M. D.; Kjelgaard, S. O.; Perkins, J. N.

    1986-01-01

    An experimental investigation of the flowfield in the near-wake of an aspect ratio 4 rectangular wing was conducted, providing a complete detailed set of data for use in the validation of computational methods. An angle of attack of 8 degrees and two Reynolds numbers 530,000 and 391,000 were investigated using pitot and six-hole probes. In addition, two types of flow visualization were employed. The data presented includes contours of total pressure, mean velocity, flow angularity, and vorticity distribution data at five chordwise stations of the near-wake ranging from 0.167 to 5.00 chord lengths aft of the trailing edge. The experimental results were compared to the predicted results of a 2-D Euler numerical method. The results predicted by an Euler method failed to accurately define the flowfield. Tangential velocities remained relatively constant over the range of X/C considered though increased in angle of attack and Reynolds number did bring about corresponding increases. Axial velocities also increased with angle of attack and Reynolds number but showed greater sensitivity to increases in X/C. Graphic displays and contours of the total pressure data indicate that roll-up of the wing tip vortex is essentially complete one and one half chords downstream of the trailing edge.

  12. Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

    PubMed Central

    Liu, Jiaping; Wang, Hai; Liu, Qiuhan

    2013-01-01

    The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa. PMID:24000278

  13. Recent advances in combustion flow-field imaging measurements in high-pressure liquid-fueled gas turbine combustor concepts

    NASA Astrophysics Data System (ADS)

    Locke, Randy J.; Hicks, Yolanda R.; Zaller, Michelle M.; Anderson, Robert C.

    1999-12-01

    Future gas turbine combustor designs for aerospace applications will be required to meet severe restrictions on environmentally harmful emissions. To meet the target emission reduction goals, these combustors will operate at temperatures and pressures greatly exceeding those of present day aero-powerplants. New diagnostic methods are required to provide insight into understanding the complex physical and chemical processes extant at these conditions because traditional diagnostic methods are either insufficient or incapable of providing this knowledge. At NASA Glenn Research Center (GRC), several optically accessible combustor rigs have been built which allow the implementation of a suite of optical diagnostic techniques that are capable of providing just this type of crucial information. The techniques employed in the GRC combustion research laboratory include planar laser-induced fluorescence and planar Mie scattering. Research efforts have been quite successful probing both non-reacting and reacting flowfields of many kerosene-fueled combustor and combustor subcomponent design at pressures approaching 2.0 MPa, and temperatures near 2100 K. Images that map out combustion intermediate species such as OH distribution, fuel spray patternation, and fuel to air ratio contour mapping have been obtained for many different fuel injector designs and configurations. A novel combination of multiple planar images and computational analysis allows a 3D capability that greatly enhances the evaluation of the combustion processes and flowfields examined in this study.

  14. High speed diagnostics for characterization of oxygen / hydrogen rocket injector flowfields

    NASA Astrophysics Data System (ADS)

    Locke, Justin M.

    Temporally-resolved diagnostics are needed to characterize the highly-turbulent flowfields of rocket engine combustors. Two different high speed diagnostic techniques have been applied successfully to study the combustion and mixing characteristics of single-element shear-coaxial injector flowfield in a rocket combustor. Tunable diode laser absorption spectroscopy (TDLAS) is applied to make in-situ measurements with combusting gas-gas propellants, and high speed imaging incorporating backlighting is applied to combusting and non-combusting liquid-gas and gas-gas propellants. Tunable diode laser absorption spectroscopy has been used to make path-integrated temperature and H2O mole fraction measurements in a gaseous oxygen / gaseous hydrogen uni-element rocket chamber with hot background flow. Four mixture conditions were studied at a nominal chamber pressure of 115 psia. Near infrared diode lasers were utilized to target rovibrational transitions of water vapor, which is created through the combustion processes. Both direct absorption spectroscopy and wavelength modulation spectroscopy with second harmonic normalized by first harmonic (1f-normalized WMS-2 f) techniques were applied, with the harmonic detection technique found to yield the best results. Centerline measurements were made at two axial locations, in the near-injector region and far-field region further downstream. Time-resolved measurements of temperature and H2O mole fraction in the rocket chamber are presented. The TDLAS measurements shows clear differences between the near-injector and downstream measurement locations. Mean path-integrated temperatures and H2O mole fractions in the near-injector region are lower than the downstream measurement location. Fluctuations in path-integrated temperature and H2O mole fraction in the downstream location are significantly greater than the near-injector region. This suggests increased turbulence and larger-scale mixing processes are occurring in the downstream

  15. Descent vehicles

    NASA Technical Reports Server (NTRS)

    Popov, Y. I.

    1985-01-01

    The creation of descent vehicles marked a new stage in the development of cosmonautics, involving the beginning of manned space flight and substantial progress in space research on the distant bodies of the Solar System. This booklet describes these vehicles and their structures, systems, and purposes. It is intended for the general public interested in modern problems of space technology.

  16. Calculation of convective and radiative heating on the forebody heatshield of the aeroassist flight experiment vehicle

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris, II; Greendyke, Robert B.

    1991-01-01

    The total (convective and radiative) heating is calculated over the entire forebody heatshield of the Aeroassist Flight Experiment (AFE) vehicle. The convective heating is calculated using a three-dimensional Navier-Stokes code (LAURA) which includes both chemical and thermal nonequilibrium effects. The flowfield solution is then used to provide inputs to a nonequilibrium air radiation code (NEQAIR) to calculate the nonequilibrium radiative heating. Results are presented at two points on the current Baseline 5A trajectory corresponding to the start of the primary data taking period and peak heating.

  17. Comparison of water management between two bipolar plate flow-field geometries in proton exchange membrane fuel cells at low-density current range

    NASA Astrophysics Data System (ADS)

    López, Ana M.; Barreras, Félix; Lozano, Antonio; García, Juan A.; Valiño, Luis; Mustata, Radu

    This experimental research studies some aspects of water formation and management in polymer electrolyte membrane fuel cells (PEMFCs). To this end, two different single cells of 49 cm 2 active area have been tested, the first one with a serpentine-parallel geometry and the second with a cascade-type flow-field topology. In order to visualize the processes, flow-field channels have been machined on transparent plastic. Experiments have consisted in both image acquisition using a CCD camera, and simultaneous measurements of pressure drop in both hydrogen and oxygen gas flow paths. It has been observed that with the cascade-type flow-field geometry, water produced in the cathode does not flood the gas flow channels and, consequently, can be drained in an easy way. On the other hand, it has also been verified that saturated condition for the hydrogen gas flow at the anode side produces water condensation and channel flooding for the serpentine-parallel flow-field topology. Time fluctuations in the pressure drop of the gas flow have been detected and are associated to some transient process inherent to water formation and management.

  18. Online Coupling of Flow-Field Flow Fractionation and Single Particle Inductively Coupled Plasma-Mass Spectrometry: Characterization of Nanoparticle Surface Coating Thickness and Aggregation State

    EPA Science Inventory

    Surface coating thickness and aggregation state have strong influence on the environmental fate, transport, and toxicity of engineered nanomaterials. In this study, flow-field flow fractionation coupled on-line with single particle inductively coupled plasma-mass spectrometry i...

  19. Examining rhyolite lava flow dynamics through photo-based 3D reconstructions of the 2011-2012 lava flowfield at Cordón-Caulle, Chile

    NASA Astrophysics Data System (ADS)

    Farquharson, J. I.; James, M. R.; Tuffen, H.

    2015-10-01

    During the 2011-2012 eruption at Cordón-Caulle, Chile, an extensive rhyolitic flowfield was created (in excess of 0.5 km3 in volume), affording a unique opportunity to characterise rhyolitic lava advance. In 2012 and 2013, we acquired approximately 2500 digital photographs of active flowfronts on the north and east of the flowfield. These images were processed into three-dimensional point clouds using structure-from-motion and multi-view stereo (SfM-MVS) freeware, from which digital elevation models were derived. Sequential elevation models-separated by intervals of three hours, six days, and one year-were used to reconstruct spatial distributions of lava velocity and depth, and estimate rheological parameters. Three-dimensional reconstructions of flowfronts indicate that lateral extension of the rubbly, 'a'ā-like flowfield was accompanied by vertical inflation, which differed both spatially and temporally as a function of the underlying topography and localised supply of lava beneath the cooled upper carapace. Compressive processes also drove the formation of extensive surface ridges across the flowfield. Continued evolution of the flowfield resulted in the development of a compound flowfield morphology fed by iterative emplacement of breakout lobes. The thermal evolution of flow units was modelled using a one-dimensional finite difference method, which indicated prolonged residence of magma above its glass transition across the flowfield. We compare the estimated apparent viscosity (1.21-4.03 × 1010 Pa s) of a breakout lobe, based on its advance rate over a known slope, with plausible lava viscosities from published non-Arrhenian temperature-viscosity models and accounting for crystallinity (~ 50 vol.%). There is an excellent correspondence between viscosity estimates when the lava temperature is taken to be magmatic, despite the breakout being located > 3 km from the vent, and advancing approximately nine months after vent effusion ceased. This indicates the

  20. Navier-Stokes flowfield computation of wing/rotor interaction for a tilt rotor aircraft in hover

    NASA Technical Reports Server (NTRS)

    Fejtek, Ian G.

    1993-01-01

    The download on the wing produced by the rotor-induced downwash of a tilt rotor aircraft in hover is of major concern because of its severe impact on payload-carrying capability. A method has been developed to help gain a better understanding of the fundamental fluid dynamics that causes this download, and to help find ways to reduce it. In particular, the method is employed in this work to analyze the effect of a tangential leading edge circulation-control jet on download reduction. Because of the complexities associated with modeling the complete configuration, this work focuses specifically on the wing/rotor interaction of a tilt rotor aircraft in hover. The three-dimensional, unsteady, thin-layer compressible Navier-Stokes equations are solved using a time-accurate, implicit, finite difference scheme that employs LU-ADI factorization. The rotor is modeled as an actuator disk which imparts both a radical and an azimuthal distribution of pressure rise and swirl to the flowfield. A momentum theory blade element analysis of the rotor is incorporated into the Navier-Stokes solution method. Solution blanking at interior points of the mesh has been shown here to be an effective technique in introducing the effects of the rotor and tangential leading edge jet. Results are presented both for a rotor alone and for wing/rotor interaction. The overall mean characteristics of the rotor flowfield are computed including the flow acceleration through the rotor disk, the axial and swirl velocities in the rotor downwash, and the slipstream contraction. Many of the complex tilt rotor flow features are captured including the highly three-dimensional flow over the wing, the recirculation fountain at the plane of symmetry, wing leading and trailing edge separation, and the large region of separated flow beneath the wing. Mean wing surface pressures compare fairly well with available experimental data, but the time-averaged download/thrust ratio is 20-30 percent higher than the

  1. Responses of neurons in the medial column of the inferior olive in pigeons to translational and rotational optic flowfields.

    PubMed

    Winship, I R; Wylie, D R

    2001-11-01

    The responses of neurons in the medial column of the inferior olive to translational and rotational optic flow were recorded from anaesthetized pigeons. Panoramic translational or rotational flowfields were produced by mechanical devices that projected optic flow patterns onto the walls, ceiling and floor of the room. The axis of rotation/translation could be positioned to any orientation in three-dimensional space such that axis tuning could be determined. Each neuron was assigned a vector representing the axis about/along which the animal would rotate/translate to produce the flowfield that elicited maximal modulation. Both translation-sensitive and rotation-sensitive neurons were found. For neurons responsive to translational optic flow, the preferred axis is described with reference to a standard right-handed coordinate system, where +x, +y and +z represent rightward, upward and forward translation of the animal, respectively (assuming that all recordings were from the right side of the brain). t(+y) neurons were maximally excited in response to a translational optic flowfield that results from self-translation upward along the vertical (y) axis. t(-y) neurons also responded best to translational optic flow along the vertical axis but showed the opposite direction preference. The two remaining groups, t(-x+z) and t(-x-z) neurons, responded best to translational optic flow along horizontal axes that were oriented 45 degrees to the midline. There were two types of neurons responsive to rotational optic flow: rVA neurons preferred rotation about the vertical axis, and rH135c neurons preferred rotation about a horizontal axis at 135 degrees contralateral azimuth. The locations of marking lesions indicated a clear topographical organization of the six response types. In summary, our results reinforce that the olivo-cerebellar system dedicated to the analysis of optic flow is organized according to a reference frame consisting of three approximately orthogonal axes

  2. Robotic vehicle

    DOEpatents

    Box, W.D.

    1997-02-11

    A robotic vehicle is described for travel through a conduit. The robotic vehicle includes forward and rear housings each having a hub portion, and each being provided with surface engaging mechanisms for selectively engaging the walls of the conduit such that the housings can be selectively held in stationary positions within the conduit. The surface engaging mechanisms of each housing includes a plurality of extendable appendages, each of which is radially extendable relative to the operatively associated hub portion between a retracted position and a radially extended position. The robotic vehicle also includes at least three selectively extendable members extending between the forward and rear housings, for selectively changing the distance between the forward and rear housings to effect movement of the robotic vehicle. 20 figs.

  3. Robotic vehicle

    DOEpatents

    Box, W.D.

    1998-08-11

    A robotic vehicle is described for travel through a conduit. The robotic vehicle includes forward and rear housings each having a hub portion, and each being provided with surface engaging mechanisms for selectively engaging the walls of the conduit such that the housings can be selectively held in stationary positions within the conduit. The surface engaging mechanisms of each housing includes a plurality of extendible appendages, each of which is radially extendible relative to the operatively associated hub portion between a retracted position and a radially extended position. The robotic vehicle also includes at least three selectively extendible members extending between the forward and rear housings, for selectively changing the distance between the forward and rear housings to effect movement of the robotic vehicle. 20 figs.

  4. Robotic vehicle

    SciTech Connect

    Box, W. Donald

    1998-01-01

    A robotic vehicle for travel through a conduit. The robotic vehicle includes forward and rear housings each having a hub portion, and each being provided with surface engaging mechanisms for selectively engaging the walls of the conduit such that the housings can be selectively held in stationary positions within the conduit. The surface engaging mechanisms of each housing includes a plurality of extendable appendages, each of which is radially extendable relative to the operatively associated hub portion between a retracted position and a radially extended position. The robotic vehicle also includes at least three selectively extendable members extending between the forward and rear housings, for selectively changing the distance between the forward and rear housings to effect movement of the robotic vehicle.

  5. Robotic vehicle

    SciTech Connect

    Box, W. Donald

    1997-01-01

    A robotic vehicle for travel through a conduit. The robotic vehicle includes forward and rear housings each having a hub portion, and each being provided with surface engaging mechanisms for selectively engaging the walls of the conduit such that the housings can be selectively held in stationary positions within the conduit. The surface engaging mechanisms of each housing includes a plurality of extendable appendages, each of which is radially extendable relative to the operatively associated hub portion between a retracted position and a radially extended position. The robotic vehicle also includes at least three selectively extendable members extending between the forward and rear housings, for selectively changing the distance between the forward and rear housings to effect movement of the robotic vehicle.

  6. Novel, low-cost separator plates and flow-field elements for use in PEM fuel cells

    SciTech Connect

    Edlund, D.J.

    1996-12-31

    PEM fuel cells offer promise for a wide range of applications including vehicular (e.g., automotive) and stationary power generation. The performance and cost targets that must be met for PEM technology to be commercially successful varies to some degree with the application. However, in general the cost of PEM fuel cell stacks must be reduced substantially if they are to see widespread use for electrical power generation. A significant contribution to the manufactured cost of PEM fuel cells is the machined carbon plates that traditionally serve as bipolar separator plates and flow-field elements. In addition, carbon separator plates are inherently brittle and suffer from breakage due to shock, vibration, and improper handling. This report describes a bifurcated separator device with low resistivity, low manufacturing cost, compact size and durability.

  7. Analysis of Flowfields over Four-Engine DC-X Rockets

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Cornelison, Joni

    1996-01-01

    The objective of this study is to validate a computational methodology for the aerodynamic performance of an advanced conical launch vehicle configuration. The computational methodology is based on a three-dimensional, viscous flow, pressure-based computational fluid dynamics formulation. Both wind-tunnel and ascent flight-test data are used for validation. Emphasis is placed on multiple-engine power-on effects. Computational characterization of the base drag in the critical subsonic regime is the focus of the validation effort; until recently, almost no multiple-engine data existed for a conical launch vehicle configuration. Parametric studies using high-order difference schemes are performed for the cold-flow tests, whereas grid studies are conducted for the flight tests. The computed vehicle axial force coefficients, forebody, aftbody, and base surface pressures compare favorably with those of tests. The results demonstrate that with adequate grid density and proper distribution, a high-order difference scheme, finite rate afterburning kinetics to model the plume chemistry, and a suitable turbulence model to describe separated flows, plume/air mixing, and boundary layers, computational fluid dynamics is a tool that can be used to predict the low-speed aerodynamic performance for rocket design and operations.

  8. CARS Temperature and Species Measurements For Air Vehicle Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Gord, James R.; Grisch, Frederic; Klimenko, Dmitry; Clauss, Walter

    2005-01-01

    The coherent anti-Stokes Raman spectroscopy (CARS) method has recently been used in the United States and Europe to probe several different types of propulsion systems for air vehicles. At NASA Langley Research Center in the United States, CARS has been used to simultaneously measure temperature and the mole fractions of N2, O2 and H2 in a supersonic combustor, representative of a scramjet engine. At Wright- Patterson Air Force Base in the United States, CARS has been used to simultaneously measure temperature and mole fractions of N2, O2 and CO2, in the exhaust stream of a liquid-fueled, gas-turbine combustor. At ONERA in France and the DLR in Germany researchers have used CARS to measure temperature and species concentrations in cryogenic LOX-H2 rocket combustion chambers. The primary aim of these measurements has been to provide detailed flowfield information for computational fluid dynamics (CFD) code validation.

  9. Autonomous vehicles

    SciTech Connect

    Meyrowitz, A.L.; Blidberg, D.R.; Michelson, R.C. |

    1996-08-01

    There are various kinds of autonomous vehicles (AV`s) which can operate with varying levels of autonomy. This paper is concerned with underwater, ground, and aerial vehicles operating in a fully autonomous (nonteleoperated) mode. Further, this paper deals with AV`s as a special kind of device, rather than full-scale manned vehicles operating unmanned. The distinction is one in which the AV is likely to be designed for autonomous operation rather than being adapted for it as would be the case for manned vehicles. The authors provide a survey of the technological progress that has been made in AV`s, the current research issues and approaches that are continuing that progress, and the applications which motivate this work. It should be noted that issues of control are pervasive regardless of the kind of AV being considered, but that there are special considerations in the design and operation of AV`s depending on whether the focus is on vehicles underwater, on the ground, or in the air. The authors have separated the discussion into sections treating each of these categories.

  10. Experimental and computational flow-field results for an all-body hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Cleary, Joseph W.

    1989-01-01

    A comprehensive test program is defined which is being implemented in the NASA/Ames 3.5 foot Hypersonic Wind Tunnel for obtaining data on a generic all-body hypersonic vehicle for computational fluid dynamics (CFD) code validation. Computational methods (approximate inviscid methods and an upwind parabolized Navier-Stokes code) currently being applied to the all-body model are outlined. Experimental and computational results on surface pressure distributions and Pitot-pressure surveys for the basic sharp-nose model (without control surfaces) at a free-stream Mach number of 7 are presented.

  11. Robotic vehicle

    DOEpatents

    Box, W.D.

    1996-03-12

    A robotic vehicle is described for travel through an enclosed or partially enclosed conduit or pipe including vertical and/or horizontal conduit or pipe. The robotic vehicle comprises forward and rear housings each provided with a surface engaging mechanism for selectively engaging the walls of the conduit through which the vehicle is travelling, whereby the housings are selectively held in a stationary position within the conduit. The vehicle also includes at least three selectively extendable members, each of which defines a cavity therein. The forward end portion of each extendable member is secured to the forward housing and the rear end portion of each housing is secured to the rear housing. Each of the extendable members is independently extendable from a retracted position to an extended position upon the injection of a gas under pressure into the cavity of the extendable member such that the distance between the forward housing and the rear housing can be selectively increased. Further, each of the extendable members is independently retractable from the extended position to the retracted position upon the application of a vacuum to the cavity of the extendable member such that the distance between the forward housing and the rear housing can be selectively decreased. 14 figs.

  12. Robotic vehicle

    DOEpatents

    Box, W.D.

    1994-03-15

    A robotic vehicle is described for travel through an enclosed or partially enclosed conduit or pipe including vertical and/or horizontal conduit or pipe. The robotic vehicle comprises forward and rear housings each provided with a surface engaging mechanism for selectively engaging the walls of the conduit through which the vehicle is travelling, whereby the housings are selectively held in a stationary position within the conduit. The vehicle also includes at least three selectively extendable members, each of which defines a cavity therein. The forward end portion of each extendable member is secured to the forward housing and the rear end portion of each housing is secured to the rear housing. Each of the extendable members is independently extendable from a retracted position to an extended position upon the injection of a gas under pressure into the cavity of the extendable member such that the distance between the forward housing and the rear housing can be selectively increased. Further, each of the extendable members is independently retractable from the extended position to the retracted position upon the application of a vacuum to the cavity of the extendable member such that the distance between the forward housing and the rear housing can be selectively decreased. 11 figures.

  13. Robotic vehicle

    DOEpatents

    Box, W. Donald

    1996-01-01

    A robotic vehicle (10) for travel through an enclosed or partially enclosed conduit or pipe including vertical and/or horizontal conduit or pipe. The robotic vehicle (10) comprises forward and rear housings (32 and 12) each provided with a surface engaging mechanism for selectively engaging the walls of the conduit through which the vehicle is travelling, whereby the housings (32 and 12) are selectively held in a stationary position within the conduit. The vehicle (10) also includes at least three selectively extendable members (46), each of which defines a cavity (56) therein. The forward end portion (50) of each extendable member (46) is secured to the forward housing (32) and the rear end portion (48) of each housing is secured to the rear housing (12). Each of the extendable members (46) is independently extendable from a retracted position to an extended position upon the injection of a gas under pressure into the cavity (56) of the extendable member such that the distance between the forward housing (32 ) and the rear housing (12) can be selectively increased. Further, each of the extendable members (46) is independently retractable from the extended position to the retracted position upon the application of a vacuum to the cavity (56) of the extendable member (46) such that the distance between the forward housing (32) and the rear housing (12) can be selectively decreased.

  14. Robotic vehicle

    DOEpatents

    Box, W. Donald

    1994-01-01

    A robotic vehicle (10) for travel through an enclosed or partially enclosed conduit or pipe including vertical and/or horizontal conduit or pipe. The robotic vehicle (10) comprises forward and rear housings (32 and 12) each provided with a surface engaging mechanism for selectively engaging the walls of the conduit through which the vehicle is travelling, whereby the housings (32 and 12) are selectively held in a stationary position within the conduit. The vehicle (10) also includes at least three selectively extendable members (46), each of which defines a cavity (56) therein. The forward end portion (50) of each extendable member (46) is secured to the forward housing (32) and the rear end portion (48) of each housing is secured to the rear housing (12). Each of the extendable members (46) is independently extendable from a retracted position to an extended position upon the injection of a gas under pressure into the cavity (56) of the extendable member such that the distance between the forward housing (32 ) and the rear housing (12) can be selectively increased. Further, each of the extendable members (46) is independently retractable from the extended position to the retracted position upon the application of a vacuum to the cavity (56) of the extendable member (46) such that the distance between the forward housing (32) and the rear housing (12) can be selectively decreased.

  15. Preliminary Assessment of Artificial Gravity Impacts to Deep-Space Vehicle Design

    NASA Technical Reports Server (NTRS)

    Joosten, B. Kent

    2007-01-01

    Even after more than thirty years of scientific investigation, serious concerns regarding human physiological effects of long-duration microgravity exposure remain. These include loss of bone mineral density, skeletal muscle atrophy, and orthostatic hypertension, among others. In particular, "Safe Passage: Astronaut Care for Exploration Missions," states "loss of bone density, which apparently occurs at a rate of 1% per month in microgravity, is relatively manageable on the short-duration missions of the space shuttle, but it becomes problematic on the ISS [International Space Station]. ...If this loss is not mitigated, interplanetary missions will be impossible." While extensive investigations into potential countermeasures are planned on the ISS, the delay in attaining full crew complement and onboard facilities, and the potential for extending crews tours of duty threaten the timely (< 20 years!) accumulation of sufficient data for countermeasures formulation. Indeed, there is no guarantee that even with the data, a practical or sufficiently robust set of countermeasures will be forthcoming. Providing an artificial gravity (AG) environment by crew centrifugation aboard deep-space human exploration vehicles, long a staple technique of science fiction, has received surprisingly limited engineering assessment. This is most likely due to a number of factors: the lack of definitive design requirements, especially acceptable artificial gravity levels and rotation rates, the perception of high vehicle mass and performance penalties, the incompatibility of resulting vehicle configurations with space propulsion options (i.e., aerocapture), the perception of complications associated with de-spun components such as antennae and photovoltaic arrays, and the expectation of effective crew micro-gravity countermeasures. These perception and concerns may have been overstated, or may be acceptable alternatives to countermeasures of limited efficacy. This study was undertaken as

  16. A Design Comparison of Atmospheric Flight Vehicles for the Exploration of Titan

    NASA Technical Reports Server (NTRS)

    Gasbarre, Joseph F.; Wright, Henry S.; Lewis, Mark J.

    2005-01-01

    Titan, the largest moon of Saturn, is one of the most scientifically interesting locations in the Solar System. With a very cold atmosphere that is five times as dense as Earth s, and one and a half times the surface pressure, it also provides one of the most aeronautically fascinating environments known to humankind. While this may seem the ideal place to attempt atmospheric flight, many challenges await any vehicle attempting to navigate through it. In addition to these physical challenges, any scientific exploration mission to Titan will most likely have several operational constraints. One difficult constraint is the desire for a global survey of the planet and thus, a long duration flight within the atmosphere. Since many of the scientific measurements that would be unique to a vehicle flying through the atmosphere (as opposed to an orbiting spacecraft) desire near-surface positioning of their associated instruments, the vehicle must also be able to fly within the first scale height of the atmosphere. Another difficult constraint is that interaction with the surface, whether by landing or dropped probe, is also highly desirable from a scientific perspective. Two common atmospheric flight platforms that might be used for this mission are the airplane and airship. Under the assumption of a mission architecture that would involve an orbiting relay spacecraft delivered via aerocapture and an atmospheric flight vehicle delivered via direct entry, designs were developed for both platforms that are unique to Titan. Consequently, after a viable design was achieved for each platform, their advantages and disadvantages were compared. This comparison included such factors as deployment risk, surface interaction capability, mass, and design heritage. When considering all factors, the preferred candidate platform for a global survey of Titan is an airship.

  17. Flow-field characteristics and normal-force correlations for delta wings from Mach 2.4 to 4.6

    NASA Technical Reports Server (NTRS)

    Covell, Peter F.; Wesselmann, Gary F.

    1989-01-01

    An experimental investigation has been conducted to determine the upper-surface flowfield types and the normal-force characteristics of a series of delta wing models at supersonic speeds. Flow-visualization data were used to classify the flowfields into seven primary types: shockless attached flow, separation bubble, classical vortex, vortex with shock, shock with no separation, shock-induced separation, and separation bubble with shock. The pressure distributions were integrated to obtain upper and lower surface normal-force loadings. A minimal effect of sweep was observed on the upper-surface normal force at constant Mach number and a minimal effect of Mach number was noted for the 75 deg delta wing lower-surface normal force. The normal-force coefficients for all test conditions were correlated, and a single empirical equation was formulated from which the normal-force coefficient could be calculated as a function of Mach number, angle of attack, and wing aspect ratio.

  18. Experimental and predicted pressure and heating distributions for an Aeroassist Flight Experiment vehicle in air at Mach 10

    NASA Technical Reports Server (NTRS)

    Micol, John R.

    1989-01-01

    The Aeroassisted Flight Experiment vehicle for whose scale model pressure and heat-transfer rate distributions have been measured in air at Mach 10 is a 60-deg elliptic cone, raked off at a 73-percent angle, with an ellipsoid nose and a skirt added to the base of the rake plane to reduce heating. The predictions of both an inviscid flow-field code and a Navier-Stokes solver are compared with measured values. Good agreement is obtained in the case of pressure distributions; the effect of Reynolds number on heat-transfer distributions is noted to be small.

  19. Feasibility Study of Laboratory Simulation of Single-Stage-to-Orbit Vehicle Base Heating

    NASA Technical Reports Server (NTRS)

    Park, Chung Sik; Sharma, Surendra; Edwards, Thomas A. (Technical Monitor)

    1995-01-01

    The feasibility of simulating in a laboratory the heating environment of the base region of the proposed reusable single-stage-to-orbit vehicle during its ascent is examined. The propellant is assumed to consist of hydrocarbon (RP1), liquid hydrogen (LH2), and liquid oxygen (LO2), which produces CO and H2 as the main combustible components of the exhaust effluent. Since afterburning in the recirculating region can dictate the temperature of the base flowfield and ensuing heating phenomena, laboratory simulation focuses on the thermochemistry of the afterburning. By extrapolating the Saturn V flight data, the Damkohler number, in the base region with afterburning for SSTO vehicle, is estimated to be between 30 and 140. It is shown that a flow with a Damkohler number of 1.8 to 25 can be produced in an impulse ground test facility. Even with such a reduced Damkohler number, the experiment can adequately reproduce the main features of the flight environment.

  20. Flowfield-Dependent Variation (FDV) method for compressible, incompressible, viscous, and inviscid flow interactions with FDV adaptive mesh refinements and parallel processing

    NASA Astrophysics Data System (ADS)

    Heard, Gary Wayne

    A new approach to solution-adaptive grid refinement using the finite element method and Flowfield-Dependent Variation (FDV) theory applied to the Navier-Stokes system of equations is discussed. Flowfield-Dependent Variation (FDV) parameters are introduced into a modified Taylor series expansion of the conservation variables, with the Navier-Stokes system of equations substituted into the Taylor series. The FDV parameters are calculated from the current Fowfield conditions, and automatically adjust the resulting equations from elliptic to parabolic to hyperbolic in type to assure solution accuracy in evolving fluid flowfields that may consist of interactions between regions of compressible and incompressible flow, viscous and inviscid flow, and turbulent and laminar flow. The system of equations is solved using an element-by-element iterative GMRES solver with the elements grouped together to allow the element operations to be performed in parallel. The FDV parameters play many roles in the numerical scheme. One of these roles is to control formations of shock wave discontinuities in high speeds and pressure oscillations in low speeds. To demonstrate these abilities, various example problems are shown, including supersonic flows over a flat plate and a compression corner, and flows involving triple shock waves generated on fin geometries for high speed compressible flows. Furthermore, analysis of low speed incompressible flows is presented in the form of flow in a lid-driven cavity at various Reynolds numbers. Another role of the FDV parameters is their use as error indicators for a solution-adaptive mesh. The finite element grid is refined as dictated by the magnitude of the FDV parameters. Examples of adaptive grids generated using the FDV parameters as error indicators are presented for supersonic flow over flat plate/compression ramp combinations in both two and three dimensions. Grids refined using the FDV parameters as error indicators are comparable to ones

  1. Mathematical Modeling of Air Flowfield at Urban Environment: the Case of Road Network at the Historical Centre of Kifissia's Municipality

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, K.; Belias, C.

    2008-09-01

    The present paper refers to the numerical analysis of air flowfield at urban environments and the conducting thermal comfort after the evaluation of the examined space using CFD methods, taking into account bioclimatic principles at the architectural design. More specially, the paper draws attention to the physical procedures governing air movement at an urban environment (a road network) at Kifissia (a Municipality of north Athens), trying to form them in such way that will lead to the thermal comfort of the area's users. The study presents a mathematical model, implemented in a general computer code that can provide detailed information on velocity, prevailing in three-dimensional spaces of any geometrical complexity. Turbulent flow is simulated and buoyancy effects are taken into account. This simulation procedure is intended to contribute to the effort towards designing urban environments, using thermal comfort criteria at the bioclimatic design. A computer model of this kind will provide the architects or the environmental engineers with powerful and economical means of evaluating alternative spaces' designs.

  2. Conjugate conduction-convection heat transfer model for the valve flow-field region of four-stroke piston engines

    SciTech Connect

    Blank, D.A. )

    1990-01-01

    A multidimensional method has been devised to solve the conjugate conduction-convection heat transfer process at the surface of a moving valve of finite thickness within the flow field of an operating four-stroke internal combustion (IC) engine. Heat exchange processes between the valve and the gases adjacent to these boundaries were also computed during the portions of the engine cycle when the valve was closed. Boundaries of the solution scheme were extended fixed distances into the piston and cylinder liner. The valve was simulated as having a small but measurable thickness for the purpose of heat transfer calculations and as being immeasurably thin for the purpose of other flow-field calculations. The effects of fluid entrainment caused by valve motion were also considered and modeled. The implicit finite-difference solution of the governing equations for the primitive variables in the flow field was conducted in three regions: one fixed in space and time, one using a stretching and compressing computational mesh, and one that moved with time without stretching or compressing. This paper reports use of the model to simulate a portion of an exhaust stroke for an axisymmetric four-stroke engine piston.

  3. Detailed flowfield and surface properties for high Knudsen number planar jet impingement at an inclined flat plate

    NASA Astrophysics Data System (ADS)

    Cai, Chunpei; He, Xin

    2016-05-01

    This paper presents two sets of analytical exact solutions for collisionless gas flows from a planar exit, impinging at an inclined flat plate. These analytical results are obtained by using gaskinetic theories. The first set of solutions are for a diffuse reflective plate surface, and the other set of solutions are for a specular reflective plate surface. A virtual nozzle exit is adopted to aid analyzing the specular reflective plate scenario. New formulas for plate surface properties, including velocity slips, pressure, shear stress, and heat flux distributions, are provided. For both problems, the flowfield exact solutions are investigated as well. Numerical simulations with the direct simulation Monte Carlo method are performed to validate these new analytical results, and good agreement is obtained for flows with high Knudsen numbers. The results consider effects from many factors, such as the plate inclination angle, geometry ratios, and exit gas and plate properties (such as exit gas bulk density, gas speed ratio, and exit gas and plate temperatures). Compared with past work, these new solutions are more comprehensive and practical. The results also illustrate that if the plate is quite close to the nozzle exit, it is improper to adopt the traditional treatments of a point source and a simple cosine function.

  4. Thermal Response Modeling System for a Mars Sample Return Vehicle

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Miles, Frank S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    A multi-dimensional, coupled thermal response modeling system for analysis of hypersonic entry vehicles is presented. The system consists of a high fidelity Navier-Stokes equation solver (GIANTS), a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), and a commercial finite-element thermal and mechanical analysis code (MARC). The simulations performed by this integrated system include hypersonic flowfield, fluid and solid interaction, ablation, shape change, pyrolysis gas eneration and flow, and thermal response of heatshield and structure. The thermal response of the heatshield is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of the entire vehicle can be obtained simultaneously. Representative computations for a flat-faced arc-jet test model and a proposed Mars sample return capsule are presented and discussed.

  5. Thermal Response Modeling System for a Mars Sample Return Vehicle

    NASA Technical Reports Server (NTRS)

    Chen, Y.-K.; Milos, F. S.

    2002-01-01

    A multi-dimensional, coupled thermal response modeling system for analysis of hypersonic entry vehicles is presented. The system consists of a high fidelity Navier-Stokes equation solver (GIANTS), a two-dimensional implicit thermal response, pyrolysis and ablation program (TITAN), and a commercial finite element thermal and mechanical analysis code (MARC). The simulations performed by this integrated system include hypersonic flowfield, fluid and solid interaction, ablation, shape change, pyrolysis gas generation and flow, and thermal response of heatshield and structure. The thermal response of the heatshield is simulated using TITAN, and that of the underlying structural is simulated using MARC. The ablating heatshield is treated as an outer boundary condition of the structure, and continuity conditions of temperature and heat flux are imposed at the interface between TITAN and MARC. Aerothermal environments with fluid and solid interaction are predicted by coupling TITAN and GIANTS through surface energy balance equations. With this integrated system, the aerothermal environments for an entry vehicle and the thermal response of the entire vehicle can be obtained simultaneously. Representative computations for a flat-faced arc-jet test model and a proposed Mars sample return capsule are presented and discussed.

  6. Effects of the Orion Launch Abort Vehicle Plumes on Aerodynamics and Controllability

    NASA Technical Reports Server (NTRS)

    Vicker, Darby; Childs, Robert; Rogers,Stuart E.; McMullen, Matthew; Garcia, Joseph; Greathouse, James

    2013-01-01

    Characterization of the launch abort system of the Multi-purpose Crew Vehicle (MPCV) for control design and accurate simulation has provided a significant challenge to aerodynamicists and design engineers. The design space of the launch abort vehicle (LAV) includes operational altitudes from ground level to approximately 300,000 feet, Mach numbers from 0-9, and peak dynamic pressure near 1300psf during transonic flight. Further complicating the characterization of the aerodynamics and the resultant vehicle controllability is the interaction of the vehicle flowfield with the plumes of the two solid propellant motors that provide attitude control and the main propulsive impulse for the LAV. These interactions are a function of flight parameters such as Mach number, altitude, dynamic pressure, vehicle attitude, as well as parameters relating to the operation of the motors themselves - either as a function of time for the AM, or as a result of the flight control system requests for control torque from the ACM. This paper discusses the computational aerodynamic modeling of the aerodynamic interaction caused by main abort motor and the attitude control motor of the MPCV LAV, showing the effects of these interactions on vehicle controllability.

  7. Aerothermodynamic heating analysis of aerobraking and aeromaneuvering orbital-transfer vehicles

    NASA Technical Reports Server (NTRS)

    Davies, C. B.; Wilson, J. F.; Brown, K. G.; Menees, G. P.

    1984-01-01

    The thermal-protection requirements of two aeroassisted orbital-transfer vehicles (AOTVs) are analyzed for return missions between the geosynchronous and Shuttle orbits. One of the designs is a specialized version of a previously proposed generic aerobraking vehicle that is capable of only delivery-type operations. The other is a high-lift aeromaneuvering vehicle that is optimized for low-earth orbit sortie missions involving large, multiple plane-inclination changes. The aerothermal environment of the aerobraking vehicle is analyzed using state-of-the-art methods for nonequilibrium-radiative and convective heating that incorporate refinements unique to the configuration. The heating analysis of the aeromaneuvering vehicle required the development of a flow-field model for rarefied-hypersonic flow over a lifting surface at incidence. The predicted aerothermodynamic heating characteristics for both vehicles are correlated with thermal-control requirements and flight performance capabilities for the specified mission guidelines. The results help identify technical issues related to the development of future operational systems.

  8. Vehicle barrier

    DOEpatents

    Hirsh, Robert A.

    1991-01-01

    A vehicle security barrier which can be conveniently placed across a gate opening as well as readily removed from the gate opening to allow for easy passage. The security barrier includes a barrier gate in the form of a cable/gate member in combination with laterally attached pipe sections fixed by way of the cable to the gate member and lateral, security fixed vertical pipe posts. The security barrier of the present invention provides for the use of cable restraints across gate openings to provide necessary security while at the same time allowing for quick opening and closing of the gate areas without compromising security.

  9. Innovative Measurement Diagnostics for Analysis of Jet Interactions in Rotating Flowfields

    SciTech Connect

    AMATUCCI, VINCENT A.; BERESH, STEVEN J.; HENFLING, JOHN F.; ERVEN, ROCKY J.; BOURDON, CHRIS J.

    2002-01-01

    The present document summarizes the experimental efforts of a three-year study funded under the Laboratory Directed Research and Development program of Sandia National Laboratories. The Innovative Diagnostics LDRD project was designed to develop new measurement capabilities to examine the interaction of a propulsive spin jet in a transonic freestream for a model in a wind tunnel. The project motivation was the type of jet/fin interactions commonly occurring during deployment of weapon systems. In particular, the two phenomena of interest were the interaction of the propulsive spin jet with the freestream in the vicinity of the nozzle and the impact of the spin rocket plume and its vortices on the downstream fins. The main thrust of the technical developments was to incorporate small-size, Lagrangian sensors for pressure and roll-rate on a scale model and include data acquisition, transmission, and power circuitry onboard. FY01 was the final year of the three-year LDRD project and the team accomplished much of the project goals including use of micron-scale pressure sensors, an onboard telemetry system for data acquisition and transfer, onboard jet exhaust, and roll-rate measurements. A new wind tunnel model was designed, fabricated, and tested for the program which incorporated the ability to house multiple MEMS-based pressure sensors, interchangeable vehicle fins with pressure instrumentation, an onboard multiple-channel telemetry data package, and a high-pressure jet exhaust simulating a spin rocket motor plume. Experiments were conducted for a variety of MEMS-based pressure sensors to determine performance and sensitivity in order to select pressure transducers for use. The data acquisition and analysis path was most successful by using multiple, 16-channel data processors with telemetry capability to a receiver outside the wind tunnel. The development of the various instrumentation paths led to the fabrication and installation of a new wind tunnel model for

  10. Flowfield Analysis of a Small Entry Probe (SPRITE) Tested in an Arc Jet

    NASA Technical Reports Server (NTRS)

    Prabhu, Dinesh K.

    2012-01-01

    A novel concept of small size (diameter less than 15 inches) entry probes named SPRITE (Small Probe Re-entry Investigation for TPS Engineering) has been developed at NASA Ames Research Center (ARC). These flight probes have on-board data acquisition systems that have also been developed in parallel at NASA ARC by Greg Swanson1. Flight probes of this size facilitate testing over a wide range of conditions in arc jets available at NASA ARC, thereby fulfilling a 'test what you fly' paradigm. As indicated by the acronym, these probes, with suitably tailored trajectories, are primarily meant to be robotic flight test beds for TPS materials, although the design is flexible enough to accommodate additional objectives of flight-testing other vehicle subsystems. A first step towards establishing the feasibility of the SPRITE concept is to arc-jet test fully instrumented models at flight scale. In a follow-on to the Large-Scale Article Tests (LSAT2) performed in the 60 MW Interaction Heating Facility (IHF) in late 2008/early 2009, a full-scale model of Deep Space-2 (DS23) made of red oak was tested in the 20 MW Aerodynamic Heating Facility (AHF). There were no issues with mass capture by the diffuser for blunt bodies of roughly 15 inches diameter tested in the 18-inch nozzle of the AHF. Building on this initial success, two identical test articles - SPRITE-T1-1 and SPRITE-T1-2 (T1 indicating the choice of back shell geometry) - were fabricated, and one of them, SPRITE-T1-1, was tested in the AHF recently. Both these test articles, 14 inches in diameter, have a 45deg sphere-cone (like DS2) made of PICA bonded on to a 1/8th inch thick aluminum shell using RTV. The aft portion of the test article is a conical frustum (15deg cone angle) with LI-2200 bonded on to the aluminum shell. Each model is fully instrumented with: (a) thermocouples imbedded in plugs in the heat shield, (b) thermocouples bonded to the aluminum substructure; the thermocouples are distributed over the entire

  11. Forestry Vehicle

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Power Pack II provides an economical means of moving a power source into remote roadless forest areas. It was developed by Prof. Miles and his associates, working in cooperation with the University of California's Department of Forestry. The team combined its own design of an all-terrain vehicle with a suspension system based on the NASA load equalization technology. Result is an intermediate-sized unit which carries a power source and the powered tools to perform a variety of forest management tasks which cannot be done economically with current equipment. Power Pack II can traverse very rough terrain and climb a 60 degree slope; any one of the wheels can move easily over an obstacle larger than itself. Work is being done on a more advanced Power Pack III.

  12. Dynamics of aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Schmidt, David K.

    1991-01-01

    Papers on the following subjects are presented: (1) multivariable flight control synthesis and literal robustness analysis for an aeroelastic vehicles; (2) numerical and literal aeroelastic-vehicle-model reduction for feedback control synthesis; and (3) dynamics of aerospace vehicles.

  13. Trajectory-based heating analysis for the European Space Agency/Rosetta Earth Return Vehicle

    NASA Technical Reports Server (NTRS)

    Henline, William D.; Tauber, Michael E.

    1994-01-01

    A coupled, trajectory-based flowfield and material thermal-response analysis is presented for the European Space Agency proposed Rosetta comet nucleus sample return vehicle. The probe returns to earth along a hyperbolic trajectory with an entry velocity of 16.5 km/s and requires an ablative heat shield on the forebody. Combined radiative and convective ablating flowfield analyses were performed for the significant heating portion of the shallow ballistic entry trajectory. Both quasisteady ablation and fully transient analyses were performed for a heat shield composed of carbon-phenolic ablative material. Quasisteady analysis was performed using the two-dimensional axisymmetric codes RASLE and BLIMPK. Transient computational results were obtained from the one-dimensional ablation/conduction code CMA. Results are presented for heating, temperature, and ablation rate distributions over the probe forebody for various trajectory points. Comparison of transient and quasisteady results indicates that, for the heating pulse encountered by this probe, the quasisteady approach is conservative from the standpoint of predicted surface recession.

  14. Vehicle/engine integration. [orbit transfer vehicles

    NASA Technical Reports Server (NTRS)

    Cooper, L. P.; Vinopal, T. J.; Florence, D. E.; Michel, R. W.; Brown, J. R.; Bergeron, R. P.; Weldon, V. A.

    1984-01-01

    VEHICLE/ENGINE Integration Issues are explored for orbit transfer vehicles (OTV's). The impact of space basing and aeroassist on VEHICLE/ENGINE integration is discussed. The AOTV structure and thermal protection subsystem weights were scaled as the vehicle length and surface was changed. It is concluded that for increased allowable payload lengths in a ground-based system, lower length-to-diameter (L/D) is as important as higher mixture ration (MR) in the range of mid L/D ATOV's. Scenario validity, geometry constraints, throttle levels, reliability, and servicing are discussed in the context of engine design and engine/vehicle integration.

  15. Fast emplacement of extensive pahoehoe flow-fields: the case of the 1736 flows from Montaña de las Nueces, Lanzarote

    NASA Astrophysics Data System (ADS)

    Solana, M. C.; Kilburn, C. R. J.; Rodriguez Badiola, E.; Aparicio, A.

    2004-04-01

    The 1730-36 Timanfaya eruption on Lanzarote, in the Canary Islands, is the second largest historical effusion on record. During its final stages, in 1736, the eruption produced the Montaña de las Nueces flow-field, consisting of sheets of pahoehoe lava that, within 4 weeks, had covered 32 km 2 and reached a maximum length of almost 21 km. The tholeiitic lavas have pahoehoe surface features, but internal structures that are normally associated with massive aa flows, suggesting that their fronts advanced as single units rather than as a collection of budding pahoehoe tongues. Volume conservation and a simple model of crustal failure suggest that the main flows advanced at about 0.02 ms -1 over the prevailing slopes of ˜1°. The rates of advance are (1) consistent with emplacement near the transition from pahoehoe to aa, and (2) about an order of magnitude greater than would have been expected by analogy with Hawaiian pahoehoe flow-fields of similar dimensions. Surface texture and morphology, therefore, is an insufficient guide for constraining the rate and style of pahoehoe emplacement, and a flow's internal structure must be established before its characteristics are used to infer eruption conditions and potential hazard.

  16. Electric and hybrid vehicles

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Report characterizes state-of-the-art electric and hybrid (combined electric and heat engine) vehicles. Performance data for representative number of these vehicles were obtained from track and dynamometer tests. User experience information was obtained from fleet operators and individual owners of electric vehicles. Data on performance and physical characteristics of large number of vehicles were obtained from manufacturers and available literature.

  17. Nozzle design study for a quasi-axisymmetric scramjet-powered vehicle at Mach 7.9 flight conditions

    NASA Astrophysics Data System (ADS)

    Tanimizu, Katsuyoshi; Mee, David J.; Stalker, Raymond J.; Jacobs, Peter A.

    2013-09-01

    A nozzle shape optimization study for a quasi-axisymmetric scramjet has been performed for a Mach 7.9 operating condition with hydrogen fuel, aiming at the application of a hypersonic airbreathing vehicle. In this study, the nozzle geometry which is parameterized by a set of design variables, is optimized for the single objective of maximum net thrust using an in-house CFD solver for inviscid flowfields with a simple force prediction methodology. The combustion is modelled using a simple chemical reaction code. The effects of the nozzle design on the overall vehicle performance are discussed. For the present geometry, net thrust is achieved for the optimized vehicle design. The results of the nozzle-optimization study show that performance is limited by the nozzle area ratio that can be incorporated into the vehicle without leading to too large a base diameter of the vehicle and increasing the external drag of the vehicle. This study indicates that it is very difficult to achieve positive thrust at Mach 7.9 using the basic geometry investigated.

  18. Design and performance analysis of an aero-maneuvering orbital-transfer vehicle concept

    NASA Technical Reports Server (NTRS)

    Menees, G. P.

    1985-01-01

    Systems requirements for design-optimized, lateral-turn performance were determined for reusable, space-based applications and low-Earth orbits involving large multiple plane-inclination changes. The aerothermodynamic analysis is the most advanced available for rarefield-hypersonic flow over lifting surfaces at incidence. The effects of leading-edge bluntness, low-density viscous phenomena, and finite-rate flow-field chemistry and surface catalysis are accounted for. The predicted aerothermal heating characteristics are correlated with thermal-control and flight-performance capabilities. The mission payload capacity for delivery, retrieval, and combined operations was determined for round-trip sorties extending to polar orbits. Recommendations are given for future design refinements. The results help to identify technology issues required to develop prototype operational vehicles.

  19. Design and performance analysis of an aeromaneuvering orbital-transfer vehicle concept

    NASA Technical Reports Server (NTRS)

    Menees, G. P.

    1985-01-01

    Systems requirements for design-optimized, lateral-turn performance were determined for reusable, space-based applications and low-earth orbits involving large multiple plane-inclination changes. The aerothermodynamic analysis is the most advanced available for rarefied-hypersonic flow over lifting surfaces at incidence. The effects of leading-edge bluntness, low-density viscous phenomena, and finite-rate flow-field chemistry and surface catalysis are accounted for. The predicted aerothermal heating characteristics are correlated with thermal-control and flight-performance capabilities. The mission payload capacity for delivery, retrieval, and combined operations was determined for round-trip sorties extending to polar orbits. Recommendations are given for future design refinements. The results help to identify technology issues required to develop prototype operational vehicles.

  20. Advanced Technology Vehicle Testing

    SciTech Connect

    James Francfort

    2003-11-01

    The light-duty vehicle transportation sector in the United States depends heavily on imported petroleum as a transportation fuel. The Department of Energy’s Advanced Vehicle Testing Activity (AVTA) is testing advanced technology vehicles to help reduce this dependency, which would contribute to the economic stability and homeland security of the United States. These advanced technology test vehicles include internal combustion engine vehicles operating on 100% hydrogen (H2) and H2CNG (compressed natural gas) blended fuels, hybrid electric vehicles, neighborhood electric vehicles, urban electric vehicles, and electric ground support vehicles. The AVTA tests and evaluates these vehicles with closed track and dynamometer testing methods (baseline performance testing) and accelerated reliability testing methods (accumulating lifecycle vehicle miles and operational knowledge within 1 to 1.5 years), and in normal fleet environments. The Arizona Public Service Alternative Fuel Pilot Plant and H2-fueled vehicles are demonstrating the feasibility of using H2 as a transportation fuel. Hybrid, neighborhood, and urban electric test vehicles are demonstrating successful applications of electric drive vehicles in various fleet missions. The AVTA is also developing electric ground support equipment (GSE) test procedures, and GSE testing will start during the fall of 2003. All of these activities are intended to support U.S. energy independence. The Idaho National Engineering and Environmental Laboratory manages these activities for the AVTA.

  1. Asymmetric flow-field flow fractionation-multidetection coupling for assessing colloidal copper in drain waters from a Bordeaux wine-growing area.

    PubMed

    El Hadri, Hind; Lespes, Gaëtane; Chéry, Philippe; Potin-Gautier, Martine

    2014-02-01

    The objective of this study was to show that on-line asymmetric flow-field flow fractionation (AFFFF)-multidetection coupling is useful for studying environmental colloids in a qualitative and quantitative way. The utility of the technique was illustrated by assessing the colloidal fraction of the copper that was extracted from the soil, transferred to an aqueous phase and then transported by drain waters in a wine-growing area. To determine the size and composition of the colloids, AFFFF was coupled to UV, multi-angle light scattering and inductively coupled plasma mass spectrometry detectors. Colloidal copper represents between 20 and 60% of the total copper in the sub 450 nm of drain waters. Copper is mainly associated with organic-rich colloids with a size below 10 nm. It is also found in organo-mineral populations (as clay or (oxy)hydroxides), with sizes ranging between 10 and 450 nm.

  2. The effects of canard-wing flow-field interactions on longitudinal stability, effective dihedral and potential deep-stall trim

    NASA Technical Reports Server (NTRS)

    Muchmore, C. B., Jr.

    1988-01-01

    The literature available on high aspect ratio canard configurations shows them to have some unique stability characteristics. Using a generic canard-wing model, the effects of canard-wing flow-field interactions on stability were investigated in the NASA Langley Twelve-Foot Low-Speed Wind Tunnel. Results for the attached flow regime indicate linear interactions shift the neutral point of a canard configuration forward, but the effect of a canard on a wing can change significantly when the flow over the surface begins to separate, even several degrees below stall. The asymmetry of the canard downwash in a sideslip condition can result in an increment in effective dihedral roughly proportional to canard lift coefficient. At very high angles of attack the presence of a wing can cause an incremental normal force on a canard, contributing to the possibility of a deep-stall trim point. This effect is greater for a high canard and less for a low one.

  3. Effects of light intensity and pattern contrast on the ability of the land crab, Cardisoma guanhumi, to separate optic flow-field components.

    PubMed

    Johnson, Aaron P; Barnes, W Jon P; Macauley, Martin W S

    2004-01-01

    Using a novel suite of computer-generated visual stimuli that mimicked components of optic flow, the visual responses of the tropical land crab, Cardisoma guanhumi, were investigated. We show that crabs are normally successful in distinguishing the rotational and translational components of the optic flow field, showing strong optokinetic responses to the former but not the latter. This ability was not dependent on the orientation of the crab, occurring both in "forwards-walking" and "sideways-walking" configurations. However, under conditions of low overall light intensity and/or low object/background contrast, the separation mechanism shows partial failure causing the crab to generate compensatory eye movements to translation, particularly in response to low-frequency (low-velocity) stimuli. Using this discovery, we then tested the ability of crabs to separate rotational and translational components in a combined rotation/translation flow field under different conditions. We demonstrate that, while crabs can successfully separate such a combined flow field under normal circumstances, showing compensatory eye movements only to the rotational component, they are unable to make this separation under conditions of low overall light intensity and low object/background contrast. Here, the responses to both flow-field components show summation when they are in phase, but, surprisingly, there is little reduction in the amplitude of responses to rotation when the translational component is in antiphase. Our results demonstrate that the crab's visual system finds separation of flow-field components a harder task than detection of movement, since the former shows partial failure at light intensities and/or object/background contrasts at which movement of the world around the crab is still generating high-gain optokinetic responses.

  4. Automotive vehicle sensors

    SciTech Connect

    Sheen, S.H.; Raptis, A.C.; Moscynski, M.J.

    1995-09-01

    This report is an introduction to the field of automotive vehicle sensors. It contains a prototype data base for companies working in automotive vehicle sensors, as well as a prototype data base for automotive vehicle sensors. A market analysis is also included.

  5. Electric Vehicle Technician

    ERIC Educational Resources Information Center

    Moore, Pam

    2011-01-01

    With President Obama's goal to have one million electric vehicles (EV) on the road by 2015, the electric vehicle technician should have a promising and busy future. "The job force in the car industry is ramping up for a revitalized green car industry," according to Greencareersguide.com. An electric vehicle technician will safely troubleshoot and…

  6. Energy 101: Electric Vehicles

    SciTech Connect

    2012-01-01

    This edition of Energy 101 highlights the benefits of electric vehicles, including improved fuel efficiency, reduced emissions, and lower maintenance costs. For more information on electric vehicles from the Office of Energy Efficiency and Renewable Energy, visit the Vehicle Technologies Program website: http://www1.eere.energy.gov/vehiclesandfuels/

  7. Electric vehicles: Driving range

    NASA Astrophysics Data System (ADS)

    Kempton, Willett

    2016-09-01

    For uptake of electric vehicles to increase, consumers' driving-range needs must be fulfilled. Analysis of the driving patterns of personal vehicles in the US now shows that today's electric vehicles can meet all travel needs on almost 90% of days from a single overnight charge.

  8. MRV - Modular Robotic Vehicle

    NASA Technical Reports Server (NTRS)

    Ridley, Justin; Bluethmann, Bill

    2015-01-01

    The Modular Robotic Vehicle, or MRV, completed in 2013, was developed at the Johnson Space Center in order to advance technologies which have applications for future vehicles both in space and on Earth. With seating for two people, MRV is a fully electric vehicle modeled as a "city car", suited for busy urban environments.

  9. Solar space vehicle

    SciTech Connect

    Lee, R.E.

    1982-10-19

    This invention relates to space vehicle where solar energy is used to generate steam, which in turn, propels the vehicle in space. A copper boiler is provided and a novel solar radiation condensing means is used to focus the sunlight on said boiler. Steam generated in said boiler is exhausted to the environment to provide a thrust for the vehicle.

  10. Energy 101: Electric Vehicles

    ScienceCinema

    None

    2016-07-12

    This edition of Energy 101 highlights the benefits of electric vehicles, including improved fuel efficiency, reduced emissions, and lower maintenance costs. For more information on electric vehicles from the Office of Energy Efficiency and Renewable Energy, visit the Vehicle Technologies Program website: http://www1.eere.energy.gov/vehiclesandfuels/

  11. Marine vehicle ride quality

    NASA Technical Reports Server (NTRS)

    Gornstein, R. J.; Shultz, W. M.; Stair, L. D.

    1972-01-01

    The effects of marine vehicle design on passenger exposure to vibration and discomfort are discussed. The ride quality of advanced marine vehicles is examined. as a basis for marine vehicle selection in modern water transport systems. The physiological effects of rough water on passengers are identified as requiring investigation in order to determine the acceptable limits.

  12. Cooperative robotic sentry vehicles

    NASA Astrophysics Data System (ADS)

    Feddema, John T.; Lewis, Christopher L.; Klarer, Paul; Eisler, G. R.; Caprihan, Rahul

    1999-08-01

    As part of a project for the Defense Advanced Research Projects Agency, Sandia National Laboratories' Intelligent Systems and Robotics Center is developing and testing the feasibility of a cooperative team of robotic sentry vehicles to guard a perimeter and to perform a surround task. This paper describes on-going activities in the development of these robotic sentry vehicles. To date, we have developed a robotic perimeter detection system which consists of eight 'Roving All Terrain Lunar Explorer Rovers' (RATLER), a laptop-based base-station, and several Miniature Intrusion Detection Sensors (MIDS). A radio frequency receiver on each of the RATLER vehicles alerts the sentry vehicles of alarms from the hidden MIDS. When an alarm is received, each vehicle decides whether it should investigate the alarm based on the proximity of itself and the other vehicles to the alarm. As one vehicle attends an alarm, the other vehicles adjust their position around the perimeter to better prepare for another alarm. For the surround task, both potential field and A* search path planners have been added to the base-station and vehicles. At the base-station, the operator specifies goal and exclusion regions on a GIS map. The path planner generates vehicles paths that are previewed by the operator. Once the operator has validated the path, the appropriate information is downloaded t the vehicles. For the potential field path planner, the polygons and line segments that represent the obstacles and goals are downloaded to the vehicles, instead of the simulated paths. On board the vehicles, the same potential field path planner generates the path except that it uses the true location of itself and the nearest neighboring vehicle. For the A* path planner, the actual path is downloaded to the vehicles because of limited on-board computational power.

  13. Energy efficient passenger vehicle

    SciTech Connect

    Dessert, R.

    1983-02-22

    An energy efficient passenger carrying vehicle for road use. The vehicle basically comprises a long, narrow body carrying two passengers in a back-to-back relationship. The vehicle is basically a battery powered electric vehicle that can be charged by all free energy sources; namely, the sun, the wind, human muscles and momentum. The vehicle comprises four modules, namely body, solar, and two power modules. An electric power module is located within each end of the body module. This module includes electric motors driving the vehicle supporting wheels and rechargeable batteries to power the motors. Pedals, similar to those on a bicycle, located at each power module, drive generators to help recharge the batteries during operation of the vehicle, or directly help drive the vehicle wheels. A solar module comprising a large electricity generating solar cell panel covers most of the vehicle roof to aid in charging the batteries. Means are provided to tilt the solar cell panel toward the sun about a longitudinal axis. A unique flexible duct below the solar panel serves to cool the cells and, if desired, heat the passenger compartment. Further energy savings are obtained by canting the rear wheels while steering with the front wheels, so that the vehicle moves down the road at a crab angle which provides a sail effect when wind is from the vehicle beam or aft of the beam. Regenerative braking means can be used when slowing down, on a long down grade, when sailing speed is greater than required, or any other time when vehicle momentum is greater than necessary for vehicle operation, to use the excess forward momentum to drive generators to charge the batteries. Thus, a single battery charge will be conserved and vehicle operation will be assisted in a manner giving maximum vehicle range and speed.

  14. VEHICLE FOR SLAVE ROBOT

    DOEpatents

    Goertz, R.C.; Lindberg, J.F.

    1962-01-30

    A reeling device is designed for an electrical cable supplying power to the slave slde of a remote control manipulator mounted on a movable vehicle. As the vehicle carries the slave side about in a closed room, the device reels the cable in and out to maintain a variable length of the cable between the vehicle and a cable inlet in the wall of the room. The device also handles a fixed length of cable between the slave side and the vehicle, in spite of angular movement of the slave side with respect to the vehicle. (AEC)

  15. Vehicle capture system

    NASA Astrophysics Data System (ADS)

    Tacke, Kenneth L.

    1998-12-01

    Primex Aerospace Company, under contract with the U.S. Army Armament Research Development & Engineering Center (ARDEC), has developed a portable vehicle capture system for use at vehicle checkpoints. Currently when a vehicle does not stop at a checkpoint, there are three possible reactions: let the vehicle go unchallenged, pursue the vehicle or stop the vehicle with lethal force. This system provides a non-lethal alternative that will stop and contain the vehicle. The system is completely portable with the heaviest component weighing less than 120 pounds. It can be installed with no external electrical power or permanent anchors required. In its standby mode, the system does not impede normal traffic, but on command erects a barrier in less than 1.5 seconds. System tests have been conducted using 5,100 and 8.400 pound vehicles, traveling at speeds up to 45 mph. The system is designed to minimize vehicle damage and occupant injury, typically resulting in deceleration forces of less than 2.5 gs on the vehicle. According to the drivers involved in tests at 45 mph, the stopping forces feel similar to a panic stop with the vehicle brakes locked. The system is completely reusable and be rapidly reset.

  16. A vehicle health monitoring system for the Space Shuttle Reaction Control System during reentry. M.S. Thesis - Massachusetts Inst. of Technology

    NASA Technical Reports Server (NTRS)

    Rosello, Anthony David

    1995-01-01

    A general two tier framework for vehicle health monitoring of Guidance Navigation and Control (GN&C) system actuators, effectors, and propulsion devices is presented. In this context, a top level monitor that estimates jet thrust is designed for the Space Shuttle Reaction Control System (RCS) during the reentry phase of flight. Issues of importance for the use of estimation technologies in vehicle health monitoring are investigated and quantified for the Shuttle RCS demonstration application. These issues include rate of convergence, robustness to unmodeled dynamics, sensor quality, sensor data rates, and information recording objectives. Closed loop simulations indicate that a Kalman filter design is sensitive to modeling error and robust estimators may reduce this sensitivity. Jet plume interaction with the aerodynamic flowfield is shown to be a significant effect adversely impacting the ability to accurately estimate thrust.

  17. Energy efficient passenger vehicle

    SciTech Connect

    Dessert, R.

    1980-01-01

    An energy efficient passenger carrying vehicle for road use comprised of a long, narrow body carrying two passengers in a back-to-back relationship is described. The vehicle is basically a battery powered electric vehicle that can be charged by all free energy sources; namely, the sun, the wind, human muscles and momentum. The vehicle comprises four modules: body, solar, and two power modules. An electric power module is located within each end of the body module. This module includes electric motors driving the vehicle supporting wheels and rechargeable batteries to power the motors. Pedals, similar to those on a bicycle, located at each power module, drive generators to help recharge the batteries during operation of the vehicle, or directly help drive the vehicle wheels. A solar module comprising a large electricity generating solar cell panel covers most of the vehicle roof to aid in charging the batteries. Means are provided to tilt the solar cell panel toward the sun about a longitudinal axis. A unique flexible duct below the solar panel serves to cool the cells and, if desired, heat the passenger compartment. Further energy savings are obtained by canting the rear wheels while steering with the front wheels, so that the vehicle moves down the road at a crab angle which provides a sail effect when wind is from the vehicle beam or aft of the beam. Regenerative braking means can be used when slowing down, on a long down grade, when sailing speed is greater than required, or any other time when vehicle momentum is greater than necessary for vehicle operation, to use the excess forward momentum to drive generators to charge the batteries. Thus, a single battery charge will be conserved and vehicle operation will be assisted in a manner giving maximum vehicle range and speed.

  18. Aero-Assisted Spacecraft Missions Using Hypersonic Waverider Aeroshells

    NASA Astrophysics Data System (ADS)

    Knittel, Jeremy

    This work examines the use of high-lift, low drag vehicles which perform orbital transfers within a planet's atmosphere to reduce propulsive requirements. For the foreseeable future, spacecraft mission design will include the objective of limiting the mass of fuel required. One means of accomplishing this is using aerodynamics as a supplemental force, with what is termed an aero-assist maneuver. Further, the use of a lifting body enables a mission designer to explore candidate trajectory types wholly unavailable to non-lifting analogs. Examples include missions to outer planets by way of an aero-gravity assist, aero-assisted plane change, aero-capture, and steady atmospheric periapsis probing missions. Engineering level models are created in order to simulate both atmospheric and extra-atmospheric space flight. Each mission is parameterized using discrete variables which control multiple areas of design. This work combines the areas of hypersonic aerodynamics, re-entry aerothermodynamics, spacecraft orbital mechanics, and vehicle shape optimization. In particular, emphasis is given to the parametric design of vehicles known as "waveriders" which are inversely designed from known shock flowfields. An entirely novel means of generating a class of waveriders known as "starbodies" is presented. A complete analysis is performed of asymmetric starbody forms and compared to a better understood parameterization, "osculating cone" waveriders. This analysis includes characterization of stability behavior, a critical discipline within hypersonic flight. It is shown that asymmetric starbodies have significant stability improvement with only a 10% reduction in the lift-to-drag ratio. By combining the optimization of both the shape of the vehicle and the trajectory it flies, much is learned about the benefit that can be expected from lifting aero-assist missions. While previous studies have conceptually proven the viability, this work provides thorough quantification of the

  19. Inlet Aerodynamics and Ram Drag of Laser-Propelled Lightcraft Vehicles

    NASA Astrophysics Data System (ADS)

    Langener, Tobias; Myrabo, Leik; Rusak, Zvi

    2010-05-01

    Numerical simulations are used to study the aerodynamic inlet properties of three axisymmetric configurations of laser-propelled Lightcraft vehicles operating at subsonic, transonic and supersonic speeds up to Mach 5. The 60 cm vehicles were sized for launching 0.1-1.0 kg nanosatellites with combined-cycle airbreathing/rocket engines, transitioning between propulsion modes at roughly Mach 5-6. Results provide the pressure, temperature, density, and velocity flowfields around and through the three representative vehicle/engine configurations, as well as giving the resulting ram drag and total drag coefficients—all as a function of flight Mach number. Simulations with rotating boundaries were also carried out, since for stability reasons, Lightcraft are normally spun up before lift-off. Given the three alternatives, it is demonstrated that the optimal geometry for minimum drag is the configuration with a parabola nose; hence, these inlet flow conditions are being applied in subsequent "direct connect" 2D laser propulsion experiments in a small transonic flow facility.

  20. Study of Aerothermodynamic Modeling Issues Relevant to High-Speed Sample Return Vehicles

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.

    2014-01-01

    This paper examines the application of state-of-the-art coupled ablation and radiation simulations to highspeed sample return vehicles, such as those returning from Mars or an asteroid. A defining characteristic of these entries is that the surface recession rates and temperatures are driven by nonequilibrium convective and radiative heating through a boundary layer with significant surface blowing and ablation products. Measurements relevant to validating the simulation of these phenomena are reviewed and the Stardust entry is identified as providing the best relevant measurements. A coupled ablation and radiation flowfield analysis is presented that implements a finite-rate surface chemistry model. Comparisons between this finite-rate model and a equilibrium ablation model show that, while good agreement is seen for diffusion-limited oxidation cases, the finite-rate model predicts up to 50% lower char rates than the equilibrium model at sublimation conditions. Both the equilibrium and finite rate models predict significant negative mass flux at the surface due to sublimation of atomic carbon. A sensitivity analysis to flowfield and surface chemistry rates show that, for a sample return capsule at 10, 12, and 14 km/s, the sublimation rates for C and C3 provide the largest changes to the convective flux, radiative flux, and char rate. A parametric uncertainty analysis of the radiative heating due to radiation modeling parameters indicates uncertainties ranging from 27% at 10 km/s to 36% at 14 km/s. Applying the developed coupled analysis to the Stardust entry results in temperatures within 10% of those inferred from observations, and final recession values within 20% of measurements, which improves upon the 60% over-prediction at the stagnation point obtained through an uncoupled analysis. Emission from CN Violet is shown to be over-predicted by nearly and order-of-magnitude, which is consistent with the results of previous independent analyses. Finally, the

  1. Nuclear Thermal Rocket/Vehicle Characteristics And Sensitivity Trades For NASA's Mars Design Reference Architecture (DRA) 5.0 Study

    NASA Technical Reports Server (NTRS)

    Borowski, Stanley K.; McCurdy, David R.; Packard, Thomas W.

    2009-01-01

    This paper summarizes Phase I and II analysis results from NASA's recent Mars DRA 5.0 study which re-examined mission, payload and transportation system requirements for a human Mars landing mission in the post-2030 timeframe. Nuclear thermal rocket (NTR) propulsion was again identified as the preferred in-space transportation system over chemical/aerobrake because of its higher specific impulse (I(sub sp)) capability, increased tolerance to payload mass growth and architecture changes, and lower total initial mass in low Earth orbit (IMLEO) which is important for reducing the number of Ares-V heavy lift launches and overall mission cost. DRA 5.0 features a long surface stay (approximately 500 days) split mission using separate cargo and crewed Mars transfer vehicles (MTVs). All vehicles utilize a common core propulsion stage with three 25 klbf composite fuel NERVA-derived NTR engines (T(sub ex) approximately 2650 - 2700 K, p(sub ch) approximately 1000 psia, epsilon approximately 300:1, I(sub sp) approximately 900 - 910 s, engine thrust-toweight ratio approximately 3.43) to perform all primary mission maneuvers. Two cargo flights, utilizing 1-way minimum energy trajectories, pre-deploy a cargo lander to the surface and a habitat lander into a 24-hour elliptical Mars parking orbit where it remains until the arrival of the crewed MTV during the next mission opportunity (approximately 26 months later). The cargo payload elements aerocapture (AC) into Mars orbit and are enclosed within a large triconicshaped aeroshell which functions as payload shroud during launch, then as an aerobrake and thermal protection system during Mars orbit capture and subsequent entry, descent and landing (EDL) on Mars. The all propulsive crewed MTV is a 0-gE vehicle design that utilizes a fast conjunction trajectory that allows approximately 6-7 month 1-way transit times to and from Mars. Four 12.5 kW(sub e) per 125 square meter rectangular photovoltaic arrays provide the crewed MTV with

  2. Vehicle underbody fairing

    DOEpatents

    Ortega, Jason M.; Salari, Kambiz; McCallen, Rose

    2010-11-09

    A vehicle underbody fairing apparatus for reducing aerodynamic drag caused by a vehicle wheel assembly, by reducing the size of a recirculation zone formed under the vehicle body immediately downstream of the vehicle wheel assembly. The fairing body has a tapered aerodynamic surface that extends from a front end to a rear end of the fairing body with a substantially U-shaped cross-section that tapers in both height and width. Fasteners or other mounting devices secure the fairing body to an underside surface of the vehicle body, so that the front end is immediately downstream of the vehicle wheel assembly and a bottom section of the tapered aerodynamic surface rises towards the underside surface as it extends in a downstream direction.

  3. Advanced Technology Vehicle Testing

    SciTech Connect

    James Francfort

    2004-06-01

    The goal of the U.S. Department of Energy's Advanced Vehicle Testing Activity (AVTA) is to increase the body of knowledge as well as the awareness and acceptance of electric drive and other advanced technology vehicles (ATV). The AVTA accomplishes this goal by testing ATVs on test tracks and dynamometers (Baseline Performance testing), as well as in real-world applications (Fleet and Accelerated Reliability testing and public demonstrations). This enables the AVTA to provide Federal and private fleet managers, as well as other potential ATV users, with accurate and unbiased information on vehicle performance and infrastructure needs so they can make informed decisions about acquiring and operating ATVs. The ATVs currently in testing include vehicles that burn gaseous hydrogen (H2) fuel and hydrogen/CNG (H/CNG) blended fuels in internal combustion engines (ICE), and hybrid electric (HEV), urban electric, and neighborhood electric vehicles. The AVTA is part of DOE's FreedomCAR and Vehicle Technologies Program.

  4. Vehicle speed control system

    SciTech Connect

    Yoshida, D.; Tanno, T.; Fukunaga, T.

    1987-06-16

    This patent describes a vehicle speed control system for performing vehicle speed control by controlling the displacement of at least one of a hydraulic pump and a hydraulic motor of a hydraulic transmission through an electric servo device, comprising: vehicle speed setting means for generating a voltage signal corresponding to a vehicle speed to be set; compensating means interposed between the vehicle speed setting means and the electric servo device, the compensating means comprising a first delay element; and second delay element having a response characteristic slower than that of the first delay element. A selecting means for judging as to whether a voltage signal changed by the operation of the vehicle speed setting means represents an acceleration command or a deceleration command and for selecting the first delay element when the voltage signal represents an acceleration command and for selecting the second delay element when the voltage signal represents a deceleration command.

  5. Aerodynamics of Heavy Vehicles

    NASA Astrophysics Data System (ADS)

    Choi, Haecheon; Lee, Jungil; Park, Hyungmin

    2014-01-01

    We present an overview of the aerodynamics of heavy vehicles, such as tractor-trailers, high-speed trains, and buses. We introduce three-dimensional flow structures around simplified model vehicles and heavy vehicles and discuss the flow-control devices used for drag reduction. Finally, we suggest important unsteady flow structures to investigate for the enhancement of aerodynamic performance and future directions for experimental and numerical approaches.

  6. Electric vehicle propulsion alternatives

    NASA Technical Reports Server (NTRS)

    Secunde, R. R.; Schuh, R. M.; Beach, R. F.

    1983-01-01

    Propulsion technology development for electric vehicles is summarized. Analytical studies, technology evaluation, and the development of technology for motors, controllers, transmissions, and complete propulsion systems are included.

  7. Routing Vehicles with Ants

    NASA Astrophysics Data System (ADS)

    Tan, Wen Fang; Lee, Lai Soon; Majid, Zanariah Abdul; Seow, Hsin Vonn

    Routing vehicles involve the design of an optimal set of routes for a fleet of vehicles to serve a number of customers with known demands. This research develops an Ant Colony Optimization for the vehicle routing with one central depot and identical vehicles. The procedure simulates the behavior of real ants that always find the shortest path between their nest and a food source through a form of communication, pheromone trail. Finally, preliminary results on the learning of the algorithm testing on benchmark data set will be presented in this paper.

  8. An Experimental Study of the Flowfield on a Semispan Rectangular Wing with a Simulated Glaze Ice Accretion. Ph.D. Thesis, 1993 Final Report

    NASA Technical Reports Server (NTRS)

    Khodadoust, Abdollah

    1994-01-01

    Wind tunnel experiments were conducted in order to study the effect of a simulated glaze ice accretion on the flowfield of a semispan, reflection-plane, rectangular wing at Re = 1.5 million and M = 0.12. A laser Doppler velocimeter was used to map the flowfield on the upper surface of the model in both the clean and iced configurations at alpha = 0, 4, and 8 degrees angle of attack. At low angles of attack, the massive separation bubble aft of the leading edge ice horn was found to behave in a manner similar to laminar separation bubbles. At alpha = 0 and 4 degrees, the locations of transition and reattachment, as deduced from momentum thickness distributions, were found to be in good agreement with transition and reattachment locations in laminar separation bubbles. These values at y/b = 0.470, the centerline measurement location, matched well with data obtained on a similar but two dimensional model. The measured velocity profiles on the iced wing compared reasonably with the predicted profiles from Navier-Stokes computations. The iced-induced separation bubble was also found to have features similar to the recirculating region aft of rearward-facing steps. At alpha = 0 degrees and 4 degrees, reverse flow magnitudes and turbulence intensity levels were typical of those found in the recirculating region aft of rearward-facing steps. The calculated separation streamline aft of the ice horn at alpha = 4 degrees, y/b = 0.470 coincided with the locus of the maximum Reynolds normal stress. The maximum Reynolds normal stress peaked at two locations along the separation streamline. The location of the first peak-value coincided with the transition location, as deduced from the momentum thickness distributions. The location of the second peak was just upstream of reattachment, in good agreement with measurements of flows over similar obstacles. The intermittency factor in the vicinity of reattachment at alpha = 4 degrees, y/b = 0.470, revealed the time-dependent nature of

  9. Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

    SciTech Connect

    Robert J. Englar

    2000-06-19

    Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model.

  10. Vehicle barrier systems

    SciTech Connect

    Sena, P.A.

    1986-01-01

    The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper.

  11. Vehicle barrier systems

    SciTech Connect

    Sena, P.A.

    1986-01-01

    The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment, and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper.

  12. Vehicle barrier systems

    SciTech Connect

    Sena, P.A.

    1986-01-01

    The ground vehicle is one of the most effective tools available to an adversary force. Vehicles can be used to penetrate many types of perimeter barriers, transport equipment and personnel rapidly over long distances, and deliver large amounts of explosives directly to facilities in suicide missions. The function of a vehicle barrier system is to detain or disable a defined threat vehicle at a selected distance from a protected facility. Numerous facilities are installing, or planning to install, vehicle barrier systems and many of these facilities are requesting guidance to do so adequately. Therefore, vehicle barriers are being evaluated to determine their stopping capabilities so that systems can be designed that are both balanced and capable of providing a desired degree of protection. Equally important, many of the considerations that should be taken into account when establishing a vehicle barrier system have been identified. These considerations which pertain to site preparation, barrier selection, system integration and operation, and vehicle/barrier interaction, are discussed in this paper. 2 tabs.

  13. Light Vehicle Preventive Maintenance.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This correspondence course, originally developed for the Marine Corps, is designed to instruct students in the performance of preventive maintenance on motor vehicles. Instructional materials are presented in three chapters as follows: (1) Major Maintenance Areas (maintenance system, tires, batteries, cooling systems, and vehicle lubrication; (2)…

  14. Electric Vehicle Battery Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2014-01-01

    A serious drawback to electric vehicles [batteries only] is the idle time needed to recharge their batteries. In this challenge, students can develop ideas and concepts for battery change-out at automotive service stations. Such a capability would extend the range of electric vehicles.

  15. Vehicles for Outdoor Recreation.

    ERIC Educational Resources Information Center

    Exceptional Parent, 1983

    1983-01-01

    The Wheelchair Motorcycle Association tests various motorized vehicles that might help the physically disabled child get about outdoors. Vehicles found to be practical for older children and adolescents include three-wheeled motorcycles and customized go-carts. An address for obtaining more information on the association is provided. (SW)

  16. Nuclear air cushion vehicles

    NASA Technical Reports Server (NTRS)

    Anderson, J. L.

    1973-01-01

    The state-of-the-art of the still-conceptual nuclear air cushion vehicle, particularly the nuclear powerplant is identified. Using mission studies and cost estimates, some of the advantages of nuclear power for large air cushion vehicles are described. The technology studies on mobile nuclear powerplants and conceptual ACV systems/missions studies are summarized.

  17. Intelligent Vehicle Health Management

    NASA Technical Reports Server (NTRS)

    Paris, Deidre E.; Trevino, Luis; Watson, Michael D.

    2005-01-01

    As a part of the overall goal of developing Integrated Vehicle Health Management systems for aerospace vehicles, the NASA Faculty Fellowship Program (NFFP) at Marshall Space Flight Center has performed a pilot study on IVHM principals which integrates researched IVHM technologies in support of Integrated Intelligent Vehicle Management (IIVM). IVHM is the process of assessing, preserving, and restoring system functionality across flight and ground systems (NASA NGLT 2004). The framework presented in this paper integrates advanced computational techniques with sensor and communication technologies for spacecraft that can generate responses through detection, diagnosis, reasoning, and adapt to system faults in support of INM. These real-time responses allow the IIVM to modify the affected vehicle subsystem(s) prior to a catastrophic event. Furthermore, the objective of this pilot program is to develop and integrate technologies which can provide a continuous, intelligent, and adaptive health state of a vehicle and use this information to improve safety and reduce costs of operations. Recent investments in avionics, health management, and controls have been directed towards IIVM. As this concept has matured, it has become clear the INM requires the same sensors and processing capabilities as the real-time avionics functions to support diagnosis of subsystem problems. New sensors have been proposed, in addition, to augment the avionics sensors to support better system monitoring and diagnostics. As the designs have been considered, a synergy has been realized where the real-time avionics can utilize sensors proposed for diagnostics and prognostics to make better real-time decisions in response to detected failures. IIVM provides for a single system allowing modularity of functions and hardware across the vehicle. The framework that supports IIVM consists of 11 major on-board functions necessary to fully manage a space vehicle maintaining crew safety and mission

  18. Lunar material transport vehicle

    NASA Technical Reports Server (NTRS)

    Fisher, Charles D.; Lyons, Douglas; Wilkins, W. Allen, Jr.; Whitehead, Harry C., Jr.

    1988-01-01

    The proposed vehicle, the Lunar Material Transport Vehicle (LMTV), has a mission objective of efficient lunar soil material transport. The LMTV was designed to meet a required set of performance specifications while operating under a given set of constraints. The LMTV is essentially an articulated steering, double-ended dump truck. The vehicle moves on four wheels and has two identical chassis halves. Each half consists of a chassis frame, a material bucket, two wheels with integral curvilinear synchronous motors, a fuel cell and battery arrangement, an electromechanically actuated dumping mechanism, and a powerful microprocessor. The vehicle, as designed, is capable of transporting up to 200 cu ft of material over a one mile round trip per hour. The LMTV is capable of being operated from a variety of sources. The vehicle has been designed as simply as possible with attention also given to secondary usage of components.

  19. Automatic vehicle monitoring

    NASA Technical Reports Server (NTRS)

    Bravman, J. S.; Durrani, S. H.

    1976-01-01

    Automatic vehicle monitoring systems are discussed. In a baseline system for highway applications, each vehicle obtains position information through a Loran-C receiver in rural areas and through a 'signpost' or 'proximity' type sensor in urban areas; the vehicle transmits this information to a central station via a communication link. In an advance system, the vehicle carries a receiver for signals emitted by satellites in the Global Positioning System and uses a satellite-aided communication link to the central station. An advanced railroad car monitoring system uses car-mounted labels and sensors for car identification and cargo status; the information is collected by electronic interrogators mounted along the track and transmitted to a central station. It is concluded that automatic vehicle monitoring systems are technically feasible but not economically feasible unless a large market develops.

  20. Experimental investigation on axial-flow turbine arrays in erodible and non-erodible channels: Performance, flow-field, and bathymetric interactions

    NASA Astrophysics Data System (ADS)

    Hill, Craig; Sotiropoulos, Fotis; Guala, Michele

    2014-11-01

    Natural channels ideal for hydrokinetic turbine installations present complex environments containing asymmetric flow, regions of high shear and turbulent eddies that impact turbine performance. To understand the impacts caused by variable topography, baseline conditions in a laboratory flume are compared to turbine performance, flow characteristics, and channel topography measurements from two additional experiments with small-scale and large-scale bathymetric features. Both aligned and staggered multi-turbine configurations were investigated. Small-scale axial-flow rotors attached to miniature DC motors provided measurements of turbine performance and response to i) complex topographic features and ii) flow features induced by upstream turbines. Discussion will focus on optimal streamwise and lateral spacing for axial-flow devices, turbine-topography interactions within arrays and inter-array flow-field measurements. Primary focus will center on results from turbines separated by a streamwise distance of 7dT. Additionally, results indicate possible control strategies for turbines installed in complex natural environments. This work was supported by NSF PFI Grant IIP-1318201, CAREER: Geophysical Flow Control (NSF).

  1. Local mechanisms for the separation of optic flow-field components in the land crab, Cardisoma guanhumi: a role for motion parallax?

    PubMed

    Johnson, Aaron P; Barnes, W Jon P; Macauley, Martin W S

    2004-01-01

    Although a number of global mechanisms have been proposed over the years that explain how crabs might separate the rotational and translational components of their optic flow field, there has been no evidence to date that local mechanisms such as motion parallax are used in this separation. We describe here a study that takes advantage of a recently developed suite of computer-generated visual stimuli that creates a three-dimensional world surrounding the crab in which we can simulate translational and rotational optic flow. We show that, while motion parallax is not the only mechanism used in flow-field separation, it does play a role in the recognition of translational optic flow fields in that, under conditions of low overall light intensity and low contrast ratio when crabs find the distinction between rotation and translation harder, smaller eye movements occur in response to translation when motion parallax cues are present than when they are absent. Thus, motion parallax is one of many cues that crabs use to separate rotational and translational optic flow by showing compensatory eye movements to only the former.

  2. Are SUVs dangerous vehicles?

    PubMed

    Keall, Michael D; Newstead, Stuart

    2008-05-01

    This study was a population cohort study of all licensed passenger vehicles in New Zealand in the years 2005--2006. The objective of the study was to evaluate the effect on road safety of sports utility vehicles (SUVs) compared to other passenger vehicle types. Statistical models were fitted to the population of 2,996,000 vehicles of which 17,245 were involved in an injury crash. Controlling for distance driven, vehicle and owner characteristics, SUVs were found to be relatively safe vehicles in terms of injury crash involvement and in terms of the injury rate of their own occupants or other road users into which they crashed. Current research on SUV safety clearly shows them to be a road safety concern, but only once a collision occurs. The present study shows that SUVs in New Zealand have relatively few collisions compared to other passenger vehicle types, allowing for factors such as distance driven, some allowance for the type of driving exposure (via the owners' addresses) and for owner age and gender. Overall, the vehicle type implicated most frequently in injury crashes and involving the highest rate of road injuries was sports cars, causing clearly the most harm per licensed vehicle. Instead of concerning themselves primarily with SUVs, the focus of road safety agencies should be on the relatively high crash risk of sports cars, which are clearly a road safety concern. Their high crash involvement rate and injury rate is likely to be largely due to the way they are driven rather than to inherent characteristics of the vehicles themselves. PMID:18460363

  3. Hydrogen vehicle fueling station

    SciTech Connect

    Daney, D.E.; Edeskuty, F.J.; Daugherty, M.A.

    1995-09-01

    Hydrogen fueling stations are an essential element in the practical application of hydrogen as a vehicle fuel, and a number of issues such as safety, efficiency, design, and operating procedures can only be accurately addressed by a practical demonstration. Regardless of whether the vehicle is powered by an internal combustion engine or fuel cell, or whether the vehicle has a liquid or gaseous fuel tank, the fueling station is a critical technology which is the link between the local storage facility and the vehicle. Because most merchant hydrogen delivered in the US today (and in the near future) is in liquid form due to the overall economics of production and delivery, we believe a practical refueling station should be designed to receive liquid. Systems studies confirm this assumption for stations fueling up to about 300 vehicles. Our fueling station, aimed at refueling fleet vehicles, will receive hydrogen as a liquid and dispense it as either liquid, high pressure gas, or low pressure gas. Thus, it can refuel any of the three types of tanks proposed for hydrogen-powered vehicles -- liquid, gaseous, or hydride. The paper discusses the fueling station design. Results of a numerical model of liquid hydrogen vehicle tank filling, with emphasis on no vent filling, are presented to illustrate the usefulness of the model as a design tool. Results of our vehicle performance model illustrate our thesis that it is too early to judge what the preferred method of on-board vehicle fuel storage will be in practice -- thus our decision to accommodate all three methods.

  4. Mars manned transportation vehicle

    NASA Technical Reports Server (NTRS)

    Perez-Davis, Marla E.; Faymon, Karl A.

    1987-01-01

    A viable power system technology for a surface transportation vehicle to explore the planet Mars is presented. A number of power traction systems were investigated, and it was found that a regenerative hydrogen-oxygen fuel cell appears to be attractive for a manned Mars rover application. Mission requirements were obtained from the Manned Mars Mission Working Group. Power systems weights, power, and reactants requirements were determined as a function of vehicle weights for vehicles weighing from 6,000 to 16,000 lb (2,722 to 7,257 kg), (Earth weight). The vehicle performance requirements were: velocity, 10 km/hr; range, 100 km; slope climbing capability, 30 deg uphill for 50 km; mission duration, 5 days; and crew, 5. Power requirements for the operation of scientific equipment and support system capabilities were also specified and included in this study. The concept developed here would also be applicable to a Lunar based vehicle for Lunar exploration. The reduced gravity on the Lunar surface, (over that on the Martian surface), would result in an increased range or capability over that of the Mars vehicle since many of the power and energy requirements for the vehicle are gravity dependent.

  5. Mars manned transportation vehicle

    SciTech Connect

    Perez-Davis, M.E.; Faymon, K.A.

    1987-07-01

    A viable power system technology for a surface transportation vehicle to explore the planet Mars is presented. A number of power traction systems were investigated, and it was found that a regenerative hydrogen-oxygen fuel cell appears to be attractive for a manned Mars rover application. Mission requirements were obtained from the Manned Mars Mission Working Group. Power systems weights, power, and reactants requirements were determined as a function of vehicle weights for vehicles weighing from 6,000 to 16,000 lb (2,722 to 7,257 kg), (Earth weight). The vehicle performance requirements were: velocity, 10 km/hr; range, 100 km; slope climbing capability, 30 deg uphill for 50 km; mission duration, 5 days; and crew, 5. Power requirements for the operation of scientific equipment and support system capabilities were also specified and included in this study. The concept developed here would also be applicable to a Lunar based vehicle for Lunar exploration. The reduced gravity on the Lunar surface, (over that on the Martian surface), would result in an increased range or capability over that of the Mars vehicle since many of the power and energy requirements for the vehicle are gravity dependent.

  6. Blast resistant vehicle seat

    SciTech Connect

    Ripley, Edward B

    2013-02-12

    Disclosed are various seats for vehicles particularly military vehicles that are susceptible to attack by road-bed explosive devices such as land mines or improvised explosive devices. The seats often have rigid seat shells and may include rigid bracing for rigidly securing the seat to the chassis of the vehicle. Typically embodiments include channels and particulate media such as sand disposed in the channels. A gas distribution system is generally employed to pump a gas through the channels and in some embodiments the gas is provided at a pressure sufficient to fluidize the particulate media when an occupant is sitting on the seat.

  7. Vehicle gas producers

    NASA Astrophysics Data System (ADS)

    Donath, E. E.

    1980-05-01

    The present petroleum supply situation with the possibility of unscheduled interruptions and the definite expectation of continued price increases calls for an investigation of the use of solid fuels for the propulsion of vehicles. The paper reviews the use of solid fuel gas producers with high thermal efficiency on motor vehicles, especially trucks and buses. Some economic comparisons are presented for pre-World War II conditions. Suggestions are made for possible future development of vehicle gas producers. The types of producers are described, along with their performance, special problems, and the importance of fuel properties.

  8. Rapid road repair vehicle

    SciTech Connect

    Mara, L.M.

    1999-09-07

    Disclosed are improvements to a rapid road repair vehicle comprising an improved cleaning device arrangement, two dispensing arrays for filling defects more rapidly and efficiently, an array of pre-heaters to heat the road way surface in order to help the repair material better bond to the repaired surface, a means for detecting, measuring, and computing the number, location and volume of each of the detected surface imperfection, and a computer means schema for controlling the operation of the plurality of vehicle subsystems. The improved vehicle is, therefore, better able to perform its intended function of filling surface imperfections while moving over those surfaces at near normal traffic speeds.

  9. Assured crew return vehicle

    NASA Technical Reports Server (NTRS)

    Cerimele, Christopher J. (Inventor); Ried, Robert C. (Inventor); Peterson, Wayne L. (Inventor); Zupp, George A., Jr. (Inventor); Stagnaro, Michael J. (Inventor); Ross, Brian P. (Inventor)

    1991-01-01

    A return vehicle is disclosed for use in returning a crew to Earth from low earth orbit in a safe and relatively cost effective manner. The return vehicle comprises a cylindrically-shaped crew compartment attached to the large diameter of a conical heat shield having a spherically rounded nose. On-board inertial navigation and cold gas control systems are used together with a de-orbit propulsion system to effect a landing near a preferred site on the surface of the Earth. State vectors and attitude data are loaded from the attached orbiting craft just prior to separation of the return vehicle.

  10. Rapid road repair vehicle

    DOEpatents

    Mara, Leo M.

    1999-01-01

    Disclosed are improvments to a rapid road repair vehicle comprising an improved cleaning device arrangement, two dispensing arrays for filling defects more rapidly and efficiently, an array of pre-heaters to heat the road way surface in order to help the repair material better bond to the repaired surface, a means for detecting, measuring, and computing the number, location and volume of each of the detected surface imperfection, and a computer means schema for controlling the operation of the plurality of vehicle subsystems. The improved vehicle is, therefore, better able to perform its intended function of filling surface imperfections while moving over those surfaces at near normal traffic speeds.

  11. Combat vehicle visualization system

    NASA Astrophysics Data System (ADS)

    Belt, Ronald A.; Hauge, Jim; Kelley, Jim; Knowles, Gary R.; Lewandowski, Ronald J.; Riddle, Larry; Mandelbaum, Robert; Reich, Barry; Girolamo, Henry J.

    2000-06-01

    A combat vehicle visualization system is described that enhances the situation awareness of the vehicle commander. The system consists of a 360 degree(s) panoramic sensor, a gimbaled 8 - 12 micrometers infrared sensor, and a helmet-mounted display with head tracker. The helmet-mounted display can display the fused sensor data to aid the commander in vehicle maneuvering and threat acquisition while buttoned up. It can also display situation awareness information down-loaded from the tactical internet while standing in the hatch. Construction and operation features will be described.

  12. Space Vehicle Valve System

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  13. Aerodynamics of Small Vehicles

    NASA Astrophysics Data System (ADS)

    Mueller, Thomas J.

    In this review we describe the aerodynamic problems that must be addressed in order to design a successful small aerial vehicle. The effects of Reynolds number and aspect ratio (AR) on the design and performance of fixed-wing vehicles are described. The boundary-layer behavior on airfoils is especially important in the design of vehicles in this flight regime. The results of a number of experimental boundary-layer studies, including the influence of laminar separation bubbles, are discussed. Several examples of small unmanned aerial vehicles (UAVs) in this regime are described. Also, a brief survey of analytical models for oscillating and flapping-wing propulsion is presented. These range from the earliest examples where quasi-steady, attached flow is assumed, to those that account for the unsteady shed vortex wake as well as flow separation and aeroelastic behavior of a flapping wing. Experiments that complemented the analysis and led to the design of a successful ornithopter are also described.

  14. TRACKED VEHICLE Rev 75

    SciTech Connect

    Raby, Eric Y.

    2007-05-08

    Revision 75 of the Tracked Vehicle software is a soft real-time simulation of a differentially steered, tracked mobile robot, which, because of the track flippers, resembles the iRobot PackBot (http://www.irobot.com/). Open source libraries are used for the physics engine (http://www.ode.org/), the display and user interface (http://www.mathies.com/cpw/), and the program command line and configuration file parameters (http://www.boost.org/). The simulation can be controlled by a USB joystick or the keyboard. The configuration file contains demonstration model parameters of no particular vehicle. This simulation can be used as a starting point for those doing tracked vehicle simulations. This simulation software is essentially a research tool which can be modified and adapted for certain types of tracked vehicle research. An open source license allows an individual researchers to tailor the code to their specific research needs.

  15. Hybrid vehicle control

    DOEpatents

    Shallvari, Iva; Velnati, Sashidhar; DeGroot, Kenneth P.

    2015-07-28

    A method and apparatus for heating a catalytic converter's catalyst to an efficient operating temperature in a hybrid electric vehicle when the vehicle is in a charge limited mode such as e.g., the charge depleting mode or when the vehicle's high voltage battery is otherwise charge limited. The method and apparatus determine whether a high voltage battery of the vehicle is incapable of accepting a first amount of charge associated with a first procedure to warm-up the catalyst. If it is determined that the high voltage battery is incapable of accepting the first amount of charge, a second procedure with an acceptable amount of charge is performed to warm-up the catalyst.

  16. Vehicle Technologies Program Implementation

    SciTech Connect

    none,

    2009-06-19

    The Vehicle Technologies Program takes a systematic approach to Program implementation. Elements of this approach include the evaluation of new technologies, competitive selection of projects and partners, review of Program and project improvement, project tracking, and portfolio management and adjustment.

  17. Vehicle Technologies Program Planning

    SciTech Connect

    2009-06-19

    The Vehicle Technologies Program’s strategic goal is to develop sustainable, cost-competitive technologies to reduce U.S. dependence on petroleum, increase fuel efficiency, reduce greenhouse gas emissions and improve the Nation's energy security.

  18. TRACKED VEHICLE Rev 75

    2007-05-08

    Revision 75 of the Tracked Vehicle software is a soft real-time simulation of a differentially steered, tracked mobile robot, which, because of the track flippers, resembles the iRobot PackBot (http://www.irobot.com/). Open source libraries are used for the physics engine (http://www.ode.org/), the display and user interface (http://www.mathies.com/cpw/), and the program command line and configuration file parameters (http://www.boost.org/). The simulation can be controlled by a USB joystick or the keyboard. The configuration file contains demonstration model parametersmore » of no particular vehicle. This simulation can be used as a starting point for those doing tracked vehicle simulations. This simulation software is essentially a research tool which can be modified and adapted for certain types of tracked vehicle research. An open source license allows an individual researchers to tailor the code to their specific research needs.« less

  19. Vehicle Technologies Program Overview

    SciTech Connect

    none,

    2006-09-05

    Overview of the Vehicle Technologies Program including external assessment and market view; internal assessment, program history and progress; program justification and federal role; program vision, mission, approach, strategic goals, outputs, and outcomes; and performance goals.

  20. Constellation Launch Vehicles Overview

    NASA Technical Reports Server (NTRS)

    Cook, Steve; Fragola, Joseph R.; Priskos, Alex; Davis, Danny; Kaynard, Mike; Hutt, John; Davis, Stephan; Creech, Steve

    2009-01-01

    This slide presentation reviews the current status of the launch vehicles associated with the Constellation Program. These are the Ares I and the Ares V. An overview of the Ares launch vehicles is included. The presentation stresses that the major criteria for the Ares I launcher is the safety of the crew, and the presentation reviews the various features that are designed to assure that aim. The Ares I vehicle is being built on a foundation of proven technologies, and the Ares V will give NASA unprecedented performance and payload volume that can enable a range of future missions. The CDs contain videos of scenes from various activities surrounding the design, construction and testing of the vehicles.

  1. Hypersonic vehicle design

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The design task for the Advanced Aeronautics Design Project at UCLA is to provide a design for a hypersonic trans-atmospheric vehicle capable of horizontal take-off and landing from conventional runways. To accomplish this task, students are developing unclassified, unrestricted generic hypersonic vehicle models. These models include aerodynamic, propulsive, and thermal effects. The models will be used in the 1987-1988 academic year for vehicle design emphasizing the use of trajectory studies to optimize the vehicle design. The design problem is being considered both in terms of conventional issues such as aerodynamics, propulsion, and thermal systems and also in terms of flight systems, flight controls, and flight testing. The goal of this program is to consider testing as an integral part of design.

  2. Vehicle speed control device

    SciTech Connect

    Thornton-Trump, W.E.

    1987-03-10

    An apparatus is described for automatically limiting the speed of a vehicle powered by an internal combustion engine having a spark ignition system with an ignition coil, comprising: sensor means for generating a speed signal directly representative of the speed of the vehicle comprising a series of speed signal pulses having a pulse repetition frequency proportional to the speed of the vehicle; control means for converting speed signal pulses into a DC voltage proportional to the vehicle speed; means for comparing the DC voltage to a predetermined DC voltage having substantially zero AC components representative of a predetermined maximum speed and for generating a difference signal in response thereto; and means for generating a pulse-width modulated control signal responsive to the difference signal; power means responsive to the control signal for intermittently interrupting the ignition system.

  3. Launch Vehicle Operations Simulator

    NASA Technical Reports Server (NTRS)

    Blackledge, J. W.

    1974-01-01

    The Saturn Launch Vehicle Operations Simulator (LVOS) was developed for NASA at Kennedy Space Center. LVOS simulates the Saturn launch vehicle and its ground support equipment. The simulator was intended primarily to be used as a launch crew trainer but it is also being used for test procedure and software validation. A NASA/contractor team of engineers and programmers implemented the simulator after the Apollo XI lunar landing during the low activity periods between launches.

  4. Nuclear air cushion vehicles.

    NASA Technical Reports Server (NTRS)

    Anderson, J. L.

    1973-01-01

    This paper serves several functions. It identifies the 'state-of-the-art' of the still-conceptual nuclear air cushion vehicle, particularly the nuclear powerplant. Using mission studies and cost estimates, the report describes some of the advantages of nuclear power for large air cushion vehicles. The paper also summarizes the technology studies on mobile nuclear powerplants and conceptual ACV systems/missions studies that have been performed at NASA Lewis Research Center.

  5. Space robot simulator vehicle

    NASA Technical Reports Server (NTRS)

    Cannon, R. H., Jr.; Alexander, H.

    1985-01-01

    A Space Robot Simulator Vehicle (SRSV) was constructed to model a free-flying robot capable of doing construction, manipulation and repair work in space. The SRSV is intended as a test bed for development of dynamic and static control methods for space robots. The vehicle is built around a two-foot-diameter air-cushion vehicle that carries batteries, power supplies, gas tanks, computer, reaction jets and radio equipment. It is fitted with one or two two-link manipulators, which may be of many possible designs, including flexible-link versions. Both the vehicle body and its first arm are nearly complete. Inverse dynamic control of the robot's manipulator has been successfully simulated using equations generated by the dynamic simulation package SDEXACT. In this mode, the position of the manipulator tip is controlled not by fixing the vehicle base through thruster operation, but by controlling the manipulator joint torques to achieve the desired tip motion, while allowing for the free motion of the vehicle base. One of the primary goals is to minimize use of the thrusters in favor of intelligent control of the manipulator. Ways to reduce the computational burden of control are described.

  6. Electric/Hybrid Vehicle Simulation

    NASA Technical Reports Server (NTRS)

    Slusser, R. A.; Chapman, C. P.; Brennand, J. P.

    1985-01-01

    ELVEC computer program provides vehicle designer with simulation tool for detailed studies of electric and hybrid vehicle performance and cost. ELVEC simulates performance of user-specified electric or hybrid vehicle under user specified driving schedule profile or operating schedule. ELVEC performs vehicle design and life cycle cost analysis.

  7. Advanced Vehicle Testing and Evaluation

    SciTech Connect

    Garetson, Thomas

    2013-03-31

    The objective of the United States (U.S.) Department of Energy's (DOEs) Advanced Vehicle Testing and Evaluation (AVTE) project was to provide test and evaluation services for advanced technology vehicles, to establish a performance baseline, to determine vehicle reliability, and to evaluate vehicle operating costs in fleet operations.Vehicles tested include light and medium-duty vehicles in conventional, hybrid, and all-electric configurations using conventional and alternative fuels, including hydrogen in internal combustion engines. Vehicles were tested on closed tracks and chassis dynamometers, as well as operated on public roads, in fleet operations, and over prescribed routes. All testing was controlled by procedures developed specifically to support such testing.

  8. Upgraded demonstration vehicle task report

    NASA Technical Reports Server (NTRS)

    Bryant, J.; Hardy, K.; Livingston, R.; Sandberg, J.

    1981-01-01

    Vehicle/battery performance capabilities and interface problems that occurred when upgraded developmental batteries were integrated with upgraded versions of comercially available electric vehicles were investigated. Developmental batteries used included nickel zinc batteries, a nickel iron battery, and an improved lead acid battery. Testing of the electric vehicles and upgraded batteries was performed in the complete vehicle system environment to characterize performance and identify problems unique to the vehicle/battery system. Constant speed tests and driving schedule range tests were performed on a chassis dynamometer. The results from these tests of the upgraded batteries and vehicles were compared to performance capabilities for the same vehicles equipped with standard batteries.

  9. 77 FR 12355 - Enabling a Secure Environment for Vehicle-to-Vehicle and Vehicle-to-Infrastructure Transactions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-29

    ... Enabling a Secure Environment for Vehicle-to-Vehicle and Vehicle- to-Infrastructure Transactions Workshop... Environment for Vehicle- to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) Transactions on April 19-20... contact Adam Hopps at Ahopps@ITSA.org . About the Connected Vehicle Secure Environment Establishing...

  10. China's Launch Vehicle Operations

    NASA Astrophysics Data System (ADS)

    Bai, Jingwu

    2002-01-01

    China's Launch Vehicle technologies have been started since 1950s. With the efforts made by several-generation Chinese Space people, the Long March (LM) Launch Vehicles, China's main space transportation tools, have undergone a development road from conventional propellants to cryogenic propellants, from stage-by-stage to strap-on, from dedicated-launch to multiple-launch, from satellite-launching to space capsule-launching. The LM Launch Vehicles are capable of sending various payloads to different orbits with low cost and high reliability. Till now, the LM Launch Vehicles have conducted 67 launch missions, putting 76 spacecraft into the given orbits since the successful mission made by LM-1 in 1970. Especially, they have performed 22 international commercial satellite-launching missions, sending 27 foreign satellites successfully. The footprints of LM Launch Vehicles reflect the development and progress of Chinese Space Industry. At the beginning of the 21st century, with the development of launch vehicle technology and the economic globalization, it is an inexorable trend that Chinese space industry must participate in the international cooperation and competition. Being faced with both opportunities and challenges, Chinese Space Industry should promote actively the commercial launch service market to increase service quality and improve the comprehensive competition capabilities. In order to maintain the sustaining development of China's launch vehicle technology and to meet the increasing needs in the international commercial launch service market, Chinese space industry is now doing research work on developing new-generation Chinese launchers. The new launchers will be large-scale, powerful and non-contamination. The presence of the new-generation Chinese launchers will greatly speed up the development of the whole space-related industries in China, as well as other parts of the world. In the first part, this paper gives an overview on China Aerospace Science

  11. Methylotroph cloning vehicle

    DOEpatents

    Hanson, Richard S.; Allen, Larry N.

    1989-04-25

    A cloning vehicle comprising: a replication determinant effective for replicating the vehicle in a non-C.sub.1 -utilizing host and in a C.sub.1 -utilizing host; DNA effective to allow the vehicle to be mobilized from the non-C.sub.1 -utilizing host to the C.sub.1 -utilizing host; DNA providing resistance to two antibiotics to which the wild-type C.sub.1 -utilizing host is susceptible, each of the antibiotic resistance markers having a recognition site for a restriction endonuclease; a cos site; and a means for preventing replication in the C.sub.1 -utilizing host. The vehicle is used for complementation mapping as follows. DNA comprising a gene from the C.sub.1 -utilizing organism is inserted at the restriction nuclease recognition site, inactivating the antibiotic resistance marker at that site. The vehicle can then be used to form a cosmid structure to infect the non-C.sub.1 -utilizing (e.g., E. coli) host, and then conjugated with a selected C.sub.1 -utilizing mutant. Resistance to the other antibiotic by the mutant is a marker of the conjugation. Other phenotypical changes in the mutant, e.g., loss of an auxotrophic trait, is attributed to the C.sub.1 gene. The vector is also used to inactivate genes whose protein products catalyze side reactions that divert compounds from a biosynthetic pathway to a desired product, thereby producing an organism that makes the desired product in higher yields.

  12. Space vehicle concepts

    NASA Technical Reports Server (NTRS)

    Tucker, Michael; Meredith, Oliver; Brothers, Bobby

    1986-01-01

    Several concepts of chemical-propulsion Space Vehicles (SVs) for manned Mars landing missions are presented. For vehicle sizing purposes, several specific missions were chosen from opportunities in the late 1990's and early 2000's, and a vehicle system concept is then described which is applicable to the full range of missions and opportunities available. In general, missions utilizing planetary opposition alignments can be done with smaller vehicles than those utilizing planetary opposition alignments. The conjunction missions have a total mission time of about 3 years, including a required stay-time of about 60 days. Both types of missions might be desirable during a Mars program, the opposition type for early low-risk missions and/or for later unmanned cargo missions, and the conjunction type for more extensive science/exploration missions and/or for Mars base activities. Since the opposition missions appeared to drive the SV size more severely, there were probably more cases examined for them. Some of the concepts presented utilize all-propulsive braking, some utilize and all aerobraking approach, and some are hybrids. Weight statements are provided for various cases. Most of the work was done on 0-g vehicle concepts, but partial-g and 1-g concepts are also provided and discussed. Several options for habitable elements are shown, such as large-diameter modules and space station (SS) types of modules.

  13. Distributed Propulsion Vehicles

    NASA Technical Reports Server (NTRS)

    Kim, Hyun Dae

    2010-01-01

    Since the introduction of large jet-powered transport aircraft, the majority of these vehicles have been designed by placing thrust-generating engines either under the wings or on the fuselage to minimize aerodynamic interactions on the vehicle operation. However, advances in computational and experimental tools along with new technologies in materials, structures, and aircraft controls, etc. are enabling a high degree of integration of the airframe and propulsion system in aircraft design. The National Aeronautics and Space Administration (NASA) has been investigating a number of revolutionary distributed propulsion vehicle concepts to increase aircraft performance. The concept of distributed propulsion is to fully integrate a propulsion system within an airframe such that the aircraft takes full synergistic benefits of coupling of airframe aerodynamics and the propulsion thrust stream by distributing thrust using many propulsors on the airframe. Some of the concepts are based on the use of distributed jet flaps, distributed small multiple engines, gas-driven multi-fans, mechanically driven multifans, cross-flow fans, and electric fans driven by turboelectric generators. This paper describes some early concepts of the distributed propulsion vehicles and the current turboelectric distributed propulsion (TeDP) vehicle concepts being studied under the NASA s Subsonic Fixed Wing (SFW) Project to drastically reduce aircraft-related fuel burn, emissions, and noise by the year 2030 to 2035.

  14. Apparatus for stopping a vehicle

    DOEpatents

    Wattenburg, Willard H.; McCallen, David B.

    2007-03-20

    An apparatus for externally controlling one or more brakes on a vehicle having a pressurized fluid braking system. The apparatus can include a pressurizable vessel that is adapted for fluid-tight coupling to the braking system. Impact to the rear of the vehicle by a pursuit vehicle, shooting a target mounted on the vehicle or sending a signal from a remote control can all result in the fluid pressures in the braking system of the vehicle being modified so that the vehicle is stopped and rendered temporarily inoperable. A control device can also be provided in the driver's compartment of the vehicle for similarly rendering the vehicle inoperable. A driver or hijacker of the vehicle preferably cannot overcome the stopping action from the driver's compartment.

  15. Assured Crew Return Vehicle

    NASA Technical Reports Server (NTRS)

    Stone, D. A.; Craig, J. W.; Drone, B.; Gerlach, R. H.; Williams, R. J.

    1991-01-01

    The developmental status is discussed regarding the 'lifeboat' vehicle to enhance the safety of the crew on the Space Station Freedom (SSF). NASA's Assured Crew Return Vehicle (ACRV) is intended to provide a means for returning the SSF crew to earth at all times. The 'lifeboat' philosophy is the key to managing the development of the ACRV which further depends on matrixed support and total quality management for implementation. The risk of SSF mission scenarios are related to selected ACRV mission requirements, and the system and vehicle designs are related to these precepts. Four possible ACRV configurations are mentioned including the lifting-body, Apollo shape, Discoverer shape, and a new lift-to-drag concept. The SCRAM design concept is discussed in detail with attention to the 'lifeboat' philosophy and requirements for implementation.

  16. Personnel emergency carrier vehicle

    NASA Technical Reports Server (NTRS)

    Owens, Lester J. (Inventor); Fedor, Otto H. (Inventor)

    1987-01-01

    A personnel emergency carrier vehicle is disclosed which includes a vehicle frame supported on steerable front wheels and driven rear wheels. A supply of breathing air is connected to quick connect face mask coupling and umbilical cord couplings for supplying breathing air to an injured worker or attendant either with or without a self-contained atmospheric protection suit for protection against hazardous gases at an accident site. A non-sparking hydraulic motion is utilized to drive the vehicle and suitable direction and throttling controls are provided for controlling the delivery of a hydraulic driving fluid from a pressurized hydraulic fluid accumulator. A steering axis is steerable through a handle to steer the front wheels through a linkage assembly.

  17. Dynamics of aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Schmidt, David K.

    1991-01-01

    The focus of this research was to address the modeling, including model reduction, of flexible aerospace vehicles, with special emphasis on models used in dynamic analysis and/or guidance and control system design. In the modeling, it is critical that the key aspects of the system being modeled be captured in the model. In this work, therefore, aspects of the vehicle dynamics critical to control design were important. In this regard, fundamental contributions were made in the areas of stability robustness analysis techniques, model reduction techniques, and literal approximations for key dynamic characteristics of flexible vehicles. All these areas are related. In the development of a model, approximations are always involved, so control systems designed using these models must be robust against uncertainties in these models.

  18. Remote vehicle survey tool

    SciTech Connect

    Armstrong, G.A.; Burks, B.L.; Kress, R.L.; Wagner, D.G.; Ward, C.R.

    1993-05-01

    The Remote Vehicle Survey Tool (RVS7) is a color graphical display tool for viewing remotely acquired scientific data. The RVST displays the data in the form of a color two-dimensional world model map. The world model map allows movement of the remote vehicle to be tracked by the operator and the data from sensors to be graphically depicted in the interface. Linear and logarithmic meters, dual channel oscilloscopes, and directional compasses are used to display sensor information. The RVST is user-configurable by the use of ASCII text files. The operator can configure the RVST to work with any remote data acquisition system and teleoperated or autonomous vehicle. The modular design of the RVST and its ability to be quickly configured for varying system requirements make the RVST ideal for remote scientific data display in all environmental restoration and waste management programs.

  19. Remote vehicle survey tool

    SciTech Connect

    Armstrong, G.A.; Burks, B.L.; Kress, R.L. ); Wagner, D.G.; Ward, C.R. )

    1993-01-01

    The Remote Vehicle Survey Tool (RVS7) is a color graphical display tool for viewing remotely acquired scientific data. The RVST displays the data in the form of a color two-dimensional world model map. The world model map allows movement of the remote vehicle to be tracked by the operator and the data from sensors to be graphically depicted in the interface. Linear and logarithmic meters, dual channel oscilloscopes, and directional compasses are used to display sensor information. The RVST is user-configurable by the use of ASCII text files. The operator can configure the RVST to work with any remote data acquisition system and teleoperated or autonomous vehicle. The modular design of the RVST and its ability to be quickly configured for varying system requirements make the RVST ideal for remote scientific data display in all environmental restoration and waste management programs.

  20. Aeroacoustics of Space Vehicles

    NASA Technical Reports Server (NTRS)

    Panda, Jayanta

    2014-01-01

    While for airplanes the subject of aeroacoustics is associated with community noise, for space vehicles it is associated with vibro-acoustics and structural dynamics. Surface pressure fluctuations encountered during launch and travel through lower part of the atmosphere create intense vibro-acoustics environment for the payload, electronics, navigational equipment, and a large number of subsystems. All of these components have to be designed and tested for flight-certification. This presentation will cover all three major sources encountered in manned and unmanned space vehicles: launch acoustics, ascent acoustics and abort acoustics. Launch pads employ elaborate acoustic suppression systems to mitigate the ignition pressure waves and rocket plume generated noise during the early part of the liftoff. Recently we have used large microphone arrays to identify the noise sources during liftoff and found that the standard model by Eldred and Jones (NASA SP-8072) to be grossly inadequate. As the vehicle speeds up and reaches transonic speed in relatively denser part of the atmosphere, various shock waves and flow separation events create unsteady pressure fluctuations that can lead to high vibration environment, and occasional coupling with the structural modes, which may lead to buffet. Examples of wind tunnel tests and computational simulations to optimize the outer mold line to quantify and reduce the surface pressure fluctuations will be presented. Finally, a manned space vehicle needs to be designed for crew safety during malfunctioning of the primary rocket vehicle. This brings the subject of acoustic environment during abort. For NASAs Multi-Purpose Crew Vehicle (MPCV), abort will be performed by lighting rocket motors atop the crew module. The severe aeroacoustics environments during various abort scenarios were measured for the first time by using hot helium to simulate rocket plumes in the Ames unitary plan wind tunnels. Various considerations used for the

  1. Hybrid electric vehicles TOPTEC

    SciTech Connect

    1994-06-21

    This one-day TOPTEC session began with an overview of hybrid electric vehicle technology. Updates were given on alternative types of energy storage, APU control for low emissions, simulation programs, and industry and government activities. The keynote speech was about battery technology, a key element to the success of hybrids. The TOPEC concluded with a panel discussion on the mission of hybrid electric vehicles, with a perspective from industry and government experts from United States and Canada on their view of the role of this technology.

  2. BEEST: Electric Vehicle Batteries

    SciTech Connect

    2010-07-01

    BEEST Project: The U.S. spends nearly a $1 billion per day to import petroleum, but we need dramatically better batteries for electric and plug-in hybrid vehicles (EV/PHEV) to truly compete with gasoline-powered cars. The 10 projects in ARPA-E’s BEEST Project, short for “Batteries for Electrical Energy Storage in Transportation,” could make that happen by developing a variety of rechargeable battery technologies that would enable EV/PHEVs to meet or beat the price and performance of gasoline-powered cars, and enable mass production of electric vehicles that people will be excited to drive.

  3. Vehicle brake testing system

    DOEpatents

    Stevens, Samuel S [Harriman, TN; Hodgson, Jeffrey W [Lenoir City, TN

    2002-11-19

    This invention relates to a force measuring system capable of measuring forces associated with vehicle braking and of evaluating braking performance. The disclosure concerns an invention which comprises a first row of linearly aligned plates, a force bearing surface extending beneath and beside the plates, vertically oriented links and horizontally oriented links connecting each plate to a force bearing surface, a force measuring device in each link, a transducer coupled to each force measuring device, and a computing device coupled to receive an output signal from the transducer indicative of measured force in each force measuring device. The present invention may be used for testing vehicle brake systems.

  4. Affordable Vehicle Avionics Overview

    NASA Technical Reports Server (NTRS)

    Cockrell, James J.

    2015-01-01

    Public and private launch vehicle developers are reducing the cost of propulsion for small commercial launchers, but conventional high-performance, high-reliability avionics remain the disproportionately high cost driver for launch. AVA technology performs as well or better than conventional launch vehicle avionics, but with a fraction of the recurring costs. AVA enables small launch providers to offer affordable rides to LEO to nano-satellites as primary payloads meaning, small payloads can afford to specify their own launch and orbit parameters

  5. Affordable Vehicle Avionics Overview

    NASA Technical Reports Server (NTRS)

    Cockrell, James J.

    2015-01-01

    Public and private launch vehicle developers are reducing the cost of propulsion for small commercial launchers, but conventional high-performance, high-reliability avionics remain the disproportionately high cost driver for launch. AVA technology performs as well or better than conventional launch vehicle avionics, but with a fraction of the recurring costs. AVA enables small launch providers to offer affordable rides to LEO to nano-satellites as primary payloads meaning, small payloads can afford to specify their own launch and orbit parameters.

  6. Environmental Evaluation of New Generation Vehicles and Vehicle Components

    SciTech Connect

    Schexnayder, S.M.

    2002-02-06

    This report documents assessments that address waste issues and life cycle impacts associated with the vehicle materials and vehicle technologies being developed under the Partnership for a New Generation of Vehicles (PNGV) program. We refer to these vehicles as 3XVs, referring to the PNGV goal that their fuel mileage be three times better than the baseline vehicle. To meet the program's fuel consumption goals, these vehicles substitute lightweight materials for heavier materials such as steel and iron that currently dominate the composition of vehicles, and use engineering and power system changes. Alternative power systems being developed through the PNGV program include batteries for hybrid electric vehicles and fuel cells. With respect to all these developments, it is imperative to learn what effects they will have on the environment before adopting these designs and technologies on a large-scale basis.

  7. Control device for vehicle speed

    SciTech Connect

    Kawata, S.; Hyodo, H.

    1987-03-03

    This patent describes a control device for vehicle speed comprising: a throttle driving means operatively coupled to a throttle valve of a vehicle; a set switch means for commanding memorization of the vehicle speed; a resume switch means for commanding read of the vehicle speed; a vehicle speed detecting means for generating a signal in accordance with the vehicle speed; a vehicle speed memory; an electronical control means for memorizing in the vehicle speed memory vehicle speed information corresponding to the signal obtained from the vehicle speed detecting means in response to actuation of the set switch means. The control means is also for reading out the content of the vehicle speed memory in response to actuation of the resume switch means to control the throttle driving means in accordance with the read-out content; a power supply means for supplying power to the electronical control means; and a power supply control switch means for controlling supply of power to the electronical control means in response to the state of at least one of the set switch means and the resume switch means and the state of the electronical control means. The improvement described here comprises the electronical control means sets the power supply control switch means into such a state that supply of power to the electronical control means is turned OFF, when vehicle speed information is not memorized in the vehicle speed memory.

  8. Silver and gold nanoparticle separation using asymmetrical flow-field flow fractionation: Influence of run conditions and of particle and membrane charges.

    PubMed

    Meisterjahn, Boris; Wagner, Stephan; von der Kammer, Frank; Hennecke, Dieter; Hofmann, Thilo

    2016-04-01

    Flow-Field Flow Fractionation (Flow-FFF), coupled with online detection systems is one of the most promising tools available for the separation and quantification of engineered nanoparticles (ENPs) in complex matrices. To correctly relate the retention of nanoparticles in the Flow-FFF-channel to the particle size, ideal separation conditions must be met. This requires optimization of the parameters that influence the separation behavior. The aim of this study was therefore to systematically investigate and evaluate the influence of parameters such as the carrier liquid, the cross flow, and the membrane material, on the separation behavior of two metallic ENPs. For this purpose the retention, recovery, and separation efficiency of sterically stabilized silver nanoparticles (AgNPs) and electrostatically stabilized gold nanoparticles (AuNPs), which represent two materials widely used in investigations on environmental fate and ecotoxicology, were investigated against a parameter matrix of three different cross-flow densities, four representative carrier solutions, and two membrane materials. The use of a complex mixture of buffers, ionic and non-ionic surfactants (FL-70 solution) together with a medium cross-flow density provided an acceptable compromise in peak quality and recovery for both types of ENPs. However, these separation conditions do not represent a perfect match for both particle types at the same time (maximized recovery at maximized retention). It could be shown that the behavior of particles within Flow-FFF channels cannot be predicted or explained purely in terms of electrostatic interactions. Particles were irreversibly lost under conditions where the measured zeta potentials suggested that there should have been sufficient electrostatic repulsion to ensure stabilization of the particles in the Flow-FFF channel resulting in good recoveries. The wide variations that we observed in ENP behavior under different conditions, together with the different

  9. AST Launch Vehicle Acoustics

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  10. Heavy Vehicle Systems

    SciTech Connect

    Sid Diamond; Richard Wares; Jules Routbort

    2000-04-11

    Heavy Vehicle (HV) systems are a necessary component of achieving OHVT goals. Elements are in place for a far-ranging program: short, intermediate, and long-term. Solicitation will bring industrial input and support. Future funding trend is positive, outlook for HV systems is good.

  11. Recreational Vehicle Trades.

    ERIC Educational Resources Information Center

    Felice, Michael

    This curriculum guide provides materials for a competency-based course in recreational vehicle trades at the secondary level. The curriculum design uses the curriculum infused model for the teaching of basic skills as part of vocational education and demonstrates the relationship of vocationally related skills to communication, mathematics, and…

  12. Engine & Vehicle Mechanics Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum includes all competencies a student will acquire in an engine and vehicle mechanics educational program. It follows guidelines established for automobile technician training programs leading toward certification and addresses requirements of the National Institute for Automotive Service Excellence (ASE). The…

  13. The Electric Vehicle Challenge

    ERIC Educational Resources Information Center

    Roman, Harry T.

    2010-01-01

    This article describes a design activity that provides students with a solid understanding of the many issues involved with alternate energy system design. In this activity, students will be able to learn about electric vehicles and have the opportunity to design a way to recharge the batteries while the cars are parked in a commuter garage. The…

  14. Diesel Vehicle Maintenance Competencies.

    ERIC Educational Resources Information Center

    Braswell, Robert; And Others

    Designed to provide a model set of competencies, this manual presents tasks which were identified by employers, employees, and teachers as important in a postsecondary diesel vehicle maintenance curriculum. The tasks are divided into seven major component areas of instruction: chassis and suspension, diesel engines, diesel fuel, electrical,…

  15. Hybrid Turbine Electric Vehicle

    NASA Technical Reports Server (NTRS)

    Viterna, Larry A.

    1997-01-01

    Hybrid electric power trains may revolutionize today's ground passenger vehicles by significantly improving fuel economy and decreasing emissions. The NASA Lewis Research Center is working with industry, universities, and Government to develop and demonstrate a hybrid electric vehicle. Our partners include Bowling Green State University, the Cleveland Regional Transit Authority, Lincoln Electric Motor Division, the State of Ohio's Department of Development, and Teledyne Ryan Aeronautical. The vehicle will be a heavy class urban transit bus offering double the fuel economy of today's buses and emissions that are reduced to 1/10th of the Environmental Protection Agency's standards. At the heart of the vehicle's drive train is a natural-gas-fueled engine. Initially, a small automotive engine will be tested as a baseline. This will be followed by the introduction of an advanced gas turbine developed from an aircraft jet engine. The engine turns a high-speed generator, producing electricity. Power from both the generator and an onboard energy storage system is then provided to a variable-speed electric motor attached to the rear drive axle. An intelligent power-control system determines the most efficient operation of the engine and energy storage system.

  16. Mars Exploratory Vehicles.

    ERIC Educational Resources Information Center

    Canizo, Thea L.; And Others

    1997-01-01

    Presents an activity in which students learn about the characteristics of the planet Mars. Challenges students to design and build a model of a robotic vehicle that can travel on the surface of Mars and accomplish an assigned task that will provide information useful for future manned trips to the planet. Outlines mission task cards and progress…

  17. Batteries for Electric Vehicles

    NASA Technical Reports Server (NTRS)

    Conover, R. A.

    1985-01-01

    Report summarizes results of test on "near-term" electrochemical batteries - (batteries approaching commercial production). Nickel/iron, nickel/zinc, and advanced lead/acid batteries included in tests and compared with conventional lead/acid batteries. Batteries operated in electric vehicles at constant speed and repetitive schedule of accerlerating, coasting, and braking.

  18. Motor Vehicle Safety

    MedlinePlus

    ... vehicle is safe and in working order Use car seats for children Wear your seat belt Don't speed or drive aggressively Don't drive impaired Safety also involves being aware of others. Share the road with bicycles and motorcycles, and watch for pedestrians.

  19. Battery for vehicle

    SciTech Connect

    Uehara, M.

    1984-04-24

    In a battery of a vehicle such as motorcycle, the bottom is indented at both ends in the longitudinal direction; i.e., with respect to both end portions, in the longitudinal direction of the bottom, the middle portion protrudes downwardly, so that the battery is more advantageously accommodated in the triangular space formed by the motorcycle frame.

  20. Vehicle Cabin Atmosphere Monitor

    NASA Technical Reports Server (NTRS)

    Chutjian, Ara; Darrach, Muray

    2007-01-01

    Vehicle Cabin Atmosphere Monitor (VCAM) identifies gases that are present in minute quantities in the International Space Station (ISS) breathing air that could harm the crew s health. If successful, instruments like VCAM could accompany crewmembers during long-duration exploration missions to the Moon or traveling to Mars.

  1. Vehicle fuel system

    DOEpatents

    Risse, John T.; Taggart, James C.

    1976-01-01

    A vehicle fuel system comprising a plurality of tanks, each tank having a feed and a return conduit extending into a lower portion thereof, the several feed conduits joined to form one supply conduit feeding fuel to a supply pump and using means, unused fuel being returned via a return conduit which branches off to the several return conduits.

  2. Household vehicles energy consumption 1991

    SciTech Connect

    Not Available

    1993-12-09

    The purpose of this report is to provide information on the use of energy in residential vehicles in the 50 States and the District of Columbia. Included are data about: the number and type of vehicles in the residential sector, the characteristics of those vehicles, the total annual Vehicle Miles Traveled (VMT), the per household and per vehicle VMT, the vehicle fuel consumption and expenditures, and vehicle fuel efficiencies. The data for this report are based on the household telephone interviews from the 1991 RTECS, conducted during 1991 and early 1992. The 1991 RTECS represents 94.6 million households, of which 84.6 million own or have access to 151.2 million household motor vehicles in the 50 States and the District of Columbia.

  3. Hybrid-Vehicle Transmission System

    NASA Technical Reports Server (NTRS)

    Lupo, G.; Dotti, G.

    1985-01-01

    Continuously-variable transmission system for hybrid vehicles couples internal-combustion engine and electric motor section, either individually or in parallel, to power vehicle wheels during steering and braking.

  4. Vehicle Integrated Propulsion Research Tests

    NASA Technical Reports Server (NTRS)

    Lekki, John D.; Hunter, Gary W.; Simon, Don; Meredith, Roger; Wrbanek, John; Woike, Mark; Tokars, Roger; Guffanti, Marianne; Lyall, Eric

    2013-01-01

    Overview of the Vehicle Integrated Propulsion Research Tests in the Vehicle Systems Safety Technologies project. This overview covers highlights of the completed VIPR I and VIPR II tests and also covers plans for the VIPR III test.

  5. Methylotroph cloning vehicle

    DOEpatents

    Hanson, R.S.; Allen, L.N.

    1989-04-25

    A cloning vehicle comprising: a replication determinant effective for replicating the vehicle in a non-C[sub 1]-utilizing host and in a C[sub 1]-utilizing host; DNA effective to allow the vehicle to be mobilized from the non-C[sub 1]-utilizing host to the C[sub 1]-utilizing host; DNA providing resistance to two antibiotics to which the wild-type C[sub 1]-utilizing host is susceptible, each of the antibiotic resistance markers having a recognition site for a restriction endonuclease; a cos site; and a means for preventing replication in the C[sub 1]-utilizing host. The vehicle is used for complementation mapping as follows. DNA comprising a gene from the C[sub 1]-utilizing organism is inserted at the restriction nuclease recognition site, inactivating the antibiotic resistance marker at that site. The vehicle can then be used to form a cosmid structure to infect the non-C[sub 1]-utilizing (e.g., E. coli) host, and then conjugated with a selected C[sub 1]-utilizing mutant. Resistance to the other antibiotic by the mutant is a marker of the conjugation. Other phenotypical changes in the mutant, e.g., loss of an auxotrophic trait, is attributed to the C[sub 1] gene. The vector is also used to inactivate genes whose protein products catalyze side reactions that divert compounds from a biosynthetic pathway to a desired product, thereby producing an organism that makes the desired product in higher yields. 3 figs.

  6. Emergency-vehicle VHF antenna

    NASA Technical Reports Server (NTRS)

    Anderson, R. E.; Carlson, A. W.; Lewis, J.

    1977-01-01

    Helical VHF antenna mounts on roof of moving vehicle to communicate with distant stations via earth satellites. Antenna requires no pointing and can provide two-way communication while vehicle moves at high speed. Device has proved extremely successful in electrocardiogram transmission tests between medical services vehicle and hospital emergency room.

  7. Motor Vehicle Theft. Special Report.

    ERIC Educational Resources Information Center

    Harlow, Caroline Wolf

    Thirteen years of data from the National Crime Survey were analyzed to examine the characteristics of motor vehicle theft, to identify trends during the past 13 years, and to determine who are most likely to be victims of motor vehicle theft. All motor vehicle thefts reported to the National Crime Survey from 1973 through 1985 were examined.…

  8. Knowledge Navigation for Virtual Vehicles

    NASA Technical Reports Server (NTRS)

    Gomez, Julian E.

    2004-01-01

    A virtual vehicle is a digital model of the knowledge surrounding a potentially real vehicle. Knowledge consists not only of the tangible information, such as CAD, but also what is known about the knowledge - its metadata. This paper is an overview of technologies relevant to building a virtual vehicle, and an assessment of how to bring those technologies together.

  9. Appendix J - GPRA06 vehicle technologies program

    SciTech Connect

    None, None

    2009-01-18

    The target market for the Office of FreedomCAR and Vehicle Technologies (FCVT) program include light vehicles (cars and light trucks) and heavy vehicles (trucks more than 10,000 pounds Gross Vehicle Weight).

  10. Modeling of dilution jet flowfields

    NASA Technical Reports Server (NTRS)

    Holdeman, J. D.; Srinivasan, R.

    1984-01-01

    The present paper will compare temperature field measurements from selected cases in these investigations with distributions calculated with an empirical model based on assumed vertical profile similarity and superposition and with a 3-D elliptic code using a standard K-E turbulence model. The results will show the capability (or lack thereof) of the models to predict the effects of the principle flow and geometric variables.

  11. Developments at the Kinetic Kill Vehicle Hardware-in-the-Loop Simulator (KHILS) facility

    NASA Astrophysics Data System (ADS)

    Murrer, Robert Lee, Jr.; Thompson, Rhoe A.; Coker, Charles F.

    1999-07-01

    The Ballistic Missile Defense Organization (BMDO) sponsored the development of the Kinetic Kill Vehicle Hardware-in-the- Loop Simulator (KHILS) to provide a comprehensive ground test capability for end game performance evaluation of BMDO interceptor concepts. Since its inception in 1986, the KHILS facility has been on the forefront of HWIL test technology development. This development has culminated in closed-loop testing involving large format resistive element projection arrays, 3D scene rendering systems, and real-time high fidelity phenomenology codes. Each of these components has been integrated into a real-time environment that allows KHILS to perform dynamic closed-loop testing of BMDO interceptor systems or subsystems. Ongoing activities include the integration of multiple resistor arrays into both a cold chamber and flight motion simulator environment, increasing the update speed of existing arrays to 180 Hz, development of newer 200 Hz snapshot resistor arrays, design of next generation 1024 X 1024 resistor arrays, development of a 1000 Hz seeker motion stage, integration of a resistor array into an RF chamber, and development of advanced real-time plume flow-field codes. This paper describes these activities and test results of the major facility components.

  12. Two-layer convective heating prediction procedures and sensitivities for blunt body reentry vehicles

    NASA Technical Reports Server (NTRS)

    Bouslog, Stanley A.; An, Michael Y.; Wang, K. C.; Tam, Luen T.; Caram, Jose M.

    1993-01-01

    This paper provides a description of procedures typically used to predict convective heating rates to hypersonic reentry vehicles using the two-layer method. These procedures were used to compute the pitch-plane heating distributions to the Apollo geometry for a wind tunnel test case and for three flight cases. Both simple engineering methods and coupled inviscid/boundary layer solutions were used to predict the heating rates. The sensitivity of the heating results in the choice of metrics, pressure distributions, boundary layer edge conditions, and wall catalycity used in the heating analysis were evaluated. Streamline metrics, pressure distributions, and boundary layer edge properties were defined from perfect gas (wind tunnel case) and chemical equilibrium and nonequilibrium (flight cases) inviscid flow-field solutions. The results of this study indicated that the use of CFD-derived metrics and pressures provided better predictions of heating when compared to wind tunnel test data. The study also showed that modeling entropy layer swallowing and ionization had little effect on the heating predictions.

  13. Miniature Autonomous Robotic Vehicle (MARV)

    SciTech Connect

    Feddema, J.T.; Kwok, K.S.; Driessen, B.J.; Spletzer, B.L.; Weber, T.M.

    1996-12-31

    Sandia National Laboratories (SNL) has recently developed a 16 cm{sup 3} (1 in{sup 3}) autonomous robotic vehicle which is capable of tracking a single conducting wire carrying a 96 kHz signal. This vehicle was developed to assess the limiting factors in using commercial technology to build miniature autonomous vehicles. Particular attention was paid to the design of the control system to search out the wire, track it, and recover if the wire was lost. This paper describes the test vehicle and the control analysis. Presented in the paper are the vehicle model, control laws, a stability analysis, simulation studies and experimental results.

  14. Intelligent behaviors through vehicle-to-vehicle and vehicle-to-infrastructure communication

    NASA Astrophysics Data System (ADS)

    Garcia, Richard D.; Sturgeon, Purser; Brown, Mike

    2012-06-01

    The last decade has seen a significant increase in intelligent safety devices on private automobiles. These devices have both increased and augmented the situational awareness of the driver and in some cases provided automated vehicle responses. To date almost all intelligent safety devices have relied on data directly perceived by the vehicle. This constraint has a direct impact on the types of solutions available to the vehicle. In an effort to improve the safety options available to a vehicle, numerous research laboratories and government agencies are investing time and resources into connecting vehicles to each other and to infrastructure-based devices. This work details several efforts in both the commercial vehicle and the private auto industries to increase vehicle safety and driver situational awareness through vehicle-to-vehicle and vehicle-to-infrastructure communication. It will specifically discuss intelligent behaviors being designed to automatically disable non-compliant vehicles, warn tractor trailer vehicles of unsafe lane maneuvers such as lane changes, passing, and merging, and alert drivers to non-line-of-sight emergencies.

  15. Simple Electric Vehicle Simulation

    1993-07-29

    SIMPLEV2.0 is an electric vehicle simulation code which can be used with any IBM compatible personal computer. This general purpose simulation program is useful for performing parametric studies of electric and series hybrid electric vehicle performance on user input driving cycles.. The program is run interactively and guides the user through all of the necessary inputs. Driveline components and the traction battery are described and defined by ASCII files which may be customized by themore » user. Scaling of these components is also possible. Detailed simulation results are plotted on the PC monitor and may also be printed on a printer attached to the PC.« less

  16. Methane-Powered Vehicles

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Liquid methane is beginning to become an energy alternative to expensive oil as a power source for automotive vehicles. Methane is the principal component of natural gas, costs less than half as much as gasoline, and its emissions are a lot cleaner than from gasoline or diesel engines. Beech Aircraft Corporation's Boulder Division has designed and is producing a system for converting cars and trucks to liquid methane operation. Liquid methane (LM) is a cryogenic fuel which must be stored at a temperature of 260 degrees below zero Fahrenheit. The LM system includes an 18 gallon fuel tank in the trunk and simple "under the hood" carburetor conversion equipment. Optional twin-fuel system allows operator to use either LM or gasoline fuel. Boulder Division has started deliveries for 25 vehicle conversions and is furnishing a liquid methane refueling station. Beech is providing instruction for Northwest Natural Gas, for conversion of methane to liquid state.

  17. Small reentry vehicles

    NASA Astrophysics Data System (ADS)

    Sudmeijer, K. J.

    1987-12-01

    The design and potential applications of a small modular unguided reentry vehicle (SMURV) being developed for ESA are discussed. The first studies of the SMURV concept in the Spacemail program (for transporting small payloads from the Space Shuttle to earth) are recalled; the steps in a typical Spacemail operation are listed and briefly characterized; and the smaller version of SMURV (40 kg instead of 120 kg) developed for a Space Station Spacemail project (requiring 1000-1500 SMURVs) is described. This SMURV configuration comprises a detachable propulsion module and a reentry module (containing the parachute system and the recovery module). Consideration is given to a SMURV-type vehicle to return microgravity processing samples from the ESA Interim Flight Opportunity spacecraft, the technological challenges posed by SMURV design, and SMURV applications to the Comet Nucleus Sample Return and Cassini Titan Lander missions. Diagrams and drawings are provided.

  18. Rapid road repair vehicle

    DOEpatents

    Mara, L.M.

    1998-05-05

    Disclosed is a rapid road repair vehicle capable of moving over a surface to be repaired at near normal posted traffic speeds to scan for and find at the high rate of speed, imperfections in the pavement surface, prepare the surface imperfection for repair by air pressure and vacuum cleaning, applying a correct amount of the correct patching material to effect the repair, smooth the resulting repaired surface, and catalog the location and quality of the repairs for maintenance records of the road surface. The rapid road repair vehicle can repair surface imperfections at lower cost, improved quality, at a higher rate of speed than was not heretofor possible, with significantly reduced exposure to safety and health hazards associated with this kind of road repair activities in the past. 2 figs.

  19. Rapid road repair vehicle

    DOEpatents

    Mara, Leo M.

    1998-01-01

    Disclosed is a rapid road repair vehicle capable of moving over a surface to be repaired at near normal posted traffic speeds to scan for and find an the high rate of speed, imperfections in the pavement surface, prepare the surface imperfection for repair by air pressure and vacuum cleaning, applying a correct amount of the correct patching material to effect the repair, smooth the resulting repaired surface, and catalog the location and quality of the repairs for maintenance records of the road surface. The rapid road repair vehicle can repair surface imperfections at lower cost, improved quality, at a higher rate of speed than was was heretofor possible, with significantly reduced exposure to safety and health hazards associated with this kind of road repair activities in the past.

  20. Suspension for automotive vehicles

    SciTech Connect

    Pierce, W.C.

    1986-10-07

    This patent describes a vehicle suspension system for mounting ground-engaging wheels to a vehicle frame. The suspension system comprises at least two substantially rigid arms secured to opposite sides of the frame through substantially aligned pivot mounts; at least one wheel-carrying axle between the arms; and a bracket means securing the at least one axle to each of the arms. The improvements described here is in each of the bracket means comprising: an axle plate means rigidly secured to the axle and having an elongated planar complementary surface at least partially wrapping around the axle; two spaced connecting plates secured transversely to the axle plate means and to one of the arms; and a bracing means comprising at least one curved gusset plate rigidly and angularly secured to and between the axle plate means and one of the connecting plates.

  1. Household vehicles energy consumption 1994

    SciTech Connect

    1997-08-01

    Household Vehicles Energy Consumption 1994 reports on the results of the 1994 Residential Transportation Energy Consumption Survey (RTECS). The RTECS is a national sample survey that has been conducted every 3 years since 1985. For the 1994 survey, more than 3,000 households that own or use some 6,000 vehicles provided information to describe vehicle stock, vehicle-miles traveled, energy end-use consumption, and energy expenditures for personal vehicles. The survey results represent the characteristics of the 84.9 million households that used or had access to vehicles in 1994 nationwide. (An additional 12 million households neither owned or had access to vehicles during the survey year.) To be included in then RTECS survey, vehicles must be either owned or used by household members on a regular basis for personal transportation, or owned by a company rather than a household, but kept at home, regularly available for the use of household members. Most vehicles included in the RTECS are classified as {open_quotes}light-duty vehicles{close_quotes} (weighing less than 8,500 pounds). However, the RTECS also includes a very small number of {open_quotes}other{close_quotes} vehicles, such as motor homes and larger trucks that are available for personal use.

  2. Electric Vehicle Battery Performance

    1992-02-20

    DIANE is used to analyze battery performance in electric vehicle (EV) applications. The principal objective of DIANE is to enable the prediction of EV performance on the basis of laboratory test data for batteries. The model provides a second-by-second simulation of battery voltage and current for any specified velocity/time or power/time profile. Two releases are included with the package. Diane21 has a graphics capability; DIANENP has no graphics capability.

  3. Unmanned Aerospace Vehicle Workshop

    SciTech Connect

    Vitko, J. Jr.

    1995-04-01

    The Unmanned Aerospace Vehicle (UAV) Workshop concentrated on reviewing and refining the science experiments planned for the UAV Demonstration Flights (UDF) scheduled at the Oklahoma Cloud and Radiation Testbed (CART) in April 1994. These experiments were focused around the following sets of parameters: Clear sky, daylight; Clear-sky, night-to-day transition; Clear sky - improve/validate the accuracy of radiative fluxes derived from satellite-based measurements; Daylight, clouds of opportunity; and, Daylight, broken clouds.

  4. Electric vehicle drive systems

    NASA Astrophysics Data System (ADS)

    Appleyard, M.

    1992-01-01

    New legislation in the State of California requires that 2% of vehicles sold there from 1998 will be 'zero-emitting'. This provides a unique market opportunity for developers of electric vehicles but substantial improvements in the technology are probably required if it is to be successfully exploited. There are around a dozen types of battery that are potentially relevant to road vehicles but, at the present, lead/acid and sodium—sulphur come closest to combining acceptable performance, life and cost. To develop an efficient, lightweight electric motor system requires up-to-date techniques of magnetics design, and the latest power-electronic and microprocessor control methods. Brushless machines, coupled with solid-state inverters, offer the most economical solution for mass production, even though their development costs are higher than for direct-current commutator machines. Fitted to a small car, even the highest energy-density batteries will only provide around 200 km average range before recharging. Therefore, some form of supplementary on-board power generation will probably be needed to secure widespread acceptance by the driving public. Engine-driven generators of quite low power can achieve useful increases in urban range but will fail to qualify as 'zero-emitting'. On the other hand, if the same function could be economically performed by a small fuel-cell using hydrogen derived from a methanol reformer, then most of the flexibility provided by conventional vehicles would be retained. The market prospects for electric cars would then be greatly enhanced and their dependence on very advanced battery technology would be reduced.

  5. Expendable launch vehicle propulsion

    NASA Technical Reports Server (NTRS)

    Fuller, Paul N.

    1991-01-01

    The current status is reviewed of the U.S. Expendable Launch Vehicle (ELV) fleet, the international competition, and the propulsion technology of both domestic and foreign ELVs. The ELV propulsion technology areas where research, development, and demonstration are most needed are identified. These propulsion technology recommendations are based on the work performed by the Commercial Space Transportation Advisory Committee (COMSTAC), an industry panel established by the Dept. of Transportation.

  6. Computational Fluid Dynamics (CFD) Image of Hyper-X Research Vehicle at Mach 7 with Engine Operating

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This computational fluid dynamics (CFD) image shows the Hyper-X vehicle at a Mach 7 test condition with the engine operating. The solution includes both internal (scramjet engine) and external flow fields, including the interaction between the engine exhaust and vehicle aerodynamics. The image illustrates surface heat transfer on the vehicle surface (red is highest heating) and flowfield contours at local Mach number. The last contour illustrates the engine exhaust plume shape. This solution approach is one method of predicting the vehicle performance, and the best method for determination of vehicle structural, pressure and thermal design loads. The Hyper-X program is an ambitious series of experimental flights to expand the boundaries of high-speed aeronautics and develop new technologies for space access. When the first of three aircraft flies, it will be the first time a non-rocket engine has powered a vehicle in flight at hypersonic speeds--speeds above Mach 5, equivalent to about one mile per second or approximately 3,600 miles per hour at sea level. Hyper-X, the flight vehicle for which is designated as X-43A, is an experimental flight-research program seeking to demonstrate airframe-integrated, 'air-breathing' engine technologies that promise to increase payload capacity for future vehicles, including hypersonic aircraft (faster than Mach 5) and reusable space launchers. This multiyear program is currently underway at NASA Dryden Flight Research Center, Edwards, California. The Hyper-X schedule calls for its first flight later this year (2000). Hyper-X is a joint program, with Dryden sharing responsibility with NASA's Langley Research Center, Hampton, Virginia. Dryden's primary role is to fly three unpiloted X-43A research vehicles to validate engine technologies and hypersonic design tools as well as the hypersonic test facility at Langley. Langley manages the program and leads the technology development effort. The Hyper-X Program seeks to significantly

  7. Coupling device for moving vehicles

    NASA Technical Reports Server (NTRS)

    Rudmann, A. A. (Inventor)

    1979-01-01

    A mechanical system is disclosed to capture and/or deploy a device or vehicle having relative motion with respect to another vehicle. The mechanism includes an onboard controlled collapsible iris assembly located at the end of a controlled manipulator system carried by one moving vehicle. The iris assembly by means of the manipulator system encircles a probe located on the other moving vehicle whereupon the iris assembly is activated and one or more iris elements close around the probe, thus capturing, and axially aligning the other vehicle with the iris assembly. Additionally, a rotator assembly is included for spinning the iris assembly in a manner adapted to engage the probe of a spinning vehicle. Deployment of the other vehicle is accomplished by reversing the capture procedure.

  8. Vehicle dynamic stability and rollover

    NASA Astrophysics Data System (ADS)

    Allen, R. W.; Szostak, H. T.; Klyde, D. H.; Rosenthal, T. J.; Owens, K. J.

    1992-06-01

    The report considers ground vehicle lateral/directional stability which is of primary concern in traffic safety. Lateral/directional dynamics involve yawing, rolling, and lateral acceleration motions, and stability concerns include spinout and rollover. The report describes accident analysis, vehicle testing, and computer simulation analysis designed to give insight into basic vehicle design variables that contribute to stability problems. The results of vehicle testing and simulation analysis indicate that a vehicle that has both a relatively low ratio of track width to center of gravity height and is equipped with tires which have a relatively high peak coefficient of friction will have a propensity to rollover during steering maneuvers on a flat surface. Vehicle testing and computer simulation analysis also indicate that directional stability is significantly influenced by the relationship between vehicle weight distribution and lateral load transfer distribution that is greater than or equal to the percent weight on the front axle.

  9. High mobility vehicle

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H. (Inventor); Nasif, Annette K. (Inventor)

    2001-01-01

    A vehicle, for driving over a ground surface, has a body with a left side, a right side, a front and a back. The vehicle includes left and right drive mechanisms. Each mechanism includes first and second traction elements for engaging the ground surface and transmitting a driving force between the vehicle and ground surface. Each mechanism includes first and second arms coupled to the first and second traction elements for relative rotation about first and second axis respectively. Each mechanism includes a rotor having a third axis, the rotor coupled to the body for rotation about the third axis and coupled to the first and second arms for relative rotation about the third axis. The mechanism includes first and second drive motors for driving the first and second traction elements and first and second transmissions, driven by the first and second motors and engaging the rotor. Driving the first and second traction elements simultaneously rotates the rotor relative to the first and second arms, respectively.

  10. Modular Robotic Vehicle

    NASA Technical Reports Server (NTRS)

    Borroni-Bird, Christopher E. (Inventor); Vitale, Robert L. (Inventor); Lee, Chunhao J. (Inventor); Ambrose, Robert O. (Inventor); Bluethmann, William J. (Inventor); Junkin, Lucien Q. (Inventor); Lutz, Jonathan J. (Inventor); Guo, Raymond (Inventor); Lapp, Anthony Joseph (Inventor); Ridley, Justin S. (Inventor)

    2015-01-01

    A modular robotic vehicle includes a chassis, driver input devices, an energy storage system (ESS), a power electronics module (PEM), modular electronic assemblies (eModules) connected to the ESS via the PEM, one or more master controllers, and various embedded controllers. Each eModule includes a drive wheel containing a propulsion-braking module, and a housing containing propulsion and braking control assemblies with respective embedded propulsion and brake controllers, and a mounting bracket covering a steering control assembly with embedded steering controllers. The master controller, which is in communication with each eModule and with the driver input devices, communicates with and independently controls each eModule, by-wire, via the embedded controllers to establish a desired operating mode. Modes may include a two-wheel, four-wheel, diamond, and omni-directional steering modes as well as a park mode. A bumper may enable docking with another vehicle, with shared control over the eModules of the vehicles.

  11. Lunar construction utility vehicle

    NASA Technical Reports Server (NTRS)

    1989-01-01

    The lunar construction utility vehicle (LCUV) is an all-purpose construction vehicle which will aid in the robotic assembly of a lunar outpost. The LCUV will have the following capabilities: (1) must be self supporting including repairs; (2) must offload itself from a lunar lander; (3) must be telerobotic and semi-autonomous; (4) must be able to transport one space station common module; (5) must allow for man-rated operation; and (6) must be able to move lunar regolith for site preparation. This study recommends the use of an elastic tracked vehicle. Detailed material analyses of most of the LCUV components were accomplished. The body frame, made of pinned truss elements, was stress analyzed using NASTRAN. A track connection system was developed; however, kinematic and stress analyses are still required. This design recommends the use of hydrogen-oxygen fuel cells for power. Thermal control has proven to be a problem which may be the most challenging technically. A tentative solution has been proposed which utilizes an onboard and towable radiator. Detailed study of the heat dissipation requirements is needed to finalize radiator sizing. Preliminary work on a man-rated cabin has begun; however, this is not required during the first mission phase of the LCUV. Finally, still in the conceptual phases, are the communication, navigation and mechanical arm systems.

  12. Launch vehicle selection model

    NASA Technical Reports Server (NTRS)

    Montoya, Alex J.

    1990-01-01

    Over the next 50 years, humans will be heading for the Moon and Mars to build scientific bases to gain further knowledge about the universe and to develop rewarding space activities. These large scale projects will last many years and will require large amounts of mass to be delivered to Low Earth Orbit (LEO). It will take a great deal of planning to complete these missions in an efficient manner. The planning of a future Heavy Lift Launch Vehicle (HLLV) will significantly impact the overall multi-year launching cost for the vehicle fleet depending upon when the HLLV will be ready for use. It is desirable to develop a model in which many trade studies can be performed. In one sample multi-year space program analysis, the total launch vehicle cost of implementing the program reduced from 50 percent to 25 percent. This indicates how critical it is to reduce space logistics costs. A linear programming model has been developed to answer such questions. The model is now in its second phase of development, and this paper will address the capabilities of the model and its intended uses. The main emphasis over the past year was to make the model user friendly and to incorporate additional realistic constraints that are difficult to represent mathematically. We have developed a methodology in which the user has to be knowledgeable about the mission model and the requirements of the payloads. We have found a representation that will cut down the solution space of the problem by inserting some preliminary tests to eliminate some infeasible vehicle solutions. The paper will address the handling of these additional constraints and the methodology for incorporating new costing information utilizing learning curve theory. The paper will review several test cases that will explore the preferred vehicle characteristics and the preferred period of construction, i.e., within the next decade, or in the first decade of the next century. Finally, the paper will explore the interaction

  13. Three-wheeled motor vehicle

    SciTech Connect

    Irimajiri, S.; Komuro, K.; Aikawa, K.

    1986-03-04

    A three-wheeled motor vehicle is described consisting of: (a) a vehicle body; (b) two front wheels rotatably mounted on the vehicle body; (c) a single rear wheel rotatably mounted on the vehicle body; (d) an engine disposed on the vehicle body between the front wheels; (e) a driver's compartment defined in the vehicle body; (f) the vehicle body including a front portion covering the engine and the front wheels and a rear portion disposed behind the front portion and covering the compartment and the rear wheel, the front portion having a relatively wide and flat shape and the rear portion being narrower than the front portion and progressively higher in a rearward direction for a substantial proportion of the rear portion; and (g) the vehicle body also including lateral wing portions on each side extending longitudinally rearwardly from behind the front wheels and tapering into the rear portion for causing the vehicle body to have a substantially constant cross-sectional area throughout a substantial proportion of both the front and rear portions and the transition between the front and rear portions for producing an aerodynamically improved vehicle body shape.

  14. Vehicle following controller design for autonomous intelligent vehicles

    NASA Technical Reports Server (NTRS)

    Chien, C. C.; Lai, M. C.; Mayr, R.

    1994-01-01

    A new vehicle following controller is proposed for autonomous intelligent vehicles. The proposed vehicle following controller not only provides smooth transient maneuvers for unavoidable nonzero initial conditions but also guarantees the asymptotic platoon stability without the availability of feedforward information. Furthermore, the achieved asymptotic platoon stability is shown to be robust to sensor delays and an upper bound for the allowable sensor delays is also provided in this paper.

  15. Sensor Technology for Integrated Vehicle Health Management of Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.; Brown, T. L.; Woodard, S. E.; Fleming, G. A.; Cooper, E. G.

    2002-01-01

    NASA is focusing considerable efforts on technology development for Integrated Vehicle Health Management systems. The research in this area is targeted toward increasing aerospace vehicle safety and reliability, while reducing vehicle operating and maintenance costs. Onboard, real-time sensing technologies that can provide detailed information on structural integrity are central to such a health management system. This paper describes a number of sensor technologies currently under development for integrated vehicle health management. The capabilities, current limitations, and future research needs of these technologies are addressed.

  16. Laser powered interorbital vehicle

    NASA Technical Reports Server (NTRS)

    Clarke, M. T.; Cooper, J. J.; Eggleston, G. P.; Farkas, M. A.; Hunt, D. C.; King, J.; Nguyen, H.; Rahal, G.; Saw, K.; Tipton, R.

    1989-01-01

    A preliminary design of a low-thrust Laser Powered Interorbital Vehicle (LPIV) intended for cargo transportation between an Earth space station and a lunar base is presented. The selected mission utilizes a spiral trajectory, characteristic of a low-thrust spacecraft, requiring eight days for a lunar rendezvous and an additional nine days for return. The ship's configuration consists primarily of an optical train, two hydrogen plasma engines, a 37.1 m box-beam truss, a payload module, and propellant tanks. The total mass of the vehicle, fully loaded, is 63,300 kg. A single plasma, regeneratively cooled engine design is incorporated into the two 500 N engines. These are connected to the spacecraft by turntables that allow the vehicle to thrust tangential to the flight path. Proper collection and transmission of the laser beam to the thrust chambers is provided through the optical train. This system consists of a 23-m-diameter primary mirror, a convex parabolic secondary mirror, a beam splitter, and two concave parabolic tertiary mirrors. The payload bay is capable of carrying 18,000 kg of cargo and is located opposite the primary mirror on the main truss. Fuel tanks carrying a maximum of 35,000 kg of liquid hydrogen are fastened to tracks that allow the tanks to be moved perpendicular to the main truss. This capability is required to prevent the center of mass from moving out of the thrust vector line. The laser beam is located and tracked by means of an acquisition, pointing, and tracking system that can be locked onto the space-based laser station. Correct orientation of the spacecraft with the laser beam is maintained by control moment gyros and reaction control rockets. In addition, an aerobrake configuration was designed to provide the option of using the atmospheric drag in place of propulsion for a return trajectory.

  17. Hybrid vehicle motor alignment

    DOEpatents

    Levin, Michael Benjamin

    2001-07-03

    A rotor of an electric motor for a motor vehicle is aligned to an axis of rotation for a crankshaft of an internal combustion engine having an internal combustion engine and an electric motor. A locator is provided on the crankshaft, a piloting tool is located radially by the first locator to the crankshaft. A stator of the electric motor is aligned to a second locator provided on the piloting tool. The stator is secured to the engine block. The rotor is aligned to the crankshaft and secured thereto.

  18. Alternative fuels: Electric vehicles

    SciTech Connect

    Riddell, E.

    1994-12-31

    National concerns about energy security and air quality have prompted government and industry to accelerate the introduction of electric vehicles. Today`s EVs are being developed for use in fleets, and careful attention is being paid to creating the necessary infrastructure and support systems. By the end of the 1990s, EVs should begin appearing in public and private fleets throughout the United States. EV buyers and operators are now welcome to share in the challenge of building a new era in transportation.

  19. Hybrid and Plug-in Electric Vehicles

    SciTech Connect

    2014-05-20

    Hybrid and plug-in electric vehicles use electricity either as their primary fuel or to improve the efficiency of conventional vehicle designs. This new generation of vehicles, often called electric drive vehicles, can be divided into three categories: hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles(PHEVs), and all-electric vehicles (EVs). Together, they have great potential to reduce U.S. petroleum use.

  20. Energy management and vehicle synthesis

    NASA Technical Reports Server (NTRS)

    Czysz, P.; Murthy, S. N. B.

    1995-01-01

    The major drivers in the development of launch vehicles for the twenty-first century are reduction in cost of vehicles and operations, continuous reusability, mission abort capability with vehicle recovery, and readiness. One approach to the design of such vehicles is to emphasize energy management and propulsion as being the principal means of improvements given the available industrial capability and the required freedom in selecting configuration concept geometries. A methodology has been developed for the rational synthesis of vehicles based on the setting up and utilization of available data and projections, and a reference vehicle. The application of the methodology is illustrated for a single stage to orbit (SSTO) with various limits for the use of airbreathing propulsion.

  1. Energy management and vehicle synthesis

    NASA Astrophysics Data System (ADS)

    Czysz, P.; Murthy, S. N. B.

    The major drivers in the development of launch vehicles for the twenty-first century are reduction in cost of vehicles and operations, continuous reusability, mission abort capability with vehicle recovery, and readiness. One approach to the design of such vehicles is to emphasize energy management and propulsion as being the principal means of improvements given the available industrial capability and the required freedom in selecting configuration concept geometries. A methodology has been developed for the rational synthesis of vehicles based on the setting up and utilization of available data and projections, and a reference vehicle. The application of the methodology is illustrated for a single stage to orbit (SSTO) with various limits for the use of airbreathing propulsion.

  2. Remote control for motor vehicle

    NASA Technical Reports Server (NTRS)

    Johnson, Dale R. (Inventor); Ciciora, John A. (Inventor)

    1984-01-01

    A remote controller is disclosed for controlling the throttle, brake and steering mechanism of a conventional motor vehicle, with the remote controller being particularly advantageous for use by severely handicapped individuals. The controller includes a remote manipulator which controls a plurality of actuators through interfacing electronics. The remote manipulator is a two-axis joystick which controls a pair of linear actuators and a rotary actuator, with the actuators being powered by electric motors to effect throttle, brake and steering control of a motor vehicle adapted to include the controller. The controller enables the driver to control the adapted vehicle from anywhere in the vehicle with one hand with minimal control force and range of motion. In addition, even though a conventional vehicle is adapted for use with the remote controller, the vehicle may still be operated in the normal manner.

  3. Idling Reduction for Personal Vehicles

    SciTech Connect

    2015-05-07

    Fact sheet on reducing engine idling in personal vehicles. Idling your vehicle--running your engine when you're not driving it--truly gets you nowhere. Idling reduces your vehicle's fuel economy, costs you money, and creates pollution. Idling for more than 10 seconds uses more fuel and produces more emissions that contribute to smog and climate change than stopping and restarting your engine does.

  4. Systems Challenges for Hypersonic Vehicles

    NASA Technical Reports Server (NTRS)

    Hunt, James L.; Laruelle, Gerard; Wagner, Alain

    1997-01-01

    This paper examines the system challenges posed by fully reusable hypersonic cruise airplanes and access to space vehicles. Hydrocarbon and hydrogen fueled airplanes are considered with cruise speeds of Mach 5 and 10, respectively. The access to space matrix is examined. Airbreathing and rocket powered, single- and two-stage vehicles are considered. Reference vehicle architectures are presented. Major systems/subsystems challenges are described. Advanced, enhancing systems concepts as well as common system technologies are discussed.

  5. Vehicle systems design optimization study

    NASA Technical Reports Server (NTRS)

    Gilmour, J. L.

    1980-01-01

    The optimum vehicle configuration and component locations are determined for an electric drive vehicle based on using the basic structure of a current production subcompact vehicle. The optimization of an electric vehicle layout requires a weight distribution in the range of 53/47 to 62/38 in order to assure dynamic handling characteristics comparable to current internal combustion engine vehicles. Necessary modification of the base vehicle can be accomplished without major modification of the structure or running gear. As long as batteries are as heavy and require as much space as they currently do, they must be divided into two packages, one at front under the hood and a second at the rear under the cargo area, in order to achieve the desired weight distribution. The weight distribution criteria requires the placement of batteries at the front of the vehicle even when the central tunnel is used for the location of some batteries. The optimum layout has a front motor and front wheel drive. This configuration provides the optimum vehicle dynamic handling characteristics and the maximum passenger and cargo space for a given size vehicle.

  6. Visiting Vehicle Ground Trajectory Tool

    NASA Technical Reports Server (NTRS)

    Hamm, Dustin

    2013-01-01

    The International Space Station (ISS) Visiting Vehicle Group needed a targeting tool for vehicles that rendezvous with the ISS. The Visiting Vehicle Ground Trajectory targeting tool provides the ability to perform both realtime and planning operations for the Visiting Vehicle Group. This tool provides a highly reconfigurable base, which allows the Visiting Vehicle Group to perform their work. The application is composed of a telemetry processing function, a relative motion function, a targeting function, a vector view, and 2D/3D world map type graphics. The software tool provides the ability to plan a rendezvous trajectory for vehicles that visit the ISS. It models these relative trajectories using planned and realtime data from the vehicle. The tool monitors ongoing rendezvous trajectory relative motion, and ensures visiting vehicles stay within agreed corridors. The software provides the ability to update or re-plan a rendezvous to support contingency operations. Adding new parameters and incorporating them into the system was previously not available on-the-fly. If an unanticipated capability wasn't discovered until the vehicle was flying, there was no way to update things.

  7. Manrating orbital transfer vehicle propulsion

    NASA Technical Reports Server (NTRS)

    Cooper, L. P.

    1985-01-01

    The expended capabilities for Orbital Transfer Vehicles (OTV) which will be needed to meet increased payload requirements for transporting materials and men to geosynchronous orbit are discussed. The requirement to provide manrating offers challenges and opportunities to the propulsion system designers. The propulsion approaches utilized in previous manned space vehicles of the United States are reviewed. The principals of reliability analysis are applied to the Orbit Transfer Vehicle. Propulsion system options are characterized in terms of the test requirements to demonstrate reliability goals and are compared to earlier vehicle approaches.

  8. Hybrid Vehicle Program. Final report

    SciTech Connect

    1984-06-01

    This report summarizes the activities on the Hybrid Vehicle Program. The program objectives and the vehicle specifications are reviewed. The Hybrid Vehicle has been designed so that maximum use can be made of existing production components with a minimum compromise to program goals. The program status as of the February 9-10 Hardware Test Review is presented, and discussions of the vehicle subsystem, the hybrid propulsion subsystem, the battery subsystem, and the test mule programs are included. Other program aspects included are quality assurance and support equipment. 16 references, 132 figures, 47 tables.

  9. Gearbox assembly for vehicles

    SciTech Connect

    Imaizumi, M.; Masumura, M.; Ishikawa, T.; Hosoya, E.

    1987-01-13

    A gearbox assembly is described for a vehicle for transmitting an output of an engine to driving wheels of the vehicle, comprising: a main gearbox receiving the output and having plural forward gear-shift steps; a shift lever; a sub gearbox coupled to an output of the main gearbox having at least two relatively high and low speed gearshift steps (GH,GL) and a reverse transmission system (GR), the two steps and the reverse transmission system being selectively established through switching operation of the shift lever; wherein the sub gearbox further comprises: a rotary member connected to the shift lever for selecting one of the steps and the reverse transmission system according to its rotation; a stopper mechanism engaging the rotary member for preventing the rotary member from rotating to a position where the reverse transmission system is established; and interlinking means between the stopper mechanism and the main gearbox for releasing the stopper mechanism only when the main gearbox is in neutral or in a low speed gear-shift step; wherein the stopper mechanism comprises: a cam rotatable in response to the gear-shift operation of the main gearbox; a stopper lever one end of which faces the periphery of the cam and the other end facing the rotary member, the stopper lever being pivotally supported at its middle portion; and a spring urging the stopper level to abut against the periphery of the cam.

  10. Electric-vehicle batteries

    NASA Astrophysics Data System (ADS)

    Oman, Henry; Gross, Sid

    1995-02-01

    Electric vehicles that can't reach trolley wires need batteries. In the early 1900's electric cars disappeared when owners found that replacing the car's worn-out lead-acid battery costs more than a new gasoline-powered car. Most of today's electric cars are still propelled by lead-acid batteries. General Motors in their prototype Impact, for example, used starting-lighting-ignition batteries, which deliver lots of power for demonstrations, but have a life of less than 100 deep discharges. Now promising alternative technology has challenged the world-wide lead miners, refiners, and battery makers into forming a consortium that sponsors research into making better lead-acid batteries. Horizon's new bipolar battery delivered 50 watt-hours per kg (Wh/kg), compared with 20 for ordinary transport-vehicle batteries. The alternatives are delivering from 80 Wh/kg (nickel-metal hydride) up to 200 Wh/kg (zinc-bromine). A Fiat Panda traveled 260 km on a single charge of its zinc-bromine battery. A German 3.5-ton postal truck traveled 300 km with a single charge in its 650-kg (146 Wh/kg) zinc-air battery. Its top speed was 110 km per hour.

  11. Superpressure stratospheric vehicle

    SciTech Connect

    Chocol, C.; Robinson, W.; Epley, L.

    1990-09-15

    Our need for wide-band global communications, earth imaging and sensing, atmospheric measurements and military reconnaissance is extensive, but growing dependence on space-based systems raises concerns about vulnerability. Military commanders require space assets that are more accessible and under local control. As a result, a robust and low cost access to space-like capability has become a national priority. Free floating buoyant vehicles in the middle stratosphere can provide the kind of cost effective access to space-like capability needed for a variety of missions. These vehicles are inexpensive, invisible, and easily launched. Developments in payload electronics, atmospheric modeling, and materials combined with improving communications and navigation infrastructure are making balloon-borne concepts more attractive. The important milestone accomplished by this project was the planned test flight over the continental United States. This document is specifically intended to review the technology development and preparations leading up to the test flight. Although the test flight experienced a payload failure just before entering its assent altitude, significant data were gathered. The results of the test flight are presented here. Important factors included in this report include quality assurance testing of the balloon, payload definition and characteristics, systems integration, preflight testing procedures, range operations, data collection, and post-flight analysis. 41 figs., 5 tabs.

  12. Vehicle with magnetic engine

    SciTech Connect

    Wortham, C.

    1993-06-15

    A vehicle is described comprising a vehicle frame fitted with axles and wheels rotatably carried by the axles; an engine block mounted on the frame; a plurality of magnetic cylinders provided in the engine block and a plurality of magnetic pistons disposed in the magnetic cylinders, respectively, in reciprocating relationship, the magnetic cylinders having a first magnetic polarity in one end and a second magnetic polarity in the opposite end for alternately attracting and repelling the magnetic pistons, respectively; a crankshaft journalled for rotation in the engine block; power transmission means connecting the crankshaft to at least one of the axles in driving relationship; and connecting rods connecting the crankshaft to the magnetic pistons, respectively, whereby reciprocation of the magnetic pistons in the magnetic cylinders effects rotation of the crankshaft; a cylinder head provided on the engine block and piston electromagnetic means provided in the cylinder head above the magnetic cylinders and the magnetic pistons, respectively for alternately attracting and repelling the magnetic pistons; at least one battery carried by the frame; and polarity timing means electrically connected to the battery and the piston electromagnetic means, for alternating the polarity of the piston electromagnet means, whereby electric current is supplied to the piston electromagnetic means in current-reversing relationship to alternately attract and repel the magnetic pistons in reciprocating relationship responsive to operation of the polarity timing means.

  13. Vehicle to grid: electric vehicles as an energy storage solution

    NASA Astrophysics Data System (ADS)

    McGee, Rodney; Waite, Nicholas; Wells, Nicole; Kiamilev, Fouad E.; Kempton, Willett M.

    2013-05-01

    With increased focus on intermittent renewable energy sources such as wind turbines and photovoltaics, there comes a rising need for large-scale energy storage. The vehicle to grid (V2G) project seeks to meet this need using electric vehicles, whose high power capacity and existing power electronics make them a promising energy storage solution. This paper will describe a charging system designed by the V2G team that facilitates selective charging and backfeeding by electric vehicles. The system consists of a custom circuit board attached to an embedded linux computer that is installed both in the EVSE (electric vehicle supply equipment) and in the power electronics unit of the vehicle. The boards establish an in-band communication link between the EVSE and the vehicle, giving the vehicle internet connectivity and the ability to make intelligent decisions about when to charge and discharge. This is done while maintaining compliance with existing charging protocols (SAEJ1772, IEC62196) and compatibility with standard "nonintelligent" cars and chargers. Through this system, the vehicles in a test fleet have been able to successfully serve as portable temporary grid storage, which has implications for regulating the electrical grid, providing emergency power, or supplying power to forward military bases.

  14. Hybrid vehicle potential assessment. Volume 7: Hybrid vehicle review

    NASA Technical Reports Server (NTRS)

    Leschly, K. O.

    1979-01-01

    Review of hybrid vehicles built during the past ten years or planned to be built in the near future is presented. An attempt is made to classify and analyze these vehicles to get an overall picture of their key characteristics. The review includes onroad hybrid passenger cars, trucks, vans, and buses.

  15. Experimental Evaluation of the Effect of Angle-of-attack on the External Aerodynamics and Mass Capture of a Symmetric Three-engine Air-breathing Launch Vehicle Configuration at Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    Kim, Hyun D.; Frate, Franco C.

    2001-01-01

    A subscale aerodynamic model of the GTX air-breathing launch vehicle was tested at NASA Glenn Research Center's 10- by 10-Foot Supersonic Wind Tunnel from Mach 2.0 to 3.5 at various angles-of-attack. The objective of the test was to investigate the effect of angle-of-attack on inlet mass capture, inlet diverter effectiveness, and the flowfield at the cowl lip plane. The flow-through inlets were tested with and without boundary-layer diverters. Quantitative measurements such as inlet mass flow rates and pitot-pressure distributions in the cowl lip plane are presented. At a 3deg angle-of-attack, the flow rates for the top and side inlets were within 8 percent of the zero angle-of-attack value, and little distortion was evident at the cowl lip plane. Surface oil flow patterns showing the shock/boundary-layer interaction caused by the inlet spikes are shown. In addition to inlet data, vehicle forebody static pressure distributions, boundary-layer profiles, and temperature-sensitive paint images to evaluate the boundary-layer transition are presented. Three-dimensional parabolized Navier-Stokes computational fluid dynamics calculations of the forebody flowfield are presented and show good agreement with the experimental static pressure distributions and boundary-layer profiles. With the boundary-layer diverters installed, no adverse aerodynamic phenomena were found that would prevent the inlets from operating at the required angles-of-attack. We recommend that phase 2 of the test program be initiated, where inlet contraction ratio and diverter geometry variations will be tested.

  16. Expendable launch vehicle studies

    NASA Technical Reports Server (NTRS)

    Bainum, Peter M.; Reiss, Robert

    1995-01-01

    Analytical support studies of expendable launch vehicles concentrate on the stability of the dynamics during launch especially during or near the region of maximum dynamic pressure. The in-plane dynamic equations of a generic launch vehicle with multiple flexible bending and fuel sloshing modes are developed and linearized. The information from LeRC about the grids, masses, and modes is incorporated into the model. The eigenvalues of the plant are analyzed for several modeling factors: utilizing diagonal mass matrix, uniform beam assumption, inclusion of aerodynamics, and the interaction between the aerodynamics and the flexible bending motion. Preliminary PID, LQR, and LQG control designs with sensor and actuator dynamics for this system and simulations are also conducted. The initial analysis for comparison of PD (proportional-derivative) and full state feedback LQR Linear quadratic regulator) shows that the split weighted LQR controller has better performance than that of the PD. In order to meet both the performance and robustness requirements, the H(sub infinity) robust controller for the expendable launch vehicle is developed. The simulation indicates that both the performance and robustness of the H(sub infinity) controller are better than that for the PID and LQG controllers. The modelling and analysis support studies team has continued development of methodology, using eigensensitivity analysis, to solve three classes of discrete eigenvalue equations. In the first class, the matrix elements are non-linear functions of the eigenvector. All non-linear periodic motion can be cast in this form. Here the eigenvector is comprised of the coefficients of complete basis functions spanning the response space and the eigenvalue is the frequency. The second class of eigenvalue problems studied is the quadratic eigenvalue problem. Solutions for linear viscously damped structures or viscoelastic structures can be reduced to this form. Particular attention is paid to

  17. Launch Vehicle Dynamics Demonstrator Model

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Launch Vehicle Dynamics Demonstrator Model. The effect of vibration on launch vehicle dynamics was studied. Conditions included three modes of instability. The film includes close up views of the simulator fuel tank with and without stability control. [Entire movie available on DVD from CASI as Doc ID 20070030984. Contact help@sti.nasa.gov

  18. Going Green with Electric Vehicles

    ERIC Educational Resources Information Center

    Deal, Walter F., III

    2010-01-01

    There is considerable interest in electric and hybrid cars because of environmental and climate change concerns, tougher fuel efficiency standards, and increasing dependence on imported oil. In this article, the author describes the history of electric vehicles in the automotive world and discusses the components of a hybrid electric vehicle.…

  19. 1997 hybrid electric vehicle specifications

    SciTech Connect

    Sluder, S.; Larsen, R.; Duoba, M.

    1996-10-01

    The US DOE sponsors Advanced Vehicle Technology competitions to help educate the public and advance new vehicle technologies. For several years, DOE has provided financial and technical support for the American Tour de Sol. This event showcases electric and hybrid electric vehicles in a road rally across portions of the northeastern United States. The specifications contained in this technical memorandum apply to vehicles that will be entered in the 1997 American Tour de Sol. However, the specifications were prepared to be general enough for use by other teams and individuals interested in developing hybrid electric vehicles. The purpose of the specifications is to ensure that the vehicles developed do not present a safety hazard to the teams that build and drive them or to the judges, sponsors, or public who attend the competitions. The specifications are by no means the definitive sources of information on constructing hybrid electric vehicles - as electric and hybrid vehicles technologies advance, so will the standards and practices for their construction. In some cases, the new standards and practices will make portions of these specifications obsolete.

  20. Vehicle Safety. Managing Liability Series.

    ERIC Educational Resources Information Center

    Newby, Deborah, Ed.

    This monograph discusses the safety of vehicles owned, leased, maintained, and operated by colleges and universities. First, the risks by colleges and universities is discussed. First, the risks associated with college vehicles are outlined, including the liability that comes with staff/faculty and student drivers and such special concerns as…

  1. Launch Vehicle Systems Analysis

    NASA Technical Reports Server (NTRS)

    Olds, John R.

    1999-01-01

    This report summaries the key accomplishments of Georgia Tech's Space Systems Design Laboratory (SSDL) under NASA Grant NAG8-1302 from NASA - Marshall Space Flight Center. The report consists of this summary white paper, copies of technical papers written under this grant, and several viewgraph-style presentations. During the course of this grant four main tasks were completed: (1)Simulated Combined-Cycle Rocket Engine Analysis Module (SCCREAM), a computer analysis tool for predicting the performance of various RBCC engine configurations; (2) Hyperion, a single stage to orbit vehicle capable of delivering 25,000 pound payloads to the International Space Station Orbit; (3) Bantam-X Support - a small payload mission; (4) International Trajectory Support for interplanetary human Mars missions.

  2. Personal watercraft vehicle engine

    SciTech Connect

    Webb, E.H.

    1991-12-17

    This paper describes a personal watercraft vehicle engine. It comprises: a crankcase having an upper portion and a lower portion a crankshaft operatively mounted in the crankcase, the crankshaft residing in a substantially horizontal orientation, the crankshaft having a longitudinal axis; a sealed flywheel housing, the sealed flywheel housing being axially aligned with the crankshaft; a flywheel cooperatively connected to the crankshaft, the flywheel residing in the flywheel housing, the flywheel housing being rigidly affixed to the crankcase; the flywheel having a plurality of gear teeth around its periphery; and a starter mounted in an opening defined in a plane parallel to the crankshaft and perpendicular to the starter axis, the starter being perpendicular to the crankshaft, in an upper-most portion of the sealed flywheel housing, the starter having a pinion gear, the pinion gear being engagable with the plurality of gear teeth on the periphery of the flywheel, whereby the starter is not as adversely affected by water.

  3. Hydrogen ICE Vehicle Testing Activities

    SciTech Connect

    J. Francfort; D. Karner

    2006-04-01

    The Advanced Vehicle Testing Activity teamed with Electric Transportation Applications and Arizona Public Service to develop and monitor the operations of the APS Alternative Fuel (Hydrogen) Pilot Plant. The Pilot Plant provides 100% hydrogen, and hydrogen and compressed natural gas (H/CNG)-blended fuels for the evaluation of hydrogen and H/CNG internal combustion engine (ICE) vehicles in controlled and fleet testing environments. Since June 2002, twenty hydrogen and H/CNG vehicles have accumulated 300,000 test miles and 5,700 fueling events. The AVTA is part of the Department of Energy’s FreedomCAR and Vehicle Technologies Program. These testing activities are managed by the Idaho National Laboratory. This paper discusses the Pilot Plant design and monitoring, and hydrogen ICE vehicle testing methods and results.

  4. Advanced small launch vehicle study

    NASA Technical Reports Server (NTRS)

    Reins, G. E.; Alvis, J. F.

    1972-01-01

    A conceptual design study was conducted to determine the most economical (lowest cost/launch) approach for the development of an advanced small launch vehicle (ASLV) for use over the next decade. The ASLV design objective was to place a 340 kg (750 lb) payload into a 556 km (300 n.mi.) circular orbit when launched due east from Wallops Island, Virginia. The investigation encompassed improvements to the current Scout launch vehicle; use of existing military and NASA launch vehicle stages; and new, optionally staged vehicles. Staging analyses included use of liquid, solid, and hybrid propellants. Improvements in guidance, controls, interstages, telemetry, and payload shroud were also considered. It was concluded that the most economical approach is to progressively improve the Scout launch vehicle in three phased steps which are discussed.

  5. Propane Vehicle Demonstration Grant Program

    SciTech Connect

    Jack Mallinger

    2004-08-27

    Project Description: Propane Vehicle Demonstration Grants The Propane Vehicle Demonstration Grants was established to demonstrate the benefits of new propane equipment. The US Department of Energy, the Propane Education & Research Council (PERC) and the Propane Vehicle Council (PVC) partnered in this program. The project impacted ten different states, 179 vehicles, and 15 new propane fueling facilities. Based on estimates provided, this project generated a minimum of 1,441,000 new gallons of propane sold for the vehicle market annually. Additionally, two new off-road engines were brought to the market. Projects originally funded under this project were the City of Portland, Colorado, Kansas City, Impco Technologies, Jasper Engines, Maricopa County, New Jersey State, Port of Houston, Salt Lake City Newspaper, Suburban Propane, Mutual Liquid Propane and Ted Johnson.

  6. 2012 Vehicle Technologies Market Report

    SciTech Connect

    Davis, Stacy Cagle; Diegel, Susan W; Boundy, Robert Gary

    2013-03-01

    The Oak Ridge National Laboratory s Center for Transportation Analysis developed and published the first Vehicle Technologies Market Report in 2008. Three editions of the report have been published since that time. This 2012 report details the major trends in U.S. light vehicle and medium/heavy truck markets as well as the underlying trends that caused them. The opening section on Energy and Economics discusses the role of transportation energy and vehicle markets on a national scale. The following section examines light-duty vehicle use, markets, manufacture, and supply chains. The discussion of medium and heavy trucks offers information on truck sales and fuel use. The technology section offers information on alternative fuel vehicles and infrastructure, and the policy section concludes with information on recent, current, and near-future Federal policies like the Corporate Average Fuel Economy standards.

  7. The aerobraking space transfer vehicle

    NASA Technical Reports Server (NTRS)

    Andrews, Glen; Carpenter, Brian; Corns, Steve; Harris, Robert; Jun, Brian; Munro, Bruce; Pulling, Eric; Sekhon, Amrit; Welton, Walt; Jakubowski, A.

    1990-01-01

    With the advent of the Space Station and the proposed Geosynchronous Operation Support Center (GeoShack) in the early 21st century, the need for a cost effective, reusable orbital transport vehicle has arisen. This transport vehicle will be used in conjunction with the Space Shuttle, the Space Station, and GeoShack. The vehicle will transfer mission crew and payloads between low earth and geosynchronous orbits with minimal cost. Recent technological advances in thermal protection systems such as those employed in the Space Shuttle have made it possible to incorporate and aerobrake on the transfer vehicle to further reduce transport costs. The research and final design configuration of the aerospace senior design team from VPISU, working in conjunction with NASA, are presented. The topic of aerobraking and focuses on the evolution of an Aerobraking Space Transfer Vehicle (ASTV), is addressed.

  8. Aggregate vehicle travel forecasting model

    SciTech Connect

    Greene, D.L.; Chin, Shih-Miao; Gibson, R.

    1995-05-01

    This report describes a model for forecasting total US highway travel by all vehicle types, and its implementation in the form of a personal computer program. The model comprises a short-run, econometrically-based module for forecasting through the year 2000, as well as a structural, scenario-based longer term module for forecasting through 2030. The short-term module is driven primarily by economic variables. It includes a detailed vehicle stock model and permits the estimation of fuel use as well as vehicle travel. The longer-tenn module depends on demographic factors to a greater extent, but also on trends in key parameters such as vehicle load factors, and the dematerialization of GNP. Both passenger and freight vehicle movements are accounted for in both modules. The model has been implemented as a compiled program in the Fox-Pro database management system operating in the Windows environment.

  9. Large engines and vehicles, 1958

    NASA Technical Reports Server (NTRS)

    1978-01-01

    During the mid-1950s, the Air Force sponsored work on the feasibility of building large, single-chamber engines, presumably for boost-glide aircraft or spacecraft. In 1956, the Army missile development group began studies of large launch vehicles. The possibilities opened up by Sputnik accelerated this work and gave the Army an opportunity to bid for the leading role in launch vehicles. The Air Force had the responsibility for the largest ballistic missiles and hence a ready-made base for extending their capability for spaceflight. During 1958, actions taken to establish a civilian space agency, and the launch vehicle needs seen by its planners, added a third contender to the space vehicle competition. These activities during 1958 are examined as to how they resulted in the initiation of a large rocket engine and the first large launch vehicle.

  10. An optimized international vehicle monitor

    SciTech Connect

    York, R.L.; Close, D.A.; Fehlau, P.E.

    1997-03-01

    The security plans for many DOE facilities require the monitoring of pedestrians and vehicles to control the movement of special nuclear material (SNM). Vehicle monitors often provide the outer-most barrier against the theft of SNM. Automatic monitors determine the presence of SNM by comparing the gamma-ray and neutron intensity while occupied, to the continuously updated background radiation level which is measured while the unit is unoccupied. The most important factors in choosing automatic vehicle monitors are sensitivity, cost and in high traffic applications total monitoring time. The two types of automatic vehicle monitors presently in use are the vehicle monitoring station and the drive-through vehicle monitor. These two types have dramatically different cost and sensitivities. The vehicle monitoring station has a worst-case detection sensitivity of 40 g of highly enriched uranium, HEU, and a cost approximately $180k. This type of monitor is very difficult to install and can only be used in low traffic flow locations. The drive-through vehicle portal has a worst-case detection sensitivity of 1 kg of HEU and a cost approximately $20k. The world`s political situation has created a pressing need to prevent the diversion of SNM from FSU nuclear facilities and across international borders. Drive-through vehicle monitors would be an effective and practical nuclear material proliferation deterrent if their sensitivity can be improved to a sufficient level. The goal of this project is to evaluate different detector configurations as a means of improving the sensitivity of these instruments to achieve a vehicle monitor that is economical, practical to install, and has adequate sensitivity to be an effective barrier to illegal transportation of SNM.

  11. Heavy Vehicle and Engine Resource Guide

    SciTech Connect

    Not Available

    2004-03-01

    The Heavy Vehicle and Engine Resource Guide is a catalog of medium- and heavy-duty engines and vehicles with alternative fuel and advanced powertrain options. This edition covers model year 2003 engines and vehicles.

  12. 77 FR 72337 - Apps for Vehicles Challenge

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-05

    ... of Energy Efficiency and Renewable Energy Apps for Vehicles Challenge AGENCY: Office of Energy... Vehicles: improving safety and fuel efficiency through technology innovation''. DATES: See, 1. Key Challenge Dates & Deadlines in SUPPLEMENTARY INFORMATION. ADDRESSES: The Apps for Vehicles Challenge...

  13. 77 FR 40921 - Communication With Transport Vehicles

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-11

    ... COMMISSION Communication With Transport Vehicles AGENCY: Nuclear Regulatory Commission. ACTION: Regulatory... withdrawing Regulatory Guide 5.32, Revision 1, ``Communication with Transport Vehicles,'' published in May..., ``Communication with Transport Vehicles,'' published in May 1975. This RG describes radiotelephone...

  14. Mobile remote manipulator vehicle system

    NASA Technical Reports Server (NTRS)

    Bush, Harold G. (Inventor); Mikulas, Martin M., Jr. (Inventor); Wallsom, Richard E. (Inventor); Jensen, J. Kermit (Inventor)

    1987-01-01

    A mobile remote manipulator system is disclosed for assembly, repair and logistics transport on, around and about a space station square bay truss structure. The vehicle is supported by a square track arrangement supported by guide pins integral with the space station truss structure and located at each truss node. Propulsion is provided by a central push-pull drive mechanism that extends out from the vehicle one full structural bay over the truss and locks drive rods into the guide pins. The draw bar is now retracted and the mobile remote manipulator system is pulled onto the next adjacent structural bay. Thus, translation of the vehicle is inchworm style. The drive bar can be locked onto two guide pins while the extendable draw bar is within the vehicle and then push the vehicle away one bay providing bidirectional push-pull drive. The track switches allow the vehicle to travel in two orthogonal directions over the truss structure which coupled with the bidirectional drive, allow movement in four directions on one plane. The top layer of this trilayered vehicle is a logistics platform. This platform is capable of 369 degees of rotation and will have two astronaut foot restraint platforms and a space crane integral.

  15. Vehicle systems design optimization study

    SciTech Connect

    Gilmour, J. L.

    1980-04-01

    The optimization of an electric vehicle layout requires a weight distribution in the range of 53/47 to 62/38 in order to assure dynamic handling characteristics comparable to current production internal combustion engine vehicles. It is possible to achieve this goal and also provide passenger and cargo space comparable to a selected current production sub-compact car either in a unique new design or by utilizing the production vehicle as a base. Necessary modification of the base vehicle can be accomplished without major modification of the structure or running gear. As long as batteries are as heavy and require as much space as they currently do, they must be divided into two packages - one at front under the hood and a second at the rear under the cargo area - in order to achieve the desired weight distribution. The weight distribution criteria requires the placement of batteries at the front of the vehicle even when the central tunnel is used for the location of some batteries. The optimum layout has a front motor and front wheel drive. This configuration provides the optimum vehicle dynamic handling characteristics and the maximum passsenger and cargo space for a given size vehicle.

  16. The automation of remote vehicle control. [in Mars roving vehicles

    NASA Technical Reports Server (NTRS)

    Paine, G.

    1977-01-01

    The automation of remote vehicles is becoming necessary to overcome the requirement of having man present as a controller. By removing man, remote vehicles can be operated in areas where the environment is too hostile for man, his reaction times are too slow, time delays are too long, and where his presence is too costly, or where system performance can be improved. This paper addresses the development of automated remote vehicle control for nonspace and space tasks from warehouse vehicles to proposed Mars rovers. The state-of-the-art and the availability of new technology for implementing automated control are reviewed and the major problem areas are outlined. The control strategies are divided into those where the path is planned in advance or constrained, or where the system is a teleoperator, or where automation or robotics have been introduced.

  17. Launch vehicles for communications satellites

    NASA Technical Reports Server (NTRS)

    Mahon, J. B.

    1982-01-01

    After giving brief development histories of the Delta and the Atlas Centaur launch vehicles, attention is given to the operational characteristics of the ascent, parking orbit, transfer orbit, and orbital insertion phases of the delivery of a communications satellite to a geostationary orbit by means of a Delta launch vehicle. NASA plans to employ Delta vehicles for as long as they are needed during the transition period to the Space Shuttle. NASA planning for Atlas Centaur includes launches through 1985 for INTELSAT-VA, and through 1986 for FLTSATCOM satellites.

  18. X-24C research vehicle

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A group of experiments that might be accomplished on the X-24C research vehicle are discussed indicating in each case the technology development needed to ready the experiments for flight, and also indicating interface problems between the vehicle and the experiment. Experiments that could be cheaply done using test platforms other than the X-24C have been eliminated. Experiments that are clearly applicable only to the X-24C research vehicle are, of course, included. Experiments that might be accomplished on either the X-24C or some other platform requiring further investigation concerning proper applicability are included for consideration.

  19. Mission and vehicle sizing sensitivities

    NASA Technical Reports Server (NTRS)

    Young, Archie C.

    1986-01-01

    Representative interplanetary space vehicle systems are sized to compare and show sensitivity of the initial mass required in low Earth orbit to one mission mode and mission opportunity. Data are presented to show the requirements for Earth-Mars opposition and conjunction class roundtrip flyby and stopover mission opportunities available during the time period from year 1997 to year 2045. The interplanetary space vehicle consists of a spacecraft and a space vehicle acceleration system. Propellant boil-off for the various mission phases is given for the Lox/LH (Liquid Oxygen/Liquid Hydrogen) propulsion systems. Mission abort information is presented for the 1999 Venus outbound swingby trajectory, transfer profile.

  20. Research on Hybrid Vehicle Drivetrain

    NASA Astrophysics Data System (ADS)

    Xie, Zhongzhi

    Hybrid cars as a solution to energy saving, emission reduction measures, have received widespread attention. Motor drive system as an important part of the hybrid vehicles as an important object of study. Based on the hybrid electric vehicle powertrain control system for permanent magnet synchronous motor as the object of study. Can be applied to hybrid car compares the characteristics of traction motors, chose permanent magnet synchronous Motors as drive motors for hybrid vehicles. Building applications in hybrid cars in MATLAB/Simulink simulation model of permanent-magnet synchronous motor speed control system and analysis of simulation results.