Internal performance of a nonaxisymmetric nozzle with a rotating upper flap and a center-pivoted lower flap

NASA Technical Reports Server (NTRS)

Wing, David J.; Leavitt, Laurence D.; Re, Richard J.

1993-01-01

An investigation was conducted at wind-off conditions in the static-test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance characteristics of a single expansion-ramp nozzle with thrust-vectoring capability to 105 degrees. Thrust vectoring was accomplished by the downward rotation of an upper flap with adaptive capability for internal contouring and a corresponding rotation of a center-pivoted lower flap. The static internal performance of configurations with pitch thrust-vector angles of 0 degrees, 60 degrees, and 105 degrees each with two throat areas, was investigated. The nozzle pressure ratio was varied from 1.5 to approximately 8.0 (5.0 for the maximum throat area configurations). Results of this study indicated that the nozzle configuration of the present investigation, when vectored, provided excellent flow-turning capability with relatively high levels of internal performance. In all cases, the thrust vector angle was a function of the nozzle pressure ratio. This result is expected because the flow is bounded by a single expansion surface on both vectored- and unvectored-nozzle geometries.

14 CFR 23.1325 - Static pressure system.

Code of Federal Regulations, 2013 CFR

2013-01-01

... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure case...

14 CFR 23.1325 - Static pressure system.

Code of Federal Regulations, 2014 CFR

2014-01-01

... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure case...

14 CFR 23.1325 - Static pressure system.

Code of Federal Regulations, 2011 CFR

2011-01-01

... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure case...

14 CFR 23.1325 - Static pressure system.

Code of Federal Regulations, 2012 CFR

2012-01-01

... the correlation between air pressure in the static pressure system and true ambient atmospheric static... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Static pressure system. 23.1325 Section 23...: Installation § 23.1325 Static pressure system. (a) Each instrument provided with static pressure case...

Modeling Scala Media as a Pressure Vessel

NASA Astrophysics Data System (ADS)

Lepage, Eric; Olofsson, A.˚Ke

2011-11-01

The clinical condition known as endolymphatic hydrops is the swelling of scala media and may result in loss in hearing sensitivity consistent with other forms of low-frequency biasing. Because outer hair cells (OHCs) are displacement-sensitive and hearing levels tend to be preserved despite large changes in blood pressure and CSF pressure, it seems unlikely that the OHC respond passively to changes in static pressures in the chambers. This suggests the operation of a major feedback control loop which jointly regulates homeostasis and hearing sensitivity. Therefore the internal forces affecting the cochlear signal processing amplifier cannot be just motile responses. A complete account of the cochlear amplifier must include static pressures. To this end we have added a third, pressure vessel to our 1-D 140-segment, wave-digital filter active model of cochlear mechanics, incorporating the usual nonlinear forward transduction. In each segment the instantaneous pressure is the sum of acoustic pressure and global static pressure. The object of the model is to maintain stable OHC operating point despite any global rise in pressure in the third chamber. Such accumulated pressure is allowed to dissipate exponentially. In this first 3-chamber implementation we explore the possibility that acoustic pressures are rectified. The behavior of the model is critically dependent upon scaling factors and time-constants, yet by initial assumption, the pressure tends to accumulate in proportion to sound level. We further explore setting of the control parameters so that the accumulated pressure either stays within limits or may rise without bound.

Non-axisymmetric flow characteristics in centrifugal compressor

NASA Astrophysics Data System (ADS)

Wang, Leilei; Lao, Dazhong; Liu, Yixiong; Yang, Ce

2015-06-01

The flow field distribution in centrifugal compressor is significantly affected by the non-axisymmetric geometry structure of the volute. The experimental and numerical simulation methods were adopted in this work to study the compressor flow field distribution with different flow conditions. The results show that the pressure distributionin volute is characterized by the circumferential non-uniform phenomenon and the pressure fluctuation on the high static pressure zone propagates reversely to upstream, which results in the non-axisymmetric flow inside the compressor. The non-uniform level of pressure distribution in large flow condition is higher than that in small flow condition, its effect on the upstream flow field is also stronger. Additionally, the non-uniform circumferential pressure distribution in volute brings the non-axisymmetric flow at impeller outlet. In different flow conditions,the circumferential variation of the absolute flow angle at impeller outlet is also different. Meanwhile, the non-axisymmetric flow characteristics in internal impeller can be also reflected by the distribution of the mass flow. The high static pressure region of the volute corresponds to the decrease of mass flow in upstream blade channel, while the low static pressure zone of the volute corresponds to the increase of the mass flow. In small flow condition, the mass flow difference in the blade channel is bigger than that in the large flow condition.

Analysis of the effects of non-supine sleeping positions on the stress, strain, deformation and intraocular pressure of the human eye

NASA Astrophysics Data System (ADS)

Volpe, Peter A.

This thesis presents analytical models, finite element models and experimental data to investigate the response of the human eye to loads that can be experienced when in a non-supine sleeping position. The hypothesis being investigated is that non-supine sleeping positions can lead to stress, strain and deformation of the eye as well as changes in intraocular pressure (IOP) that may exacerbate vision loss in individuals who have glaucoma. To investigate the quasi-static changes in stress and internal pressure, a Fluid-Structure Interaction simulation was performed on an axisymmetrical model of an eye. Common Aerospace Engineering methods for analyzing pressure vessels and hyperelastic structural walls are applied to developing a suitable model. The quasi-static pressure increase was used in an iterative code to analyze changes in IOP over time.

Atmospheric Dynamics on Venus, Jupiter, and Saturn: An Observational and Analytical Study

NASA Technical Reports Server (NTRS)

Bridger, Alison; Magalhaes, Julio A.; Young, Richard E.

2000-01-01

Determining the static stability of Jupiter's atmosphere below the visible cloud levels is important for understanding the dynamical modes by which energy and momentum are transported through Jupiter's deep troposphere. The Galileo Probe Atmospheric Structure Investigation (ASI) employed pressure and temperature sensors to directly measure these state variables during the parachute-descent phase, which started at a pressure (p) of 0.4 bars and ended at p= 22 bars. The internal temperature of the probe underwent large temperature fluctuations which significantly exceeded design specifications. Corrections for these anomalous interior temperatures have been evaluated based on laboratory data acquired after the mission using the flight spare hardware. The corrections to the pressure sensor readings was particularly large and the uncertainties in the atmospheric pressures derived from the p sensor measurements may still be significant. We have sought to estimate the formal uncertainties in the static stability derived from the p and T sensor measurements directly and to devise means of assessing the static stability of Jupiter's atmosphere which do not rely on the p sensor data.

Static test-stand performance of the YF-102 turbofan engine with several exhaust configurations for the Quiet Short-Haul Research Aircraft (QSRA)

NASA Technical Reports Server (NTRS)

Mcardle, J. G.; Homyak, L.; Moore, A. S.

1979-01-01

The performance of a YF-102 turbofan engine was measured in an outdoor test stand with a bellmouth inlet and seven exhaust-system configurations. The configurations consisted of three separate-flow systems of various fan and core nozzle sizes and four confluent-flow systems of various nozzle sizes and shapes. A computer program provided good estimates of the engine performance and of thrust at maximum rating for each exhaust configuration. The internal performance of two different-shaped core nozzles for confluent-flow configurations was determined to be satisfactory. Pressure and temperature surveys were made with a traversing probe in the exhaust-nozzle flow for some confluent-flow configurations. The survey data at the mixing plane, plus the measured flow rates, were used to calculate the static-pressure variation along the exhaust nozzle length. The computed pressures compared well with experimental wall static-pressure data. External-flow surveys were made, for some confluent-flow configurations, with a large fixed rake at various locations in the exhaust plume.

Effect of attack angle on flow characteristic of centrifugal fan

NASA Astrophysics Data System (ADS)

Wu, Y.; Dou, H. S.; Wei, Y. K.; Chen, X. P.; Chen, Y. N.; Cao, W. B.

2016-05-01

In this paper, numerical simulation is performed for the performance and internal flow of a centrifugal fan with different operating conditions using steady three-dimensional incompressible Navier-Stokes equations coupled with the RNG k-e turbulent model. The performance curves, the contours of static pressure, total pressure, radial velocity, relative streamlines and turbulence intensity at different attack angles are obtained. The distributions of static pressure and velocity on suction surface and pressure surface in the same impeller channel are compared for various attack angles. The research shows that the efficiency of the centrifugal fan is the highest when the attack angle is 8 degree. The main reason is that the vortex flow in the impeller is reduced, and the jet-wake pattern is weakened at the impeller outlet. The pressure difference between pressure side and suction side is smooth and the amplitude of the total pressure fluctuation is low along the circumferential direction. These phenomena may cause the loss reduced for the attack angle of about 8 degree.

Static-stress analysis of dual-axis confinement vessel

NASA Astrophysics Data System (ADS)

Bultman, D. H.

1992-11-01

This study evaluates the static-pressure containment capability of a 6-ft-diameter, spherical vessel, made of HSLA-100 steel, to be used for high-explosive (HE) containment. The confinement vessel is designed for use with the Dual-Axis Radiographic Hydrotest Facility (DARHT) being developed at Los Alamos National Laboratory. Two sets of openings in the vessel are covered with x-ray transparent covers to allow radiographic imaging of an explosion as it occurs inside the vessel. The confinement vessel is analyzed as a pressure vessel based on the ASME Boiler and Pressure Vessel Code, Section 8, Division 1, and the Welding Research Council Bulletin, WRC-107. Combined stresses resulting from internal pressure and external loads on nozzles are calculated and compared with the allowable stresses for HSLA-100 steel. Results confirm that the shell and nozzles of the confinement vessel are adequately designed to safely contain the maximum residual pressure of 1675 psi that would result from an HE charge of 24.2 kg detonated in a vacuum. Shell stresses at the shell-to-nozzle interface, produced from external loads on the nozzles, were less than 400 psi. The maximum combined stress resulting from the internal pressure plus external loads was 16,070 psi, which is less than half the allowable stress of 42,375 psi for HSLA-100 steel.

The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact.

PubMed

Simon, Julianna C; Sapozhnikov, Oleg A; Kreider, Wayne; Breshock, Michael; Williams, James C; Bailey, Michael R

2018-01-09

The color Doppler ultrasound twinkling artifact, which highlights kidney stones with rapidly changing color, has the potential to improve stone detection; however, its inconsistent appearance has limited its clinical utility. Recently, it was proposed stable crevice bubbles on the kidney stone surface cause twinkling; however, the hypothesis is not fully accepted because the bubbles have not been directly observed. In this paper, the micron or submicron-sized bubbles predicted by the crevice bubble hypothesis are enlarged in kidney stones of five primary compositions by exposure to acoustic rarefaction pulses or hypobaric static pressures in order to simultaneously capture their appearance by high-speed photography and ultrasound imaging. On filming stones that twinkle, consecutive rarefaction pulses from a lithotripter caused some bubbles to reproducibly grow from specific locations on the stone surface, suggesting the presence of pre-existing crevice bubbles. Hyperbaric and hypobaric static pressures were found to modify the twinkling artifact; however, the simple expectation that hyperbaric exposures reduce and hypobaric pressures increase twinkling by shrinking and enlarging bubbles, respectively, largely held for rough-surfaced stones but was inadequate for smoother stones. Twinkling was found to increase or decrease in response to elevated static pressure on smooth stones, perhaps because of the compression of internal voids. These results support the crevice bubble hypothesis of twinkling and suggest the kidney stone crevices that give rise to the twinkling phenomenon may be internal as well as external.

The role of trapped bubbles in kidney stone detection with the color Doppler ultrasound twinkling artifact

NASA Astrophysics Data System (ADS)

Simon, Julianna C.; Sapozhnikov, Oleg A.; Kreider, Wayne; Breshock, Michael; Williams, James C., Jr.; Bailey, Michael R.

2018-01-01

The color Doppler ultrasound twinkling artifact, which highlights kidney stones with rapidly changing color, has the potential to improve stone detection; however, its inconsistent appearance has limited its clinical utility. Recently, it was proposed stable crevice bubbles on the kidney stone surface cause twinkling; however, the hypothesis is not fully accepted because the bubbles have not been directly observed. In this paper, the micron or submicron-sized bubbles predicted by the crevice bubble hypothesis are enlarged in kidney stones of five primary compositions by exposure to acoustic rarefaction pulses or hypobaric static pressures in order to simultaneously capture their appearance by high-speed photography and ultrasound imaging. On filming stones that twinkle, consecutive rarefaction pulses from a lithotripter caused some bubbles to reproducibly grow from specific locations on the stone surface, suggesting the presence of pre-existing crevice bubbles. Hyperbaric and hypobaric static pressures were found to modify the twinkling artifact; however, the simple expectation that hyperbaric exposures reduce and hypobaric pressures increase twinkling by shrinking and enlarging bubbles, respectively, largely held for rough-surfaced stones but was inadequate for smoother stones. Twinkling was found to increase or decrease in response to elevated static pressure on smooth stones, perhaps because of the compression of internal voids. These results support the crevice bubble hypothesis of twinkling and suggest the kidney stone crevices that give rise to the twinkling phenomenon may be internal as well as external.

Multi-Scaled Modeling the Mechanical Properties of Tubular Composites Reinforced with Innovated 3D Weft Knitted Spacer Fabrics

NASA Astrophysics Data System (ADS)

Omrani, Elahe; Hasani, Hossein; Dibajian, Sayed Houssain

2018-02-01

Textile composites of 3D integrated spacer configurations have been recently focused by several researchers all over the world. In the present study, newly-designed tubular composites reinforced with 3D spacer weft knitted fabrics were considered and the effects of their structural parameters on some applicable mechanical properties were investigated. For this purpose, two different samples of 3D spacer weft knitted textile types in tubular form were produced on an electronic flat knitting machine, using glass/nylon hybrid yarns. Thermoset tubular-shaped composite parts were manufactured via vacuum infusion molding process using epoxy resin. The mechanical properties of the produced knitted composites in term of external static and internal hydrostatic pressures were evaluated. Resistance of the produced composites against the external static and internal hydrostatic pressures was numerically simulated using multi-scale modeling method. The finding revealed that there is acceptable correlation between experimental and theoretical results.

The 727/JT8D refan side nacelle airloads

NASA Technical Reports Server (NTRS)

Bailey, R. W.; Vadset, H. J.

1974-01-01

Airloads on the 727/JT8D refan side engine nacelle are presented. These consist of surface static pressure distributions from two low speed wind tunnel tests. External nacelle surface pressures are from testing of a flow-through, body mounted nacelle model, and internal inlet surface pressures are from performance testing of a forced air inlet model. The method for obtaining critical airloads on nacelle components and a representative example are discussed.

Measurement of static pressure on aircraft

NASA Technical Reports Server (NTRS)

Gracey, William

1958-01-01

Existing data on the errors involved in the measurement of static pressure by means of static-pressure tubes and fuselage vents are presented. The errors associated with the various design features of static-pressure tubes are discussed for the condition of zero angle of attack and for the case where the tube is inclined to flow. Errors which result from variations in the configuration of static-pressure vents are also presented. Errors due to the position of a static-pressure tube in the flow field of the airplane are given for locations ahead of the fuselage nose, ahead of the wing tip, and ahead of the vertical tail fin. The errors of static-pressure vents on the fuselage of an airplane are also presented. Various methods of calibrating static-pressure installations in flight are briefly discussed.

A Parametric Investigation of Nozzle Planform and Internal/External Geometry at Transonic Speeds

NASA Technical Reports Server (NTRS)

Cler, Daniel L.

1995-01-01

An experimental investigation of multidisciplinary (scarfed trailing edge) nozzle divergent flap geometry was conducted at transonic speeds in the NASA Langley 16-Foot Transonic Tunnel. The geometric parameters investigated include nozzle planform, nozzle contouring location (internal and/or external), and nozzle area ratio (area ratio 1.2 and 2.0). Data were acquired over a range of Mach Numbers from 0.6 to 1.2, angle-of-attack from 0.0 degrees to 9.6 degrees and nozzle pressure ratios from 1.0 to 20.0. Results showed that increasing the rate of change internal divergence angle across the width of the nozzle or increasing internal contouring will decrease static, aeropropulsive and thrust removed drag performance regardless of the speed regime. Also, increasing the rate of change in boattail angle across the width of the nozzle or increasing external contouring will provide the lowest thrust removed drag. Scarfing of the nozzle trailing edges reduces the aeropropulsive performance for the most part and adversely affects the nozzle plume shape at higher nozzle pressure ratios thus increasing the thrust removed drag. The effects of contouring were primary in nature and the effects of planform were secondary in nature. Larger losses occur supersonically than subsonically when scarfing of nozzle trailing edges occurs. The single sawtooth nozzle almost always provided lower thrust removed drag than the double sawtooth nozzles regardless the speed regime. If internal contouring is required, the double sawtooth nozzle planform provides better static and aeropropulsive performance than the single sawtooth nozzle and if no internal contouring is required the single sawtooth provides the highest static and aeropropulsive performance.

14 CFR 25.1325 - Static pressure systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented to the outside... or other foreign matter, and that the correlation between air pressure in the static pressure system... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Static pressure systems. 25.1325 Section 25...

14 CFR 25.1325 - Static pressure systems.

Code of Federal Regulations, 2012 CFR

2012-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented to the outside... or other foreign matter, and that the correlation between air pressure in the static pressure system... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Static pressure systems. 25.1325 Section 25...

14 CFR 25.1325 - Static pressure systems.

Code of Federal Regulations, 2013 CFR

2013-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented to the outside... or other foreign matter, and that the correlation between air pressure in the static pressure system... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Static pressure systems. 25.1325 Section 25...

14 CFR 25.1325 - Static pressure systems.

Code of Federal Regulations, 2011 CFR

2011-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented to the outside... or other foreign matter, and that the correlation between air pressure in the static pressure system... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Static pressure systems. 25.1325 Section 25...

Static internal performance characteristics of two thrust reverser concepts for axisymmetric nozzles

NASA Technical Reports Server (NTRS)

Leavitt, L. D.; Re, R. J.

1982-01-01

The statis performance of two axisymmetric nozzle thrust reverser concepts was investigated. A rotating vane thrust reverser represented a concept in which reversing is accomplished upstream of the nozzle throat, and a three door reverser concept provided reversing downstream of the nozzle throat. Nozzle pressure ratio was varied from 2.0 to approximately 6.0. The results of this investigation indicate that both the rotating vane and three door reverser concepts were effective static thrust spoilers with the landing approach nozzle geometry and were capable of providing at least a 50 percent reversal of static thrust when fully deployed with the ground roll nozzle geometry.

14 CFR 27.1325 - Static pressure systems.

Code of Federal Regulations, 2011 CFR

2011-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented so that the influence... located in such manner that the correlation between air pressure in the static pressure system and true... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Static pressure systems. 27.1325 Section 27...

14 CFR 27.1325 - Static pressure systems.

Code of Federal Regulations, 2012 CFR

2012-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented so that the influence... located in such manner that the correlation between air pressure in the static pressure system and true... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Static pressure systems. 27.1325 Section 27...

14 CFR 27.1325 - Static pressure systems.

Code of Federal Regulations, 2013 CFR

2013-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented so that the influence... located in such manner that the correlation between air pressure in the static pressure system and true... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Static pressure systems. 27.1325 Section 27...

14 CFR 27.1325 - Static pressure systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... pressure systems. (a) Each instrument with static air case connections must be vented so that the influence... located in such manner that the correlation between air pressure in the static pressure system and true... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Static pressure systems. 27.1325 Section 27...

Static internal performance of a single expansion ramp nozzle with multiaxis thrust vectoring capability

NASA Technical Reports Server (NTRS)

Capone, Francis J.; Schirmer, Alberto W.

1993-01-01

An investigation was conducted at static conditions in order to determine the internal performance characteristics of a multiaxis thrust vectoring single expansion ramp nozzle. Yaw vectoring was achieved by deflecting yaw flaps in the nozzle sidewall into the nozzle exhaust flow. In order to eliminate any physical interference between the variable angle yaw flap deflected into the exhaust flow and the nozzle upper ramp and lower flap which were deflected for pitch vectoring, the downstream corners of both the nozzle ramp and lower flap were cut off to allow for up to 30 deg of yaw vectoring. The effects of nozzle upper ramp and lower flap cutout, yaw flap hinge line location and hinge inclination angle, sidewall containment, geometric pitch vector angle, and geometric yaw vector angle were studied. This investigation was conducted in the static-test facility of the Langley 16-Foot Transonic Tunnel at nozzle pressure ratios up to 8.0.

Application of Pressure Sensitive Paint to Confined Flow at Mach Number 2.5

NASA Technical Reports Server (NTRS)

Lepicovsky, J.; Bencic, T. J.; Bruckner, R. J.

1998-01-01

Pressure sensitive paint (PSP) is a novel technology that is being used frequently in external aerodynamics. For internal flows in narrow channels, and applications at elevated nonuniform temperatures, however, there are still unresolved problems that complicate the procedures for calibrating PSP signals. To address some of these problems, investigations were carried out in a narrow channel with supersonic flows of Mach 2.5. The first set of tests focused on the distribution of the wall pressure in the diverging section of the test channel downstream of the nozzle throat. The second set dealt with the distribution of wall static pressure due to the shock/wall interaction caused by a 25 deg. wedge in the constant Mach number part of the test section. In addition, the total temperature of the flow was varied to assess the effects of temperature on the PSP signal. Finally, contamination of the pressure field data, caused by internal reflection of the PSP signal in a narrow channel, was demonstrated. The local wall pressures were measured with static taps, and the wall pressure distributions were acquired by using PSP. The PSP results gave excellent qualitative impressions of the pressure field investigated. However, the quantitative results, specifically the accuracy of the PSP data in narrow channels, show that improvements need to be made in the calibration procedures, particularly for heated flows. In the cases investigated, the experimental error had a standard deviation of +/- 8.0% for the unheated flow, and +/- 16.0% for the heated flow, at an average pressure of 11 kpa.

Unified Static and Dynamic Recrystallization Model for the Minerals of Earth's Mantle Using Internal State Variable Model

NASA Astrophysics Data System (ADS)

Cho, H. E.; Horstemeyer, M. F.; Baumgardner, J. R.

2017-12-01

In this study, we present an internal state variable (ISV) constitutive model developed to model static and dynamic recrystallization and grain size progression in a unified manner. This method accurately captures temperature, pressure and strain rate effect on the recrystallization and grain size. Because this ISV approach treats dislocation density, volume fraction of recrystallization and grain size as internal variables, this model can simultaneously track their history during the deformation with unprecedented realism. Based on this deformation history, this method can capture realistic mechanical properties such as stress-strain behavior in the relationship of microstructure-mechanical property. Also, both the transient grain size during the deformation and the steady-state grain size of dynamic recrystallization can be predicted from the history variable of recrystallization volume fraction. Furthermore, because this model has a capability to simultaneously handle plasticity and creep behaviors (unified creep-plasticity), the mechanisms (static recovery (or diffusion creep), dynamic recovery (or dislocation creep) and hardening) related to dislocation dynamics can also be captured. To model these comprehensive mechanical behaviors, the mathematical formulation of this model includes elasticity to evaluate yield stress, work hardening in treating plasticity, creep, as well as the unified recrystallization and grain size progression. Because pressure sensitivity is especially important for the mantle minerals, we developed a yield function combining Drucker-Prager shear failure and von Mises yield surfaces to model the pressure dependent yield stress, while using pressure dependent work hardening and creep terms. Using these formulations, we calibrated against experimental data of the minerals acquired from the literature. Additionally, we also calibrated experimental data for metals to show the general applicability of our model. Understanding of realistic mantle dynamics can only be acquired once the various deformation regimes and mechanisms are comprehensively modeled. The results of this study demonstrate that this ISV model is a good modeling candidate to help reveal the realistic dynamics of the Earth's mantle.

14 CFR 27.1325 - Static pressure systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... ambient atmospheric static pressure is not altered when the rotorcraft encounters icing conditions. An... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Static pressure systems. 27.1325 Section 27... pressure systems. (a) Each instrument with static air case connections must be vented so that the influence...

Analytical and experimental study of axisymmetric truncated plug nozzle flow fields

NASA Technical Reports Server (NTRS)

Muller, T. J.; Sule, W. P.; Fanning, A. E.; Giel, T. V.; Galanga, F. L.

1972-01-01

Experimental and analytical investigation of the flow field and base pressure of internal-external-expansion truncated plug nozzles are discussed. Experimental results for two axisymmetric, conical plug-cylindrical shroud, truncated plug nozzles are presented for both open and closed wake operations. These results include extensive optical and pressure data covering nozzle flow field and base pressure characteristics, diffuser effects, lip shock strength, Mach disc behaviour, and the recompression and reverse flow regions. Transonic experiments for a special planar transonic section are presented. An extension of the analytical method of Hall and Mueller to include the internal shock wave from the shroud exit is presented for closed wake operation. Results of this analysis include effects on the flow field and base pressure of ambient pressure ratio, nozzle geometry, and the ratio of specific heats. Static thrust is presented as a function of ambient pressure ratio and nozzle geometry. A new transonic solution method is also presented.

Internal flow characteristics of a multistage compressor with inlet pressure distortion. [J85-13 turbojet engine studies

NASA Technical Reports Server (NTRS)

Debogdan, C. E.; Moss, J. E., Jr.; Braithwaite, W. M.

1977-01-01

The measured distribution of compressor interstage pressures and temperatures resulting from a 180 deg inlet-total-pressure distortion for a J85-13 turbojet engine is reported. Extensive inner stage instrumentation combined with stepwise rotation of the inlet distortion gave data of high circumferential resolution. The steady-state pressures and temperatures along with the amplitude, extent, and location of the distorted areas are given. Data for 80, 90, and 100 percent of rotor design speed are compared with clean (undistorted) inlet flow conditions to show pressure and temperature behavior within the compressor. Both overall and stagewise compressor performances vary only slightly when clean and distorted inlet conditions are compared. Total and static pressure distortions increase in amplitude in the first few stages of the compressor and then attenuate fairly uniformly to zero at the discharge. Total-temperature distortion induced by the pressure distortion reached a maximum amplitude by the first two stages and decayed only a little through the rest of the compressor. Distortion amplitude tended to peak in line with the screen edges, and, except for total and static pressure in the tip zone, there was little swirl in the axial direction.

Utility of Functional Hemodynamics and Echocardiography to Aid Diagnosis and Management of Shock.

PubMed

McGee, William T; Raghunathan, Karthik; Adler, Adam C

2015-12-01

The utility of functional hemodynamics and bedside ultrasonography is increasingly recognized as advantageous for both improved diagnosis and management of shock states. In contrast to conventional "static" measures, "dynamic" hemodynamic measures and bedside imaging modalities enhance pathophysiology-based comprehensive understanding of shock states and the response to therapy. The current editions of major textbooks in the primary specialties--in which clinicians routinely encounter patients in shock--including surgery, anesthesia, emergency medicine, and internal medicine continue to incorporate traditional (conventional) descriptions of shock that use well-described (but potentially misleading) intravascular pressures to classify shock states. Reliance on such intravascular pressure measurements is not as helpful as newer "dynamic" functional measures including ultrasonography to both better assess volume responsiveness and biventricular cardiac function. This review thus emphasizes the application of current functional hemodynamics and ultrasonography to the diagnosis and management of shock as a contrast to conventional "static" pressure-based measures.

Surface-pressure Distributions on a Systematic Group of NACA 1-series Cowlings with and Without Spinners

NASA Technical Reports Server (NTRS)

Boswinkle, Robert W JR; Keith, Arvid L JR

1948-01-01

A method for calculating the flow fields of axially symmetric bodies from their pressure distributions is reported in NACA RM No. L8I17. In order to facilitate application of this method to the important case of the cowling-spinner combination, for use in the design of propellers, the present paper presents static-pressure distributions on the tops of 79 high-critical-speed NACA 1-series cowling-spinner combinations over wide ranges of inlet-velocity ratio at angles of attack of 0 degrees, 2 degrees, 4 degrees, and 6 degrees. Static-pressure distributions around the nose sections of several cowlings are given in greater detail to aid in estimating the pressures near the stagnation points and to show the effect of changes in the internal lip shape. The effects of the operation of a typical propeller on the surface pressures on the cowling are shown for one configuration. The pressure distributions over the nine NACA 1-series nose inlets used as the basic components of these combinations are also presented ro supplement the existing open-nose-cowling data of NACA ACR No. L5F30a which are applicable to the case of the rotating cowling.

Trasonic Cascade Wind Tunnel Modification and Initial Tests.

DTIC Science & Technology

1980-06-01

27.57 Mathr 1.432 la No. 2 t S atic Pressure = 14.040 P.-ptg= .2686 Mach= 1.510 laz~r t~o. 29 Static Pressure= 13.946 p.ptO .26f2 Macha 1.513 T tp...54 Mach = 1.475 3. Ho. 45 Static Pressure t 12.811 PPto= .2451 Mach = 1.572 Tap No. 46 Static Pressures 12.563 P/Ptow .2403 Macha 1.586 Table c-i...T al) tNo. 64 Static Pressure- 11.981 P,/PtO= .2292 Macha 1.61:3 Twi:. No. 65 Static Pressure= 11.726 P’PtG= .2243 Mach= 1.632 af l N. 66 Sttatic

Hydrogen gas embrittlement and the disc pressure test

NASA Technical Reports Server (NTRS)

Bachelet, E. J.; Troiano, A. R.

1973-01-01

A disc pressure test has been used to study the influenced of a hydrogen gas environment on the mechanical properties of three high strength superalloys, Inconel 718, L-605 and A-286, in static and dynamic conditions. The influence of the hydrogen pressure, loading rate, temperature, mechanical and thermal fatigue has investigated. The permeation characteristics of Inconel 718 have been determined in collaboration with the French AEC. The results complemented by a fractographic study are consistent either with a stress-sorption or with an internal embrittlement type of mechanism.

Use of Pressure Sensitive Paint for Diagnostics in Turbomachinery Flows With Shocks

NASA Technical Reports Server (NTRS)

Lepicovsky, Jan; Bencic, Timothy J.

2001-01-01

The technology of pressure sensitive paint (PSP) is well established in external aerodynamics. In internal flows in narrow channels and in turbomachinery cascades, however, there are still unresolved problems. In particular, the internal flows with complex shock structures inside highly curved channels present a challenge. It is not always easy and straightforward to distinguish between true signals and "ghost" images due to multiple internal reflections in narrow channels. To address some of the problems, investigations were first carried out in a narrow supersonic channel of Mach number 2.5. A single wedge or a combination of two wedges were used to generate a complex shock wave structure in the flow. The experience gained in a small supersonic channel was used for surface pressure measurements on the stator vane of a supersonic throughflow fan. The experimental results for several fan operating conditions are shown in a concise form, including performance map points, midspan static tap pressure distributions, and vane suction side pressure fields. Finally, the PSP technique was used in the NASA transonic flutter cascade to compliment flow visualization data and to acquire backwall pressure fields to assess the cascade flow periodicity. A summary of shortcomings of the pressure sensitive paint technology for internal flow application and lessons learned are presented in the conclusion of the paper.

Space Shuttle Redesigned Solid Rocket Motor nozzle natural frequency variations with burn time

NASA Technical Reports Server (NTRS)

Lui, C. Y.; Mason, D. R.

1991-01-01

The effects of erosion and thermal degradation on the Space Shuttle Redesigned Solid Rocket Motor (RSRM) nozzle's structural dynamic characteristics were analytically evaluated. Also considered was stiffening of the structure due to internal pressurization. A detailed NASTRAN finite element model of the nozzle was developed and used to evaluate the influence of these effects at several discrete times during motor burn. Methods were developed for treating erosion and thermal degradation, and a procedure was developed to account for internal pressure stiffening using differential stiffness matrix techniques. Results were verified using static firing test accelerometer data. Fast Fourier Transform and Maximum Entropy Method techniques were applied to the data to generate waterfall plots which track modal frequencies with burn time. Results indicate that the lower frequency nozzle 'vectoring' modes are only slightly affected by erosion, thermal effects and internal pressurization. The higher frequency shell modes of the nozzle are, however, significantly reduced.

33 CFR 156.170 - Equipment tests and inspections.

Code of Federal Regulations, 2014 CFR

2014-07-01

... distort under static liquid pressure at least 11/2 times the maximum allowable working pressure; and (iv... static liquid pressure test is successfully completed in the presence of the COTP. The test medium is not... static liquid pressure at least 11/2 times the maximum allowable working pressure; and (5) Each item of...

33 CFR 156.170 - Equipment tests and inspections.

Code of Federal Regulations, 2012 CFR

2012-07-01

... distort under static liquid pressure at least 11/2 times the maximum allowable working pressure; and (iv... static liquid pressure test is successfully completed in the presence of the COTP. The test medium is not... static liquid pressure at least 11/2 times the maximum allowable working pressure; and (5) Each item of...

33 CFR 156.170 - Equipment tests and inspections.

Code of Federal Regulations, 2013 CFR

2013-07-01

... distort under static liquid pressure at least 11/2 times the maximum allowable working pressure; and (iv... static liquid pressure test is successfully completed in the presence of the COTP. The test medium is not... static liquid pressure at least 11/2 times the maximum allowable working pressure; and (5) Each item of...

Unmanned Evaluation of Mares Abyss 22 Navy Open Circuit Scuba Regulator for Cold Water Diving

DTIC Science & Technology

2011-05-05

regulator is shown above the water. Note the blue mouthpiece adaptor, white oral static pressure pick-up ring , and gray routing block attached for...e.g., an inflation whip or a second-stage octopus ), submersible pressure gage, or gas-integrated computer were connected to the first stage. As...adaptor (shown in blue ) inward into the second-stage assembly, Figure 9 indicates typical 9 internal second-stage icing experienced during Phase

In-Flight Pitot-Static Calibration

NASA Technical Reports Server (NTRS)

Foster, John V. (Inventor); Cunningham, Kevin (Inventor)

2016-01-01

A GPS-based pitot-static calibration system uses global output-error optimization. High data rate measurements of static and total pressure, ambient air conditions, and GPS-based ground speed measurements are used to compute pitot-static pressure errors over a range of airspeed. System identification methods rapidly compute optimal pressure error models with defined confidence intervals.

Pylon Effects on a Scramjet Cavity Flameholder Flowfield

DTIC Science & Technology

2008-09-01

39 ix Page Figure 20. Static and pitot probes ...pressure (Pa) Ppitot Pitot probe pressure (Pa) Pcone Static cone probe pressure (Pa) P Static pressure (Pa) q Dynamic pressure (Pa) R...create strong shocks within the combustor section of the engine. An oblique or bow shock will form off the leading edge of the pylon reflecting

Static pressure accelerates ox-LDL-induced cholesterol accumulation via SREBP-1-mediated caveolin-1 downregulation in cultured vascular smooth muscle cells

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

Luo, Di-xian, E-mail: luodixian_2@163.com; Institute of Pharmacy and Pharmacology, College of Science and Technology, University of South China, Hengyang 421001, Hunan; First People's Hospital of Chenzhou City, Chenzhou 423000, Hunan

Research highlights: {yields} Vertical static pressure accelerates ox-LDL-induced cholesterol accumulation in cultured vascular smooth muscle cells. {yields} Static pressure induces SREBP-1 activation. {yields} Static pressure downregulates the expressions of caveolin-1 by activating SREBP-1. {yields} Static pressure also downregulates the transcription of ABCA1 by activating SREBP-1. {yields} Static pressure increases ox-LDL-induced cholesterol accumulation by SREBP-1-mediated caveolin-1 downregulation in vascular smooth muscle cells cultured in vitro. -- Abstract: Objective: To investigate the effect of static pressure on cholesterol accumulation in vascular smooth muscle cells (VSMCs) and its mechanism. Methods: Rat-derived VSMC cell line A10 treated with 50 mg/L ox-LDL and different staticmore » pressures (0, 60, 90, 120, 150, 180 mm Hg) in a custom-made pressure incubator for 48 h. Intracellular lipid droplets and lipid levels were assayed by oil red O staining and HPLC; The mRNA levels of caveolin-1 and ABCA1, the protein levels of caveolin-1 SREBP-1 and mature SREBP-1 were respectively detected by RT-PCR or western blot. ALLN, an inhibitor of SREBP metabolism, was used to elevate SREBP-1 protein level in VSMCs treated with static pressure. Results: Static pressures significantly not only increase intracellular lipid droplets in VSMCs, but also elevate cellular lipid content in a pressure-dependent manner. Intracellular free cholesterol (FC), cholesterol ester (CE), total cholesterol (TC) were respectively increased from 60.5 {+-} 2.8 mg/g, 31.8 {+-} 0.7 mg/g, 92.3 {+-} 2.1 mg/g at atmosphere pressure (ATM, 0 mm Hg) to 150.8 {+-} 9.4 mg/g, 235.9 {+-} 3.0 mg/g, 386.7 {+-} 6.4 mg/g at 180 mm Hg. At the same time, static pressures decrease the mRNA and protein levels of caveolin-1, and induce the activation and nuclear translocation of SREBP-1. ALLN increases the protein level of mature SREBP-1 and decreases caveolin-1 expression, so that cellular lipid levels were upregulated. Conclusion: Static pressures stimulate ox-LDL-induced cholesterol accumulation in cultured VSMCs through decreasing caveolin-1 expression via inducing the maturation and nuclear translocation of SREBP-1.« less

Use of pressure-sensitive paint for diagnostics in turbomachinery flows with shocks

NASA Astrophysics Data System (ADS)

Lepicovsky, J.; Bencic, T. J.

2002-07-01

The technology of pressure-sensitive paint (PSP) is well established in external aerodynamics. In internal flows in narrow channels and in turbomachinery cascades, however, there are still unresolved problems. In particular, the internal flows with complex shock structures inside highly curved channels present a challenge. It is not always easy and straightforward to distinguish between true signals and 'ghost' images due to multiple internal reflections in narrow channels. To address some of the problems, investigations were first carried out in a narrow supersonic channel of Mach number 2.5. A single wedge or a combination of two wedges was used to generate a complex shock wave structure in the flow. The experience gained in a small supersonic channel was used for surface pressure measurements on the stator vane of a supersonic throughflow fan. The experimental results for several fan operating conditions are shown in a concise form, including performance map test points, midspan static tap pressure distributions, and vane suction side pressure fields. Finally, the PSP technique was used in the NASA transonic flutter cascade to compliment flow visualization data and to acquire backwall pressure fields to assess the cascade flow periodicity. Lessons learned from this investigation and shortcomings of the PSP technology for internal flow application are presented in the conclusion of the paper.

Exhaust Simulation Testing of a Hypersonic Airbreathing Model at Transonic Speeds

NASA Technical Reports Server (NTRS)

Huebner, Lawrence D.; Witte, David W.; Andrews, Earl H., Jr.

2004-01-01

An experimental study was performed to examine jet-effects for an airframe-integrated, scramjet-rocket combined-cycle vehicle configuration at transonic test conditions. This investigation was performed by testing an existing exhaust simulation wind tunnel model, known as Model 5B, in the NASA Langley 16-Ft. Transonic Tunnel. Tests were conducted at freestream Mach numbers from 0.7 to 1.2, at angles of attack from 2 to +14 degrees, and at up to seven nozzle static pressure ratio values for a set of horizontal-tail and body-flap deflections. The model aftbody, horizontal tails, and body flaps were extensively pressure instrumented to provide an understanding of jet-effects and control-surface/plume interactions, as well as for the development of analytical methodologies and calibration of computational fluid dynamic codes to predict this type of flow phenomenon. At all transonic test conditions examined, the exhaust flow at the exit of the internal nozzle was over-expanded, generating an exhaust plume that turned toward the aftbody. Pressure contour plots for the aftbody of Model 5B are presented for freestream transonic Mach numbers of 0.70, 0.95, and 1.20. These pressure data, along with shadowgraph images, indicated the impingement of an internal plume shock and at least one reflected shock onto the aftbody for all transonic conditions tested. These results also provided evidence of the highly three-dimensional nature of the aftbody exhaust flowfield. Parametric testing showed that angle-of-attack, static nozzle pressure ratio, and freestream Mach number all affected the exhaust-plume size, exhaust-flowfield shock structure, and the aftbody-pressure distribution, with Mach number having the largest effect. Integration of the aftbody pressure data showed large variations in the pitching moment throughout the transonic regime.

Fracture resistance of welded thick-walled high-pressure vessels in power plants. Report No. 2. Approach to evaluating static strength

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

Gorynin, I.V.; Filatov, V.M.; Ignatov, V.A.

1986-07-01

The authors examine data on the effect of defects on the fracture resistance of high-pressure vessels and their models obtained within the framework of the HSST program. Results of internal-pressure tests of two types of vessels with a wall thickness of 152 mm made from forgings of steels SA508 and SA533, as well as small vessels with a wall thickness of 11.5 and 23mm made of steel SA533 are shown. The authors state that testing thick-walled welded high-pressure vessels and thin-walled vessels with surface defects of different sizes has demonstrated that there are substantial static-strength reserves in structures designed bymore » existing domestic and foreign standards on the strength of power-plant equipment. A correction was proposed for the presently used method of calculating the resistance of highpressure vessels to brittle fracture that allows for the dimensions of the defects in relation to the type of vessel, the manufacturing technology, and the method of inspection.« less

Flight evaluation of an engine static pressure noseprobe in an F-15 airplane

NASA Technical Reports Server (NTRS)

Foote, C. H.; Jaekel, R. F.

1981-01-01

The flight testing of an inlet static pressure probe and instrumented inlet case produced results consistent with sea-level and altitude stand testing. The F-15 flight test verified the basic relationship of total to static pressure ratio versus corrected airflow and automatic distortion downmatch with the engine pressure ratio control mode. Additionally, the backup control inlet case statics demonstrated sufficient accuracy for backup control fuel flow scheduling, and the station 6 manifolded production probe was in agreement with the flight test station 6 tota pressure probes.

Dynamic considerations for composite metal-rubber laminate acoustic power coupling bellows with application to thermoacoustic refrigeration

NASA Astrophysics Data System (ADS)

Smith, Robert William

Many electrically driven thermoacoustic refrigerators have employed corrugated metal bellows to couple work from an electro-mechanical transducer to the working fluid typically. An alternative bellows structure to mediate this power transfer is proposed: a laminated hollow cylinder comprised of alternating layers of rubber and metal 'hoop-stack'. Fatigue and visoelastic power dissipation in the rubber are critical considerations; strain energy density plays a role in both. Optimal aspect ratios for a rectangle corss-section in the rubber, for given values of bellows axial strain and oscillatory pressure loads are discussed. Comparisons of tearing energies estimated from known load cases and those obtained by finite element analysis for candidate dimensions are presented. The metal layers of bellows are subject to an out-of-plane buckling instability for the case of external pressure loading; failure of this type was experimentally observed. The proposed structure also exhibits column instability when subject to internal pressure, as do metal bellows. For hoop-stack bellows, shear deflection cannot be ignored and this leads to column instability for both internal and external pressures, the latter being analogous to the case of tension buckling of a beam. During prototype bellows testing, transverse modes of vibration are believed to have been excited parametrically as a consequence of the oscillatory pressures. Some operating frequencies of interest in this study lie above the cut-on frequency at which Timoshenko beam theory (TBT) predicts multiple phase speeds; it is shown that TBT fails to accurately predict both mode shapes and resonance frequencies in this regime. TBT is also shown to predict multiple phase speeds in the presence of axial tension, or external pressures, at magnitudes of interest in this study, over the entire frequency spectrum. For modes below cut-on absent a pressure differential (or equivalently, axial load) TBT predicts decreasing resonance frequencies for both internal external static pressure, and converges on known, valid static buckling solutions. Parametric stability in the presence of oscillatory pressure is discussed for such modes; periodic solutions to the Whittaker-Hill equation are pursued to illustrate the shape of the parametric instability regions, and contrasted with results of the more well-known Mathieu equation.

14 CFR Appendix E to Part 43 - Altimeter System Test and Inspection

Code of Federal Regulations, 2011 CFR

2011-01-01

... made that would affect the relationship between air pressure in the static pressure system and true ambient static air pressure for any flight condition. (b) Altimeter: (1) Test by an appropriately rated... inspections required by § 91.411 shall comply with the following: (a) Static pressure system: (1) Ensure...

Wind-Tunnel Tests of Seven Static-Pressure Probes at Transonic Speeds

NASA Technical Reports Server (NTRS)

Capone, Francis J.

1961-01-01

Wind-tunnel tests have been conducted to determine the errors of 3 seven static-pressure probes mounted very close to the nose of a body of revolution simulating a missile forebody. The tests were conducted at Mach numbers from 0.80 to 1.08 and at angles of attack from -1.7 deg to 8.4 deg. The test Reynolds number per foot varied from 3.35 x 10(exp 6) to 4.05 x 10(exp 6). For three 4-vane, gimbaled probes, the static-pressure errors remained constant throughout the test angle-of-attack range for all Mach numbers except 1.02. For two single-vane, self-rotating probes having two orifices at +/-37.5 deg. from the plane of symmetry on the lower surface of the probe body, the static-pressure error varied as much as 1.5 percent of free-stream static pressure through the test angle-of- attack range for all Mach numbers. For two fixed, cone-cylinder probes of short length and large diameter, the static-pressure error varied over the test angle-of-attack range at constant Mach numbers as much as 8 to 10 percent of free-stream static pressure.

Experimental Investigation and Numerical Predication of a Cross-Flow Fan

DTIC Science & Technology

2006-12-01

Figure 3. Combination probes and pressure tap layout .....................................................6 Figure 4. CFF_DAQ graphical user interface...properties were United Sensor Devices model USD-C-161 3 mm (1/8-inch) combination thermocouple/pressure probes, and static pressure taps . The...was applied to the three static pressure tapes at the throat of the bell-mouth and to the two exhaust duct static pressure taps . Once the data

On the Health Risk of the Lumbar Spine due to Whole-Body VIBRATION—THEORETICAL Approach, Experimental Data and Evaluation of Whole-Body Vibration

NASA Astrophysics Data System (ADS)

Seidel, H.; Blüthner, R.; Hinz, B.; Schust, M.

1998-08-01

The guidance on the effects of vibration on health in standards for whole-body vibration (WBV) does not provide quantitative relationships between WBV and health risk. The paper aims at the elucidation of exposure-response relationships. An analysis of published data on the static and dynamic strength of vertebrae and bone, loaded with various frequencies under different conditions, provided the basis for a theoretical approach to evaluate repetitive loads on the lumbar spine (“internal loads”). The approach enabled the calculation of “equivalent”—with respect to cumulative fatigue failure—combinations of amplitudes and numbers of internal cyclic stress. In order to discover the relation between external peak accelerations at the seat and internal peak loads, biodynamic data of experiments (36 subjects, three somatotypes, two different postures—relaxed and bent forward; random WBV,aw, r.m.s. 1·4 ms-2, containing high transients) were used as input to a biomechanical model. Internal pressure changes were calculated using individual areas of vertebral endplates. The assessment of WBV was based on the quantitative relations between peak accelerations at the seat and pressures predicted for the disk L5/S1. For identical exposures clearly higher rates of pressure rise in the bent forward compared to the relaxed posture were predicted. The risk assessment for internal forces considered the combined internal static and dynamic loads, in relation to the predicted individual strength, and Miner's hypothesis. For exposure durations between 1 min and 8 h, energy equivalent vibration magnitudes (formula B.1, ISO 2631-1, 1997) and equivalent vibration magnitudes according to formula B.2 (time dependence over-energetic) were compared with equivalent combinations of upward peak accelerations and exposure durations according to predicted cumulative fatigue failures of lumbar vertebrae. Formula B.1 seems to underestimate the health risk caused by high magnitudes, formula B.2 is recommended for the evaluation of such conditions.

Ontogenetic scaling of hydrostatic skeletons: geometric, static stress and dynamic stress scaling of the earthworm lumbricus terrestris

PubMed

Quillin

1998-05-21

Soft-bodied organisms with hydrostatic skeletons range enormously in body size, both during the growth of individuals and in the comparison of species. Therefore, body size is an important consideration in an examination of the mechanical function of hydrostatic skeletons. The scaling of hydrostatic skeletons cannot be inferred from existing studies of the lever-like skeletons of vertebrates and arthropods because the two skeleton types function by different mechanisms. Hydrostats are constructed of an extensible body wall in tension surrounding a fluid or deformable tissue under compression. It is the pressurized internal fluid (rather than the rigid levers of vertebrates and arthropods) that enables the maintenance of posture, antagonism of muscles and transfer of muscle forces to the environment. The objectives of the present study were (1) to define the geometric, static stress and dynamic stress similarity scaling hypotheses for hydrostatic skeletons on the basis of their generalized form and function, and (2) to apply these similarity hypotheses in a study of the ontogenetic scaling of earthworms, Lumbricus terrestris, to determine which parameters of skeletal function are conserved or changed as a function of body mass during growth (from 0.01 to 8 g). Morphometric measurements on anesthetized earthworms revealed that the earthworms grew isometrically; the external proportions and number of segments were constant as a function of body size. Calculations of static stresses (forces per cross-sectional area in the body wall) during rest and dynamic stresses during peristaltic crawling (calculated from measurements of internal pressure and body wall geometry) revealed that the earthworms also maintained static and dynamic stress similarity, despite a slight increase in body wall thickness in segment 50 (but not in segment 15). In summary, the hydrostatic skeletons of earthworms differ fundamentally from the rigid, lever-like skeletons of their terrestrial counterparts in their ability to grow isometrically while maintaining similarity in both static and dynamic stresses.

Experimental and Computational Studies of Molecular and Lattice Symmetries of Energetic Materials at High Pressure

DTIC Science & Technology

2002-01-01

Prescribed by ANSI Std Z39-18 Research and Technology Department Dynamics and Diagnostics Division, Static High- Pressure Group Overall Research...Department Dynamics and Diagnostics Division, Static High- Pressure Group Impact of this Basic Research • This research generates phase and density...Static High- Pressure Group Experimental Methodology Use Diamond Anvil Cells (DAC) with coil Heaters (HDAC) to achieve • High pressures (P) to 10 GPa

14 CFR 25.1325 - Static pressure systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... installation of the static pressure system must be such that— (1) Positive drainage of moisture is provided..., the other is blocked off; and (2) Both sources cannot be blocked off simultaneously. (h) For... other static pressure source being open or blocked. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as...

Experimental Investigation of the Mixing of Highly Swirling Flows

DTIC Science & Technology

1982-05-01

inner stream has received an increasing amount of attention during recent years. The primary motivations for this have been the application to...2) wall Static Pressures (averaged over all subruns) and their locations PS4 (J) - Static pressure on 4" OD centerbody at location "J" (J = 1 to N(l...ZS4(J) - Axial location of static pressure PS4 (J) PS6(J) - Static pressure on inside wall of 6U tube at location "J" (J = 1 to N(2)) TH6(J) - Angular

A 'Quad-Disc' static pressure probe for measurement in adverse atmospheres - With a comparative review of static pressure probe designs

NASA Astrophysics Data System (ADS)

Nishiyama, Randall T.; Bedard, Alfred J., Jr.

1991-09-01

There are many areas of need for accurate measurements of atmospheric static pressure. These include observations of surface meteorology, airport altimeter settings, pressure distributions around buildings, moving measurement platforms, as well as basic measurements of fluctuating pressures in turbulence. Most of these observations require long-term observations in adverse environments (e.g., rain, dust, or snow). Currently, many pressure measurements are made, of necessity, within buildings, thus involving potential errors of several millibars in mean pressure during moderate winds, accompanied by large fluctuating pressures induced by the structure. In response to these needs, a 'Quad-Disk' pressure probe for continuous, outdoor monitoring purposes was designed which is inherently weather-protected. This Quad-Disk probe has the desirable features of omnidirectional response and small error in pitch. A review of past static pressure probes contrasts design approaches and capabilities.

Effect on fan flow characteristics of length and axial location of a cascade thrust reverser

NASA Technical Reports Server (NTRS)

Dietrich, D. A.

1975-01-01

A series of static tests were conducted on a model fan with a diameter of 14.0 cm to determine the fan operating characteristics, the inlet static pressure contours, the fan-exit total and static pressure contours, and the fan-exit pressure distortion parameters associated with the installation of a partial-circumferential-emission cascade thrust reverser. The tests variables included the cascade axial length, the axial location of the reverser, and the type of fan inlet. It was shown that significant total and static pressure distortions were produced in the fan aft duct, and that some configurations induced a static pressure distortion at the fan face. The amount of flow passed by the fan and the level of the flow distortions were dependent upon all the variables tested.

Bubble dynamics in a standing sound field: the bubble habitat.

PubMed

Koch, P; Kurz, T; Parlitz, U; Lauterborn, W

2011-11-01

Bubble dynamics is investigated numerically with special emphasis on the static pressure and the positional stability of the bubble in a standing sound field. The bubble habitat, made up of not dissolving, positionally and spherically stable bubbles, is calculated in the parameter space of the bubble radius at rest and sound pressure amplitude for different sound field frequencies, static pressures, and gas concentrations of the liquid. The bubble habitat grows with static pressure and shrinks with sound field frequency. The range of diffusionally stable bubble oscillations, found at positive slopes of the habitat-diffusion border, can be increased substantially with static pressure.

Limitations and possibilities of AC calorimetry in diamond anvil cells

NASA Astrophysics Data System (ADS)

Geballe, Zachary; Colins, Gilbert; Jeanloz, Raymond

2013-06-01

Dynamic laser heating or internal resistive heating could allow for the determination of calorimetric properties of samples that are held statically at high pressure. However, the highly non-adiabatic environment of high-pressure cells presents several challenges. Here, we quantify the errors in AC calorimetry measurements using laser heating or internal resistive heating inside diamond anvil cells, summarize the equipment requirements of supplying sufficient power modulated at a high enough frequency to measure specific heats and latent heats of phase transitions, and propose two new experiments in internally-heated diamond anvil cells: an absolute measurement of specific heat (with ~10% uncertainty) of non-magnetic metals using resistive heating at ~10 MHz, and a relative measurement to detect changes in either the specific heat of metals or in the effusively (the product of specific heat, density and thermal conductivity) of an insulator.

Static and dynamic deflection studies of the SRM aft case-nozzle joint

NASA Technical Reports Server (NTRS)

Christian, David C.; Kos, Lawrence D.; Torres, Isaias

1989-01-01

The redesign of the joints on the solid rocket motor (SRM) has prompted the need for analyzing the behavior of the joints using several different types of analyses. The types of analyses performed include modal analysis, static analysis, transient response analysis, and base driving response analysis. The forces used in these analyses to drive the mathematical model include SRM internal chamber pressure, nozzle blowout and side forces, shuttle vehicle lift-off dynamics, SRM pressure transient rise curve, gimbal forces and moments, actuator gimbal loads, and vertical and radial bolt preloads. The math model represented the SRM from the aft base tangent point (1,823.95 in) all the way back to the nozzle, where a simplified, tuned nozzle model was attached. The new design used the radial bolts as an additional feature to reduce the gap opening at the aft dome/nozzle fixed housing interface.

Probe systems for static pressure and cross-stream turbulence intensity

NASA Technical Reports Server (NTRS)

Rossow, Vernon, J.

1991-01-01

A recent study of total-pressure probes for use in highly turbulent streams is extended herein by developing probe systems that measure time-averaged static or ambient pressure and turbulence intensity. Arrangements of tubular probes of circular and elliptical cross section are described that measure the pressure at orifices on the sides of the probes to obtain different responses to the cross-stream velocity fluctuations. When the measured data are combined to remove the effect of the presence of the probes on the local pressure, the time-averaged static pressure and the cross-stream components of turbulence intensity can be determined. If a system of total pressure tubes, as described in an accompanying paper, is added to the static pressure group to form a single cluster, redundant measurements are obtained that permit accuracy and consistency checks.

Static investigation of a two-dimensional convergent-divergent exhaust nozzle with multiaxis thrust-vectoring capability

NASA Technical Reports Server (NTRS)

Taylor, John G.

1990-01-01

An investigation was conducted in the Static Test Facility of the NASA Langley 16-Foot Transonic Tunnel to determine the internal performance of two-dimensional convergent-divergent nozzles designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap rotation of thrust vectoring in the pitch plane and deflection of flat yaw flaps hinged at the end of the sidewalls for yaw thrust vectoring. The hinge location of the yaw flaps was varied at four positions from the nozzle exit plane to the throat plane. The yaw flaps were designed to contain the flow laterally independent of power setting. In order to eliminate any physical interference between the yaw flap deflected into the exhaust stream and the divergent flaps, the downstream corners of both upper and lower divergent flaps were cut off to allow for up to 30 deg of yaw flap deflection. The impact of varying the nozzle pitch vector angle, throat area, yaw flap hinge location, yaw flap length, and yaw flap deflection angle on nozzle internal performance characteristics, was studied. High-pressure air was used to simulate jet exhaust at nozzle pressure ratios up to 7.0. Static results indicate that configurations with the yaw flap hinge located upstream of the exit plane provide relatively high levels of thrust vectoring efficiency without causing large losses in resultant thrust ratio. Therefore, these configurations represent a viable concept for providing simultaneous pitch and yaw thrust vectoring.

Investigations of High Pressure Acoustic Waves in Resonators with Seal-like Features

NASA Technical Reports Server (NTRS)

Daniels, Christopher; Steinetz, Bruce; Finkbeiner, Joshua

2003-01-01

A conical resonator (having a dissonant acoustic design) was tested in four configurations: (1) baseline resonator with closed ends and no blockage, (2) closed resonator with internal blockage, (3) ventilated resonator with no blockage, and (4) ventilated resonator with an applied pressure differential. These tests were conducted to investigate the effects of blockage and ventilation holes on dynamic pressurization. Additionally, the investigation was to determine the ability of acoustic pressurization to impede flow through the resonator. In each of the configurations studied, the entire resonator was oscillated at the gas resonant frequency while dynamic pressure, static pressure, and temperature of the fluid were measured. In the final configuration, flow through the resonator was recorded for three oscillation conditions. Ambient condition air was used as the working fluid.

33 CFR 183.580 - Static pressure test for fuel tanks.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Static pressure test for fuel... SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.580 Static pressure test for fuel tanks. A fuel tank is tested by performing the following procedures in the following...

33 CFR 183.580 - Static pressure test for fuel tanks.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Static pressure test for fuel... SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.580 Static pressure test for fuel tanks. A fuel tank is tested by performing the following procedures in the following...

33 CFR 183.580 - Static pressure test for fuel tanks.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Static pressure test for fuel... SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.580 Static pressure test for fuel tanks. A fuel tank is tested by performing the following procedures in the following...

33 CFR 183.580 - Static pressure test for fuel tanks.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Static pressure test for fuel... SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.580 Static pressure test for fuel tanks. A fuel tank is tested by performing the following procedures in the following...

33 CFR 183.580 - Static pressure test for fuel tanks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Static pressure test for fuel... SECURITY (CONTINUED) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Tests § 183.580 Static pressure test for fuel tanks. A fuel tank is tested by performing the following procedures in the following...

Resistance to forced airflow through layers of composting organic material.

PubMed

Teixeira, Denis Leocádio; de Matos, Antonio Teixeira; Melo, Evandro de Castro

2015-02-01

The objective of this study was to adjust equations to estimate the static pressure gradient of airflow through layers of organic residues submitted to two stages of biochemical degradation, and to evaluate the static pressure drop of airflow thought the material layer. Measurements of static pressure drop in the layers of sugarcane bagasse and coffee husks mixed with poultry litter on day 0 and after 30 days of composting were performed using a prototype with specific airflow rates ranging from 0.02 to 0.13 m(3) s(-1) m(-2). Static pressure gradient and specific airflow rate data were properly fit to the Shedd, Hukill & Ives and Ergun models, which may be used to predict the static pressure gradient of air to be blown through the organic residue layers. However, the Shedd model was that which best represented the phenomenon studied. The static pressure drop of airflow increased as a power of the material layer thickness and showed tendency for decreasing with the biochemical degradation time of the organic material. Copyright © 2014 Elsevier Ltd. All rights reserved.

46 CFR 52.01-95 - Design (modifies PG-16 through PG-31 and PG-100).

Code of Federal Regulations, 2010 CFR

2010-10-01

... exceeding 525 °F. Refer to § 56.30-30(b)(1) of this subchapter for applicable requirements. (e) Stresses. (Modifies PG-22.) The stresses due to hydrostatic head shall be taken into account in determining the... stresses, imposed by effects other than internal pressure or static head, which increase the average stress...

46 CFR 52.01-95 - Design (modifies PG-16 through PG-31 and PG-100).

Code of Federal Regulations, 2012 CFR

2012-10-01

... exceeding 525 °F. Refer to § 56.30-30(b)(1) of this subchapter for applicable requirements. (e) Stresses. (Modifies PG-22.) The stresses due to hydrostatic head shall be taken into account in determining the... stresses, imposed by effects other than internal pressure or static head, which increase the average stress...

46 CFR 52.01-95 - Design (modifies PG-16 through PG-31 and PG-100).

Code of Federal Regulations, 2011 CFR

2011-10-01

... exceeding 525 °F. Refer to § 56.30-30(b)(1) of this subchapter for applicable requirements. (e) Stresses. (Modifies PG-22.) The stresses due to hydrostatic head shall be taken into account in determining the... stresses, imposed by effects other than internal pressure or static head, which increase the average stress...

Patellofemoral Pressure Changes After Static and Dynamic Medial Patellofemoral Ligament Reconstructions.

PubMed

Rood, Akkie; Hannink, Gerjon; Lenting, Anke; Groenen, Karlijn; Koëter, Sander; Verdonschot, Nico; van Kampen, Albert

2015-10-01

Reconstructing the medial patellofemoral ligament (MPFL) has become a key procedure for stabilizing the patella. Different techniques to reconstruct the MPFL have been described: static techniques in which the graft is fixed rigidly to the bone or dynamic techniques with soft tissue fixation. Static MPFL reconstruction is most commonly used. However, dynamic reconstruction deforms more easily and presumably functions more like the native MPFL. The aim of the study was to evaluate the effect of the different MPFL fixation techniques on patellofemoral pressures compared with the native situation. The hypothesis was that dynamic reconstruction would result in patellofemoral pressures closer to those generated in an intact knee. Controlled laboratory study. Seven fresh-frozen knee specimens were tested in an in vitro knee joint loading apparatus. Tekscan pressure-sensitive films fixed to the retropatellar cartilage measured mean patellofemoral and peak pressures, contact area, and location of the center of force (COF) at fixed flexion angles from 0° to 110°. Four different conditions were tested: intact, dynamic, partial dynamic, and static MPFL reconstruction. Data were analyzed using linear mixed models. Static MPFL reconstruction resulted in higher peak and mean pressures from 60° to 110° of flexion (P < .001). There were no differences in pressure between the 2 different dynamic reconstructions and the intact situation (P > .05). The COF in the static reconstruction group moved more medially on the patella from 50° to 110° of flexion compared with the other conditions. The contact area showed no significant differences between the test conditions. After static MPFL reconstruction, the patellofemoral pressures in flexion angles from 60° to 110° were 3 to 5 times higher than those in the intact situation. The pressures after dynamic MPFL reconstruction were similar as compared with those in the intact situation, and therefore, dynamic MPFL reconstruction could be a safer option than static reconstruction for stabilizing the patella. This study showed that static MPFL reconstruction results in higher patellofemoral pressures and thus enhances the chance of osteoarthritis in the long term, while dynamic reconstruction results in more normal pressures. © 2015 The Author(s).

Small scale model static acoustic investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap

NASA Technical Reports Server (NTRS)

Cole, T. W.; Rathburn, E. A.

1974-01-01

A static acoustic and propulsion test of a small radius Jacobs-Hurkamp and a large radius Flex Flap combined with four upper surface blowing (USB) nozzles was performed. Nozzle force and flow data, flap trailing edge total pressure survey data, and acoustic data were obtained. Jacobs-Hurkamp flap surface pressure data, flow visualization photographs, and spoiler acoustic data from the limited mid-year tests are reported. A pressure ratio range of 1.2 to 1.5 was investigated for the USB nozzles and for the auxiliary blowing slots. The acoustic data were scaled to a four-engine STOL airplane of roughly 110,000 kilograms or 50,000 pounds gross weight, corresponding to a model scale of approximately 0.2 for the nozzles without deflector. The model nozzle scale is actually reduced to about .17 with deflector although all results in this report assume 0.2 scale factor. Trailing edge pressure surveys indicated that poor flow attachment was obtained even at large flow impingement angles unless a nozzle deflector plate was used. Good attachment was obtained with the aspect ratio four nozzle with deflector, confirming the small scale wind tunnel tests.

Dynamic Pressure Probes Developed for Supersonic Flow-Field Measurements

NASA Technical Reports Server (NTRS)

Porro, A. Robert

2001-01-01

A series of dynamic flow-field pressure probes were developed for use in large-scale supersonic wind tunnels at the NASA Glenn Research Center. These flow-field probes include pitot and static pressure probes that can capture fast-acting flow-field pressure transients occurring on a millisecond timescale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The flow-field pressure probe contains four major components: 1) Static pressure aerodynamic tip; 2) Pressure-sensing cartridge assembly; 3) Pitot pressure aerodynamic tip; 4) Mounting stem. This modular design allows for a variety of probe tips to be used for a specific application. Here, the focus is on flow-field pressure measurements in supersonic flows, so we developed a cone-cylinder static pressure tip and a pitot pressure tip. Alternatively, probe tips optimized for subsonic and transonic flows could be used with this design. The pressure-sensing cartridge assembly allows the simultaneous measurement of steady-state and transient pressure which allows continuous calibration of the dynamic pressure transducer.

Terapascal static pressure generation with ultrahigh yield strength nanodiamond.

PubMed

Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Solopova, Natalia A; Abakumov, Artem; Turner, Stuart; Hanfland, Michael; Bykova, Elena; Bykov, Maxim; Prescher, Clemens; Prakapenka, Vitali B; Petitgirard, Sylvain; Chuvashova, Irina; Gasharova, Biliana; Mathis, Yves-Laurent; Ershov, Petr; Snigireva, Irina; Snigirev, Anatoly

2016-07-01

Studies of materials' properties at high and ultrahigh pressures lead to discoveries of unique physical and chemical phenomena and a deeper understanding of matter. In high-pressure research, an achievable static pressure limit is imposed by the strength of available strong materials and design of high-pressure devices. Using a high-pressure and high-temperature technique, we synthesized optically transparent microballs of bulk nanocrystalline diamond, which were found to have an exceptional yield strength (~460 GPa at a confining pressure of ~70 GPa) due to the unique microstructure of bulk nanocrystalline diamond. We used the nanodiamond balls in a double-stage diamond anvil cell high-pressure device that allowed us to generate static pressures beyond 1 TPa, as demonstrated by synchrotron x-ray diffraction. Outstanding mechanical properties (strain-dependent elasticity, very high hardness, and unprecedented yield strength) make the nanodiamond balls a unique device for ultrahigh static pressure generation. Structurally isotropic, homogeneous, and made of a low-Z material, they are promising in the field of x-ray optical applications.

Terapascal static pressure generation with ultrahigh yield strength nanodiamond

PubMed Central

Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Solopova, Natalia A.; Abakumov, Artem; Turner, Stuart; Hanfland, Michael; Bykova, Elena; Bykov, Maxim; Prescher, Clemens; Prakapenka, Vitali B.; Petitgirard, Sylvain; Chuvashova, Irina; Gasharova, Biliana; Mathis, Yves-Laurent; Ershov, Petr; Snigireva, Irina; Snigirev, Anatoly

2016-01-01

Studies of materials’ properties at high and ultrahigh pressures lead to discoveries of unique physical and chemical phenomena and a deeper understanding of matter. In high-pressure research, an achievable static pressure limit is imposed by the strength of available strong materials and design of high-pressure devices. Using a high-pressure and high-temperature technique, we synthesized optically transparent microballs of bulk nanocrystalline diamond, which were found to have an exceptional yield strength (~460 GPa at a confining pressure of ~70 GPa) due to the unique microstructure of bulk nanocrystalline diamond. We used the nanodiamond balls in a double-stage diamond anvil cell high-pressure device that allowed us to generate static pressures beyond 1 TPa, as demonstrated by synchrotron x-ray diffraction. Outstanding mechanical properties (strain-dependent elasticity, very high hardness, and unprecedented yield strength) make the nanodiamond balls a unique device for ultrahigh static pressure generation. Structurally isotropic, homogeneous, and made of a low-Z material, they are promising in the field of x-ray optical applications. PMID:27453944

A short static-pressure probe design for supersonic flow

NASA Technical Reports Server (NTRS)

Pinckney, S. Z.

1975-01-01

A static-pressure probe design concept was developed which has the static holes located close to the probe tip and is relatively insensitive to probe angle of attack and circumferential static hole location. Probes were constructed with 10 and 20 deg half-angle cone tips followed by a tangent conic curve section and a tangent cone section of 2, 3, or 3.5 deg, and were tested at Mach numbers of 2.5 and 4.0 and angles of attack up to 12 deg. Experimental results indicate that for stream Mach numbers of 2.5 and 4.0 and probe angle of attack within + or - 10 deg, values of stream static pressure can be determined from probe calibration to within about + or - 4 percent. If the probe is aligned within about 7 deg of the flow experimental results indicated, the stream static pressures can be determined to within 2 percent from probe calibration.

Effect of revised high-heeled shoes on foot pressure and static balance during standing.

PubMed

Bae, Young-Hyeon; Ko, Mansoo; Park, Young-Soul; Lee, Suk-Min

2015-04-01

[Purpose] The purpose of this study was to investigate the effects of revised high-heeled shoes on the foot pressure ratio and static balance during standing. [Subjects and Methods] A single-subject design was used, 15 healthy women wearing revised high-heeled shoes and general high-heeled shoes in a random order. The foot pressure ratio and static balance scores during standing were measured using a SpaceBalance 3D system. [Results] Forefoot and rearfoot pressures were significantly different between the 2 types of high-heeled shoes. Under the 3 conditions tested, the static balance score was higher for the revised high-heeled shoes than for the general high-heeled shoes, but this difference was not statistically significant. [Conclusion] Revised high-heeled shoes are preferable to general high-heeled shoes, as they result in normalization of normalized foot pressure and a positive effect on static balance.

Effect of revised high-heeled shoes on foot pressure and static balance during standing

PubMed Central

Bae, Young-Hyeon; Ko, Mansoo; Park, Young-Soul; Lee, Suk-Min

2015-01-01

[Purpose] The purpose of this study was to investigate the effects of revised high-heeled shoes on the foot pressure ratio and static balance during standing. [Subjects and Methods] A single-subject design was used, 15 healthy women wearing revised high-heeled shoes and general high-heeled shoes in a random order. The foot pressure ratio and static balance scores during standing were measured using a SpaceBalance 3D system. [Results] Forefoot and rearfoot pressures were significantly different between the 2 types of high-heeled shoes. Under the 3 conditions tested, the static balance score was higher for the revised high-heeled shoes than for the general high-heeled shoes, but this difference was not statistically significant. [Conclusion] Revised high-heeled shoes are preferable to general high-heeled shoes, as they result in normalization of normalized foot pressure and a positive effect on static balance. PMID:25995572

Experimental study of planetary gases with applications to planetary interior models

NASA Technical Reports Server (NTRS)

Bell, Peter M.; Mao, Ho-Kwang

1988-01-01

High-pressure experimental data on planetary materials are critical in developing planetary models and in addressing otherwise insoluble problems of the internal structure of the major planets. Progress in the last five years has been particularly marked. Maximum static pressure of 550 GPa was achieved. For the first time, X-ray diffraction of solidified gases (Ne, Xe) and ices (H2O) were obtained at pressures above one megabar, single-crystal diffraction of ultralight elements (H2, He) were detected up to 25 GPa, pressures over 200 GPa at 77 K were reached in solid hydrogen, including the discovery of a phase transformation in the molecular solid. Advances in instrumentation and new measurements performed during 1983 to 1988 are summarized.

Abdominal drainage following cholecystectomy: high, low, or no suction?

PubMed Central

McCormack, T. T.; Abel, P. D.; Collins, C. D.

1983-01-01

A prospective trial to assess the effect of suction in an abdominal drain following cholecystectomy was carried out. Three types of closed drainage system were compared: a simple tube drain, a low negative pressure drain, and a high negative pressure drain: 120 consecutive patients undergoing cholecystectomy were randomly allocated to one of the three drainage groups. There was no significant difference in postoperative pyrexia, wound infection, chest infection, or hospital stay. This study failed to demonstrate any clinically useful difference between high negative pressure, low negative pressure, and static drainage system were compared: a simple tube drain, a low negative used, suction is not necessary and a simple tube drain (greater than 6 mm internal diameter) is the most effective form of drainage. PMID:6614773

Experimental studies on the tripping behavior of narrow T-stiffened flat plates subjected to hydrostatic pressure and underwater shock

NASA Technical Reports Server (NTRS)

Budweg, H. L.; Shin, Y. S.

1987-01-01

An experimental investigation was conducted to determine the static and dynamic responses of a specific stiffened flat plate design. The air-backed rectangular flat plates of 6061-T6 aluminum with an externally machined longitudinal narrow-flanged T-stiffener and clamped boundary conditions were subjected to static loading by water hydropump pressure and shock loading from an eight pound TNT charge detonated underwater. The dynamic test plate was instrumented to measure transient strains and free field pressure. The static test plate was instrumented to measure transient strains, plate deflection, and pressure. Emphasis was placed upon forcing static and dynamic stiffener tripping, obtaining relevant strain and pressure data, and studying the associated plate-stiffener behavior.

Internal performance characteristics of vectored axisymmetric ejector nozzles

NASA Technical Reports Server (NTRS)

Lamb, Milton

1993-01-01

A series of vectoring axisymmetric ejector nozzles were designed and experimentally tested for internal performance and pumping characteristics at NASA-Langley Research Center. These ejector nozzles used convergent-divergent nozzles as the primary nozzles. The model geometric variables investigated were primary nozzle throat area, primary nozzle expansion ratio, effective ejector expansion ratio (ratio of shroud exit area to primary nozzle throat area), ratio of minimum ejector area to primary nozzle throat area, ratio of ejector upper slot height to lower slot height (measured on the vertical centerline), and thrust vector angle. The primary nozzle pressure ratio was varied from 2.0 to 10.0 depending upon primary nozzle throat area. The corrected ejector-to-primary nozzle weight-flow ratio was varied from 0 (no secondary flow) to approximately 0.21 (21 percent of primary weight-flow rate) depending on ejector nozzle configuration. In addition to the internal performance and pumping characteristics, static pressures were obtained on the shroud walls.

The effect of prewhirl on the internal aerodynamics and performance of a mixed flow research centrifugal compressor

NASA Technical Reports Server (NTRS)

Bryan, William B.; Fleeter, Sanford

1987-01-01

The internal three-dimensional steady and time-varying flow through the diffusing elements of a centrifugal impeller were investigated using a moderate scale, subsonic, mixed flow research compressor facility. The characteristics of the test facility which permit the measurement of internal flow conditions throughout the entire research compressor and radial diffuser for various operating conditions are described. Results are presented in the form of graphs and charts to cover a range of mass flow rates with inlet guide vane settings varying from minus 15 degrees to plus 45 degrees. The static pressure distributions in the compressor inlet section and on the impeller and exit diffuser vanes, as well as the overall pressure and temperature rise and mass flow rate, were measured and analyzed at each operating point to determine the overall performance as well as the detailed aerodynamics throughout the compressor.

Should care homes adopt a static-led approach to pressure ulcer prevention?

PubMed

Keen, Delia Catherine

A static-led approach refers to the provision of high-specification foam mattresses for the whole of a population at risk of pressure damage. Such mattresses have been found to reduce the risk of pressure ulceration and cost less overall than standard mattresses, even in populations where only 1 in 100 patients develops a pressure ulcer. Reduced pressure ulcer prevalence and reduced costs resulting from decreased expenditure on dynamic mattresses following the implementation of a static-led approach have been reported. Pressure ulcers cause pain, a reduced quality of life, loss of independence, depression and social isolation for those in whom they develop. Organizations are increasingly having to pay out large sums of money following litigation surrounding pressure ulcers. This article explains why NHS healthcare providers and private care organizations need to work together to consider implementing a static-led approach to pressure ulcer prevention within care homes in order to reduce pressure ulcer incidence cost-effectively within their local populations.

Flexible Piezoelectric-Induced Pressure Sensors for Static Measurements Based on Nanowires/Graphene Heterostructures.

PubMed

Chen, Zefeng; Wang, Zhao; Li, Xinming; Lin, Yuxuan; Luo, Ningqi; Long, Mingzhu; Zhao, Ni; Xu, Jian-Bin

2017-05-23

The piezoelectric effect is widely applied in pressure sensors for the detection of dynamic signals. However, these piezoelectric-induced pressure sensors have challenges in measuring static signals that are based on the transient flow of electrons in an external load as driven by the piezopotential arisen from dynamic stress. Here, we present a pressure sensor with nanowires/graphene heterostructures for static measurements based on the synergistic mechanisms between strain-induced polarization charges in piezoelectric nanowires and the caused change of carrier scattering in graphene. Compared to the conventional piezoelectric nanowire or graphene pressure sensors, this sensor is capable of measuring static pressures with a sensitivity of up to 9.4 × 10 -3 kPa -1 and a fast response time down to 5-7 ms. This demonstration of pressure sensors shows great potential in the applications of electronic skin and wearable devices.

Dynamics of a Pipeline under the Action of Internal Shock Pressure

NASA Astrophysics Data System (ADS)

Il'gamov, M. A.

2017-11-01

The static and dynamic bending of a pipeline in the vertical plane under the action of its own weight is considered with regard to the interaction of the internal pressure with the curvature of the axial line and the axisymmetric deformation. The pressure consists of a constant and timevarying parts and is assumed to be uniformly distributed over the entire span between the supports. The pipeline reaction to the stepwise increase in the pressure is analyzed in the case where it is possible to determine the exact solution of the problem. The initial stage of bending determined by the smallness of elastic forces as compared to the inertial forces is introduced into the consideration. At this stage, the solution is sought in the form of power series and the law of pressure variation can be arbitrary. This solution provides initial conditions for determining the further process. The duration of the inertial stage is compared with the times of sharp changes of the pressure and the shock waves in fluids. The structure parameters are determined in the case where the shock pressure is accepted only by the inertial forces in the pipeline.

Miniature Flow-Direction/Pitot-Static Pressure Probes

NASA Technical Reports Server (NTRS)

Ashby, George C., Jr.; Coombs, David S.; Eves, John W.; Price, Howard E.; Vasquez, Peter

1989-01-01

Precision flow-direction/pitot-static pressure probes, ranging from 0.035 to 0.090 inch (0.89 to 2.29 mm) in outside diameter, successfully fabricated and calibrated for use in Langley 20-inch Mach 6 Tunnel. Probes simultaneously measure flow direction and static and pitot pressures in flow fields about configurations in hypersonic flow at temperatures up to 500 degree F (260 degree C).

Diastolic viscous properties of the intact canine left ventricle.

PubMed

Nikolic, S D; Tamura, K; Tamura, T; Dahm, M; Frater, R W; Yellin, E L

1990-08-01

The viscoelastic model of the ventricle predicts that the rate of change of volume (strain rate) is a determinant of the instantaneous pressure in the ventricle during diastole. Because relaxation is not complete before the onset of filling, one cannot distinguish the individual effects of relaxation and viscosity unless the passive and active components that determine the ventricular pressure are separated. To overcome this problem, we used the method of ventricular volume clamping to compare the pressures in the fully relaxed ventricle at a given volume at zero strain rate (static pressure) and high strain rate (dynamic pressure). Six open-chest, fentanyl-anesthetized dogs were instrumented with micromanometers and an electronically controlled mitral valve occluder in series with the electromagnetic flow probe. We reasoned as follows: If there were significant viscosity, then the dynamic pressure would be higher than the static pressure. The static pressure was measured when the ventricle was completely relaxed following a mitral valve occlusion after an arbitrary filling volume had been achieved. The dynamic pressure was determined by delaying the onset of filling until relaxation was complete and then measuring the pressure at the same volume that was achieved when the static pressure was measured. In 19 different hemodynamic situations, the dynamic and static pressures were identical (mean difference, 0.1 +/- 0.8 mm Hg), indicating that in the passive ventricle viscoelastic effects are insignificant and do not contribute to the left ventricular diastolic pressure under normal filling rates.

Atmospheric Probe Model: Construction and Wind Tunnel Tests

NASA Technical Reports Server (NTRS)

Vogel, Jerald M.

1998-01-01

The material contained in this document represents a summary of the results of a low speed wind tunnel test program to determine the performance of an atmospheric probe at low speed. The probe configuration tested consists of a 2/3 scale model constructed from a combination of hard maple wood and aluminum stock. The model design includes approximately 130 surface static pressure taps. Additional hardware incorporated in the baseline model provides a mechanism for simulating external and internal trailing edge split flaps for probe flow control. Test matrix parameters include probe side slip angle, external/internal split flap deflection angle, and trip strip applications. Test output database includes surface pressure distributions on both inner and outer annular wings and probe center line velocity distributions from forward probe to aft probe locations.

Experiment/Analytical Characterization of the RBCC Rocket-Ejector Mode

NASA Technical Reports Server (NTRS)

Ruf, J. H.; Lehman, M.; Pal, S.; Santoro, R. J.; West, J.; Turner, James E. (Technical Monitor)

2000-01-01

Experimental and complementary CFD results from the study of the rocket-ejector mode of a Rocket Based Combined Cycle (RBCC) engine are presented and discussed. The experiments involved systematic flowfield measurements in a two-dimensional, variable geometry rocket-ejector system. The rocket-ejector system utilizes a single two-dimensional, gaseous oxygen/gaseous hydrogen rocket as the ejector. To gain a thorough understanding of the rocket-ejector's internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static configurations for a range of rocket operating conditions. Overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust, whereas detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (oxygen, hydrogen, nitrogen and water vapor). The experimental results for both the direct-connect and sea-level static configurations are compared with CFD predictions of the flowfield.

Device to lower NOx in a gas turbine engine combustion system

DOEpatents

Laster, Walter R; Schilp, Reinhard; Wiebe, David J

2015-02-24

An emissions control system for a gas turbine engine including a flow-directing structure (24) that delivers combustion gases (22) from a burner (32) to a turbine. The emissions control system includes: a conduit (48) configured to establish fluid communication between compressed air (22) and the combustion gases within the flow-directing structure (24). The compressed air (22) is disposed at a location upstream of a combustor head-end and exhibits an intermediate static pressure less than a static pressure of the combustion gases within the combustor (14). During operation of the gas turbine engine a pressure difference between the intermediate static pressure and a static pressure of the combustion gases within the flow-directing structure (24) is effective to generate a fluid flow through the conduit (48).

Water cooled static pressure probe

NASA Technical Reports Server (NTRS)

Lagen, Nicholas T. (Inventor); Eves, John W. (Inventor); Reece, Garland D. (Inventor); Geissinger, Steve L. (Inventor)

1991-01-01

An improved static pressure probe containing a water cooling mechanism is disclosed. This probe has a hollow interior containing a central coolant tube and multiple individual pressure measurement tubes connected to holes placed on the exterior. Coolant from the central tube symmetrically immerses the interior of the probe, allowing it to sustain high temperature (in the region of 2500 F) supersonic jet flow indefinitely, while still recording accurate pressure data. The coolant exits the probe body by way of a reservoir attached to the aft of the probe. The pressure measurement tubes are joined to a single, larger manifold in the reservoir. This manifold is attached to a pressure transducer that records the average static pressure.

Free-stream static pressure measurements in the Longshot hypersonic wind tunnel and sensitivity analysis

NASA Astrophysics Data System (ADS)

Grossir, Guillaume; Van Hove, Bart; Paris, Sébastien; Rambaud, Patrick; Chazot, Olivier

2016-05-01

The performance of fast-response slender static pressure probes is evaluated in the short-duration, cold-gas, VKI Longshot hypersonic wind tunnel. Free-stream Mach numbers range between 9.5 and 12, and unit Reynolds numbers are within 3-10 × 106/m. Absolute pressure sensors are fitted within the probes, and an inexpensive calibration method, suited to low static pressure environments (200-1000 Pa), is described. Transfer functions relating the probe measurements p w to the free-stream static pressure p ∞ are established for the Longshot flow conditions based on numerical simulations. The pressure ratios p w / p ∞ are found to be close to unity for both laminar and turbulent boundary layers. Weak viscous effects characterized by small viscous interaction parameters {bar{χ }}<1.5 are confirmed experimentally for probe aspect ratios of L/ D > 16.5 by installing multiple pressure sensors in a single probe. The effect of pressure orifice geometry is also evaluated experimentally and found to be negligible for either straight or chamfered holes, 0.6-1 mm in diameter. No sensitivity to probe angle of attack could be evidenced for α < 0.33°. Pressure measurements are compared to theoretical predictions assuming an isentropic nozzle flow expansion. Significant deviations from this ideal case and the Mach 14 contoured nozzle design are uncovered. Validation of the static pressure measurements is obtained by comparing shock wave locations on Schlieren photographs to numerical predictions using free-stream properties derived from the static pressure probes. While these results apply to the Longshot wind tunnel, the present methodology and sensitivity analysis can guide similar investigations for other hypersonic test facilities.

Rugged, no-moving-parts windspeed and static pressure probe designs for measurements in planetary atmospheres

NASA Technical Reports Server (NTRS)

Bedard, A. J., Jr.; Nishiyama, R. T.

1993-01-01

Instruments developed for making meteorological observations under adverse conditions on Earth can be applied to systems designed for other planetary atmospheres. Specifically, a wind sensor developed for making measurements within tornados is capable of detecting induced pressure differences proportional to wind speed. Adding strain gauges to the sensor would provide wind direction. The device can be constructed in a rugged form for measuring high wind speeds in the presence of blowing dust that would clog bearings and plug passages of conventional wind speed sensors. Sensing static pressure in the lower boundary layer required development of an omnidirectional, tilt-insensitive static pressure probe. The probe provides pressure inputs to a sensor with minimum error and is inherently weather-protected. The wind sensor and static pressure probes have been used in a variety of field programs and can be adapted for use in different planetary atmospheres.

Results of tests on a Rockwell International space shuttle orbiter (-139 configuration) 0.0175-scale model (no. 29-0) in AEDC tunnel B to determine boundary layer characteristics

NASA Technical Reports Server (NTRS)

Quan, M.

1975-01-01

Results of wind tunnel tests were conducted to determine boundary layer characteristics on the lower surface of a space shuttle orbiter. Total pressure and temperature profile data at various model stations were obtained using a movable, four-degree-of-freedom probe mechanism and static pressure taps on the model surface. During a typical run, the probe was located over a preselected model location, then driven down through the bondary layer until contact was made with the model surface.

Wind Tunnel Results from a Nozzle Afterbody Test of a 0.2-Scale Fighter Aircraft in the Mach Number Regime of 0.6 to 1.5. Volume 1. Test Technique Evaluation

DTIC Science & Technology

1979-04-01

edge up. The influence of the aircraft on the static pressure reading from the pitot boom was determined with a scaled version of the pltot probe...stabilization before advancing to the next port. Jet exhaust simulation flow was monitored by internal duct pressure and temperature rakes . Standard...Mach numbers 0.6 and 1.2, Figs. 24 and 25. 13 AE DC-TR-79-10 At supersonic speeds, changes in the afterbody and nozzle axial loads (Fig. 22b) are

Program Helps To Determine Chemical-Reaction Mechanisms

NASA Technical Reports Server (NTRS)

Bittker, D. A.; Radhakrishnan, K.

1995-01-01

General Chemical Kinetics and Sensitivity Analysis (LSENS) computer code developed for use in solving complex, homogeneous, gas-phase, chemical-kinetics problems. Provides for efficient and accurate chemical-kinetics computations and provides for sensitivity analysis for variety of problems, including problems involving honisothermal conditions. Incorporates mathematical models for static system, steady one-dimensional inviscid flow, reaction behind incident shock wave (with boundary-layer correction), and perfectly stirred reactor. Computations of equilibrium properties performed for following assigned states: enthalpy and pressure, temperature and pressure, internal energy and volume, and temperature and volume. Written in FORTRAN 77 with exception of NAMELIST extensions used for input.

Static Thrust and Vectoring Performance of a Spherical Convergent Flap Nozzle with a Nonrectangular Divergent Duct

NASA Technical Reports Server (NTRS)

Wing, David J.

1998-01-01

The static internal performance of a multiaxis-thrust-vectoring, spherical convergent flap (SCF) nozzle with a non-rectangular divergent duct was obtained in the model preparation area of the Langley 16-Foot Transonic Tunnel. Duct cross sections of hexagonal and bowtie shapes were tested. Additional geometric parameters included throat area (power setting), pitch flap deflection angle, and yaw gimbal angle. Nozzle pressure ratio was varied from 2 to 12 for dry power configurations and from 2 to 6 for afterburning power configurations. Approximately a 1-percent loss in thrust efficiency from SCF nozzles with a rectangular divergent duct was incurred as a result of internal oblique shocks in the flow field. The internal oblique shocks were the result of cross flow generated by the vee-shaped geometric throat. The hexagonal and bowtie nozzles had mirror-imaged flow fields and therefore similar thrust performance. Thrust vectoring was not hampered by the three-dimensional internal geometry of the nozzles. Flow visualization indicates pitch thrust-vector angles larger than 10' may be achievable with minimal adverse effect on or a possible gain in resultant thrust efficiency as compared with the performance at a pitch thrust-vector angle of 10 deg.

Measurement of the True Dynamic and Static Pressures in Flight

NASA Technical Reports Server (NTRS)

Kiel, Georg

1939-01-01

In this report, two reliable methods are presented, with the aid of which the undisturbed flight dynamic pressure and the true static pressure may be determined without error. These problems were solved chiefly through practical flight tests.

30 CFR 7.307 - Static pressure test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Static pressure test. 7.307 Section 7.307 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Electric Motor Assemblies § 7.307 Static...

Internal Flow Analysis of Large L/D Solid Rocket Motors

NASA Technical Reports Server (NTRS)

Laubacher, Brian A.

2000-01-01

Traditionally, Solid Rocket Motor (SRM) internal ballistic performance has been analyzed and predicted with either zero-dimensional (volume filling) codes or one-dimensional ballistics codes. One dimensional simulation of SRM performance is only necessary for ignition modeling, or for motors that have large length to port diameter ratios which exhibit an axial "pressure drop" during the early burn times. This type of prediction works quite well for many types of motors, however, when motor aspect ratios get large, and port to throat ratios get closer to one, two dimensional effects can become significant. The initial propellant grain configuration for the Space Shuttle Reusable Solid Rocket Motor (RSRM) was analyzed with 2-D, steady, axi-symmetric computational fluid dynamics (CFD). The results of the CFD analysis show that the steady-state performance prediction at the initial burn geometry, in general, agrees well with 1-D transient prediction results at an early time, however, significant features of the 2-D flow are captured with the CFD results that would otherwise go unnoticed. Capturing these subtle differences gives a greater confidence to modeling accuracy, and additional insight with which to model secondary internal flow effects like erosive burning. Detailed analysis of the 2-D flowfield has led to the discovery of its hidden 1-D isentropic behavior, and provided the means for a thorough and simplified understanding of internal solid rocket motor flow. Performance parameters such as nozzle stagnation pressure, static pressure drop, characteristic velocity, thrust and specific impulse are discussed in detail and compared for different modeling and prediction methods. The predicted performance using both the 1-D codes and the CFD results are compared with measured data obtained from static tests of the RSRM. The differences and limitations of predictions using ID and 2-D flow fields are discussed and some suggestions for the design of large L/D motors and more critically, motors with port to throat ratios near one, are covered.

Investigation of two pitot-static tubes at supersonic speeds

NASA Technical Reports Server (NTRS)

Hasel, Lowell E; Coletti, Donald E

1948-01-01

The results of tests at a Mach number of 1.94 of an ogives-nose cylindrical pitot-static tube and similar tests at Mach numbers of 1.93 and 1.62 of a service pitot-static tube to determine body static pressures and indicated Mach numbers are presented and discussed. The radial pressure distribution on the cylindrical bodies is compared with that calculated by an approximate theory.

Instance Analysis for the Error of Three-pivot Pressure Transducer Static Balancing Method for Hydraulic Turbine Runner

NASA Astrophysics Data System (ADS)

Weng, Hanli; Li, Youping

2017-04-01

The working principle, process device and test procedure of runner static balancing test method by weighting with three-pivot pressure transducers are introduced in this paper. Based on an actual instance of a V hydraulic turbine runner, the error and sensitivity of the three-pivot pressure transducer static balancing method are analysed. Suggestions about improving the accuracy and the application of the method are also proposed.

Static respiratory muscle work during immersion with positive and negative respiratory loading.

PubMed

Taylor, N A; Morrison, J B

1999-10-01

Upright immersion imposes a pressure imbalance across the thorax. This study examined the effects of air-delivery pressure on inspiratory muscle work during upright immersion. Eight subjects performed respiratory pressure-volume relaxation maneuvers while seated in air (control) and during immersion. Hydrostatic, respiratory elastic (lung and chest wall), and resultant static respiratory muscle work components were computed. During immersion, the effects of four air-delivery pressures were evaluated: mouth pressure (uncompensated); the pressure at the lung centroid (PL,c); and at PL,c +/-0.98 kPa. When breathing at pressures less than the PL,c, subjects generally defended an expiratory reserve volume (ERV) greater than the immersed relaxation volume, minus residual volume, resulting in additional inspiratory muscle work. The resultant static inspiratory muscle work, computed over a 1-liter tidal volume above the ERV, increased from 0.23 J. l(-1), when subjects were breathing at PL,c, to 0.83 J. l(-1) at PL,c -0.98 kPa (P < 0.05), and to 1.79 J. l(-1) at mouth pressure (P < 0.05). Under the control state, and during the above experimental conditions, static expiratory work was minimal. When breathing at PL,c +0.98 kPa, subjects adopted an ERV less than the immersed relaxation volume, minus residual volume, resulting in 0.36 J. l(-1) of expiratory muscle work. Thus static inspiratory muscle work varied with respiratory loading, whereas PL,c air supply minimized this work during upright immersion, restoring lung-tissue, chest-wall, and static muscle work to levels obtained in the control state.

A FORTRAN program for calculating three dimensional, inviscid and rotational flows with shock waves in axial compressor blade rows: User's manual

NASA Technical Reports Server (NTRS)

Thompkins, W. T., Jr.

1982-01-01

A FORTRAN-IV computer program was developed for the calculation of the inviscid transonic/supersonic flow field in a fully three dimensional blade passage of an axial compressor rotor or stator. Rotors may have dampers (part span shrouds). MacCormack's explicit time marching method is used to solve the unsteady Euler equations on a finite difference mesh. This technique captures shocks and smears them over several grid points. Input quantities are blade row geometry, operating conditions and thermodynamic quanities. Output quantities are three velocity components, density and internal energy at each mesh point. Other flow quanities are calculated from these variables. A short graphics package is included with the code, and may be used to display the finite difference grid, blade geometry and static pressure contour plots on blade to blade calculation surfaces or blade suction and pressure surfaces. The flow in a low aspect ratio transonic compressor was analyzed and compared with high response total pressure probe measurements and gas fluorescence static density measurements made in the MIT blowdown wind tunnel. These comparisons show that the computed flow fields accurately model the measured shock wave locations and overall aerodynamic performance.

Propulsion Simulations with the Unstructured-Grid CFD Tool TetrUSS

NASA Technical Reports Server (NTRS)

Deere, Karen A.; Pandya, Mohagna J.

2002-01-01

A computational investigation has been completed to assess the capability of the NASA Tetrahedral Unstructured Software System (TetrUSS) for simulation of exhaust nozzle flows. Three configurations were chosen for this study: (1) a fluidic jet effects model, (2) an isolated nacelle with a supersonic cruise nozzle, and (3) a fluidic pitchthrust- vectoring nozzle. These configurations were chosen because existing data provided a means for measuring the ability of the TetrUSS flow solver USM3D for simulating complex nozzle flows. Fluidic jet effects model simulations were compared with structured-grid CFD (computational fluid dynamics) data at Mach numbers from 0.3 to 1.2 at nozzle pressure ratios up to 7.2. Simulations of an isolated nacelle with a supersonic cruise nozzle were compared with wind tunnel experimental data and structured-grid CFD data at Mach numbers of 0.9 and 1.2, with a nozzle pressure ratio of 5. Fluidic pitch-thrust-vectoring nozzle simulations were compared with static experimental data and structured-grid CFD data at static freestream conditions and nozzle pressure ratios from 3 to 10. A fluidic injection case was computed with the third configuration at a nozzle pressure ratio of 4.6 and a secondary pressure ratio of 0.7. Results indicate that USM3D with the S-A turbulence model provides accurate exhaust nozzle simulations at on-design conditions, but does not predict internal shock location at overexpanded conditions or pressure recovery along a boattail at transonic conditions.

Laser-heated rotating specimen autoignition test

NASA Technical Reports Server (NTRS)

Au, A. C.

1988-01-01

Specimens of 440 C steel were rotated in a chamber pressurized with oxygen gas and heated with a 5-kW CO2 laser to determine the temperature required for autoignition to occur. Tests included exposures of static and rotating (25,000 rpm) specimens in oxygen pressurized to 5.51 MPa, and with focused laser fluences of more than 3.5 billion W/sq m. Specimen surface temperatures were monitored with a scanning infrared camera. Temperature measurement difficulties were experienced due to a problem with internal reflection inside the test chamber; however, posttest specimen examinations confirmed that surface melt (1371 C) was achieved in several tests. No sustained combustion was initiated in any rotating specimen. One static specimen was ignited. Results indicated that conditions necessary for autoignition of 440 C steel are more dependent on specimen geometry and available heat removal mechanisms. Sustained combustion occurred in the ignited static specimen with an estimated 130 C/sec cooling rate due to conduction. The rotating specimens could not sustain combustion due to a greater conductive/convective cooling rate of about 4000 C/sec and ejection of molten material. These results were applied to the Space Shuttle Main Engine (SSME) oxygen turbopump bearings to conclude that the LOX-cooled 440 C steel bearings cannot sustain combustion initiated by skidding friction.

Landing pressure loads of the 140A/B space shuttle orbiter (model 43-0) determined in the Rockwell International low speed wind tunnel (OA69), volume 1. [wind tunnel tests

NASA Technical Reports Server (NTRS)

Soard, T. L.

1975-01-01

Wind tunnel tests of a 0.0405 scale model of the -1404A/B configuration of the Space Shuttle Vehicle Orbiter are presented. Pressure loads data were obtained from the orbiter in the landing configuration in the presence of the ground for structural strength analysis. This was accomplished by locating as many as 30 static pressure bugs at various locations on external model surfaces as each configuration was tested. A complete pressure loads survey was generated for each configuration by combining data from all bug locations, and these loads are described for the fuselage, wing, vertical tail, and landing gear doors. Aerodynamic force data was measured by a six component internal strain gage balance. This data was recorded to correct model angles of attack and sideslip for sting and balance deflections and to determine the aerodynamic effects of landing gear extension. All testing was conducted at a Mach number of 0.165 and a Reynolds number of 1.2 million per foot. Photographs of test configurations are shown.

SACCON Forced Oscillation Tests at DNW-NWB and NASA Langley 14x22-Foot Tunnel

NASA Technical Reports Server (NTRS)

Vicroy Dan D.; Loeser, Thomas D.; Schuette, Andreas

2010-01-01

A series of three wind tunnel static and forced oscillation tests were conducted on a generic unmanned combat air vehicle (UCAV) geometry. These tests are part of an international research effort to assess the state-of-the-art of computational fluid dynamics (CFD) methods to predict the static and dynamic stability and control characteristics. The experimental dataset includes not only force and moment time histories but surface pressure and off body particle image velocimetry measurements as well. The extent of the data precludes a full examination within the scope of this paper. This paper provides some examples of the dynamic force and moment data available as well as some of the observed trends.

14 CFR 33.64 - Pressurized engine static parts.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Pressurized engine static parts. 33.64 Section 33.64 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.64 Pressurized...

14 CFR 33.64 - Pressurized engine static parts.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Pressurized engine static parts. 33.64 Section 33.64 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.64 Pressurized...

14 CFR 33.64 - Pressurized engine static parts.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Pressurized engine static parts. 33.64 Section 33.64 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.64 Pressurized...

14 CFR 33.64 - Pressurized engine static parts.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Pressurized engine static parts. 33.64 Section 33.64 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.64 Pressurized...

14 CFR 33.64 - Pressurized engine static parts.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Pressurized engine static parts. 33.64 Section 33.64 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.64 Pressurized...

Thrust performance of a variable-geometry, divergent exhaust nozzle on a turbojet engine at altitude

NASA Technical Reports Server (NTRS)

Straight, D. M.; Collom, R. R.

1983-01-01

A variable geometry, low aspect ratio, nonaxisymmetric, two dimensional, convergent-divergent exhaust nozzle was tested at simulated altitude on a turbojet engine to obtain baseline axial, dry thrust performance over wide ranges of operating nozzle pressure ratios, throat areas, and internal expansion area ratios. The thrust data showed good agreement with theory and scale model test results after the data were corrected for seal leakage and coolant losses. Wall static pressure profile data were also obtained and compared with one dimensional theory and scale model data. The pressure data indicate greater three dimensional flow effects in the full scale tests than with models. The leakage and coolant penalties were substantial, and the method to determine them is included.

Static Internal Performance of a Two-Dimensional Convergent-Divergent Nozzle with External Shelf

NASA Technical Reports Server (NTRS)

Lamb, Milton; Taylor, John G.; Frassinelli, Mark C.

1996-01-01

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a two-dimensional convergent-divergent nozzle. The nozzle design was tested with dry and afterburning throat areas, which represent different power settings and three expansion ratios. For each of these configurations, three trailing-edge geometries were tested. The baseline geometry had a straight trailing edge. Two different shaping techniques were applied to the baseline nozzle design to reduce radar observables: the scarfed design and the sawtooth design. A flat plate extended downstream of the lower divergent flap trailing edge parallel to the model centerline to form a shelf-like expansion surface. This shelf was designed to shield the plume from ground observation (infrared radiation (IR) signature suppression). The shelf represents the part of the aircraft structure that might be present in an installed configuration. These configurations were tested at nozzle pressure ratios from 2.0 to 12.0.

Effect of empennage arrangement on single-engine nozzle/afterbody static pressures at transonic speeds

NASA Technical Reports Server (NTRS)

Henderson, William P.; Burley, James R., II

1987-01-01

An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to determine the effects on empennage arrangement on single-engine nozzle/afterbody static pressures. Tests were done at Mach numbers from 0.60 to 1.20, nozzle pressure ratios from 1.0 (jet off) to 8.0. and angles of attack from -3 to 9 deg (at jet off conditions), depending on Mach number. Three empennage arrangements (aft, staggered, and forward) were investigated. Extensive measurements were made of static pressure on the nozzle/afterbody in the vicinity of the tail surfaces.

The Influence of Forward Flight on Propeller Noise

NASA Technical Reports Server (NTRS)

Magliozzi, B.

1977-01-01

The effect of flight on blade surface pressures and propeller noise was reported. There were significant differences in blade surface pressures and far-field noise between static and flight conditions. The static data showed many high-intensity, tone-like peaks whereas the flight data was generally free from tones. The turbulence ingested by the propeller operating statically was dominated by long, thin eddies. In flight the scale of the turbulence was greately reduced from that observed statically.

The Response of Frozen Soils to Vibratory Loads

DTIC Science & Technology

1975-06-01

Construction. i | The report was technically reviewed by Dr. Y . Nakano of USA CRREL, and A.F. Müller of the Office of Chief of Engineers. Their suggestions...B.I.S. Helme, Jr., t M.J. Dabney III, F. Berrego, R.N. Lachenmaier and D.J. Coombes. Dr. T.M. Lee, Dr. D.M. Norris, Jr. and Dr. Y . Nakano gave... y /g stress static confining pressure, (a, + 2a ^/3 axial (vertical) static pressure lateral static pressure dynamic stress (peak) phase shift

Description of a Pressure Measurement Technique for Obtaining Surface Static Pressures of a Radial Turbine

NASA Technical Reports Server (NTRS)

Dicicco, L. Danielle; Nowlin, Brent C.; Tirres, Lizet

1992-01-01

The aerodynamic performance of a solid uncooled version of a cooled radial turbine was evaluated in the Small Engine Components Test Facility Turbine rig at the NASA Lewis Research Center. Specifically, an experiment was conducted to rotor surface static pressures. This was the first time surface static pressures had been measured on a radial turbine at NASA Lewis. These pressures were measured by a modified Rotating Data Package (RDP), a standard product manufactured by Scanivalve, Inc. Described here are the RDP, and the modifications that were made, as well as the checkout, installation, and testing procedures. The data presented are compared to analytical results obtained from NASA's MERIDL TSONIC BLAYER (MTSB) code.

Description of a pressure measurement technique for obtaining surface static pressures of a radial turbine

NASA Technical Reports Server (NTRS)

Dicicco, L. D.; Nowlin, Brent C.; Tirres, Lizet

1992-01-01

The aerodynamic performance of a solid uncooled version of a cooled radial turbine was evaluated in the Small Engine Components Test Facility Turbine rig at the NASA Lewis Research Center. Specifically, an experiment was conducted to rotor surface static pressures. This was the first time surface static pressures had been measured on a radial turbine at NASA Lewis. These pressures were measured by a modified Rotating Data Package (RDP), a standard product manufactured by Scanivalve, Inc. Described here are the RDP, and the modifications that were made, as well as the checkout, installation, and testing procedures. The data presented are compared to analytical results obtained from NASA's MERIDL TSONIC BLAYER (MTSB) code.

Fluctuation Pressure Assisted Ejection of DNA From Bacteriophage

NASA Astrophysics Data System (ADS)

Harrison, Michael J.

2011-03-01

The role of thermal pressure fluctuations excited within tightly packaged DNA while it is ejected from protein capsid shells is discussed in a model calculation. At equilibrium before ejection we assume the DNA is folded many times into a bundle of parallel segments that forms an equilibrium conformation at minimum free energy, which presses tightly against capsid walls. Using a canonical ensemble at temperature T we calculate internal pressure fluctuations against a slowly moving or static capsid mantle for an elastic continuum model of the folded DNA bundle. It is found that fluctuating pressures on the capsid from thermal excitation of longitudinal acoustic vibrations in the bundle whose wavelengths are exceeded by the bend persistence length may have root-mean-square values that are several tens of atmospheres for typically small phage dimensions. Comparisons are given with measured data on three mutants of lambda phage with different base pair lengths and total genome ejection pressures.

Recovering Aerodynamic Side Loads on Rocket Nozzles using Quasi-Static Strain-Gage Measurements

NASA Technical Reports Server (NTRS)

Brown, Andrew; Ruf, Joseph H.; McDaniels, David M.

2009-01-01

During over-expanded operation of rocket nozzles, which is defined to be when the exit pressure is greater than internal pressure over some part of the nozzle, the nozzle will experience a transverse forcing function due to the pressure differential across the nozzle wall. Over-expansion occurs during the nozzle start-up and shutdown transient, even in high-altitude engines, because most test facilities cannot completely reproduce the near-vacuum pressures at those altitudes. During this transient, the pressure differential moves axially down the nozzle as it becomes pressurized, but this differential is never perfectly symmetric circumferentially. The character of the forcing function is highly complex and defined by a series of restricted and free shock separations. The subject of this paper is the determination of the magnitude of this loading during sub-scale testing via measurement of the structural dynamic response of the nozzle and its support structure. An initial attempt at back-calculating this load using the inverse of the transfer function was performed, but this attempt was shown to be highly susceptible to numerical error. The final method chosen was to use statically calibrated strain data and to filter out the system fundamental frequency such that the measured response yields close to the correct dynamic loading function. This method was shown to capture 93% of the pressure spectral energy using controlled load shaker testing. This method is one of the only practical ways for the inverse determination of the forcing function for non-stationary excitations, and, to the authors' knowledge, has not been described in the literature to date.

Effect of reducing rotor blade inlet diameter on the performance of a 11.66-Centimeter radial-inflow turbine

NASA Technical Reports Server (NTRS)

Kofskey, M. G.; Haas, J. E.

1973-01-01

The effect of increased rotor blade loading on turbine performance was investigated by reducing rotor blade inlet diameter. The reduction was made in four stages. Each modification was tested with the same stator using cold air as the working fluid. Results are presented in terms of equivalent mass flow and efficiency at equivalent design rotative speed and over a range of pressure ratios. Internal flow characteristics are shown in terms of stator exit static pressure and the radial variation of local loss and rotor-exit flow angle with radius ratio. Included are velocity diagrams calculated from the experimental results.

Comparisons Between Stability Prediction and Measurements for the Reusable Solid Rocket Motor

NASA Technical Reports Server (NTRS)

Fischbach, Sean R.; Kenny, R. Jeremy

2010-01-01

The Space Transportation System has used the solid rocket boosters for lift-off and ascent propulsion over the history of the program. Part of the structural loads assessment of the assembled vehicle is the contribution due to solid rocket booster thrust oscillations. These thrust oscillations are a consequence of internal motor pressure oscillations active during operation. Understanding of these pressure oscillations is key to predicting the subsequent thrust oscillations and vehicle loading. The pressure oscillation characteristics of the Reusable Solid Rocket Motor (RSRM) design are reviewed in this work. Dynamic pressure data from the static test and flight history are shown, with emphasis on amplitude, frequency, and timing of the oscillations. Physical mechanisms that cause these oscillations are described by comparing data observations to predictions made by the Solid Stability Prediction (SSP) code.

Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

NASA Astrophysics Data System (ADS)

Rodi, A. R.; Leon, D. C.

2012-05-01

Geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system on the University of Wyoming King Air research aircraft are used to estimate acceleration effects on static pressure measurement. Using data collected during periods of accelerated flight, comparison of measured pressure with that derived from GNSS/IMU geometric altitude show that errors exceeding 150 Pa can occur which is significant in airspeed and atmospheric air motion determination. A method is developed to predict static pressure errors from analysis of differential pressure measurements from a Rosemount model 858 differential pressure air velocity probe. The method was evaluated with a carefully designed probe towed on connecting tubing behind the aircraft - a "trailing cone" - in steady flight, and shown to have a precision of about ±10 Pa over a wide range of conditions including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, compared to the GNSS/IMU data, this algorithm predicts corrections to a precision of better than ±20 Pa. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are examined.

Integration of piezo-capacitive and piezo-electric nanoweb based pressure sensors for imaging of static and dynamic pressure distribution.

PubMed

Jeong, Y J; Oh, T I; Woo, E J; Kim, K J

2017-07-01

Recently, highly flexible and soft pressure distribution imaging sensor is in great demand for tactile sensing, gait analysis, ubiquitous life-care based on activity recognition, and therapeutics. In this study, we integrate the piezo-capacitive and piezo-electric nanowebs with the conductive fabric sheets for detecting static and dynamic pressure distributions on a large sensing area. Electrical impedance tomography (EIT) and electric source imaging are applied for reconstructing pressure distribution images from measured current-voltage data on the boundary of the hybrid fabric sensor. We evaluated the piezo-capacitive nanoweb sensor, piezo-electric nanoweb sensor, and hybrid fabric sensor. The results show the feasibility of static and dynamic pressure distribution imaging from the boundary measurements of the fabric sensors.

Static and Wind Tunnel Aero-Performance Tests of NASA AST Separate Flow Nozzle Noise Reduction Configurations

NASA Technical Reports Server (NTRS)

Mikkelsen, Kevin L.; McDonald, Timothy J.; Saiyed, Naseem (Technical Monitor)

2001-01-01

This report presents the results of cold flow model tests to determine the static and wind tunnel performance of several NASA AST separate flow nozzle noise reduction configurations. The tests were conducted by Aero Systems Engineering, Inc., for NASA Glenn Research Center. The tests were performed in the Channels 14 and 6 static thrust stands and the Channel 10 transonic wind tunnel at the FluiDyne Aerodynamics Laboratory in Plymouth, Minnesota. Facility checkout tests were made using standard ASME long-radius metering nozzles. These tests demonstrated facility data accuracy at flow conditions similar to the model tests. Channel 14 static tests reported here consisted of 21 ASME nozzle facility checkout tests and 57 static model performance tests (including 22 at no charge). Fan nozzle pressure ratio varied from 1.4 to 2.0, and fan to core total pressure ratio varied from 1.0 to 1.19. Core to fan total temperature ratio was 1.0. Channel 10 wind tunnel tests consisted of 15 tests at Mach number 0.28 and 31 tests at Mach 0.8. The sting was checked out statically in Channel 6 before the wind tunnel tests. In the Channel 6 facility, 12 ASME nozzle data points were taken and 7 model data points were taken. In the wind tunnel, fan nozzle pressure ratio varied from 1.73 to 2.8, and fan to core total pressure ratio varied from 1.0 to 1.19. Core to fan total temperature ratio was 1.0. Test results include thrust coefficients, thrust vector angle, core and fan nozzle discharge coefficients, total pressure and temperature charging station profiles, and boat-tail static pressure distributions in the wind tunnel.

Sound attenuation of a finite length dissipative flow duct silencer with internal mean flow in the absorbent

NASA Astrophysics Data System (ADS)

Cummings, A.; Chang, I.-J.

1988-11-01

Internal mean flow within the pores of a bulk-reacting porous acoustic absorbent, driven by mean static pressure gradients, is shown here to be an important feature of the acoustics of dissipative silencers in flow ducts, particularly in the case of internal combustion engine exhaust silencers. Theoretical treatments are presented here, both to describe the effect of internal flow on the bulk acoustic perties of the porous medium and to find the effect of the absorbent in situ, in the form of the sound transmission loss of the silencer. The measured transmission loss of an experimental silencer is compared to predicted data and good agreement between the two is obtained. The effects of mean fluid flow in the central passage and internal flow in the absorbent are separately demonstrated.

Martian Atmospheric Pressure Static Charge Elimination Tool

NASA Technical Reports Server (NTRS)

Johansen, Michael R.

2014-01-01

A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

Static investigation of several yaw vectoring concepts on nonaxisymmetric nozzles

NASA Technical Reports Server (NTRS)

Mason, M. L.; Berrier, B. L.

1985-01-01

A test has been conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to determine the flow-turning capability and the effects on nozzle internal performance of several yaw vectoring concepts. Nonaxisymmetric convergent-divergent nozzles with throat areas simulating dry and afterburning power settings and single expansion ramp nozzles with a throat area simulating a dry power setting were modified for yaw thrust vectoring. Forward-thrust and pitch-vectored nozzle configurations were tested with each yaw vectoring concept. Four basic yaw vectoring concepts were investigated on the nonaxisymmetric convergent-divergent nozzles: (1) translating sidewall; (2) downstream (of throat) flaps; (3) upstream (of throat) port/flap; and (4) powered rudder. Selected combinations of the rudder with downstream flaps or upstream port/flap were also tested. A single yaw vectoring concept, post-exit flaps, was investigated on the single expansion ramp nozzles. All testing was conducted at static (no external flow) conditions and nozzle pressure ratios varied from 2.0 up to 10.0.

Wind tunnel and ground static tests of a .094 scale powered model of a modified T-39 lift/cruise fan V/STOL research airplane

NASA Technical Reports Server (NTRS)

Hunt, D.; Clinglan, J.; Salemann, V.; Omar, E.

1977-01-01

Ground static and wind tunnel test of a scale model modified T-39 airplane are reported. The configuration in the nose and replacement of the existing nacelles with tilting lift/cruise fans. The model was powered with three 14 cm diameter tip driven turbopowered simulators. Forces and moments were measured by an internal strain guage balance. Engine simulator thrust and mass flow were measured by calibrated pressure and temperature instrumentation mounted downstream of the fans. The low speed handling qualities and general aerodynamic characteristics of the modified T-39 were defined. Test variables include thrust level and thrust balance, forward speed, model pitch and sideslip angle at forward speeds, model pitch, roll, and ground height during static tests, lift/cruise fan tilt angle, flap and aileron deflection angle, and horizonal stabilizer angle. The effects of removing the landing gear, the lift/cruise fans, and the tail surfaces were also investigated.

42 CFR 84.91 - Breathing resistance test; exhalation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 25 mm. (1 inch) water-column height. (c) The exhalation resistance of pressure-demand apparatus shall not exceed the static pressure in the facepiece by more than 51 mm. (2 inches) water-column height. (d) The static pressure (at zero flow) in the facepiece shall not exceed 38 mm. (1.5 inches) water-column...

42 CFR 84.91 - Breathing resistance test; exhalation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 25 mm. (1 inch) water-column height. (c) The exhalation resistance of pressure-demand apparatus shall not exceed the static pressure in the facepiece by more than 51 mm. (2 inches) water-column height. (d) The static pressure (at zero flow) in the facepiece shall not exceed 38 mm. (1.5 inches) water-column...

42 CFR 84.91 - Breathing resistance test; exhalation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 25 mm. (1 inch) water-column height. (c) The exhalation resistance of pressure-demand apparatus shall not exceed the static pressure in the facepiece by more than 51 mm. (2 inches) water-column height. (d) The static pressure (at zero flow) in the facepiece shall not exceed 38 mm. (1.5 inches) water-column...

40 CFR 60.274a - Monitoring of operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the equipment that is important to the performance of the total capture system (i.e., pressure sensors... this subpart shall check and record on a once-per-shift basis the furnace static pressure (if DEC system is in use, and a furnace static pressure gauge is installed according to paragraph (f) of this...

42 CFR 84.91 - Breathing resistance test; exhalation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 25 mm. (1 inch) water-column height. (c) The exhalation resistance of pressure-demand apparatus shall not exceed the static pressure in the facepiece by more than 51 mm. (2 inches) water-column height. (d) The static pressure (at zero flow) in the facepiece shall not exceed 38 mm. (1.5 inches) water-column...

42 CFR 84.91 - Breathing resistance test; exhalation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 25 mm. (1 inch) water-column height. (c) The exhalation resistance of pressure-demand apparatus shall not exceed the static pressure in the facepiece by more than 51 mm. (2 inches) water-column height. (d) The static pressure (at zero flow) in the facepiece shall not exceed 38 mm. (1.5 inches) water-column...

A comparison of the calculated and experimental off-design performance of a radial flow turbine

NASA Technical Reports Server (NTRS)

Tirres, Lizet

1992-01-01

Off design aerodynamic performance of the solid version of a cooled radial inflow turbine is analyzed. Rotor surface static pressure data and other performance parameters were obtained experimentally. Overall stage performance and turbine blade surface static to inlet total pressure ratios were calculated by using a quasi-three dimensional inviscid code. The off design prediction capability of this code for radial inflow turbines shows accurate static pressure prediction. Solutions show a difference of 3 to 5 points between the experimentally obtained efficiencies and the calculated values.

A comparison of the calculated and experimental off-design performance of a radial flow turbine

NASA Technical Reports Server (NTRS)

Tirres, Lizet

1991-01-01

Off design aerodynamic performance of the solid version of a cooled radial inflow turbine is analyzed. Rotor surface static pressure data and other performance parameters were obtained experimentally. Overall stage performance and turbine blade surface static to inlet total pressure ratios were calculated by using a quasi-three dimensional inviscid code. The off design prediction capability of this code for radial inflow turbines shows accurate static pressure prediction. Solutions show a difference of 3 to 5 points between the experimentally obtained efficiencies and the calculated values.

Effects of internal yaw-vectoring devices on the static performance of a pitch-vectoring nonaxisymmetric convergent-divergent nozzle

NASA Technical Reports Server (NTRS)

Asbury, Scott C.

1993-01-01

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to evaluate the internal performance of a nonaxisymmetric convergent divergent nozzle designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap deflection for thrust vectoring in the pitch plane and flow-turning deflectors installed within the divergent flaps for yaw thrust vectoring. Modifications consisting of reducing the sidewall length and deflecting the sidewall outboard were investigated as means to increase yaw-vectoring performance. This investigation studied the effects of multiaxis (pitch and yaw) thrust vectoring on nozzle internal performance characteristics. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 2.0 to approximately 13.0. The results indicate that this nozzle concept can successfully generate multiaxis thrust vectoring. Deflection of the divergent flaps produced resultant pitch vector angles that, although dependent on nozzle pressure ratio, were nearly equal to the geometric pitch vector angle. Losses in resultant thrust due to pitch vectoring were small or negligible. The yaw deflectors produced resultant yaw vector angles up to 21 degrees that were controllable by varying yaw deflector rotation. However, yaw deflector rotation resulted in significant losses in thrust ratios and, in some cases, nozzle discharge coefficient. Either of the sidewall modifications generally reduced these losses and increased maximum resultant yaw vector angle. During multiaxis (simultaneous pitch and yaw) thrust vectoring, little or no cross coupling between the thrust vectoring processes was observed.

Foreword: 18th Aps-Sccm and 24th Airapt

NASA Astrophysics Data System (ADS)

Collins, Gilbert; Moore, David S.; Yoo, Choong-Shik

2014-05-01

This second joint conference between the APS Topical Group on Shock Compression of Condensed Matter and the International Association for the Advancement of High Pressure Science and Technology (AIRAPT) demonstrates that static and dynamic compression of condensed matter continues to be a vibrant field of science and engineering. It is also by its nature an interdisciplinary field, incorporating chemistry, materials science, solid mechanics, plasma physics, and condensed matter physics, and utilizes theoretical, computational, and experimental tools. Recent years have brought about many advances in loading platforms, diagnostics, and computations that are leading to the emergence of many new avenues of research. These advances are also breathing new life into traditional topics such as equations of state, phase transformations, and chemistry at extreme conditions. The plenary lectures by Gennady Kanel, Karl Syassen, David Ceperley, Jon Eggert, Duck Young Kim, and Richard Kraus spanned the disciplines of static and dynamic high pressure physics and illustrated the breadth of the field. They also showed that interesting and important problems remain for researchers of the future to solve. The main guiding principal in the organization of this conference was to intertwine static and dynamical experimental alongside computational and theoretical studies of similar materials. To achieve this goal, we arranged the conference to include static, dynamic, and computational components in the same sessions, quite often taking presenters out of their comfort zone. The three special sessions on Deep Carbon Budget (organized by Giulia Galli and Rus Hemley), High Energy Density Materials (organized by Raymond Jeanloz and Jon Eggert), and Dynamic Response of Materials (organized by Yogendra Gupta and John Sarrao) furthered this guiding principal. We also endeavored to represent the breadth of static and dynamic high pressure science and technology, notably beyond that done at national laboratories. To this end, a significant fraction of the plenary, invited and contributed presentations showcased work done in academia, defense laboratories and industry, as well as internationally. Although travel distance and visa issues always present difficulties, the conference had strong representation from a record number of international participants, including sizable groups from Russia and China (thanks to Tony Zocher and Frank Cherne), as well as Japan, the United Kingdom, France, Canada, Germany, Israel, and Italy. It is our sincere hope that international interactions that occurred at the conference will lead to further collaborations in the future. Finally, we strived to increase student participation at the conference. Through the leadership of Scott Alexander and his committee, a new all-day student symposium was held the day before the main conference, with only student attendees and presenters, in order to acclimate the students to conference participation and help them network with their peers. In cooperation with the APS Topical Group and the AIRAPT and with additional support from DTRA and the AWE, the conference was able to provide financial assistance to a large number of students to attend the conference and present their research. This aid helped increase the number of student attendees significantly over previous conferences. Finally, the conference sponsored a networking lunch for students and representatives from a number of laboratories and other institutions, which was well attended. Seattle proved itself to be an excellent venue for the conference. The international flavor of the city provided ample dining options and numerous activity choices outside of the conference sessions. The major international airport made travel as easy as possible, as Seattle is a convenient central location for attendees from Europe and Asia. The conference was truly a team effort with critical contributions from many individuals. We deeply appreciate their contributions to the success of the conference and the publication of these proceedings. Gilbert (RIP) Collins David S Moore Choong-Shik Yoo

Internal performance of a hybrid axisymmetric/nonaxisymmetric convergent-divergent nozzle

NASA Technical Reports Server (NTRS)

Taylor, John G.

1991-01-01

An investigation was conducted in the static test facility of the Langley 16-foot transonic tunnel to determine the internal performance of a hybrid axisymmetric/nonaxisymmetric nozzle in forward-thrust mode. Nozzle cross-sections in the spherical convergent section were axisymmetric whereas cross-sections in the divergent flap area nonaxisymmetric (two-dimensional). Nozzle concepts simulating dry and afterburning power settings were investigated. Both subsonic cruise and supersonic cruise expansion ratios were tested for the dry power nozzle concepts. Afterburning power configurations were tested at an expansion ratio typical for subsonic acceleration. The spherical convergent flaps were designed in such a way that the transition from axisymmetric to nonaxisymmetric cross-section occurred in the region of the nozzle throat. Three different nozzle throat geometries were tested for each nozzle power setting. High-pressure air was used to simulate jet exhaust at nozzle pressure ratios up to 12.0.

Wake orientation and its influence on the performance of diffusers with inlet distortion

NASA Astrophysics Data System (ADS)

Coffman, Jesse M.

Distortion at the inlet to diffusers is very common in internal flow applications. Inlet velocity distortion influences the pressure recovery and flow regimes of diffusers. This work introduced a centerline wake at the square inlet of a plane wall diffuser in two orthogonal orientations to investigate its influence on the diffuser performance. Two different wakes were generated. One was from a mesh strip which produced a velocity deficit with low turbulence intensity and two shear layers. The other wake generator was a D-shaped cylinder which produced a wake with high turbulence intensity and large length scales. These inlet conditions were generated for a diffuser with a diffusion angle of 3° and 6°. A pair of RANS simulations were used to investigate the influence of the orthogonal inlet orientations on the solution. The inlet conditions were taken from the inlet velocity field measured for the mesh strip. The flow development and exit conditions showed some similarities and some differences with the experimental results. The performance of a diffuser is typically measured through the static pressure recovery coefficient and the total pressure losses. The definition of these metrics commonly found in the literature were insufficient to discern differences between the wake orientations. New metrics were derived using the momentum flux profile parameter which related the static pressure recovery, the total pressure losses, and the velocity uniformity at the inlet and exit of the diffuser. These metrics revealed a trade-off between the total pressure losses and the uniformity of the velocity field.

Reduction of Orifice-Induced Pressure Errors

NASA Technical Reports Server (NTRS)

Plentovich, Elizabeth B.; Gloss, Blair B.; Eves, John W.; Stack, John P.

1987-01-01

Use of porous-plug orifice reduces or eliminates errors, induced by orifice itself, in measuring static pressure on airfoil surface in wind-tunnel experiments. Piece of sintered metal press-fitted into static-pressure orifice so it matches surface contour of model. Porous material reduces orifice-induced pressure error associated with conventional orifice of same or smaller diameter. Also reduces or eliminates additional errors in pressure measurement caused by orifice imperfections. Provides more accurate measurements in regions with very thin boundary layers.

Transonic Performance Characteristics of Several Jet Noise Suppressors

NASA Technical Reports Server (NTRS)

Schmeer, James W.; Salters, Leland B., Jr.; Cassetti, Marlowe D.

1960-01-01

An investigation of the transonic performance characteristics of several noise-suppressor configurations has been conducted in the Langley 16-foot transonic tunnel. The models were tested statically and over a Mach number range from 0.70 to 1.05 at an angle of attack of 0 deg. The primary jet total-pressure ratio was varied from 1.0 (jet off) to about 4.5. The effect of secondary air flow on the performance of two of the configurations was investigated. A hydrogen peroxide turbojet-engine simulator was used to supply the hot-jet exhaust. An 8-lobe afterbody with centerbody, short shroud, and secondary air had the highest thrust-minus-drag coefficients of the six noise-suppressor configurations tested. The 12-tube and 12-lobe afterbodies had the lowest internal losses. The presence of an ejector shroud partially shields the external pressure distribution of the 8-lobe after-body from the influence of the primary jet. A ring-airfoil shroud increased the static thrust of the annular nozzle but generally decreased the thrust minus drag at transonic Mach numbers.

A calculation and uncertainty evaluation method for the effective area of a piston rod used in quasi-static pressure calibration

NASA Astrophysics Data System (ADS)

Gu, Tingwei; Kong, Deren; Shang, Fei; Chen, Jing

2018-04-01

This paper describes the merits and demerits of different sensors for measuring propellant gas pressure, the applicable range of the frequently used dynamic pressure calibration methods, and the working principle of absolute quasi-static pressure calibration based on the drop-weight device. The main factors affecting the accuracy of pressure calibration are analyzed from two aspects of the force sensor and the piston area. To calculate the effective area of the piston rod and evaluate the uncertainty between the force sensor and the corresponding peak pressure in the absolute quasi-static pressure calibration process, a method for solving these problems based on the least squares principle is proposed. According to the relevant quasi-static pressure calibration experimental data, the least squares fitting model between the peak force and the peak pressure, and the effective area of the piston rod and its measurement uncertainty, are obtained. The fitting model is tested by an additional group of experiments, and the peak pressure obtained by the existing high-precision comparison calibration method is taken as the reference value. The test results show that the peak pressure obtained by the least squares fitting model is closer to the reference value than the one directly calculated by the cross-sectional area of the piston rod. When the peak pressure is higher than 150 MPa, the percentage difference is less than 0.71%, which can meet the requirements of practical application.

The energy density distribution of an ideal gas and Bernoulli’s equations

NASA Astrophysics Data System (ADS)

Santos, Leonardo S. F.

2018-05-01

This work discusses the energy density distribution in an ideal gas and the consequences of Bernoulli’s equation and the corresponding relation for compressible fluids. The aim of this work is to study how Bernoulli’s equation determines the energy flow in a fluid, although Bernoulli’s equation does not describe the energy density itself. The model from molecular dynamic considerations that describes an ideal gas at rest with uniform density is modified to explore the gas in motion with non-uniform density and gravitational effects. The difference between the component of the speed of a particle that is parallel to the gas speed and the gas speed itself is called ‘parallel random speed’. The pressure from the ‘parallel random speed’ is denominated as parallel pressure. The modified model predicts that the energy density is the sum of kinetic and potential gravitational energy densities plus two terms with static and parallel pressures. The application of Bernoulli’s equation and the corresponding relation for compressible fluids in the energy density expression has resulted in two new formulations. For incompressible and compressible gas, the energy density expressions are written as a function of stagnation, static and parallel pressures, without any dependence on kinetic or gravitational potential energy densities. These expressions of the energy density are the main contributions of this work. When the parallel pressure was uniform, the energy density distribution for incompressible approximation and compressible gas did not converge to zero for the limit of null static pressure. This result is rather unusual because the temperature tends to zero for null pressure. When the gas was considered incompressible and the parallel pressure was equal to static pressure, the energy density maintained this unusual behaviour with small pressures. If the parallel pressure was equal to static pressure, the energy density converged to zero for the limit of the null pressure only if the gas was compressible. Only the last situation describes an intuitive behaviour for an ideal gas.

Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a slot air jet

NASA Astrophysics Data System (ADS)

M, Adimurthy; Katti, Vadiraj V.

2017-02-01

Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing ( Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio ( l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.

Effect of Intracranial Stenosis Revascularization on Dynamic and Static Cerebral Autoregulation.

PubMed

Ortega-Gutierrez, Santiago; Samaniego, Edgar A; Huang, Amy; Masurkar, Arjun; Zheng-Lin, Binbin; Derdeyn, Colin P; Hasan, David; Marshall, Randolph; Petersen, Nils

2018-06-01

Severe intracranial stenosis might lead to acute cerebral ischemia. It is imperative to better assess patients who may benefit from immediate reperfusion and blood pressure management to prevent injury to peri-infarct tissue. We assessed cerebral autoregulation using static and dynamic methods in an 81-year-old woman suffering acute cerebral ischemia from severe intracranial stenosis in the petrous segment of the left internal carotid artery (LICA). Static cerebral autoregulation, which is evaluated by magnetic resonance imaging and magnetic resonance perfusion studies showed a progression of infarcts and a large perfusion-diffusion mismatch in the entire LICA territory between the second and third days after onset despite maximized medical therapy. Dynamic methods, including transfer function analysis and mean velocity index, demonstrated an increasingly impaired dynamic cerebral autoregulation (DCA) on the affected side between these days. Revascularization through acute intracranial stenting resulted in improved perfusion in the LICA territory and normalization of both dynamic and static cerebral autoregulation. Thus, DCA, a noninvasive bedside method, may be useful in helping to identify and select patients with large-vessel flow-failure syndromes that would benefit from immediate revascularization of intracranial atherosclerotic disease.

Influence of tip end-plate on noise of small axial fan

NASA Astrophysics Data System (ADS)

Mao, Hongya; Wang, Yanping; Lin, Peifeng; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

2017-02-01

In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent.

Constitutive models for static and dynamic response of geotechnical materials

NASA Astrophysics Data System (ADS)

Nemat-Nasser, S.

1983-11-01

The objective of this research program has been to develop realistic macroscopic constitutive relations which describe static and dynamic properties of geotechnical materials (soils and rocks). To this end a coordinated theoretical and experimental activity has been followed. The theoretical work includes a balanced combination of statistical microscopic (at the grain size level) modeling and a nonclassical elasto-plastic macroscopic formulation. The latter includes the effects of internal friction, plastic compressibility, and pressure sensitivity, as well as anisotropy which is commonly observed in geotechnical materials. The following specific goals have been sought: (1) to develop three-dimensional constitutive relations under ordinary or high pressures (such as those induced by blasting or tectonic forces which may cause a large amount of densification by relative motion and possible crushing of grains); and (2) to examine and characterize the behavior of saturated granular materials under dynamic loading. The latter item includes characterization of possible liquefaction and subsidence which may be induced in granular materials under confining pressure by ground vibration or passage of waves. The theoretical work has been carefully coordinated with key experiments in order to: (1) understand the basic physics of the process, both at macroscopic and microscopic levels; (2) to verify the corresponding theoretical predictions; and (3) to establish relevant material parameters.

Aerodynamic Performance Predictions of Single and Twin Jet Afterbodies

NASA Technical Reports Server (NTRS)

Carlson, John R.; Pao, S. Paul; Abdol-Hamid, Khaled S.; Jones, William T.

1995-01-01

The multiblock three-dimensional Navier-Stokes method PAB3D was utilized by the Component Integration Branch (formerly Propulsion Aerodynamics Branch) at the NASA-Langley Research Center in an international study sponsored by AGARD Working Group #17 for the assessment of the state-of-the-art of propulsion-airframe integration testing techniques and CFD prediction technologies. Three test geometries from ONERA involving fundamental flow physics and four geometries from NASA-LaRC involving realistic flow interactions of wing, body, tail, and jet plumes were chosen by the Working Group. An overview of results on four (1 ONERA and 3 LaRC) of the seven test cases is presented. External static pressures, integrated pressure drag and total drag were calculated for the Langley test cases and jet plume velocity profiles and turbulent viscous stresses were calculated for the ONERA test case. Only selected data from these calculations are presented in this paper. The complete data sets calculated by the participants will be presented in an AGARD summary report. Predicted surface static pressures compared favorably with experimental data for the Langley geometries. Predicted afterbody drag compared well with experiment. Predicted nozzle drag was typically low due to over-compression of the flow near the trailing edge. Total drag was typically high. Predicted jet plume quantities on the ONERA case compared generally well with data.

Estimation of Time Dependent Properties from Surface Pressure in Open Cavities

DTIC Science & Technology

2008-02-01

static pressure of the cavity. The stagnation and static pressures are measured separately with Druck Model DPI 145 pressure transducers (with a quoted...interacting with the ZNMF actuator jets, the 2D shape of the vortical structures transform to a 3D shape with spanwise vortical structures. These...Therefore, the pressure gradient in the d direction is dd ° 3d Substituting Equation (5.3) into Equation (5.5) results in ^l = PJk(e^-Re^)/c^ (5.6

Error in Airspeed Measurement Due to the Static-Pressure Field Ahead of an Airplane at Transonic Speeds

NASA Technical Reports Server (NTRS)

O'Bryan, Thomas C; Danforth, Edward C B; Johnston, J Ford

1955-01-01

The magnitude and variation of the static-pressure error for various distances ahead of sharp-nose bodies and open-nose air inlets and for a distance of 1 chord ahead of the wing tip of a swept wing are defined by a combination of experiment and theory. The mechanism of the error is discussed in some detail to show the contributing factors that make up the error. The information presented provides a useful means for choosing a proper location for measurement of static pressure for most purposes.

Investigation of flow fields within large scale hypersonic inlet models

NASA Technical Reports Server (NTRS)

Gnos, A. V.; Watson, E. C.; Seebaugh, W. R.; Sanator, R. J.; Decarlo, J. P.

1973-01-01

Analytical and experimental investigations were conducted to determine the internal flow characteristics in model passages representative of hypersonic inlets for use at Mach numbers to about 12. The passages were large enough to permit measurements to be made in both the core flow and boundary layers. The analytical techniques for designing the internal contours and predicting the internal flow-field development accounted for coupling between the boundary layers and inviscid flow fields by means of a displacement-thickness correction. Three large-scale inlet models, each having a different internal compression ratio, were designed to provide high internal performance with an approximately uniform static-pressure distribution at the throat station. The models were tested in the Ames 3.5-Foot Hypersonic Wind Tunnel at a nominal free-stream Mach number of 7.4 and a unit free-stream Reynolds number of 8.86 X one million per meter.

Cold Flow Determination of the Internal Flow Environment Around the Submerged TVC Nozzle for the Space Shuttle SRM

NASA Technical Reports Server (NTRS)

Whitesides, R. H.; Ghosh, A.; Jenkins, S. L.; Bacchus, D. L.

1989-01-01

A series of subscale cold flow tests was performed to quantify the gas flow characteristics at the aft end of the Space Shuttle Solid Rocket Motor. This information was used to support the analyses of the redesigned nozzle/case joint. A portion of the thermal loads at the joint are due to the circumferential velocities and pressure gradients caused primarily by the gimbaling of the submerged nose TVC nozzle. When the nozzle centerline is vectored with respect to the motor centerline, asymmetries are set up in the flow field under the submerged nozzle and immediately adjacent to the nozzle/case joint. Specific program objectives included: determination of the effects of nozzle gimbal angle and propellant geometry on the circumferential flow field; measurement of the static pressure and gas velocities in the vicinity of the nozzle/case joint; use of scaling laws to apply the subscale cold flow data to the full scale SRM; and generation of data for use in validation of 3-D computational fluid dynamic, CFD, models of the SRM flow field. These tests were conducted in the NASA Marshall Space Flight Center Airflow Facility with a 7.5 percent scale model of the aft segment of the SRM. Static and dynamic pressures were measured in the model to quantify the flow field. Oil flow data was also acquired to obtain qualitative visual descriptions of the flow field. Nozzle gimbal angles of 0, 3.5, and 7 deg were used with propellant grain configurations corresponding to motor burn times of 0, 9, 19, and 114 seconds. This experimental program was successful in generating velocity and pressure gradient data for the flow field around the submerged nose nozzle of the Space Shuttle SRM at various burn times and gimbal angles. The nature of the flow field adjacent to the nozzle/case joint was determined with oil droplet streaks, and the velocity and pressure gradients were quantified with pitot probes and wall static pressure measurements. The data was applied to the full scale SRM thru a scaling analysis and the results compared well with the 3-D computational fluid dynamics computer model.

Static lung compliance and body pressures in Tupinambis merianae with and without post-hepatic septum.

PubMed

Klein, Wilfried; Abe, Augusto S; Perry, Steven F

2003-04-15

The surgical removal of the post-hepatic septum (PHS) in the tegu lizard, Tupinambis merianae, significantly reduces resting lung volume (V(Lr)) and maximal lung volume (V(Lm)) when compared with tegus with intact PHS. Standardised for body mass (M(B)), static lung compliance was significantly less in tegus without PHS. Pleural and abdominal pressures followed, like ventilation, a biphasic pattern. In general, pressures increased during expiration and decreased during inspiration. However, during expiration pressure changes showed a marked intra- and interindividual variation. The removal of the PHS resulted in a lower cranio-caudal intracoelomic pressure differential, but had no effect on the general pattern of pressure changes accompanying ventilation. These results show that a perforated PHS that lacks striated muscle has significant influence on static breathing mechanics in Tupinambis and by analogy provides valuable insight into similar processes that led to the evolution of the mammalian diaphragm.

Initial Transient in Zn-doped InSb Grown in Microgravity

NASA Technical Reports Server (NTRS)

Ostrogorsky, A G.; Marin, C.; Volz, M.; Duffar, T.

2009-01-01

Three Zn-doped InSb crystals were directionally solidified under microgravity conditions at the International Space Station (ISS) Alpha. The distribution of the Zn was measured using SIMS. A short diffusion-controlled transient, typical for systems with k greater than 1 was demonstrated. Static pressure of approximately 4000 N/m2 was imposed on the melt, to prevent bubble formation and dewetting. Still, partial de-wetting has occurred in one experiment, and apparently has disturbed the diffusive transport of Zn in the melt.

Experimental dynamic response of a two-dimensional, Mach 2.7, mixed compression inlet

NASA Technical Reports Server (NTRS)

Baumbick, R. J.; Neiner, G. H.; Cole, G. L.

1972-01-01

A test program was conducted on a two-dimensional supersonic inlet. Internal disturbances in diffuser exit mass flow were produced by oscillating overboard bypass doors. Open-loop dynamic responses of shock position, throat exit and diffuser exit static pressures are presented. The steady-state and dynamic coupling between ducts were also obtained. The experimental results from the two-dimensional inlet are compared to results from a similar size axisymmetric inlet and also to a transfer function synthesis program.

An alternating pressure sequence proposal for an air-cell cushion for preventing pressure ulcers.

PubMed

Arias, Sandra; Cardiel, Eladio; Rogeli, Pablo; Mori, Taketoshi; Nakagami, Gojiro; Noguchi, Hiroshi; Sanada, Hiromi

2014-01-01

The distribution and release of pressure on ischial regions are two important parameters for evaluating the effectiveness of a cushion; especially the release of pressure over time on ischial tuberosities, which is significant for preventing pressure ulcers. The aim of this work is to evaluate the effect on interface pressure through the application of a proposed alternating pressure sequence for an air-cell cushion. Six healthy volunteers were asked to sit on the air cell cushion, in static and alternating modes, as well as on a typical foam cushion for 12 minutes. Interface pressure was monitored with a matrix sensor system. Interface pressure values on ischial tuberosities, user contact area and pressure distribution were analyzed. Results showed that IP on IT tends to increase in both foam and static cushions, while in alternating cushion IP on IT tends to decrease. User contact area was significantly larger in alternating cushion than in static or foam cushions. Moreover, there is a better pressure re-distribution with alternating cushion than with the other cushions. The goal of the alternating sequence is to redistribute pressure and stimulate the ischial regions in order to promote blood flow and prevent pressure occurring in wheelchair users.

Experimental and Computational Investigation of Multiple Injection Ports in a Convergent-Divergent Nozzle for Fluidic Thrust Vectoring

NASA Technical Reports Server (NTRS)

Waithe, Kenrick A.; Deere, Karen A.

2003-01-01

A computational and experimental study was conducted to investigate the effects of multiple injection ports in a two-dimensional, convergent-divergent nozzle, for fluidic thrust vectoring. The concept of multiple injection ports was conceived to enhance the thrust vectoring capability of a convergent-divergent nozzle over that of a single injection port without increasing the secondary mass flow rate requirements. The experimental study was conducted at static conditions in the Jet Exit Test Facility of the 16-Foot Transonic Tunnel Complex at NASA Langley Research Center. Internal nozzle performance was obtained at nozzle pressure ratios up to 10 with secondary nozzle pressure ratios up to 1 for five configurations. The computational study was conducted using the Reynolds Averaged Navier-Stokes computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. Internal nozzle performance was predicted for nozzle pressure ratios up to 10 with a secondary nozzle pressure ratio of 0.7 for two configurations. Results from the experimental study indicate a benefit to multiple injection ports in a convergent-divergent nozzle. In general, increasing the number of injection ports from one to two increased the pitch thrust vectoring capability without any thrust performance penalties at nozzle pressure ratios less than 4 with high secondary pressure ratios. Results from the computational study are in excellent agreement with experimental results and validates PAB3D as a tool for predicting internal nozzle performance of a two dimensional, convergent-divergent nozzle with multiple injection ports.

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

NASA Technical Reports Server (NTRS)

Jenkins, R. V.

1977-01-01

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

Experimental investigation of the subsonic high-altitude operation of the NASA Lewis 10- by 10-foot supersonic wind tunnel

NASA Technical Reports Server (NTRS)

Hughes, Christopher E.; Jeracki, Robert J.

1988-01-01

An experimental investigation was conducted in the NASA Lewis 10- by 10-Foot Supersonic Wind Tunnel during subsonic tunnel operation in the aerodynamic cycle to determine the test section flow characteristics near the Advanced Turboprop Project propeller model plane of rotation. The investigation used an eight-probe pitot static flow survey rake to measure total and static pressures at two locations in the wind tunnel: the test section and the bellmouth section (upstream of the two-dimensional flexible-wall nozzle). A cone angularity probe was used to measure any flow angularity in the test section. The evaluation was conducted at tunnel Mach numbers from 0.10 to 0.35 and at three operating altitudes from 2,000 to 50,000 ft. which correspond to tunnel reference total pressures from 1960 to 245 psfa, respectively. The results of this experimental investigation indicate a total-pressure loss area in the center of the test section and a static-pressure gradient from the test section centerline to the wall. These total and static pressure differences were observed at all tunnel operating altitudes and diminished at lower tunnel velocities. The total-pressure loss area was also found in the bellmouth section, which indicates that the loss mechanism is not the tunnel flexible-wall nozzle. The flow in the test section is essentially axial since very small flow angles were measured. The results also indicate that a correction to the tunnel total and static pressures must be applied in order to determine accurate freestream conditions at the test section centerline.

Local distribution of wall static pressure and heat transfer on a rough flat plate impinged by a slot air jet

NASA Astrophysics Data System (ADS)

Meda, Adimurthy; Katti, Vadiraj V.

2017-08-01

The present work experimentally investigates the local distribution of wall static pressure and the heat transfer coefficient on a rough flat plate impinged by a slot air jet. The experimental parameters include, nozzle-to-plate spacing (Z /D h = 0.5-10.0), axial distance from stagnation point ( x/D h ), size of detached rib ( b = 4-12 mm) and Reynolds number ( Re = 2500-20,000). The wall static pressure on the surface is recorded using a Pitot tube and a differential pressure transmitter. Infrared thermal imaging technique is used to capture the temperature distribution on the target surface. It is observed that, the maximum wall static pressure occurs at the stagnation point ( x/D h = 0) for all nozzle-to-plate spacing ( Z/D h ) and rib dimensions studied. Coefficient of wall static pressure ( C p ) decreases monotonically with x/D h . Sub atmospheric pressure is evident in the detached rib configurations for jet to plate spacing up to 6.0 for all ribs studied. Sub atmospheric region is stronger at Z/D h = 0.5 due to the fluid accelerating under the rib. As nozzle to plate spacing ( Z/D h ) increases, the sub-atmospheric region becomes weak and vanishes gradually. Reasonable enhancement in both C p as well as Nu is observed for the detached rib configuration. Enhancement is found to decrease with the increase in the rib width. The results of the study can be used in optimizing the cooling system design.

Multiple Launch Rocket System (MLRS) Fuze.

DTIC Science & Technology

1982-06-18

8217This is to be expected, since the probes are near the axis of symmetry 08 (where the bow shock wave is most nearly normal) and, being Pitot probes ...that simulated altitudes from 15.2 Km to 21 Km. The fuze ogive was instrumented with both static and pitot pressure probes , from which the pressure data...insights into the flow. Because the bow shock wave is curved, the static-pressure on the-- .urface should decrease from avalue__ of the stagnation pressure

Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

NASA Astrophysics Data System (ADS)

Rodi, A. R.; Leon, D. C.

2012-11-01

A method is described that estimates the error in the static pressure measurement on an aircraft from differential pressure measurements on the hemispherical surface of a Rosemount model 858AJ air velocity probe mounted on a boom ahead of the aircraft. The theoretical predictions for how the pressure should vary over the surface of the hemisphere, involving an unknown sensitivity parameter, leads to a set of equations that can be solved for the unknowns - angle of attack, angle of sideslip, dynamic pressure and the error in static pressure - if the sensitivity factor can be determined. The sensitivity factor was determined on the University of Wyoming King Air research aircraft by comparisons with the error measured with a carefully designed sonde towed on connecting tubing behind the aircraft - a trailing cone - and the result was shown to have a precision of about ±10 Pa over a wide range of conditions, including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system are used to estimate acceleration effects on the error, and the algorithm is shown to predict corrections to a precision of better than ±20 Pa under those conditions. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are discussed.

Microenvironment is involved in cellular response to hydrostatic pressures during chondrogenesis of mesenchymal stem cells.

PubMed

Ye, Rui; Hao, Jin; Song, Jinlin; Zhao, Zhihe; Fang, Shanbao; Wang, Yating; Li, Juan

2014-06-01

Chondrocytes integrate numerous microenvironmental cues to mount physiologically relevant differentiation responses, and the regulation of mechanical signaling in chondrogenic differentiation is now coming into intensive focus. To facilitate tissue-engineered chondrogenesis by mechanical strategy, a thorough understanding about the interactional roles of chemical factors under mechanical stimuli in regulating chondrogenesis is in great need. Therefore, this study attempts to investigate the interaction of rat MSCs with their microenvironment by imposing dynamic and static hydrostatic pressure through modulating gaseous tension above the culture medium. Under dynamic pressure, chemical parameters (pH, pO2, and pCO2) were kept in homeostasis. In contrast, pH was remarkably reduced due to increased pCO2 under static pressure. MSCs under the dynamically pressured microenvironment exhibited a strong accumulation of GAG within and outside the alginate beads, while cells under the statically pressured environment lost newly synthesized GAG into the medium with a speed higher than its production. In addition, the synergic influence on expression of chondrogenic genes was more persistent under dynamic pressure than that under static pressure. This temporal contrast was similar to that of activation of endogenous TGF-β1. Taken altogether, it indicates that a loading strategy which can keep a homeostatic chemical microenvironment is preferred, since it might sustain the stimulatory effects of mechanical stimuli on chondrogenesis via activation of endogenous TGF-β1. © 2013 Wiley Periodicals, Inc.

Pressure activated stability-bypass-control valves to increase the stable airflow range of a Mach 2.5 inlet with 40 percent internal contraction

NASA Technical Reports Server (NTRS)

Mitchell, G. A.; Sanders, B. W.

1974-01-01

The throat of a Mach 2.5 inlet with a coldpipe termination was fitted with a stability-bypass system. The inlet stable airflow range provided by various stability-bypass entrance configurations in alternate combination with several stability-bypass exit controls was determined for both steady-state conditions and internal transient pulses. Transient results were also obtained for the inlet with a choke point at the diffuser exit. Instart angles of attack were determined for the various stability-bypass entrance configurations. The response of the inlet-coldpipe system to internal and external oscillating disturbances was determined. Poppet valves at the stability-bypass exit provided an inlet stable airflow range of 28 percent or greater at all static and transient conditions.

Schlieren photographs and internal pressure distributions for three-dimensional sidewall-compression scramjet inlets at a Mach number of 6 in CF4

NASA Technical Reports Server (NTRS)

Holland, Scott D.

1993-01-01

Three-dimensional sidewall-compression scramjet inlets with leading-edge sweeps of 30 deg and 70 deg were tested in the Langley Hypersonic CF4 Tunnel at a Mach number of 6 and a free-stream ratio of specific heats of 1.2. The parametric effects of leading-edge sweep, cowl position, contraction ratio, and Reynolds number were investigated. The models were instrumented with static pressure orifices distributed on the sidewalls, baseplate, and cowl. Schlieren movies were made of selected tunnel runs for flow visualization of the entrance plane and cowl region. Although these movies could not show the internal flow, the effect of the internal flow on the external flow was evident by way of spillage. The purpose is to provide a preliminary data release for the investigation. The models, facility, and testing methods are described, and the test matrix and a tabulation of tunnel runs are provided. Line plots highlighting the stated parametric effects and a representative set of schlieren photographs are presented without analysis.

Two-dimensional converging-diverging rippled nozzles at transonic speeds. [performed in the Langley 16-Foot Transonic Tunnel

NASA Technical Reports Server (NTRS)

Carlson, John R.; Asbury, Scott C.

1994-01-01

An experimental investigation was performed in the Langley 16-Foot Transonic tunnel to determine the effects of external and internal flap rippling on the aerodynamics of a nonaxisymmetric nozzle. Data were obtained at several Mach numbers from static conditions to 1.2 over a range of nozzle pressure ratios. Nozzles with chordal boattail angles of 10, 20, and 30 degrees, with and without surface rippling, were tested. No effect on discharge coefficient due to surface rippling was observed. Internal thrust losses due to surface rippling were measured and attributed to a combination of additional internal skin friction and shock losses. External nozzle drag for the baseline configurations were generally less than that for the rippled configurations at all free-stream Mach numbers tested. The difference between the baseline and rippled nozzle drag levels generally increased with increasing boat tail angle. The thrust-minus-drag level for each rippled nozzle configuration was less than the equivalent baseline configuration for each Mach number at the design nozzle pressure ratio.

Focused Experimental and Analytical Studies of the RBCC Rocket-Ejector

NASA Technical Reports Server (NTRS)

Lehman, M.; Pal, S.; Schwes, D.; Chen, J. D.; Santoro, R. J.

1999-01-01

The rocket-ejector mode of a Rocket Based Combined Cycle Engine (RBCC) was studied through a joint experimental/analytical approach. A two-dimensional variable geometry rocket-ejector system with enhanced optical access was designed and fabricated for experimentation. The rocket-ejector system utilizes a single two-dimensional gaseous oxygen/gaseous hydrogen rocket as the ejector. To gain a systematic understanding of the rocket ejector's internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static configurations for a range of rocket operating conditions Overall system performance was obtained through Global measurements of wall static pressure profiles, heat flux profiles and engine thrust, whereas detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (gaseous oxygen, hydrogen. nitrogen and water vapor). These experimental efforts were complemented by Computational Fluid Dynamic (CFD) flowfield analyses.

Thrust imbalance of the Space Shuttle solid rocket motors

NASA Technical Reports Server (NTRS)

Foster, W. A., Jr.; Sforzini, R. H.; Shackelford, B. W., Jr.

1981-01-01

The Monte Carlo statistical analysis of thrust imbalance is applied to both the Titan IIIC and the Space Shuttle solid rocket motors (SRMs) firing in parallel, and results are compared with those obtained from the Space Shuttle program. The test results are examined in three phases: (1) pairs of SRMs selected from static tests of the four developmental motors (DMs 1 through 4); (2) pairs of SRMs selected from static tests of the three quality assurance motors (QMs 1 through 3); (3) SRMs on the first flight test vehicle (STS-1A and STS-1B). The simplified internal ballistic model utilized for computing thrust from head-end pressure measurements on flight tests is shown to agree closely with measured thrust data. Inaccuracies in thrust imbalance evaluation are explained by possible flight test instrumentation errors.

Results of Aero/Acoustic Tests and Analytical Studies of a Two-Dimensional Eight-Lobe Mixer-Ejector Exhaust Nozzle at Takeoff Conditions

NASA Technical Reports Server (NTRS)

Harrington, Douglas (Technical Monitor); Schweiger, P.; Stern, A.; Gamble, E.; Barber, T.; Chiappetta, L.; LaBarre, R.; Salikuddin, M.; Shin, H.; Majjigi, R.

2005-01-01

Hot flow aero-acoustic tests were conducted with Pratt & Whitney's High-Speed Civil Transport (HSCT) Mixer-Ejector Exhaust Nozzles by General Electric Aircraft Engines (GEAE) in the GEAE Anechoic Freejet Noise Facility (Cell 41) located in Evendale, Ohio. The tests evaluated the impact of various geometric and design parameters on the noise generated by a two-dimensional (2-D) shrouded, 8-lobed, mixer-ejector exhaust nozzle. The shrouded mixer-ejector provides noise suppression by mixing relatively low energy ambient air with the hot, high-speed primary exhaust jet. Additional attenuation was obtained by lining the shroud internal walls with acoustic panels, which absorb acoustic energy generated during the mixing process. Two mixer designs were investigated, the high mixing "vortical" and aligned flow "axial", along with variations in the shroud internal mixing area ratios and shroud length. The shrouds were tested as hardwall or lined with acoustic panels packed with a bulk absorber. A total of 21 model configurations at 1:11.47 scale were tested. The models were tested over a range of primary nozzle pressure ratios and primary exhaust temperatures representative of typical HSCT aero thermodynamic cycles. Static as well as flight simulated data were acquired during testing. A round convergent unshrouded nozzle was tested to provide an acoustic baseline for comparison to the test configurations. Comparisons were made to previous test results obtained with this hardware at NASA Glenn's 9- by 15-foot low-speed wind tunnel (LSWT). Laser velocimetry was used to investigate external as well as ejector internal velocity profiles for comparison to computational predictions. Ejector interior wall static pressure data were also obtained. A significant reduction in exhaust system noise was demonstrated with the 2-D shrouded nozzle designs.

30 CFR 18.67 - Static-pressure tests.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Static-pressure tests. 18.67 Section 18.67 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES Inspections and Tests § 18...

Wind Tunnel Model Design for the Study of Plume Effects on Sonic Boom for Isolated Exhaust Nozzles

NASA Technical Reports Server (NTRS)

Castner, Raynold S.

2010-01-01

A low cost test capability was developed at the NASA Glenn Research Center 1- by 1-Foot Supersonic Wind Tunnel (SWT), with a goal to reduce the disturbance caused by supersonic aircraft flight over populated areas. This work focused on the shock wave structure caused by the exhaust nozzle plume. Analysis and design was performed on a new rig to test exhaust nozzle plume effects on sonic boom signature. Test capability included a baseline nozzle test article and a wind tunnel model consisting of a strut, a nosecone and an upper plenum. Analysis was performed on the external and internal aerodynamic configuration, including the shock reflections from the wind tunnel walls caused by the presence of the model nosecone. This wind tunnel model was designed to operate from Mach 1.4 to Mach 3.0 with nozzle pressure ratios from 6 to 12 and altitudes from 30,000 ft (4.36 psia) to 50,000 ft (1.68 psia). The model design was based on a 1 in. outer diameter, was 9 in. in overall length, and was mounted in the wind tunnel on a 3/8 in. wide support strut. For test conditions at 50,000 ft the strut was built to supply 90 psia of pressure, and to achieve 20 psia at the nozzle inlet with a maximum nozzle pressure of 52 psia. Instrumentation was developed to measure nozzle pressure ratio, and an external static pressure probe was designed to survey near field static pressure profiles at one nozzle diameter above the rig centerline. Model layout placed test nozzles between two transparent sidewalls in the 1 1 SWT for Schlieren photography and comparison to CFD analysis.

Wind Tunnel Model Design for the Study of Plume Effects on Sonic Boom for Isolated Exhaust Nozzles

NASA Technical Reports Server (NTRS)

Castner, Raymond S.

2009-01-01

A low cost test capability was developed at the NASA Glenn Research Center 1- by 1-Foot Supersonic Wind Tunnel (SWT), with a goal to reduce the disturbance caused by supersonic aircraft flight over populated areas. This work focused on the shock wave structure caused by the exhaust nozzle plume. Analysis and design was performed on a new rig to test exhaust nozzle plume effects on sonic boom signature. Test capability included a baseline nozzle test article and a wind tunnel model consisting of a strut, a nose cone and an upper plenum. Analysis was performed on the external and internal aerodynamic configuration, including the shock reflections from the wind tunnel walls caused by the presence of the model nosecone. This wind tunnel model was designed to operate from Mach 1.4 to Mach 3.0 with nozzle pressure ratios from 6 to 12 and altitudes from 30,000 ft (4.36 psia) to 50,000 ft (1.68 psia). The model design was based on a 1 in. outer diameter, was 9 in. in overall length, and was mounted in the wind tunnel on a 3/8 in. wide support strut. For test conditions at 50,000 ft the strut was built to supply 90 psia of pressure, and to achieve 20 psia at the nozzle inlet with a maximum nozzle pressure of 52 psia. Instrumentation was developed to measure nozzle pressure ratio, and an external static pressure probe was designed to survey near field static pressure profiles at one nozzle diameter above the rig centerline. Model layout placed test nozzles between two transparent sidewalls in the 1x1 SWT for Schlieren photography and comparison to CFD analysis.

Pressure Regulator With Internal Ejector Circulation Pump, Flow and Pressure Measurement Porting, and Fuel Cell System Integration Options

NASA Technical Reports Server (NTRS)

Vasquez, Arturo

2011-01-01

An advanced reactant pressure regulator with an internal ejector reactant circulation pump has been developed to support NASA's future fuel cell power systems needs. These needs include reliable and safe operation in variable-gravity environments, and for exploration activities with both manned and un manned vehicles. This product was developed for use in Proton Exchange Membrane Fuel Cell (PEMFC) power plant reactant circulation systems, but the design could also be applied to other fuel cell system types, (e.g., solid-oxide or alkaline) or for other gas pressure regulation and circulation needs. The regulator design includes porting for measurement of flow and pressure at key points in the system, and also includes several fuel cell system integration options. NASA has recognized ejectors as a viable alternative to mechanical pumps for use in spacecraft fuel cell power systems. The ejector motive force is provided by a variable, high-pressure supply gas that travels through the ejector s jet nozzle, whereby the pressure energy of the fluid stream is converted to kinetic energy in the gas jet. The ejector can produce circulation-to-consumption-flow ratios that are relatively high (2-3 times), and this phenomenon can potentially (with proper consideration of the remainder of the fuel cell system s design) be used to provide completely for reactant pre-humidification and product water removal in a fuel cell system. Specifically, a custom pressure regulator has been developed that includes: (1) an ejector reactant circulation pump (with interchangeable jet nozzles and mixer sections, gas-tight sliding and static seals in required locations, and internal fluid porting for pressure-sensing at the regulator's control elements) and (2) internal fluid porting to allow for flow rate and system pressure measurements. The fluid porting also allows for inclusion of purge, relief, and vacuum-breaker check valves on the regulator assembly. In addition, this regulator could also be used with NASA's advanced nonflow-through fuel cell power systems by simply incorporating a jet nozzle with an appropriate nozzle diameter.

Interaction of two-dimensional transverse jet with a supersonic mainstream

NASA Technical Reports Server (NTRS)

Kraemer, G. O.; Tiwari, S. N.

1983-01-01

The interaction of a two dimensional sonic jet injected transversely into a confined main flow was studied. The main flow consisted of air at a Mach number of 2.9. The effects of varying the jet parameters on the flow field were examined using surface pressure and composition data. Also, the downstream flow field was examined using static pressure, pitot pressure, and composition profile data. The jet parameters varied were gapwidth, jet static pressure, and injectant species of either helium or nitrogen. The values of the jet parameters used were 0.039, 0.056, and 0.109 cm for the gapwidth and 5, 10, and 20 for the jet to mainstream static pressure ratios. The features of the flow field produced by the mixing and interaction of the jet with the mainstream were related to the jet momentum. The data were used to demonstrate the validity of an existing two dimensional elliptic flow code.

MNASA as a Test for Carbon Fiber Thermal Barrier Development

NASA Technical Reports Server (NTRS)

Bauer, Paul; McCool, Alex (Technical Monitor)

2001-01-01

A carbon fiber rope thermal barrier is being evaluated as a replacement for the conventional room temperature vulcanizing (RTV) thermal barrier that is currently used to protect o-rings in Reusable Solid Rocket Motor (RSRM) nozzle joints. Performance requirements include its ability to cool any incoming, hot propellant gases that fill and pressurize the nozzle joints, filter slag and particulates, and to perform adequately in various joint assembly conditions as well as dynamic flight motion. Modified National Aeronautics and Space Administration (MNASA) motors, with their inherent and unique ability to replicate select RSRM internal environment features, were an integral step in the development path leading to full scale RSRM static test demonstration of the carbon fiber rope (CFR) joint concept. These 1/4 scale RSRM motors serve to bridge the gap between the other classes of subscale test motors (extremely small and moderate duration, or small scale and short duration) and the critical asset RSRM static test motors. A series of MNASA tests have been used to demonstrate carbon fiber rope performance and have provided rationale for implementation into a full-scale static motor and flight qualification.

Comparative Tests of Pitot-static Tubes

NASA Technical Reports Server (NTRS)

Merriam, Kenneth G; Spaulding, Ellis R

1935-01-01

Comparative tests were made on seven conventional Pitot-static tubes to determine their static, dynamic, and resultant errors. The effect of varying the dynamic opening, static opening, wall thickness, and inner-tube diameter was investigated. Pressure-distribution measurements showing stem and tip effects were also made. A tentative design for a standard Pitot-static tube for use in measuring air velocity is submitted.

Category 5 Suppressive Shield (TDP)

DTIC Science & Technology

1975-10-01

side- on overpressure. 3.1.3 Quasi -static Pressure. Pressure levels as measured by the PCB101A02 trans- ducers were in general difficult to...apparent: (1) The observed quasi -static pressures PnM are in general somewhnl less than the OOOiipomMng calculated values based on closed-box...explained by off-center combustion of the illuminant mix and directional convection of the reaction pro- ducts. Posttest ash deposits on the floor

Effect of static pressure on acoustic energy radiated by cavitation bubbles in viscous liquids under ultrasound.

PubMed

Yasui, Kyuichi; Towata, Atsuya; Tuziuti, Toru; Kozuka, Teruyuki; Kato, Kazumi

2011-11-01

The effect of static pressure on acoustic emissions including shock-wave emissions from cavitation bubbles in viscous liquids under ultrasound has been studied by numerical simulations in order to investigate the effect of static pressure on dispersion of nano-particles in liquids by ultrasound. The results of the numerical simulations for bubbles of 5 μm in equilibrium radius at 20 kHz have indicated that the optimal static pressure which maximizes the energy of acoustic waves radiated by a bubble per acoustic cycle increases as the acoustic pressure amplitude increases or the viscosity of the solution decreases. It qualitatively agrees with the experimental results by Sauter et al. [Ultrason. Sonochem. 15, 517 (2008)]. In liquids with relatively high viscosity (∼200 mPa s), a bubble collapses more violently than in pure water when the acoustic pressure amplitude is relatively large (∼20 bar). In a mixture of bubbles of different equilibrium radius (3 and 5 μm), the acoustic energy radiated by a 5 μm bubble is much larger than that by a 3 μm bubble due to the interaction with bubbles of different equilibrium radius. The acoustic energy radiated by a 5 μm bubble is substantially increased by the interaction with 3 μm bubbles.

Numerical Predictions of Static-Pressure-Error Corrections for a Modified T-38C Aircraft

DTIC Science & Technology

2014-12-15

but the more modern work of Latif et al . [11] demonstrated that compensated Pitot-static probes can be simulated accurately for subsonic and...what was originally estimated from CFD simulations in Bhamidipati et al . [3] by extracting the static-pressure error in front of the production probe...Aerodynamically Compensating Pitot Tube,” Journal of Aircraft, Vol. 25, No. 6, 1988, pp. 544–547. doi:10.2514/3.45620 [11] Latif , A., Masud, J., Sheikh, S. R., and

NMR evidence for static local nematicity and its cooperative interplay with low-energy magnetic fluctuations in FeSe under pressure

DOE PAGES

Wiecki, P.; Nandi, M.; Bohmer, Anna; ...

2017-11-13

Here, we present 77Se -NMR measurements on single-crystalline FeSe under pressures up to 2 GPa. Based on the observation of the splitting and broadening of the NMR spectrum due to structural twin domains, we discovered that static, local nematic ordering exists well above the bulk nematic ordering temperature, T s. The static, local nematic order and the low-energy stripe-type antiferromagnetic spin fluctuations, as revealed by NMR spin-lattice relaxation rate measurements, are both insensitive to pressure application. Our NMR results provide clear evidence for the microscopic cooperation between magnetism and local nematicity in FeSe.

NMR evidence for static local nematicity and its cooperative interplay with low-energy magnetic fluctuations in FeSe under pressure

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

Wiecki, P.; Nandi, M.; Bohmer, Anna

Here, we present 77Se -NMR measurements on single-crystalline FeSe under pressures up to 2 GPa. Based on the observation of the splitting and broadening of the NMR spectrum due to structural twin domains, we discovered that static, local nematic ordering exists well above the bulk nematic ordering temperature, T s. The static, local nematic order and the low-energy stripe-type antiferromagnetic spin fluctuations, as revealed by NMR spin-lattice relaxation rate measurements, are both insensitive to pressure application. Our NMR results provide clear evidence for the microscopic cooperation between magnetism and local nematicity in FeSe.

Theory for solubility in static systems

NASA Astrophysics Data System (ADS)

Gusev, Andrei A.; Suter, Ulrich W.

1991-06-01

A theory for the solubility of small particles in static structures has been developed. The distribution function of the solute in a frozen solid has been derived in analytical form for the quantum and the quasiclassical cases. The solubility at infinitesimal gas pressure (Henry's constant) as well as the pressure dependence of the solute concentration at elevated pressures has been found from the statistical equilibrium between the solute in the static matrix and the ideal-gas phase. The distribution function of a solute containing different particles has been evaluated in closed form. An application of the theory to the sorption of methane in the computed structures of glassy polycarbonate has resulted in a satisfactory agreement with experimental data.

Wall Pressure Unsteadiness and Side Loads in Overexpanded Rocket Nozzles

NASA Technical Reports Server (NTRS)

Baars, Woutijn J.; Tinney, Charles E.; Ruf, Joseph H.; Brown, Andrew M.; McDaniels, David M.

2012-01-01

Surveys of both the static and dynamic wall pressure signatures on the interior surface of a sub-scale, cold-flow and thrust optimized parabolic nozzle are conducted during fixed nozzle pressure ratios corresponding to FSS and RSS states. The motive is to develop a better understanding for the sources of off-axis loads during the transient start-up of overexpanded rocket nozzles. During FSS state, pressure spectra reveal frequency content resembling SWTBLI. Presumably, when the internal flow is in RSS state, separation bubbles are trapped by shocks and expansion waves; interactions between the separated flow regions and the waves produce asymmetric pressure distributions. An analysis of the azimuthal modes reveals how the breathing mode encompasses most of the resolved energy and that the side load inducing mode is coherent with the response moment measured by strain gauges mounted upstream of the nozzle on a flexible tube. Finally, the unsteady pressure is locally more energetic during RSS, albeit direct measurements of the response moments indicate higher side load activity when in FSS state. It is postulated that these discrepancies are attributed to cancellation effects between annular separation bubbles.

An Investigation of the McDonnell XP-85 Airplane in the Ames 40- by 80-Foot Wind Tunnel: Pressure-Distribution Tests

NASA Technical Reports Server (NTRS)

Hunton, Lynn W.; James, Harry A.

1948-01-01

Pressure measurements were made during wind-tunnel tests of the McDonnell XP-85 parasite fighter. Static-pressure orifices were located over the fuselage nose, over the canopy, along the wing root, and along the upper and lower stabilizer roots. A total-pressure and static-pressure rake was located in the turbojet engine air-intake duct. It was installed at the station where the compressor face would be located. Pressure data were obtained for two airplane conditions, clean and with skyhook extended, through a range of angle of attack and a range of yaw.

The NASA Langley Isolator Dynamics Research Lab

NASA Technical Reports Server (NTRS)

Middleton, Troy F.; Balla, Robert J.; Baurle, Robert A.; Humphreys, William M.; Wilson, Lloyd G.

2010-01-01

The Isolator Dynamics Research Lab (IDRL) is under construction at the NASA Langley Research Center in Hampton, Virginia. A unique test apparatus is being fabricated to support both wall and in-stream measurements for investigating the internal flow of a dual-mode scramjet isolator model. The test section is 24 inches long with a 1-inch by 2-inch cross sectional area and is supplied with unheated, dry air through a Mach 2.5 converging-diverging nozzle. The test section is being fabricated with two sets (glass and metallic) of interchangeable sidewalls to support flow visualization and laser-based measurement techniques as well as static pressure, wall temperature, and high frequency pressure measurements. During 2010, a CFD code validation experiment will be conducted in the lab in support of NASA s Fundamental Aerodynamics Program. This paper describes the mechanical design of the Isolator Dynamics Research Lab test apparatus and presents a summary of the measurement techniques planned for investigating the internal flow field of a scramjet isolator model.

Comparison of quasi-static and dynamic squats: a three-dimensional kinematic, kinetic and electromyographic study of the lower limbs.

PubMed

Clément, Julien; Hagemeister, Nicola; Aissaoui, Rachid; de Guise, Jacques A

2014-01-01

Numerous studies have described 3D kinematics, 3D kinetics and electromyography (EMG) of the lower limbs during quasi-static or dynamic squatting activities. One study compared these two squatting conditions but only at low speed on healthy subjects, and provided no information on kinetics and EMG of the lower limbs. The purpose of the present study was to contrast simultaneous recordings of 3D kinematics, 3D kinetics and EMG of the lower limbs during quasi-stat ic and fast-dynamic squats in healthy and pathological subjects. Ten subjects were recruited: five healthy and five osteoarthritis subjects. A motion-capture system, force plate, and surface electrodes respectively recorded 3D kinematics, 3D kinetics and EMG of the lower limbs. Each subject performed a quasi-static squat and several fast-dynamic squats from 0° to 70° of knee flexion. The two squatting conditions were compared for positions where quasi-static and fast-dynamic knee flexion-extension angles were similar. Mean differences between quasi-static and fast-dynamic squats were 1.5° for rotations, 1.9 mm for translations, 2.1% of subjects' body weight for ground reaction forces, 6.6 Nm for torques, 11.2 mm for center of pressure, and 6.3% of maximum fast-dynamic electromyographic activities for EMG. Some significant differences (p<0.05) were found in internal rotation, anterior translation, vertical force and EMG. All differences between quasi-static and fast-dynamic squats were small. 69.5% of compared data were equivalent. In conclusion, this study showed that quasi-static and fast-dynamic squatting activities are comparable in terms of 3D kinematics, 3D kinetics and EMG, although some reservations still remain. Copyright © 2014 Elsevier B.V. All rights reserved.

Scramjet Isolator Modeling and Control

DTIC Science & Technology

2011-12-01

12 γ Ratio of specific heats . . . . . . . . . . . . . . . . . . . . 12 p1 Static pressure entering shock . . . . . . . . . . . . . . . . 12 M1 Mach...138 MAve Average stream Mach number . . . . . . . . . . . . . . . . 138 γ Ratio of specific heats ... heats , p1 is the static pressure entering the shock, and M1 is the Mach number of the flow entering the shock. Subsequent researchers [9] took a

30 CFR 250.1153 - When must I conduct a static bottomhole pressure survey?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER... following conditions: If you have . . . Then you must conduct . . . (1) A new producing reservoir A static bottomhole pressure survey within 90 days after the date of first continuous production. (2) A reservoir with...

30 CFR 250.1153 - When must I conduct a static bottomhole pressure survey?

Code of Federal Regulations, 2010 CFR

2010-07-01

... INTERIOR OFFSHORE OIL AND GAS AND SULPHUR OPERATIONS IN THE OUTER CONTINENTAL SHELF Oil and Gas Production... you must conduct . . . (1) A new producing reservoir A static bottomhole pressure survey within 90 days after the date of first continuous production. (2) A reservoir with three or more producing...

Structural integrity of a confinement vessel for testing nuclear fuels for space propulsion

NASA Astrophysics Data System (ADS)

Bergmann, V. L.

Nuclear propulsion systems for rockets could significantly reduce the travel time to distant destinations in space. However, long before such a concept can become reality, a significant effort must be invested in analysis and ground testing to guide the development of nuclear fuels. Any testing in support of development of nuclear fuels for space propulsion must be safely contained to prevent the release of radioactive materials. This paper describes analyses performed to assess the structural integrity of a test confinement vessel. The confinement structure, a stainless steel pressure vessel with bolted flanges, was designed for operating static pressures in accordance with the ASME Boiler and Pressure Vessel Code. In addition to the static operating pressures, the confinement barrier must withstand static overpressures from off-normal conditions without releasing radioactive material. Results from axisymmetric finite element analyses are used to evaluate the response of the confinement structure under design and accident conditions. For the static design conditions, the stresses computed from the ASME code are compared with the stresses computed by the finite element method.

Elastoplastic State of an Elliptical Cylindrical Shell with a Circular Hole

NASA Astrophysics Data System (ADS)

Storozhuk, E. A.; Chernyshenko, I. S.; Pigol', O. V.

2017-11-01

Static problems for an elastoplastic elliptical cylindrical shell with a circular hole are formulated and a numerical method for solving it is developed. The basic equations are derived using the Kirchhoff-Love theory of deep shells and the theory of small elastoplastic strains. The method employs the method of additional stresses and the finite-element method. The influence of plastic strains and geometrical parameters of the shell subject to internal pressure on the distributions of stresses, strains, and displacements in the zone of their concentration is studied.

In-flight comparisons of boundary-layer and wake measurement probes for incompressible flow

NASA Technical Reports Server (NTRS)

Mertaugh, L. J., Jr.

1972-01-01

The results are presented of in-flight comparisons of a number of boundary-layer and wake measurement probes suitable for low-speed flight-test investigations. The tested boundary-layer probes included a traversing total-pressure probe and a hot-film probe mounted on an internally-mounted drive mechanism, a curved and a straight boundary-layer rake, and a traversing hot-film probe with an externally-mounted drive mechanism. The wake measuring devices included a traversing, self-aligning probe, a wake rake, and an integrating wake rate. The boundary-layer data are compared with a common reference velocity profile and comments given regarding the accuracy of the static-pressure and total-pressure measurements. Discussions on the various calibration presentations used with hot-wire and hot-film sensors and various aspects of improving the accuracy of hot-film sensor results are given in the appendix of this report.

Wind-tunnel tests on a 3-dimensional fixed-geometry scramjet inlet at M = 2.30 to 4.60

NASA Technical Reports Server (NTRS)

Mueller, J. N.; Trexler, C. A.; Souders, S. W.

1977-01-01

Wind-tunnel tests were conducted on a baseline scramjet inlet model having fixed geometry and swept leading edges at M = 2.30, 2.96, 3.95, and 4.60 in the Langley unitary plan wind tunnel. The unit Reynolds number of the tests was held constant at 6.56 million per meter (2 million per foot). The objectives of the tests were to establish inlet performance and starting characteristics in the lower Mach number range of operation (less than M = 5). Surface pressures obtained on the inlet components are presented, along with the results of the internal flow surveys made at the throat and capture stations of the inlet. Contour plots of the inlet-flow-field parameters such as Mach numbers, pressure recovery, flow capture, local static and total pressure ratios at the survey stations are shown for the test Mach numbers.

High temperature and frequency pressure sensor based on silicon-on-insulator layers

NASA Astrophysics Data System (ADS)

Zhao, Y. L.; Zhao, L. B.; Jiang, Z. D.

2006-03-01

Based on silicon on insulator (SOI) technology, a novel high temperature pressure sensor with high frequency response is designed and fabricated, in which a buried silicon dioxide layer in the silicon material is developed by the separation by implantation of oxygen (SIMOX) technology. This layer can isolate leak currents between the top silicon layer for the detecting circuit and body silicon at a temperature of about 200 °C. In addition, the technology of silicon and glass bonding is used to create a package of the sensor without internal strain. A structural model and test data from the sensor are presented. The experimental results showed that this kind of sensor possesses good static performance in a high temperature environment and high frequency dynamic characteristics, which may satisfy the pressure measurement demands of the oil industry, aviation and space, and so on.

Dynamics of a 4x6-Meter Thin Film Elliptical Inflated Membrane for Space Applications

NASA Technical Reports Server (NTRS)

Casiano, Matthew J.; Hamidzadeh, Hamid R.; Tinker, Michael L.; McConnaughey, Paul R. (Technical Monitor)

2002-01-01

Dynamic characterization of a thin film inflatable elliptical structure is described in detail. A two-step finite element modeling approach in MSC/NASTRAN is utilized, consisting of (1) a nonlinear static pressurization procedure used to obtain the updated stiffness matrix, and (2) a modal "restart" eigen solution that uses the modified stiffness matrix. Unique problems encountered in modeling of this large Hexameter lightweight inflatable arc identified, including considerable difficulty in obtaining convergence in the nonlinear finite element pressurization solution. It was found that the extremely thin polyimide film material (.001 in or 1 mil) presents tremendous problems in obtaining a converged solution when internal pressure loading is applied. Approaches utilized to overcome these difficulties are described. Comparison of finite element predictions for frequency and mode shapes of the inflated structure with closed-form solutions for a flat pre-tensioned membrane indicate reasonable agreement.

Steady hydromagnetic flows in open magnetic fields. II - Global flows with static zones

NASA Technical Reports Server (NTRS)

Tsinganos, K.; Low, B. C.

1989-01-01

A theoretical study of an axisymmetric steady stellar wind with a static zone is presented, with emphasis on the situation where the global magnetic field is symmetrical about the stellar equator and is partially open. In this scenario, the wind escapes in open magnetic fluxes originating from a region at the star pole and a region at an equatorial belt of closed magnetic field in static equilibrium. The two-dimensional balance of the pressure gradient and the inertial, gravitational, and Lorentz forces in different parts of the flow are studied, along with the static interplay between external sources of energy (heating and/or cooling) distributed in the flow and the pressure distribution.

High strain rate properties of off-axis composite laminates, part 2

NASA Technical Reports Server (NTRS)

Daniel, I. M.

1991-01-01

Unidirectional off-axis graphite/epoxy and graphite/S-glass/epoxy laminates were characterized in uniaxial tension at strain rates ranging from quasi-static to over 500 s(sup -1). Laminate ring specimens were loaded by internal pressure with the tensile stress at 22.5, 30, and 45 degrees relative to the fiber direction. Results were presented in the form of stress-strain curves to failure. Properties determined included moduli, Poisson's ratios, strength, and ultimate strain. In all three laminates of both materials the modulus and strength increase sharply with strain rate, reaching values roughly 100, 150, and 200 percent higher than corresponding static values for the 22.5(sub 8), 30(sub 8), and 45(sub 8) degree laminates, respectively. In the case of ultimate strain no definite trends could be established, but the maximum deviation from the average of any value for any strain rate was less than 18 percent.

Experimental Characterization of Gas Turbine Emissions at Simulated Flight Altitude Conditions

NASA Technical Reports Server (NTRS)

Howard, R. P.; Wormhoudt, J. C.; Whitefield, P. D.

1996-01-01

NASA's Atmospheric Effects of Aviation Project (AEAP) is developing a scientific basis for assessment of the atmospheric impact of subsonic and supersonic aviation. A primary goal is to assist assessments of United Nations scientific organizations and hence, consideration of emissions standards by the International Civil Aviation Organization (ICAO). Engine tests have been conducted at AEDC to fulfill the need of AEAP. The purpose of these tests is to obtain a comprehensive database to be used for supplying critical information to the atmospheric research community. It includes: (1) simulated sea-level-static test data as well as simulated altitude data; and (2) intrusive (extractive probe) data as well as non-intrusive (optical techniques) data. A commercial-type bypass engine with aviation fuel was used in this test series. The test matrix was set by parametrically selecting the temperature, pressure, and flow rate at sea-level-static and different altitudes to obtain a parametric set of data.

Characterization of Space Shuttle Reusable Rocket Motor Static Test Stand Thrust Measurements

NASA Technical Reports Server (NTRS)

Cook, Mart L.; Gruet, Laurent; Cash, Stephen F. (Technical Monitor)

2003-01-01

Space Shuttle Reusable Solid Rocket Motors (RSRM) are static tested at two ATK Thiokol Propulsion facilities in Utah, T-24 and T-97. The newer T-97 static test facility was recently upgraded to allow thrust measurement capability. All previous static test motor thrust measurements have been taken at T-24; data from these tests were used to characterize thrust parameters and requirement limits for flight motors. Validation of the new T-97 thrust measurement system is required prior to use for official RSRM performance assessments. Since thrust cannot be measured on RSRM flight motors, flight motor measured chamber pressure and a nominal thrust-to-pressure relationship (based on static test motor thrust and pressure measurements) are used to reconstruct flight motor performance. Historical static test and flight motor performance data are used in conjunction with production subscale test data to predict RSRM performance. The predicted motor performance is provided to support Space Shuttle trajectory and system loads analyses. Therefore, an accurate nominal thrust-to-pressure (F/P) relationship is critical for accurate RSRM flight motor performance and Space Shuttle analyses. Flight Support Motors (FSM) 7, 8, and 9 provided thrust data for the validation of the T-97 thrust measurement system. The T-97 thrust data were analyzed and compared to thrust previously measured at T-24 to verify measured thrust data and identify any test-stand bias. The T-97 FIP data were consistent and within the T-24 static test statistical family expectation. The FSMs 7-9 thrust data met all NASA contract requirements, and the test stand is now verified for future thrust measurements.

Constant-Differential-Pressure Two-Fluid Accumulator

NASA Technical Reports Server (NTRS)

Piecuch, Benjamin; Dalton, Luke T.

2010-01-01

A two-fluid accumulator has been designed, built, and demonstrated to provide an acceptably close approximation to constant differential static pressure between two fluids over the full ranges of (1) accumulator stroke, (2) rates of flow of the fluids, and (3) common static pressure applied to the fluids. Prior differential- pressure two-fluid accumulators are generally not capable of maintaining acceptably close approximations to constant differential pressures. The inadequacies of a typical prior differential-pressure two-fluid accumulator can be summarized as follows: The static differential pressure is governed by the intrinsic spring rate (essentially, the stiffness) of an accumulator tank. The spring rate can be tailored through selection of the tank-wall thickness, selection of the number and/or shape of accumulator convolutions, and/or selection of accumulator material(s). Reliance on the intrinsic spring rate of the tank results in three severe limitations: (1) The spring rate and the expulsion efficiency tend to be inversely proportional to each other: that is to say, as the stiffness (and thus the differential pressure) is increased, the range of motion of the accumulator is reduced. (2) As the applied common static pressure increases, the differential pressure tends to decrease. An additional disadvantage, which may or may not be considered limiting, depending on the specific application, is that an increase in stiffness entails an increase in weight. (3) The additional weight required by a low expulsion efficiency accumulator eliminates the advantage given to such gas storage systems. The high expulsion efficiency provided by this two-fluid accumulator allows for a lightweight, tightly packaged system, which can be used in conjunction with a fuel cell-based system.

The Effect of Hemodynamics on Cerebral Aneurysm Morphology

NASA Astrophysics Data System (ADS)

Metcalfe, Ralph; Mantha, Aishwarya; Karmonik, Christof; Strother, Charles

2004-11-01

One of the difficulties in applying principles of hemodynamics to the study of blood flow in aneurysms are the drastic variations in possible shape of both the aneurysms and the parent arteries in the region of interest. We have taken data from three para-opthalmic internal carotid artery aneurysms using 3D-digital subtraction angiography (3D-DSA) and performed CFD simulations of steady and unsteady flows through the three different cases using the same pressure gradients and pulsatile flow waveforms (based on the Ku model for flow through the Carotid bifurcation). We have found that the total pressure differential within the aneurysms is consistent with the direction of flow, and that the dynamic pressure gradient within the aneurysm is very small compared with the static pressure variations. Wall shear stresses were highest near regions of sharp arterial curvature, but always remained low inside the aneurysm. These results suggest a more complex role for hemodynamics in aneurysm generation, growth and rupture.

Shock-induced transformations in the system NaAlSiO4-SiO2 - A new interpretation

NASA Technical Reports Server (NTRS)

Sekine, Toshimori; Ahrens, Thomas J.

1992-01-01

New internally consistent interpretations of the phases represented by the high pressure phase shock wave data for an albite-rich rock, jadeite, and nepheline in the system NaAlSiO4-SiO2, are obtained using the results of static high pressure investigations, and the recent discovery of the hollandite phase in a shocked meteorite. We conclude that nepheline transforms directly to the calcium ferrite structure, whereas albite transforms possibly to the hollandite structure. Shock Hugoniots for the other plagioclase and alkali feldspars also indicate that these transform to hollandite structures. The pressure-volume data at high pressure could alternatively represent the compression of an amorphous phase. Moreover, the shock Hugoniot data are expected to reflect the properties of the melt above shock stresses of 60-80 GPa. The third order Birch-Murnaghan equation of state parameters are given for the calcium ferrite type NaAlSiO4 and for albite-rich, orthoclase-rich, and anorthite-rich hollandites.

Dynamic tester for rotor seals and bearings

NASA Technical Reports Server (NTRS)

Vonpragenau, George L. (Inventor)

1993-01-01

A dynamic tester for testing vibration damping seals and bearings is constructed having a hollow shaft extending through the seal or bearing, with the shaft internally supported at each end by fluid bearings on hollow bosses connected to an interior of an enclosure, with no rolling members connected to the shaft is described. A high pressure working fluid is forced through the hollow bosses to operate the bearings. Additionally, the shaft is provided with a reaction turbine that angularly vents a portion of the high pressure working fluid in order to rotate the shaft at high speed, up to 40,000 rpm. The seal or bearing is mounted in a bushing, in turn supported by rods to a shaking device that vibrates the seal or bearing as the shaft is rotated. A plurality of proximity sensors are mounted from outside the enclosure to sense shaft and seal bushing vibrations, and a plurality of pressure ports are disposed in the enclosure to allow sensing of dynamic and static pressures of the testing apparatus.

Internal performance of two nozzles utilizing gimbal concepts for thrust vectoring

NASA Technical Reports Server (NTRS)

Berrier, Bobby L.; Taylor, John G.

1990-01-01

The internal performance of an axisymmetric convergent-divergent nozzle and a nonaxisymmetric convergent-divergent nozzle, both of which utilized a gimbal type mechanism for thrust vectoring was evaluated in the Static Test Facility of the Langley 16-Foot Transonic Tunnel. The nonaxisymmetric nozzle used the gimbal concept for yaw thrust vectoring only; pitch thrust vectoring was accomplished by simultaneous deflection of the upper and lower divergent flaps. The model geometric parameters investigated were pitch vector angle for the axisymmetric nozzle and pitch vector angle, yaw vector angle, nozzle throat aspect ratio, and nozzle expansion ratio for the nonaxisymmetric nozzle. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 2.0 to approximately 12.0.

Water Ingestion into Axial Flow Compressors. Part III. Experimental Results and Discussion

DTIC Science & Technology

1981-10-01

total pressure, static pressure, and temperature at both compressor inlet and outlet. A United Sensor model PDC-12-G-l0-KL pitot-static pressure probe...Test Compressor inlet and outlet temperatures during water injection tests: United Sensor and Control Corp. type TK-8-CiA-36’-F Aspirate...ured utilizing standard aspirated thermocouples, namely an United Sensor and Control Corp. type TK-8-C/A-36-F. The Test Compressor out- let

Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators.

PubMed

Guianvarc'h, Cécile; Gavioso, Roberto M; Benedetto, Giuliana; Pitre, Laurent; Bruneau, Michel

2009-07-01

Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone's sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.

Model aerodynamic test results for two variable cycle engine coannular exhaust systems at simulated takeoff and cruise conditions. Comprehensive data report. Volume 3: Graphical data book 1

NASA Technical Reports Server (NTRS)

Nelson, D. P.

1981-01-01

A graphical presentation of the aerodynamic data acquired during coannular nozzle performance wind tunnel tests is given. The graphical data consist of plots of nozzle gross thrust coefficient, fan nozzle discharge coefficient, and primary nozzle discharge coefficient. Normalized model component static pressure distributions are presented as a function of primary total pressure, fan total pressure, and ambient static pressure for selected operating conditions. In addition, the supersonic cruise configuration data include plots of nozzle efficiency and secondary-to-fan total pressure pumping characteristics. Supersonic and subsonic cruise data are given.

User's Manual for Aerofcn: a FORTRAN Program to Compute Aerodynamic Parameters

NASA Technical Reports Server (NTRS)

Conley, Joseph L.

1992-01-01

The computer program AeroFcn is discussed. AeroFcn is a utility program that computes the following aerodynamic parameters: geopotential altitude, Mach number, true velocity, dynamic pressure, calibrated airspeed, equivalent airspeed, impact pressure, total pressure, total temperature, Reynolds number, speed of sound, static density, static pressure, static temperature, coefficient of dynamic viscosity, kinematic viscosity, geometric altitude, and specific energy for a standard- or a modified standard-day atmosphere using compressible flow and normal shock relations. Any two parameters that define a unique flight condition are selected, and their values are entered interactively. The remaining parameters are computed, and the solutions are stored in an output file. Multiple cases can be run, and the multiple case solutions can be stored in another output file for plotting. Parameter units, the output format, and primary constants in the atmospheric and aerodynamic equations can also be changed.

Radio jet refraction in galactic atmospheres with static pressure gradients

NASA Technical Reports Server (NTRS)

Henriksen, R. N.; Vallee, J. P.; Bridle, A. H.

1981-01-01

A theory of double radio sources which have a 'Z' or 'S' morphology is proposed, based on the refraction of radio jets in the extended atmosphere of an elliptical galaxy. The model describes a collimated jet of supersonic material bending self-consistently under the influence of external static pressure gradients. Gravity and magnetic fields are neglected in the simplest case except insofar as they determine the static pressure distribution. The calculation is a straightforward extension of a method used to calculate a ram-pressure model for twin radio trails ('C' morphology). It may also be described as a continuous-jet version of a buoyancy model proposed in 1973. The model has the added virtue of invoking a galactic atmosphere similar to those already indicated by X-ray measurements of some other radio galaxies and by models for the collimation of other radio jets.

Analysis of the separated boundary layer flow on the surface and in the wake of blunt trailing edge airfoils

NASA Technical Reports Server (NTRS)

Goradia, S. H.; Mehta, J. M.; Shrewsbury, G. S.

1977-01-01

The viscous flow phenomena associated with sharp and blunt trailing edge airfoils were investigated. Experimental measurements were obtained for a 17 percent thick, high performance GAW-1 airfoil. Experimental measurements consist of velocity and static pressure profiles which were obtained by the use of forward and reverse total pressure probes and disc type static pressure probes over the surface and in the wake of sharp and blunt trailing edge airfoils. Measurements of the upper surface boundary layer were obtained in both the attached and separated flow regions. In addition, static pressure data were acquired, and skin friction on the airfoil upper surface was measured with a specially constructed device. Comparison of the viscous flow data with data previously obtained elsewhere indicates reasonable agreement in the attached flow region. In the separated flow region, considerable differences exist between these two sets of measurements.

Performance of Several Conical Convergent-Divergent Rocket-Type Exhaust Nozzles

NASA Technical Reports Server (NTRS)

Campbell, C. E.; Farley, J. M.

1960-01-01

An investigation was conducted to obtain nozzle performance data with relatively large-scale models at pressure ratios as high as 120. Conical convergent-divergent nozzles with divergence angles alpha of 15, 25, and 29 deg. were each tested at area ratios of approximately 10, 25, and 40. Heated air (1200 F) was supplied at the nozzle inlet at pressures up to 145 pounds per square inch absolute and was exhausted into quiescent air at pressures as low as 1.2 pounds per square inch absolute. Thrust ratios for all nozzle configurations are presented over the range of pressure ratios attainable and were extrapolated when possible to design pressure ratio and beyond. Design thrust ratios decreased with increasing nozzle divergence angle according to the trend predicted by the (1 + cos alpha)/2 parameter. Decreasing the nozzle divergence angle resulted in sizable increases in thrust ratio for a given surface-area ratio (nozzle weight), particularly at low nozzle pressure ratios. Correlations of the nozzle static pressure at separation and of the average static pressure downstream of separation with various nozzle parameters permitted the calculation of thrust in the separated-flow region from unseparated static-pressure distributions. Thrust ratios calculated by this method agreed with measured values within about 1 percent.

Parametric study of a simultaneous pitch/yaw thrust vectoring single expansion ramp nozzle

NASA Technical Reports Server (NTRS)

Schirmer, Alberto W.; Capone, Francis J.

1989-01-01

In the course of the last eleven years, the concept of thrust vectoring has emerged as a promising method of enhancing aircraft control capabilities in post-stall flight incursions during combat. In order to study the application of simultaneous pitch and yaw vectoring to single expansion ramp nozzles, a static test was conducted in the NASA-Langley 16 foot transonic tunnel. This investigation was based on internal performance data provided by force, mass flow and internal pressure measurements at nozzle pressure ratios up to 8. The internal performance characteristics of the nozzle were studied for several combinations of six different parameters: yaw vectoring angle, pitch vectoring angle, upper ramp cutout, sidewall hinge location, hinge inclination angle and sidewall containment. Results indicated a 2-to- 3-percent decrease in resultant thrust ratio with vectoring in either pitch or yaw. Losses were mostly associated with the turning of supersonic flow. Resultant thrust ratios were also decreased by sideways expansion of the jet. The effects of cutback corners in the upper ramp and lower flap on performance were small. Maximum resultant yaw vector angles, about half of the flap angle, were achieved for the configuration with the most forward hinge location.

Wind tunnel investigation of three axisymmetric cowls of different lengths at Mach numbers from 0.60 to 0.92

NASA Technical Reports Server (NTRS)

Re, Richard J.; Abeyounis, William K.

1993-01-01

Pressure distributions on three inlets having different cowl lengths were obtained in the Langley 16-Foot Transonic Tunnel. The cowl diameter ratio (highlight diameter to maximum diameter) was 0.85 and the cowl length ratios (cowl length to maximum diameter) were 0.337, 0.439, and 0.547. The cowls had identical nondimensionalized (with respect to cowl length) external geometry and identical internal geometry. The internal contraction ratio (highlight area to throat area) was 1.250. The inlets had longitudinal rows of static pressure orifices on the top and bottom (external) surfaces and on the contraction (internal) and diffuser surfaces. The afterbody was cylindrical in shape, and its diameter was equal to the maximum diameter of the cowl. Depending on the cowl configuration and free-stream Mach number, the mass-flow ratio varied between 0.27 and 0.87 during the tests. Angle of attack varied from 0 to 4.1 deg at selected Mach numbers and mass-flow ratios, and the Reynolds number varied with the Mach number from 3.2x10(exp 6) to 4.2x10(exp 6) per foot.

Effects of sidewall geometry on the installed performance of nonaxisymmetric convergent-divergent exhaust nozzles

NASA Technical Reports Server (NTRS)

Yetter, J. A.; Leavitt, L. D.

1980-01-01

The investigation was conducted at static conditions and over a Mach number range from 0.6 to 1.2. Angle of attack was held constant at 0 deg. High pressure air was used to simulate jet exhaust flow at ratios of jet total pressure to free-stream static pressure from 1 (jet off) to approximately 10. Sidewall cutback appears to be a viable way of reducing nozzle weight and cooling requirements without compromising installed performance.

The effects of plantar flexor static stretching and dynamic stretching using an aero-step on foot pressure during gait in healthy adults: a preliminary study.

PubMed

Shim, Je-Myung; Jung, Ju-Hyeon; Kim, Hwan-Hee

2015-07-01

[Purpose] The aim of this study was to examine whether plantar flexor static stretching and dynamic stretching using an Aero-Step results in changes in foot pressure during gait in healthy adults. [Subjects] Eighteen normal adults were randomly allocated to either a dynamic stretching using an Aero-Step group (DSUAS) group (n = 8) or a static stretching (SS) group (n = 10). [Methods] The DSUAS and SS participants took part in an exercise program for 15 minutes. Outcome measures were foot plantar pressure, which was measured during the subject's gait stance phase; the asymmetric ratio of foot pressure for both feet; and the visual analogue scale (VAS) measured during the interventions. [Results] There were significant differences in the asymmetric ratio of foot pressure for both feet and VAS between the two groups after intervention. However, there were no significant differences in foot plantar pressure during the gait stance phase within both groups. [Conclusion] DSUSAS is an effective stretching method, as pain during it is lower than that with SS, which can minimize the asymmetric ratio of foot pressure for both feet during gait due to asymmetric postural alignment.

A 727 airplane center duct inlet low speed performance confirmation model test for refanned JT8D engines, phase 2

NASA Technical Reports Server (NTRS)

Kaldschmidt, G.; Syltebo, B. E.; Ting, C. T.

1973-01-01

The results from testing of a 0.3 scale model center duct inlet (S duct) for the Pratt and Whitney Aircraft JT8D-100 engines are presented. The objective of this test was to demonstrate that the required airflow of the JT8D-100 engine (480 lb/sec as compared to 334 lb/sec for JT8D-15) can be achieved with minimum modifications to the existing 727 airplane structure at acceptable levels of total pressure recovery and distortion. Steady-state pressure recovery, steady-state pressure distortion, and dynamic pressure measurements were taken at the engine face station. Surface static pressure measurements were taken along the duct. Test results indicated that the required airflow was achieved with acceptable pressure recovery (comparable to the current 727-200 S duct). Inlet inflow angle variation within the 727 airplane operating regime (minus 5 to 5 degrees) had no effect on the inlet performance. Pressure distortion at static and forward speed at takeoff airflow conditions are within P and WA limits for the Phase II duct when equipped with vortex generators. Static crosswind operation between 10 knots and 25 knots appears feasible at full takeoff power.

Preston Probe Calibrations at High Reynolds Number

NASA Technical Reports Server (NTRS)

Smits, Alexander J.

1998-01-01

The overall goal of the research effort is to study the performance of two Preston probes designed by NASA Langley Research Center across an unprecedented range of Reynolds number (based on friction velocity and probe diameter), and perform an accurate calibration over the same Reynolds number range. Using the Superpipe facility in Princeton, two rounds of experiments were performed. In each round of experiments for each Reynolds number, the pressure gradient, static pressure from the Preston probes and the total pressure from the Preston probes were measured. In the first round, 3 Preston probes having outer diameters of 0.058 inches, 0.083 inches and 0.203 inches were tested over a large range of pipe Reynolds numbers. Two data reduction methods were employed: first, the static pressure measured on the Preston probe was used to calculate P (modified Preston probe configuration), and secondly, the static pressure measured at the reference pressure tap was used to calculate P (un-modified Preston probe configuration). For both methods, the static pressure was adjusted to correspond with the static pressure at the Preston probe tip using the pressure gradient. The measurements for Preston probes with diameters of 0.058 inches, and 0.083 inches respectively were performed in the test pipe before it was polished a second time. Therefore, the measurements at high pipe Reynolds numbers may have been affected by roughness. In the second round of experiments the 0.058 inches and 0.083 inches diameter, un-modified probes were tested after the pipe was polished and prepared to ensure that the surface was smooth. The average velocity was estimated by assuming that the connection between the centerline velocity and the average velocity was known, and by using a Pitot tube to measure the centerline velocity. A preliminary error estimate suggests that it is possible to introduce a 1% to 2% error in estimating the average velocity using this approach. The evidence on the errors attending the second data set is somewhat circumstantial, and the measurements have not been repeated using a better approach, it seems probable that the correlation given applies to un-modified Preston probes over the range 6.4 less than x* less than 11.3.

Motor starting a Brayton cycle power conversion system using a static inverter

NASA Technical Reports Server (NTRS)

Curreri, J. S.; Edkin, R. A.; Kruchowy, R.

1973-01-01

The power conversion module of a 2- to 15-kWe Brayton engine was motor started using a three-phase, 400-hertz static inverter as the power source. Motor-static tests were conducted for initial gas loop pressures of 10, 14, and 17 N/sq cm (15, 20, and 25 psia) over a range of initial turbine inlet temperatures from 366 to 550 K (200 to 530 F). The data are presented to show the effects of temperature and pressure on the motor-start characteristics of the rotating unit. Electrical characteristics during motoring are also discussed.

Improvement of mass transfer characteristics and productivities of inclined tubular photobioreactors by installation of internal static mixers.

PubMed

Ugwu, C U; Ogbonna, J C; Tanaka, H

2002-04-01

The feasibility of improving mass transfer characteristics of inclined tubular photobioreactors by installation of static mixers was investigated. The mass transfer characteristics of the tubular photobioreactor varied depending on the type (shape) and the number of static mixers. The volumetric oxygen transfer coefficient ( k(L)a) and gas hold up of the photobioreactor with internal static mixers were significantly higher than those of the photobioreactor without static mixers. The k(L)a and gas hold up increased with the number of static mixers but the mixing time became longer due to restricted liquid flow through the static mixers. By installing the static mixers, the liquid flow changed from plug flow to turbulent mixing so that cells were moved between the surface and bottom of the photobioreactor. In outdoor culture of Chlorella sorokiniana, the photobioreactor with static mixers gave higher biomass productivities irrespective of the standing biomass concentration and solar radiation. The effectiveness of the static mixers (average percentage increase in the productivities of the photobioreactor with static mixers over the productivities obtained without static mixers) was higher at higher standing biomass concentrations and on cloudy days (solar radiation below 6 MJ m(-2) day(-1)).

Capturing Pressure Oscillations in Numerical Simulations of Internal Combustion Engines

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

Gubba, Sreenivasa Rao; Jupudi, Ravichandra S.; Pasunurthi, Shyam Sundar

In an earlier publication, the authors compared numerical predictions of the mean cylinder pressure of diesel and dual-fuel combustion, to that of measured pressure data from a medium-speed, large-bore engine. In these earlier comparisons, measured data from a flush-mounted in-cylinder pressure transducer showed notable and repeatable pressure oscillations which were not evident in the mean cylinder pressure predictions from computational fluid dynamics (CFD). In this paper, the authors present a methodology for predicting and reporting the local cylinder pressure consistent with that of a measurement location. Such predictions for large-bore, medium-speed engine operation demonstrate pressure oscillations in accordance with thosemore » measured. The temporal occurrences of notable pressure oscillations were during the start of combustion and around the time of maximum cylinder pressure. With appropriate resolutions in time steps and mesh sizes, the local cell static pressure predicted for the transducer location showed oscillations in both diesel and dual-fuel combustion modes which agreed with those observed in the experimental data. Fast Fourier transform (FFT) analysis on both experimental and calculated pressure traces revealed that the CFD predictions successfully captured both the amplitude and frequency range of the oscillations. Furthermore, resolving propagating pressure waves with the smaller time steps and grid sizes necessary to achieve these results required a significant increase in computer resources.« less

Capturing Pressure Oscillations in Numerical Simulations of Internal Combustion Engines

DOE PAGES

Gubba, Sreenivasa Rao; Jupudi, Ravichandra S.; Pasunurthi, Shyam Sundar; ...

2018-04-09

In an earlier publication, the authors compared numerical predictions of the mean cylinder pressure of diesel and dual-fuel combustion, to that of measured pressure data from a medium-speed, large-bore engine. In these earlier comparisons, measured data from a flush-mounted in-cylinder pressure transducer showed notable and repeatable pressure oscillations which were not evident in the mean cylinder pressure predictions from computational fluid dynamics (CFD). In this paper, the authors present a methodology for predicting and reporting the local cylinder pressure consistent with that of a measurement location. Such predictions for large-bore, medium-speed engine operation demonstrate pressure oscillations in accordance with thosemore » measured. The temporal occurrences of notable pressure oscillations were during the start of combustion and around the time of maximum cylinder pressure. With appropriate resolutions in time steps and mesh sizes, the local cell static pressure predicted for the transducer location showed oscillations in both diesel and dual-fuel combustion modes which agreed with those observed in the experimental data. Fast Fourier transform (FFT) analysis on both experimental and calculated pressure traces revealed that the CFD predictions successfully captured both the amplitude and frequency range of the oscillations. Furthermore, resolving propagating pressure waves with the smaller time steps and grid sizes necessary to achieve these results required a significant increase in computer resources.« less

Denver International Airport sensor processing and database

DOT National Transportation Integrated Search

2000-03-01

Data processing and database design is described for an instrumentation system installed on runway 34R at Denver International Airport (DIA). Static (low-speed) and dynamic (high-speed) sensors are installed in the pavement. The static sensors includ...

Five-Hole Flow Angle Probe Calibration for the NASA Glenn Icing Research Tunnel

NASA Technical Reports Server (NTRS)

Gonsalez, Jose C.; Arrington, E. Allen

1999-01-01

A spring 1997 test section calibration program is scheduled for the NASA Glenn Research Center Icing Research Tunnel following the installation of new water injecting spray bars. A set of new five-hole flow angle pressure probes was fabricated to properly calibrate the test section for total pressure, static pressure, and flow angle. The probes have nine pressure ports: five total pressure ports on a hemispherical head and four static pressure ports located 14.7 diameters downstream of the head. The probes were calibrated in the NASA Glenn 3.5-in.-diameter free-jet calibration facility. After completing calibration data acquisition for two probes, two data prediction models were evaluated. Prediction errors from a linear discrete model proved to be no worse than those from a full third-order multiple regression model. The linear discrete model only required calibration data acquisition according to an abridged test matrix, thus saving considerable time and financial resources over the multiple regression model that required calibration data acquisition according to a more extensive test matrix. Uncertainties in calibration coefficients and predicted values of flow angle, total pressure, static pressure. Mach number. and velocity were examined. These uncertainties consider the instrumentation that will be available in the Icing Research Tunnel for future test section calibration testing.

Stability Improvement of High-Pressure-Ratio Turbocharger Centrifugal Compressor by Asymmetric Flow Control-Part I: Non-Axisymmetrical Flow in Centrifugal Compressor.

PubMed

Yang, Mingyang; Zheng, Xinqian; Zhang, Yangjun; Bamba, Takahiro; Tamaki, Hideaki; Huenteler, Joern; Li, Zhigang

2013-03-01

This is Part I of a two-part paper documenting the development of a novel asymmetric flow control method to improve the stability of a high-pressure-ratio turbocharger centrifugal compressor. Part I focuses on the nonaxisymmetrical flow in a centrifugal compressor induced by the nonaxisymmetrical geometry of the volute while Part II describes the development of an asymmetric flow control method to avoid the stall on the basis of the characteristic of nonaxisymmetrical flow. To understand the asymmetries, experimental measurements and corresponding numerical simulation were carried out. The static pressure was measured by probes at different circumferential and stream-wise positions to gain insights about the asymmetries. The experimental results show that there is an evident nonaxisymmetrical flow pattern throughout the compressor due to the asymmetric geometry of the overhung volute. The static pressure field in the diffuser is distorted at approximately 90 deg in the rotational direction of the volute tongue throughout the diffuser. The magnitude of this distortion slightly varies with the rotational speed. The magnitude of the static pressure distortion in the impeller is a function of the rotational speed. There is a significant phase shift between the static pressure distributions at the leading edge of the splitter blades and the impeller outlet. The numerical steady state simulation neglects the aforementioned unsteady effects found in the experiments and cannot predict the phase shift, however, a detailed asymmetric flow field structure is obviously obtained.

Redistribution Principle Approach for Evaluation of Seismic Active Earth Pressure Behind Retaining Wall

NASA Astrophysics Data System (ADS)

Maskar, A. D.; Madhekar, S. N.; Phatak, D. R.

2017-11-01

The knowledge of seismic active earth pressure behind the rigid retaining wall is very essential in the design of retaining wall in earthquake prone regions. Commonly used Mononobe-Okabe (MO) method considers pseudo-static approach. Recently there are many pseudo-dynamic methods used to evaluate the seismic earth pressure. However, available pseudo-static and pseudo-dynamic methods do not incorporate the effect of wall movement on the earth pressure distribution. Dubrova (Interaction between soils and structures, Rechnoi Transport, Moscow, 1963) was the first, who considered such effect and till date, it is used for cohesionless soil, without considering the effect of seismicity. In this paper, Dubrova's model based on redistribution principle, considering the seismic effect has been developed. It is further used to compute the distribution of seismic active earth pressure, in a more realistic manner, by considering the effect of wall movement on the earth pressure, as it is displacement based method. The effects of a wide range of parameters like soil friction angle (ϕ), wall friction angle (δ), horizontal and vertical seismic acceleration coefficients (kh and kv); on seismic active earth pressure (Kae) have been studied. Results are presented for comparison of pseudo-static and pseudo-dynamic methods, to highlight the realistic, non-linearity of seismic active earth pressure distribution. The current study results in the variation of Kae with kh in the same manner as that of MO method and Choudhury and Nimbalkar (Geotech Geol Eng 24(5):1103-1113, 2006) study. To increase in ϕ, there is a reduction in static as well as seismic earth pressure. Also, by keeping constant ϕ value, as kh increases from 0 to 0.3, earth pressure increases; whereas as δ increases, active earth pressure decreases. The seismic active earth pressure coefficient (Kae) obtained from the present study is approximately same as that obtained by previous researchers. Though seismic earth pressure obtained by pseudo-dynamic approach and seismic earth pressure obtained by redistribution principle have different background of formulation, the final earth pressure distribution is approximately same.

Modifications to the nozzle test chamber to extend nozzle static-test capability

NASA Technical Reports Server (NTRS)

Keyes, J. W.

1985-01-01

The nozzle test chamber was modified to provide a high-pressure-ratio nozzle static-test capability. Experiments were conducted to determine the range of the ratio of nozzle total pressure to chamber pressure and to make direct nozzle thrust measurements using a three-component strain-gage force balance. Pressure ratios from 3 to 285 were measured with several axisymmetric nozzles at a nozzle total pressure of 15 to 190 psia. Devices for measuring system mass flow were calibrated using standard axisymmetric convergent choked nozzles. System mass-flow rates up to 10 lbm/sec are measured. The measured thrust results of these nozzles are in good agreement with one-dimensional theoretical predictions for convergent nozzles.

DESIGN ANALYSIS OF RADIAL INFLOW TURBINES

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

This program performs a velocity-diagram analysis required for determining geometry and estimating performance for radial-inflow turbines. Input design requirements are power, mass flow rate, inlet temperature and pressure, and rotative rate. The design variables include stator-exit angle, rotor-exit-tip to rotor-inlet radius ratio, rotor-exit-hub to tip radius ratio, and the magnitude and radial distribution of rotor-exit tangential velocity. The program output includes diameters, total and static efficiences, all absolute and relative temperatures, pressures, and velocities, and flow angles at stator inlet, stator exit, rotor inlet, and rotor exit. Losses accounted for in this program by the internal loss model are three-dimensional (profile plus end wall) viscous losses in the stator and the rotor, the disk-friction loss on the back side of the rotor, the loss due to the clearance between the rotor tip and the outer casing, and the exit velocity loss. The flow analysis is one-dimensional at the stator inlet, stator exit, and rotor inlet, each of these calculation stations being at a constant radius. At the rotor exit where there is a variation in flow-field radius, an axisymmetric two-dimensional analysis is made using constant height sectors. Simple radial equilibrium is used to establish the static pressure gradient at the rotor exit. This program is written in FORTRAN V and has been implemented on a UNIVAC 1100 series computer with a memory requirement of approximately 22K of 36 bit words.

Three Dimensional Compressible Turbulent Flow Computations for a Diffusing S-Duct With/Without Vortex Generators

NASA Technical Reports Server (NTRS)

Cho, Soo-Yong; Greber, Isaac

1994-01-01

Numerical investigations on a diffusing S-duct with/without vortex generators and a straight duct with vortex generators are presented. The investigation consists of solving the full three-dimensional unsteady compressible mass averaged Navier-Stokes equations. An implicit finite volume lower-upper time marching code (RPLUS3D) has been employed and modified. A three-dimensional Baldwin-Lomax turbulence model has been modified in conjunction with the flow physics. A model for the analysis of vortex generators in a fully viscous subsonic internal flow is evaluated. A vortical structure for modeling the shed vortex is used as a source term in the computation domain. The injected vortex paths in the straight duct are compared with the analysis by two kinds of prediction models. The flow structure by the vortex generators are investigated along the duct. Computed results of the flow in a circular diffusing S-duct provide an understanding of the flow structure within a typical engine inlet system. These are compared with the experimental wall static-pressure, static- and total-pressure field, and secondary velocity profiles. Additionally, boundary layer thickness, skin friction values, and velocity profiles in wall coordinates are presented. In order to investigate the effect of vortex generators, various vortex strengths are examined in this study. The total-pressure recovery and distortion coefficients are obtained at the exit of the S-duct. The numerical results clearly depict the interaction between the low velocity flow by the flow separation and the injected vortices.

Space shuttle Production Verification Motor 1 (PV-1) static fire

NASA Technical Reports Server (NTRS)

1989-01-01

All inspection and instrumentation data indicate that the PV-1 static test firing conducted 18 Aug. 1988 was successful. With the exception of the intentionally flawed joints and static test modifications, PV-1 was flight configuration. Fail-safe flaws guaranteeing pressure to test the sealing capability of primary O-rings were included in the aft field joint, case-to-nozzle joint, and nozzle internal Joint 5. The test was conducted at ambient conditions, with the exception of the field joints and case/nozzle joints which were maintained at a minimum of 75 F. Ballistics performance values were within specification requirements. The PV-1 motor exhibited chamber pressure oscillations similar to previously tested Space Shuttle redesigned solid rocket motors, particularly QM-7. The first longitudinal mode oscillations experienced by PV-1 were the strongest ever measured in a Space Shuttle motor. Investigation into this observation is being conducted. Joint insulation performed as designed with no evidence of gas flow within unflawed forward field joints. The intentionally flawed center and aft case field joint insulation performance was excellent. There was no evidence of hot gas past the center field joint capture feature O-ring, the case-to-nozzle joint primary O-ring, or the aft field joint primary O-ring. O-ring seals and barriers with assured pressure at the flaws showed erosion and heat effect, but all sealed against passage of hot gases with the exception of the aft field joint capture feature O-ring. There was no evidence of erosion, heat effect, or blowby on any O-ring seals or barriers at the unflawed joints. Nozzle performance was nominal with typical erosion. Post-test examination revealed that the forward nose ring was of the old high performance motor design configuration with the 150-deg ply angle. All nozzle components remained intact for post-test evaluation. The thrust vector control system operated correctly. The water deluge system, CO2 quench, and other test equipment performed as planned during all required test operations.

Structural Analysis of Pressurized Small Diameter Lines in a Random Vibration Environment

NASA Technical Reports Server (NTRS)

Davis, Mark; Ridnour, Andrew; Brethen, Mark

2011-01-01

The pressurization and propellant feed lines for the Ares 1 Upper Stage Reaction and Roll Control Systems (ReCS and RoCS) were required to be in a high g-load random vibration flight environment. The lines connected the system components and were filled with both liquid hydrazine and gaseous helium. They are considered small and varied between one fourth to one inch in diameter. The random vibration of the lines was considered to be base excitation through the mating components and mounting hardware. It was found that reducing the amount of support structure for the lines added flexibility to the system and improved the line stresses from random vibration, but caused higher stresses from the static g-loads. The locations and number of brackets were optimized by analyzing the mode shapes of the lines causing high stresses. The use of brackets that only constrain motion in the direction of concern further reduced the stresses in the lines. Finite element analysis was used to perform the analysis. The lines were pre-stressed by temperature and internal pressure with fluid and insulation included as non-structural mass. Base excitation was added to the model using Power Spectral Density (PSD) data for the expected flight loads. The random vibration and static g-load cases were combined to obtain the total stress in the lines. This approach advances the state of the art in line analysis by using FEA to predict the stresses in the lines and to optimize the entire system based on the expected flight environment. Adding flexibility to lines has been used in piping system for temperature loads, but in flight environments flexibility has been limited for the static stresses. Adding flexibility to the system in a flight environment by reducing brackets has the benefit of reducing stresses and weight

Evaluation of the internal and external responsiveness of the Pressure Ulcer Scale for Healing (PUSH) tool for assessing acute and chronic wounds.

PubMed

Choi, Edmond P H; Chin, Weng Yee; Wan, Eric Y F; Lam, Cindy L K

2016-05-01

To examine the internal and external responsiveness of the Pressure Ulcer Scale for Healing (PUSH) tool for assessing the healing progress in acute and chronic wounds. It is important to establish the responsiveness of instruments used in conducting wound care assessments to ensure that they are able to capture changes in wound healing accurately over time. Prospective longitudinal observational study. The key study instrument was the PUSH tool. Internal responsiveness was assessed using paired t-testing and effect size statistics. External responsiveness was assessed using multiple linear regression. All new patients with at least one eligible acute or chronic wound, enrolled in the Nurse and Allied Health Clinic-Wound Care programme between 1 December 2012 - 31 March 2013 were included for analysis (N = 541). Overall, the PUSH tool was able to detect statistically significant changes in wound healing between baseline and discharge. The effect size statistics were large. The internal responsiveness of the PUSH tool was confirmed in patients with a variety of different wound types including venous ulcers, pressure ulcers, neuropathic ulcers, burns and scalds, skin tears, surgical wounds and traumatic wounds. After controlling for age, gender and wound type, subjects in the 'wound improved but not healed' group had a smaller change in PUSH scores than those in the 'wound healed' group. Subjects in the 'wound static or worsened' group had the smallest change in PUSH scores. The external responsiveness was confirmed. The internal and external responsiveness of the PUSH tool confirmed that it can be used to track the healing progress of both acute and chronic wounds. © 2016 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

Static and Hypersonic Experimental Analysis of Impulse Generation in Air-Breathing Laser-Thermal Propulsion

NASA Astrophysics Data System (ADS)

Salvador, Israel Irone

The present research campaign centered on static and hypersonic experiments performed with a two-dimensional, repetitively-pulsed (RP) laser Lightcraft model. The future application of interest for this basic research endeavor is the laser launch of nano- and micro-satellites (i.e., 1-100 kg payloads) into Low Earth Orbit (LEO), at low-cost and "on-demand". This research began with an international collaboration on Beamed Energy Propulsion between the United States Air Force and Brazilian Air Force to conduct experiments at the Henry T. Nagamatsu Laboratory of Aerothermodynamics and Hypersonics (HTN-LAH). The laser propulsion (LP) experiments employed the T3 Hypersonic Shock Tunnel (HST), integrated with twin gigawatt pulsed Lumonics 620-TEA CO2 lasers to produce the required test conditions. Following an introduction of the pulsed laser thermal propulsion concept and a state-of-the-art review of the topic, the principal physical processes are outlined starting from the onset of the laser pulse and subsequent laser-induced air-breakdown, to the expansion and exhaust of the resulting blast wave. After installation of the 254 mm wide, 2D Lightcraft model into the T3 tunnel, static LP tests were performed under quiescent (no-flow) conditions at ambient pressures of 0.06, 0.15, 0.3 and 1 bar, using the T3 test-section/dump-tank as a vacuum chamber. Time-dependent surface pressure distributions were measured over the engine thrust-generating surfaces following laser energy deposition; the delivered impulse and momentum coupling coefficients (Cm) were calculated from that pressure data. A Schlieren visualization system (using a high-speed Cordin digital camera) captured the laser breakdown and blast wave expansion process. The 2D model's Cm performance of 600 to 3000 N/MW was 2.5-5x higher than theoretical projections available in the literature, but indeed in the realm of feasibility for static conditions. Also, these Cm values exceed that for smaller Lightcraft models (98 to 161 mm in diameter), probably due to the more efficient delivery of laser-induced blast wave energy across the 2D model's larger impulse surface area. Next, the hypersonic campaign was carried out, subjecting the 2D model to nominal Mach numbers ranging from 6 to 10. Again, time-dependent surface pressure distributions were recorded together with Schlieren movies of the flow field structure resulting from laser energy deposition. These visualizations of inlet and absorption chamber flowfields, enabled the qualitative analysis of important phenomena impacting laser-propelled hypersonic airbreathing flight. The laser-induced breakdown took an elongated vertically-oriented geometry, occurring off-surface and across the inlet's mid-channel---quite different from the static case in which the energy was deposited very near the shroud under-surface. The shroud under-surface pressure data indicated laser-induced increases of 0.7-0.9 bar with laser pulse energies of ˜170 J, off-shroud induced breakdown condition, and Mach number of 7. The results of this research corroborate the feasibility of laser powered, airbreathing flight with infinite specific impulse (Isp=infinity): i.e., without the need for propellant injection at the laser focus. Additionally, it is shown that further reductions in inlet air working fluid velocity---with attendant increases in static pressure and density---is necessary to generate higher absorption chamber pressure and engine impulse. Finally, building on lessons learned from the present work, the future research plan is laid out for: a) the present 2D model with full inlet forebody, exploring higher laser pulse energies and multi-pulse phenomena; b) a smaller, redesigned 2D model; c) a 254 mm diameter axisymmetric Lightcraft model; and, d) a laser-electromagnetic accelerator model, designed around a 2-Tesla pulsed electromagnet contracted under the present program.

Effect of interlaminar normal stresses on the uniaxial zero-to-tension fatigue behavior of graphite/epoxy tubes

NASA Technical Reports Server (NTRS)

Krempl, Erhard; An, Deukman

1991-01-01

Fatigue tests conducted with and without internal pressure have been found to possess approximately the same fatigue life as (+/-45)s graphite/epoxy tubes for zero-to-tension axial load-controlled conditions on an axial torsion servohydraulic apparatus. These tests therefore cannot be considered as confirmations of the suspected detrimental effect of interlaminar tensile stresses on the fatigue performance of thin-walled tubes. The addition of 90-deg plies on both the inside and the outside is found to significantly improve the tubes' static and fatigue strengths.

Terminal-shock and restart control of a Mach 2.5, axisymmetric, mixed compression inlet with 40 percent internal contraction. [wind tunnel tests

NASA Technical Reports Server (NTRS)

Baumbick, R. J.

1974-01-01

Results of experimental tests conducted on a supersonic, mixed-compression, axisymmetric inlet are presented. The inlet is designed for operation at Mach 2.5 with a turbofan engine (TF-30). The inlet was coupled to either a choked orifice plate or a long duct which had a variable-area choked exit plug. Closed-loop frequency responses of selected diffuser static pressures used in the terminal-shock control system are presented. Results are shown for Mach 2.5 conditions with the inlet coupled to either the choked orifice plate or the long duct. Inlet unstart-restart traces are also presented. High-response inlet bypass doors were used to generate an internal disturbance and also to achieve terminal-shock control.

Pressurant requirements for discharge of liquid methane from a 1.52-meter-(5-ft-) diameter spherical tank under both static and slosh conditions

NASA Technical Reports Server (NTRS)

Dewitt, R. L.; Mcintire, T. O.

1974-01-01

Pressurized expulsion tests were conducted to determine the effect of various physical parameters on the pressurant gas (methane, helium, hydrogen, and nitrogen) requirements during the expulsion of liquid methane from a 1.52-meter-(5-ft-) diameter spherical tank and to compare results with those predicted by an analytical program. Also studied were the effects on methane, helium, and hydrogen pressurant requirements of various slosh excitation frequencies and amplitudes, both with and without slosh suppressing baffles in the tank. The experimental results when using gaseous methane, helium, and hydrogen show that the predictions of the analytical program agreed well with the actual pressurant requirements for static tank expulsions. The analytical program could not be used for gaseous nitrogen expulsions because of the large quantities of nitrogen which can dissolve in liquid methane. Under slosh conditions, a pronounced increase in gaseous methane requirements was observed relative to results obtained for the static tank expulsions. Slight decreases in the helium and hydrogen requirements were noted under similar test conditions.

Updated Chemical Kinetics and Sensitivity Analysis Code

NASA Technical Reports Server (NTRS)

Radhakrishnan, Krishnan

2005-01-01

An updated version of the General Chemical Kinetics and Sensitivity Analysis (LSENS) computer code has become available. A prior version of LSENS was described in "Program Helps to Determine Chemical-Reaction Mechanisms" (LEW-15758), NASA Tech Briefs, Vol. 19, No. 5 (May 1995), page 66. To recapitulate: LSENS solves complex, homogeneous, gas-phase, chemical-kinetics problems (e.g., combustion of fuels) that are represented by sets of many coupled, nonlinear, first-order ordinary differential equations. LSENS has been designed for flexibility, convenience, and computational efficiency. The present version of LSENS incorporates mathematical models for (1) a static system; (2) steady, one-dimensional inviscid flow; (3) reaction behind an incident shock wave, including boundary layer correction; (4) a perfectly stirred reactor; and (5) a perfectly stirred reactor followed by a plug-flow reactor. In addition, LSENS can compute equilibrium properties for the following assigned states: enthalpy and pressure, temperature and pressure, internal energy and volume, and temperature and volume. For static and one-dimensional-flow problems, including those behind an incident shock wave and following a perfectly stirred reactor calculation, LSENS can compute sensitivity coefficients of dependent variables and their derivatives, with respect to the initial values of dependent variables and/or the rate-coefficient parameters of the chemical reactions.

Focused Rocket-Ejector RBCC Experiments

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh

2003-01-01

This document reports the results of additional efforts for the Rocket Based Combined Cycle (RBCC) rocket-ejector mode research work carried out at the Perm State Propulsion Engineering Research Center in support of NASA s technology development efforts for enabling 3rd generation Reusable Launch Vehicles (RLV). The two tasks conducted under this program build on earlier NASA MSFC funded research program on rocket ejector investigations. The first task continued a systematic investigation of the improvements provided by a gaseous hydrogen (GHz)/oxygen (GO2) twin thruster RBCC rocket ejector system over a single rocket system. In a similar vein, the second task continued investigations into the performance of a hydrocarbon (liquid JP-7)/gaseous oxygen single thruster rocket-ejector system. To gain a systematic understanding of the rocket-ejector s internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static diffusion and afterburning (DAB) configurations for a range of rocket operating conditions. For all experimental conditions, overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust. For the GH2/GO2 propellant rocket ejector experiments, high frequency measurements of the pressure field within the system were also made to understand the unsteady behavior of the flowfield.

LSENS: A General Chemical Kinetics and Sensitivity Analysis Code for homogeneous gas-phase reactions. Part 1: Theory and numerical solution procedures

NASA Technical Reports Server (NTRS)

Radhakrishnan, Krishnan

1994-01-01

LSENS, the Lewis General Chemical Kinetics and Sensitivity Analysis Code, has been developed for solving complex, homogeneous, gas-phase chemical kinetics problems and contains sensitivity analysis for a variety of problems, including nonisothermal situations. This report is part 1 of a series of three reference publications that describe LENS, provide a detailed guide to its usage, and present many example problems. Part 1 derives the governing equations and describes the numerical solution procedures for the types of problems that can be solved. The accuracy and efficiency of LSENS are examined by means of various test problems, and comparisons with other methods and codes are presented. LSENS is a flexible, convenient, accurate, and efficient solver for chemical reaction problems such as static system; steady, one-dimensional, inviscid flow; reaction behind incident shock wave, including boundary layer correction; and perfectly stirred (highly backmixed) reactor. In addition, the chemical equilibrium state can be computed for the following assigned states: temperature and pressure, enthalpy and pressure, temperature and volume, and internal energy and volume. For static problems the code computes the sensitivity coefficients of the dependent variables and their temporal derivatives with respect to the initial values of the dependent variables and/or the three rate coefficient parameters of the chemical reactions.

A quasi-dynamic nonlinear finite element model to investigate prosthetic interface stresses during walking for trans-tibial amputees.

PubMed

Jia, Xiaohong; Zhang, Ming; Li, Xiaobing; Lee, Winson C C

2005-07-01

To predict the interface pressure between residual limb and prosthetic socket for trans-tibial amputees during walking. A quasi-dynamic finite element model was built based on the actual geometry of residual limb, internal bones and socket liner. To simulate the friction/slip boundary conditions between the skin and liner, automated surface-to-surface contact was used. Besides variable external loads and material inertia, the coupling between the large rigid displacement of knee joint and small elastic deformation of residual limb and prosthetic components were also considered. Interface pressure distribution was found to have the same profile during walking. The high pressures fall over popliteal depression, middle patella tendon, lateral tibia and medial tibia regions. Interface pressure predicted by static or quasi-dynamic analysis had the similar double-peaked waveform shape in stance phase. The consideration of inertial effects and motion of knee joint cause 210% average variation of the area between the pressure curve and the horizontal line of pressure threshold between two cases, even though there is only a small change in the peak pressure. The findings in this paper show that the coupling dynamic effects of inertial loads and knee flexion must be considered to study interface pressure between residual limb and prosthetic socket during walking.

Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels

NASA Technical Reports Server (NTRS)

Sanchez, Christopher M.

2011-01-01

NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

High-Subsonic Performance Characteristics and Boundary-Layer Investigations of a 12 deg 10-Inch-Inlet-Diameter Conical Diffuser

DTIC Science & Technology

1950-05-11

available condition supersonic flow was obtained as far as K.5 inches downstream from the diffueer inlet with a maximum Mach number of M % 1.5...Boundary—layer total-pressure measurements were made with the rake shown in figure k. The tubes varied in size from 0.030-Inch outside diameter...at the wall to 0.050—inch outside diameter farther out. A static-pressure tube was mounted on the rake to measure static pressures at the same

Can a pilates exercise program be effective on balance, flexibility and muscle endurance? A randomized controlled trial.

PubMed

Kibar, Sibel; Yardimci, Fatma Ö; Evcik, Deniz; Ay, Saime; Alhan, Aslıhan; Manço, Miray; Ergin, Emine S

2016-10-01

This randomized controlled study aims to determine the effect of pilates mat exercises on dynamic and static balance, hamstring flexibility, abdominal muscle activity and endurance in healthy adults. Female healthy volunteer university students randomly assigned into two groups. Group 1 followed a pilates program for an hour two times a week. Group 2 continued daily activities as control group. Dynamic and static balance were evaluated by Sport Kinesthetic Ability Trainer (KAT) 4000 device. Hamstring flexibility and abdominal endurance were determined by sit-and-reach test, curl-up test respectively. Pressure biofeedback unit (PBU) was used to measure transversus abdominis and lumbar muscle activity. The physical activity of the participants was followed by International Physical Activity Questionnaire-Short Form. Twenty-three subjects in pilates group and 24 control subjects completed the study. In pilates group, statistical significant improvements were observed in curl-up, sit-and-reach test, PBU scores at sixth week (P<0.001), and KAT static and dynamic balance scores (P<0.001), waist circumference (P=0.007) at eighth week. In the comparison between two groups, there were significant improvements in pilates group for sit-and-reach test (P=0.01) and PBU scores (P<0.001) at sixth week, additionally curl-up and static KAT scores progressed in eighth week (P<0.001). No correlation was found between flexibility, endurance, trunk muscle activity and balance parameters. An eight-week pilates training program has been found to have beneficial effect on static balance, flexibility, abdominal muscle endurance, abdominal and lumbar muscle activity. These parameters have no effect on balance.

Spectra of turbulent static pressure fluctuations in jet mixing layers

NASA Technical Reports Server (NTRS)

Jones, B. G.; Adrian, R. J.; Nithianandan, C. K.; Planchon, H. P., Jr.

1977-01-01

Spectral similarity laws are derived for the power spectra of turbulent static pressure fluctuations by application of dimensional analysis in the limit of large turbulent Reynolds number. The theory predicts that pressure spectra are generated by three distinct types of interaction in the velocity fields: a fourth order interaction between fluctuating velocities, an interaction between the first order mean shear and the third order velocity fluctuations, and an interaction between the second order mean shear rate and the second order fluctuating velocity. Measurements of one-dimensional power spectra of the turbulent static pressure fluctuations in the driven mixing layer of a subsonic, circular jet are presented, and the spectra are examined for evidence of spectral similarity. Spectral similarity is found for the low wavenumber range when the large scale flow on the centerline of the mixing layer is self-preserving. The data are also consistent with the existence of universal inertial subranges for the spectra of each interaction mode.

Wave energy absorption by a submerged air bag connected to a rigid float.

PubMed

Kurniawan, A; Chaplin, J R; Hann, M R; Greaves, D M; Farley, F J M

2017-04-01

A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements are generally in good agreement with numerical predictions. Both show that the trajectory of possible combinations of pressure and elevation at which the device is in static equilibrium takes the shape of an S. This means that statically the device can have three different draughts, and correspondingly three different bag shapes, for the same pressure. The behaviour in waves depends on where the mean pressure-elevation condition is on the static trajectory. The captured power is highest for a mean condition on the middle section.

Wave energy absorption by a submerged air bag connected to a rigid float

PubMed Central

Chaplin, J. R.; Hann, M. R.; Greaves, D. M.; Farley, F. J. M.

2017-01-01

A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements are generally in good agreement with numerical predictions. Both show that the trajectory of possible combinations of pressure and elevation at which the device is in static equilibrium takes the shape of an S. This means that statically the device can have three different draughts, and correspondingly three different bag shapes, for the same pressure. The behaviour in waves depends on where the mean pressure-elevation condition is on the static trajectory. The captured power is highest for a mean condition on the middle section. PMID:28484330

Wave energy absorption by a submerged air bag connected to a rigid float

NASA Astrophysics Data System (ADS)

Kurniawan, A.; Chaplin, J. R.; Hann, M. R.; Greaves, D. M.; Farley, F. J. M.

2017-04-01

A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements are generally in good agreement with numerical predictions. Both show that the trajectory of possible combinations of pressure and elevation at which the device is in static equilibrium takes the shape of an S. This means that statically the device can have three different draughts, and correspondingly three different bag shapes, for the same pressure. The behaviour in waves depends on where the mean pressure-elevation condition is on the static trajectory. The captured power is highest for a mean condition on the middle section.

Investigating Premature Ignition of Thruster Pressure Cartridges by Vibration-Induced Electrostatic Discharge

NASA Technical Reports Server (NTRS)

Woods, Stephen S.; Saulsberry, Regor

2010-01-01

Pyrotechnic thruster pressure cartridges (TPCs) are used for aeroshell separation on a new NASA crew launch vehicle. Nondestructive evaluation (NDE) during TPC acceptance testing indicated that internal assemblies moved during shock and vibration testing due to an internal bond anomaly. This caused concerns that the launch environment might produce the same movement and release propellant grains that might be prematurely ignited through impact or through electrostatic discharge (ESD) as grains vibrated against internal surfaces. Since a new lot could not be fabricated in time, a determination had to be made as to whether the lot was acceptable to fly. This paper discusses the ESD evaluation and a separate paper addresses the impact problem. A challenge to straight forward assessment existed due to the unavailability of triboelectric data characterizing the static charging characteristics of the propellants within the TPC. The approach examined the physical limitations for charge buildup within the TPC system geometry and evaluated it for discharge under simulated vibrations used to qualify components for launch. A facsimile TPC was fabricated using SS 301 for the case and surrogate worst case materials for the propellants based on triboelectric data. System discharge behavior was evaluated by applying high voltage to the point of discharge in air and by placing worst case charge accumulations within the facsimile TPC and forcing discharge. The facsimile TPC contained simulated propellant grains and lycopodium, a well characterized indicator for static discharge in dust explosions, and was subjected to accelerations equivalent to the maximum accelerations possible during launch. The magnitude of charge generated within the facsimile TPC system was demonstrated to lie in a range of 100 to 10,000 times smaller than the spark energies measured to ignite propellant grains in industry standard discharge tests. The test apparatus, methodology, and results are described in this paper.

Quiet Clean Short-Haul Experimental Engine (QCSEE) aerodynamic characteristics of 30.5 centimeter diameter inlets

NASA Technical Reports Server (NTRS)

Paul, D. L.

1975-01-01

A low speed test program was conducted in a 9- by 15-foot V/STOL wind tunnel to investigate internal performance characteristics and determine key design features required for an inlet to meet the demanding operational conditions of the QCSEE application. Four models each having a design average throat Mach number of 0.79 were tested over a range of incidence angle, throat Mach number, and freestream velocity. Principal design variable was internal lip diameter ratio. Stable, efficient inlet performance was found to be feasible at and beyond the 50 deg incidence angle required by the QCSEE application at its 41.2 m/sec (80 knot) nominal takeoff velocity, through suitably designed inlet lip and diffuser components. Forebody design was found to significantly impact flow stability via nose curvature. Measured inlet wall pressures were used to select a location for the inlet throat Mach number control's static pressure port that properly balanced the conflicting demands of relative insensitivity to flow incidence and sufficiently high response to changes in engine flow demand.

Experimental Investigation of Aeroelastic Deformation of Slender Wings at Supersonic Speeds Using a Video Model Deformation Measurement Technique

NASA Technical Reports Server (NTRS)

Erickson, Gary E.

2013-01-01

A video-based photogrammetric model deformation system was established as a dedicated optical measurement technique at supersonic speeds in the NASA Langley Research Center Unitary Plan Wind Tunnel. This system was used to measure the wing twist due to aerodynamic loads of two supersonic commercial transport airplane models with identical outer mold lines but different aeroelastic properties. One model featured wings with deflectable leading- and trailing-edge flaps and internal channels to accommodate static pressure tube instrumentation. The wings of the second model were of single-piece construction without flaps or internal channels. The testing was performed at Mach numbers from 1.6 to 2.7, unit Reynolds numbers of 1.0 million to 5.0 million, and angles of attack from -4 degrees to +10 degrees. The video model deformation system quantified the wing aeroelastic response to changes in the Mach number, Reynolds number concurrent with dynamic pressure, and angle of attack and effectively captured the differences in the wing twist characteristics between the two test articles.

LEWICE3D/GlennHT Particle Analysis of the Honeywell Al502 Low Pressure Compressor

NASA Technical Reports Server (NTRS)

Bidwell, Colin S.; Rigby, David L.

2015-01-01

A flow and ice particle trajectory analysis was performed for the booster of the Honeywell AL502 engine. The analysis focused on two closely related conditions one of which produced a rollback and another which did not rollback during testing in the Propulsion Systems Lab at NASA Glenn Research Center. The flow analysis was generated using the NASA Glenn GlennHT flow solver and the particle analysis was generated using the NASA Glenn LEWICE3D v3.56 ice accretion software. The flow and particle analysis used a 3D steady flow, mixing plane approach to model the transport of flow and particles through the engine. The inflow conditions for the rollback case were: airspeed, 145 ms; static pressure, 33,373 Pa; static temperature, 253.3 K. The inflow conditions for the non-roll-back case were: airspeed, 153 ms; static pressure, 34,252 Pa; static temperature, 260.1 K. Both cases were subjected to an ice particle cloud with a median volume diameter of 24 microns, an ice water content of 2.0 gm3 and a relative humidity of 100 percent. The most significant difference between the rollback and non-rollback conditions was the inflow static temperature which was 6.8 K higher for the non-rollback case.

Wind Tunnel to Atmospheric Mapping for Static Aeroelastic Scaling

NASA Technical Reports Server (NTRS)

Heeg, Jennifer; Spain, Charles V.; Rivera, J. A.

2004-01-01

Wind tunnel to Atmospheric Mapping (WAM) is a methodology for scaling and testing a static aeroelastic wind tunnel model. The WAM procedure employs scaling laws to define a wind tunnel model and wind tunnel test points such that the static aeroelastic flight test data and wind tunnel data will be correlated throughout the test envelopes. This methodology extends the notion that a single test condition - combination of Mach number and dynamic pressure - can be matched by wind tunnel data. The primary requirements for affecting this extension are matching flight Mach numbers, maintaining a constant dynamic pressure scale factor and setting the dynamic pressure scale factor in accordance with the stiffness scale factor. The scaling is enabled by capabilities of the NASA Langley Transonic Dynamics Tunnel (TDT) and by relaxation of scaling requirements present in the dynamic problem that are not critical to the static aeroelastic problem. The methodology is exercised in two example scaling problems: an arbitrarily scaled wing and a practical application to the scaling of the Active Aeroelastic Wing flight vehicle for testing in the TDT.

Pressure and temperature fields associated with aero-optics tests. [transonic wind tunnel tests

NASA Technical Reports Server (NTRS)

Raman, K. R.

1980-01-01

The experimental investigation carried out in a 6 x 6 ft wind tunnel on four model configurations in the aero-optics series of tests are described. The data obtained on the random pressures (static and total pressures) and total temperatures are presented. In addition, the data for static pressure fluctuations on the Coelostat turret model are presented. The measurements indicate that the random pressures and temperature are negligible compared to their own mean (or steady state) values for the four models considered, thus allowing considerable simplification in the calculations to obtain the statistical properties of the density field. In the case of the Coelostat model tests these simplifications cannot be assumed a priori and require further investigation.

Numerical analyses of a rocket engine turbine and comparison with air test data

NASA Technical Reports Server (NTRS)

Tran, Ken; Chan, Daniel C.; Hudson, Susan T.; Gaddis, Stephen W.

1992-01-01

The study presents cold air test data on the Space Shuttle Main Engine High Pressure Fuel Turbopump turbine recently collected at the NASA Marshall Space Flight Center. Overall performance data, static pressures on the first- and second-stage nozzles, and static pressures along with the gas path at the hub and tip are gathered and compared with various (1D, quasi-3D, and 3D viscous) analysis procedures. The results of each level of analysis are compared to test data to demonstrate the range of applicability for each step in the design process of a turbine. One-dimensional performance prediction, quasi-3D loading prediction, 3D wall pressure distribution prediction, and 3D viscous wall pressure distribution prediction are illustrated.

Measurements and predictions of flyover and static noise of a TF30 afterburning turbofan engine

NASA Technical Reports Server (NTRS)

Burcham, F. W., Jr.; Lasagna, P. L.; Oas, S. C.

1978-01-01

The noise of the TF30 afterburning turbofan engine in an F-111 airplane was determined from static (ground) and flyover tests. A survey was made to measure the exhaust temperature and velocity profiles for a range of power settings. Comparisons were made between predicted and measured jet mixing, internal, and shock noise. It was found that the noise produced at static conditions was dominated by jet mixing noise, and was adequately predicted by current methods. The noise produced during flyovers exhibited large contributions from internally generated noise in the forward arc. For flyovers with the engine at nonafterburning power, the internal noise, shock noise, and jet mixing noise were accurately predicted. During flyovers with afterburning power settings, however, additional internal noise believed to be due to the afterburning process was evident; its level was as much as 8 decibels above the nonafterburning internal noise. Power settings that produced exhausts with inverted velocity profiles appeared to be slightly less noisy than power settings of equal thrust that produced uniform exhaust velocity profiles both in flight and in static testing.

30 CFR 7.307 - Static pressure test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Electric Motor Assemblies § 7.307 Static...) Permanent deformation exceeding 0.040 inches per linear foot; or (iii) Clearances, in excess of those...

30 CFR 7.307 - Static pressure test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Electric Motor Assemblies § 7.307 Static...) Permanent deformation exceeding 0.040 inches per linear foot; or (iii) Clearances, in excess of those...

30 CFR 7.307 - Static pressure test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Electric Motor Assemblies § 7.307 Static...) Permanent deformation exceeding 0.040 inches per linear foot; or (iii) Clearances, in excess of those...

30 CFR 7.307 - Static pressure test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... APPROVAL OF MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Electric Motor Assemblies § 7.307 Static...) Permanent deformation exceeding 0.040 inches per linear foot; or (iii) Clearances, in excess of those...

Study of the laser-induced decomposition of HNO3/ 2-Nitropropane mixture at static high pressures

NASA Astrophysics Data System (ADS)

Bouyer, Viviane; Hébert, Philippe; Doucet, Michel

2007-06-01

HNO3 / 2-Nitropropane is a well known energetic material on which Raman spectroscopy measurements at static high pressure in a diamond anvil cell (DAC) have already been conducted at CEA/LE RIPAULT in order to examine the evolution of the mixture as a function of composition and pressure [1]. The purpose of the work presented here was to study the laser-induced decomposition of these energetic materials at static high pressures by measuring the combustion front propagation rate in the DAC. First of all, the feasibility of the experimental device was checked with a well known homogeneous explosive, nitromethane. Our results were consistent with those of Rice and Foltz [2]. Then, we investigated the initiation of NA / 2NP mixture as a function of nitric acid proportion, for a given pressure. We chose the mixture for which both the combustion propagation rate and detonation velocity are maximum and we examined the evolution of the front propagation velocity as a function of pressure and energy deposit. [1] Hebert, P., Regache, I., and Lalanne, P., ``High-Pressure Raman Spectroscopy study of HNO3 / 2-Nitropropane Mixtures. Influence of the Composition.'' Proceedings of the 42nd European High-Pressure Research Group Meeting, Lausanne, Suisse, 2004 [2] Rice, S.F., et al., Combustion and Flame 87 (1991) 109-122.

Experimental Pressure Distributions on Axisymmetric Cowls at Mach Numbers From 0.60 to 0.92

NASA Technical Reports Server (NTRS)

Re, Richard J.

2006-01-01

Pressure distributions on four nacelle cowl models of the same length and highlight area but different geometries external to the highlight are compared. The diameter ratio (ratio of highlight diameter to maximum diameter) of the four cowls was 0.854 and the length ratio (ratio of cowl length to maximum diameter) was 0.439. The cowls had the same internal geometry from the highlight to the throat with a contraction ratio (ratio of highlight area to throat area) of 1.250. Data for two other cowls which had a diameter ratio of 0.880, a length ratio of 0.400 and a contraction ratio 1.250 are also included. All the cowls had rows of static pressure orifices on the top and bottom surfaces. Mass-flow ratio was varied between 0.27 and 0.93. Some data were obtained between angles of attack from -2.1deg and 4.1deg. The test was conducted in the Langley 16-Foot Transonic Tunnel.

Globular cluster formation - The fossil record

NASA Technical Reports Server (NTRS)

Murray, Stephen D.; Lin, Douglas N. C.

1992-01-01

Properties of globular clusters which have remained unchanged since their formation are used to infer the internal pressures, cooling times, and dynamical times of the protocluster clouds immediately prior to the onset of star formation. For all globular clusters examined, it is found that the cooling times are much less than the dynamical times, implying that the protoclusters must have been maintained in thermal equilibrium by external heat sources, with fluxes consistent with those found in previous work, and giving the observed rho-T relation. Self-gravitating clouds cannot be stably heated, so that the Jeans mass forms an upper limit to the cluster masses. The observed dependence of protocluster pressure upon galactocentric position implies that the protocluster clouds were in hydrostatic equilibrium after their formation. The pressure dependence is well fitted by that expected for a quasi-statically evolving background hot gas, shock heated to its virial temperature. The observations and inferences are combined with previous theoretical work to construct a picture of globular cluster formation.

Estimating Equivalency of Explosives Through A Thermochemical Approach

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

Maienschein, J L

2002-07-08

The Cheetah thermochemical computer code provides an accurate method for estimating the TNT equivalency of any explosive, evaluated either with respect to peak pressure or the quasi-static pressure at long time in a confined volume. Cheetah calculates the detonation energy and heat of combustion for virtually any explosive (pure or formulation). Comparing the detonation energy for an explosive with that of TNT allows estimation of the TNT equivalency with respect to peak pressure, while comparison of the heat of combustion allows estimation of TNT equivalency with respect to quasi-static pressure. We discuss the methodology, present results for many explosives, andmore » show comparisons with equivalency data from other sources.« less

Haemodynamic changes in ipsilateral and contralateral fingers caused by acute exposures to hand transmitted vibration.

PubMed Central

Bovenzi, M; Griffin, M J

1997-01-01

OBJECTIVES: To investigate changes in digital circulation during and after exposure to hand transmitted vibration. By studying two frequencies and two magnitudes of vibration, to investigate the extent to which haemodynamic changes depend on the vibration frequency, the vibration acceleration, and the vibration velocity. METHODS: Finger skin temperature (FST), finger blood flow (FBF), and finger systolic pressure were measured in the fingers of both hands in eight healthy men. Indices of digital vasomotor tone-such as critical closing pressure and vascular resistance-were estimated by pressure-flow curves obtained with different hand heights. With a static load of 10 N, the right hand was exposed for 30 minutes to each of the following root mean squared (rms) acceleration magnitudes and frequencies of vertical vibration: 22 m.s-2 at 31.5 Hz, 22 m.s-2 at 125 Hz, and 87 m.s-2 at 125 Hz. A control condition consisted of exposure to the static load only. The measures of digital circulation and vasomotor tone were taken before exposure to the vibration and the static load, and at 0, 20, 40, and 60 minutes after the end of each exposure. RESULTS: Exposure to static load caused no significant changes in FST, FBF, or indices of vasomotor tone in either the vibrated right middle finger or the non-vibrated left middle finger. In both fingers, exposure to vibration of 125 Hz and 22 m.s-2 produced a greater reduction in FBF and a greater increase in vasomotor tone than did vibration of 31.5 Hz and 22 m.s-2. In the vibrated right finger, exposure to vibration of 125 Hz and 87 m.s-2 provoked an immediate vasodilation which was followed by vasoconstriction during recovery. The non-vibrated left finger showed a significant increase in vasomotor tone throughout the 60 minute period after the end of vibration exposure. CONCLUSIONS: The digital circulatory response to acute vibration depends upon the magnitude and frequency of the vibration stimulus. Vasomotor mechanisms, mediated both centrally and locally, are involved in the reaction of digital vessels to acute vibration. The pattern of the haemodynamic changes in the fingers exposed to the vibration frequencies used in this study do not seem to support the frequency weighting assumed in the current international standard ISO 5349. PMID:9326160

An investigation of transient pressures and plasma properties in a pinched plasma column. M.S. Thesis

NASA Technical Reports Server (NTRS)

Stover, E. K.; York, T. M.

1971-01-01

The transient pinched plasma column generated in a linear Z-pinch was studied experimentally and analytically. The plasma column was investigated experimentally with several plasma diagnostics; they were: a rapid response pressure transducer, a magnetic field probe, a voltage probe, and discharge luminosity. Axial pressure profiles on the discharge chamber axis were used to identify three characteristic regions of plasma column behavior: (1) strong axial pressure asymmetry noted early in plasma column lifetime, (2) followed by plasma heating in which there is a rapid rise in static pressure, and (3) a slight decrease static pressure before plasma column breakup. Plasma column lifetime was approximately 5 microseconds. The axial pressure asymmetry was attributed to nonsimultaneous pinching of the imploding current sheet along the discharge chamber axis. The rapid heating could be attributed in part to viscous effects introduced by radial gradients in the axial streaming velocity.

Shock position sensor for supersonic inlets. [measuring pressure in the throat of a supersonic inlet

NASA Technical Reports Server (NTRS)

Dustin, M. O. (Inventor)

1975-01-01

Static pressure taps or ports are provided in the throat of a supersonic inlet, and signals indicative of the pressure at each of the ports is fed to respective comparators. Means are also provided for directing a signal indicative of the total throat pressure to the comparators. A periodic signal is superimposed on the total throat pressure so that the signal from the static pressure tabs is compared to a varying scan signal rather than to total throat pressure only. This type of comparison causes each comparator to provide a pulse width modulated output which may vary from 0% 'time on' to 100% 'time on'. The pulse width modulated outputs of the comparators are summed, filtered, and directed to a controller which operates a bypass valve such as a door whereby air is dumped from the inlet to prevent the shock wave from being expelled out the front.

Demonstration of Energy Savings in Commercial Buildings for Tiered Trim and Respond Method in Resetting Static Pressure for VAV Systems

DTIC Science & Technology

2017-03-01

FINAL REPORT Demonstration of Energy Savings in Commercial Buildings for Tiered Trim and Respond Method in Resetting Static Pressure for VAV...release Page Intentionally Left Blank This report was prepared under contract to the Department of Defense Environmental Security Technology...Certification Program (ESTCP). The publication of this report does not indicate endorsement by the Department of Defense, nor should the contents be

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak P.; Gump, Jared C.

2006-07-01

Explosive formulations with reduced-sensitivity RDX showed reduced shock sensitivity using Naval Ordnance Laboratory (NOL) Large Scale Gap Test, compared with similar formulations using standard RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light on the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. I-RDX®, a form of reduced- sensitivity RDX was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transform IR (FTIR). The pressure dependence of the Raman mode frequencies of I-RDX® was determined and compared with that of standard RDX. The behavior of I-RDX® near the pressure at which standard RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph is presented.

Measurements of compressible secondary flow in a circular S-duct

NASA Technical Reports Server (NTRS)

Vakili, A.; Wu, J. M.; Liver, P.; Bhat, M. K.

1983-01-01

This paper presents the results of an experimental study of secondary flow in a circular cross section 30 deg - 30 deg S-duct with entrance Mach number of 0.6. Local flow velocity vectors have been measured along the length of the duct at six stations. These measurements have been made using a five-port cone probe. Static and total pressure profiles in the transverse planes are obtained from the cone probe measurements. Wall static pressure measurements along three azimuth angles of 0 deg, 90 deg, and 180 deg along the duct are also made. Contour plots presenting the three dimensional velocity field as well as the total- and static-pressure fields are obtained. Surface oil flow visualization technique has been used to provide details of the flow on the S-duct boundaries. The experimental observations have been compared with typical computational results.

Analysis and testing of high entrainment single nozzle jet pumps with variable mixing tubes

NASA Technical Reports Server (NTRS)

Hickman, K. E.; Hill, P. G.; Gilbert, G. B.

1972-01-01

An analytical model was developed to predict the performance characteristics of axisymmetric single-nozzle jet pumps with variable area mixing tubes. The primary flow may be subsonic or supersonic. The computer program uses integral techniques to calculate the velocity profiles and the wall static pressures that result from the mixing of the supersonic primary jet and the subsonic secondary flow. An experimental program was conducted to measure mixing tube wall static pressure variations, velocity profiles, and temperature profiles in a variable area mixing tube with a supersonic primary jet. Static pressure variations were measured at four different secondary flow rates. These test results were used to evaluate the analytical model. The analytical results compared well to the experimental data. Therefore, the analysis is believed to be ready for use to relate jet pump performance characteristics to mixing tube design.

The Effect of Turbulence on the Drag of Flat Plates

NASA Technical Reports Server (NTRS)

Schubauer, G B; Dryden, H L

1937-01-01

in determining the effect of turbulence on the forces exerted on bodies in the air stream of a wind tunnel, it is commonly assumed that the indications of the standard Pitot-static tube used to determine the air speed are not dependent on the turbulence. To investigate the truth of this assumption, the drag of a normally exposed flat plate, the difference in pressure between the front and rear of a thin circular disk, the rate of rotation of a vane anemometer, and the pressure developed by a standard Pitot-static tube were measured in an air stream for several conditions of turbulence. The results may be interpreted as indicating that there is no appreciable effect of turbulence on the vane anemometer and the standard pitot-static tube, but that there is small effect on the drag of a flat plate and the pressure difference between front and rear of a disk.

Static and Wind-on Performance of Polymer-Based Pressure-Sensitive Paints Using Platinum and Ruthenium as the Luminophore

PubMed Central

Lo, Kin Hing; Kontis, Konstantinos

2016-01-01

An experimental study has been conducted to investigate the static and wind-on performance of two in-house-developed polymer-based pressure-sensitive paints. Platinum tetrakis (pentafluorophenyl) porphyrin and tris-bathophenanthroline ruthenium II are used as the luminophores of these two polymer-based pressure-sensitive paints. The pressure and temperature sensitivity and the photo-degradation rate of these two pressure-sensitive paints have been investigated. In the wind tunnel test, it was observed that the normalised intensity ratio of both polymer-based pressure-sensitive paints being studied decreases with increasing the number of wind tunnel runs. The exact reason that leads to the occurrence of this phenomenon is unclear, but it is deduced that the luminophore is either removed or deactivated by the incoming flow during a wind tunnel test. PMID:27128913

Fuselage and nozzle pressure distributions of a 1/12-scale F-15 propulsion model at transonic speeds. Effect of fuselage modifications and nozzle variables

NASA Technical Reports Server (NTRS)

Pendergraft, O. C., Jr.; Carson, G. T., Jr.

1984-01-01

Static pressure coefficient distributions on the forebody, afterbody, and nozzles of a 1/12 scale F-15 propulsion model was determined in the 16 foot transonic tunnel for Mach numbers from 0.60 to 1.20, angles of attack from -2 deg to 7 deg and ratio of jet total pressure to free stream static pressure from 1 up to about 7, depending on Mach number. The effects of nozzle geometry and horizontal tail deflection on the pressure distributions were investigated. Boundary layer total pressure profiles were determined at two locations ahead of the nozzles on the top nacelle surface. Reynolds number varied from about 1.0 x 10 to the 7th power per meter, depending on Mach number.

Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics.

PubMed

Hart, Roger C; Herring, G C; Balla, R Jeffrey

2007-06-15

Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

NASA Technical Reports Server (NTRS)

Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

2007-01-01

Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

Compressible flow in a diffusing S-duct with flow separation

NASA Technical Reports Server (NTRS)

Vakili, A. D.; Wu, J. M.; Bhat, M. K.; Liver, P.

1987-01-01

Local flow velocity vectors, as well as static and total pressures along ten radial traverses, were obtained at six stations for secondary flows in a diffusing 30-30-deg S-duct with circular cross section. The strong secondary flow measured in the first bend continued into the second with new vorticity produced in the opposite direction. Contour plots representing the transverse velocity field, as well as total and static pressure contours, have been obtained. As a result of the secondary flow and subsequent separation, substantial total pressure distortion is noted to occur at the duct exit.

Design and two dimensional cascade test of a jet-flap turbine stator blade with ratio of axial chord to spacing of 0.5

NASA Technical Reports Server (NTRS)

Stabe, R. G.

1971-01-01

A jet-flap blade was designed for a velocity diagram typical of the first-stage stator of a jet engine turbine and was tested in a simple two-dimensional cascade of six blades. The principal measurements were blade surface static pressure and cross-channel surveys of exit total pressure, static pressure, and flow angle. The results of the experimental investigation include blade loading, exit angle, flow, and loss data for a range of exit critical velocity ratios and three jet flow conditions.

Measuring Time-Averaged Blood Pressure

NASA Technical Reports Server (NTRS)

Rothman, Neil S.

1988-01-01

Device measures time-averaged component of absolute blood pressure in artery. Includes compliant cuff around artery and external monitoring unit. Ceramic construction in monitoring unit suppresses ebb and flow of pressure-transmitting fluid in sensor chamber. Transducer measures only static component of blood pressure.

Cardiovascular responses to static exercise in distance runners and weight lifters

NASA Technical Reports Server (NTRS)

Longhurst, J. C.; Kelly, A. R.; Gonyea, W. J.; Mitchell, J. H.

1980-01-01

Three groups of athletes including long-distance runners, competitive and amateur weight lifters, and age- and sex-matched control subjects have been studied by hemodynamic and echocardiographic methods in order to determine the effect of the training programs on the cardiovascular response to static exercise. Blood pressure, heart rate, and double product data at rest and at fatigue suggest that competitive endurance (dynamic exercise) training alters the cardiovascular response to static exercise. In contrast to endurance exercise, weight lifting (static exercise) training does not alter the cardiovascular response to static exercise: weight lifters responded to static exercise in a manner very similar to that of the control subjects.

Experimental cavity pressure measurements at subsonic and transonic speeds. Static-pressure results

NASA Technical Reports Server (NTRS)

Plentovich, E. B.; Stallings, Robert L., Jr.; Tracy, M. B.

1993-01-01

An experimental investigation was conducted to determine cavity flow-characteristics at subsonic and transonic speeds. A rectangular box cavity was tested in the Langley 8-Foot Transonic Pressure Tunnel at Mach numbers from 0.20 to 0.95 at a unit Reynolds number of approximately 3 x 10(exp 6) per foot. The boundary layer approaching the cavity was turbulent. Cavities were tested over a range of length-to-depth ratios (l/h) of 1 to 17.5 for cavity width-to-depth ratios of 1, 4, 8, and 16. Fluctuating- and static-pressure data in the cavity were obtained; however, only static-pressure data is analyzed. The boundaries between the flow regimes based on cavity length-to-depth ratio were determined. The change to transitional flow from open flow occurs at l/h at approximately 6-8 however, the change from transitional- to closed-cavity flow occurred over a wide range of l/h and was dependent on Mach number and cavity configuration. The change from closed to open flow as found to occur gradually. The effect of changing cavity dimensions showed that if the vlaue of l/h was kept fixed but the cavity width was decreased or cavity height was increased, the cavity pressure distribution tended more toward a more closed flow distribution.

Computational Investigation of the Aerodynamic Effects on Fluidic Thrust Vectoring

NASA Technical Reports Server (NTRS)

Deere, K. A.

2000-01-01

A computational investigation of the aerodynamic effects on fluidic thrust vectoring has been conducted. Three-dimensional simulations of a two-dimensional, convergent-divergent (2DCD) nozzle with fluidic injection for pitch vector control were run with the computational fluid dynamics code PAB using turbulence closure and linear Reynolds stress modeling. Simulations were computed with static freestream conditions (M=0.05) and at Mach numbers from M=0.3 to 1.2, with scheduled nozzle pressure ratios (from 3.6 to 7.2) and secondary to primary total pressure ratios of p(sub t,s)/p(sub t,p)=0.6 and 1.0. Results indicate that the freestream flow decreases vectoring performance and thrust efficiency compared with static (wind-off) conditions. The aerodynamic penalty to thrust vector angle ranged from 1.5 degrees at a nozzle pressure ratio of 6 with M=0.9 freestream conditions to 2.9 degrees at a nozzle pressure ratio of 5.2 with M=0.7 freestream conditions, compared to the same nozzle pressure ratios with static freestream conditions. The aerodynamic penalty to thrust ratio decreased from 4 percent to 0.8 percent as nozzle pressure ratio increased from 3.6 to 7.2. As expected, the freestream flow had little influence on discharge coefficient.

Study of stator-vane fluctuating pressures in a turbofan engine for static and flight tests

NASA Technical Reports Server (NTRS)

Mueller, A. W.

1984-01-01

As part of a program to study the fan noise generated from turbofan engines, fluctuating surface pressures induced by fan-rotor wakes were measured on core- and bypass-stator outlet guide vanes of a modified JT15D-1 engine. Tests were conducted with the engine operating on an outdoor test stand and in flight. The amplitudes of pressures measured at fan-rotor blade-passage fundamental frequencies were generally higher and appeared less stable for the static tests than for the flight tests. Fluctuating pressures measured at the blade-passage frequency of the high-speed core compressor were interpreted to be acoustic; however, disturbance trace velocities for either the convected rotor wakes or acoustic pressures were difficult to interpret because of the complex environment.

Static investigation of two fluidic thrust-vectoring concepts on a two-dimensional convergent-divergent nozzle

NASA Technical Reports Server (NTRS)

Wing, David J.

1994-01-01

A static investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel of two thrust-vectoring concepts which utilize fluidic mechanisms for deflecting the jet of a two-dimensional convergent-divergent nozzle. One concept involved using the Coanda effect to turn a sheet of injected secondary air along a curved sidewall flap and, through entrainment, draw the primary jet in the same direction to produce yaw thrust vectoring. The other concept involved deflecting the primary jet to produce pitch thrust vectoring by injecting secondary air through a transverse slot in the divergent flap, creating an oblique shock in the divergent channel. Utilizing the Coanda effect to produce yaw thrust vectoring was largely unsuccessful. Small vector angles were produced at low primary nozzle pressure ratios, probably because the momentum of the primary jet was low. Significant pitch thrust vector angles were produced by injecting secondary flow through a slot in the divergent flap. Thrust vector angle decreased with increasing nozzle pressure ratio but moderate levels were maintained at the highest nozzle pressure ratio tested. Thrust performance generally increased at low nozzle pressure ratios and decreased near the design pressure ratio with the addition of secondary flow.

Variable camber wing based on pneumatic artificial muscles

NASA Astrophysics Data System (ADS)

Yin, Weilong; Liu, Libo; Chen, Yijin; Leng, Jinsong

2009-07-01

As a novel bionic actuator, pneumatic artificial muscle has high power to weight ratio. In this paper, a variable camber wing with the pneumatic artificial muscle is developed. Firstly, the experimental setup to measure the static output force of pneumatic artificial muscle is designed. The relationship between the static output force and the air pressure is investigated. Experimental result shows the static output force of pneumatic artificial muscle decreases nonlinearly with increasing contraction ratio. Secondly, the finite element model of the variable camber wing is developed. Numerical results show that the tip displacement of the trailing-edge increases linearly with increasing external load and limited with the maximum static output force of pneumatic artificial muscles. Finally, the variable camber wing model is manufactured to validate the variable camber concept. Experimental result shows that the wing camber increases with increasing air pressure and that it compare very well with the FEM result.

Evaluation of Flexible Force Sensors for Pressure Monitoring in Treatment of Chronic Venous Disorders.

PubMed

Parmar, Suresh; Khodasevych, Iryna; Troynikov, Olga

2017-08-21

The recent use of graduated compression therapy for treatment of chronic venous disorders such as leg ulcers and oedema has led to considerable research interest in flexible and low-cost force sensors. Properly applied low pressure during compression therapy can substantially improve the treatment of chronic venous disorders. However, achievement of the recommended low pressure levels and its accurate determination in real-life conditions is still a challenge. Several thin and flexible force sensors, which can also function as pressure sensors, are commercially available, but their real-life sensing performance has not been evaluated. Moreover, no researchers have reported information on sensor performance during static and dynamic loading within the realistic test conditions required for compression therapy. This research investigated the sensing performance of five low-cost commercial pressure sensors on a human-leg-like test apparatus and presents quantitative results on the accuracy and drift behaviour of these sensors in both static and dynamic conditions required for compression therapy. Extensive experimental work on this new human-leg-like test setup demonstrated its utility for evaluating the sensors. Results showed variation in static and dynamic sensing performance, including accuracy and drift characteristics. Only one commercially available pressure sensor was found to reliably deliver accuracy of 95% and above for all three test pressure points of 30, 50 and 70 mmHg.

Evaluation of Flexible Force Sensors for Pressure Monitoring in Treatment of Chronic Venous Disorders

PubMed Central

Parmar, Suresh; Khodasevych, Iryna; Troynikov, Olga

2017-01-01

The recent use of graduated compression therapy for treatment of chronic venous disorders such as leg ulcers and oedema has led to considerable research interest in flexible and low-cost force sensors. Properly applied low pressure during compression therapy can substantially improve the treatment of chronic venous disorders. However, achievement of the recommended low pressure levels and its accurate determination in real-life conditions is still a challenge. Several thin and flexible force sensors, which can also function as pressure sensors, are commercially available, but their real-life sensing performance has not been evaluated. Moreover, no researchers have reported information on sensor performance during static and dynamic loading within the realistic test conditions required for compression therapy. This research investigated the sensing performance of five low-cost commercial pressure sensors on a human-leg-like test apparatus and presents quantitative results on the accuracy and drift behaviour of these sensors in both static and dynamic conditions required for compression therapy. Extensive experimental work on this new human-leg-like test setup demonstrated its utility for evaluating the sensors. Results showed variation in static and dynamic sensing performance, including accuracy and drift characteristics. Only one commercially available pressure sensor was found to reliably deliver accuracy of 95% and above for all three test pressure points of 30, 50 and 70 mmHg. PMID:28825672

Dynamic pressure sensitivity determination with Mach number method

NASA Astrophysics Data System (ADS)

Sarraf, Christophe; Damion, Jean-Pierre

2018-05-01

Measurements of pressure in fast transient conditions are often performed even if the dynamic characteristic of the transducer are not traceable to international standards. Moreover, the question of a primary standard in dynamic pressure is still open, especially for gaseous applications. The question is to improve dynamic standards in order to respond to expressed industrial needs. In this paper, the method proposed in the EMRP IND09 ‘Dynamic’ project, which can be called the ‘ideal shock tube method’, is compared with the ‘collective standard method’ currently used in the Laboratoire de Métrologie Dynamique (LNE/ENSAM). The input is a step of pressure generated by a shock tube. The transducer is a piezoelectric pressure sensor. With the ‘ideal shock tube method’ the sensitivity of a pressure sensor is first determined dynamically. This method requires a shock tube implemented with piezoelectric shock wave detectors. The measurement of the Mach number in the tube allows an evaluation of the incident pressure amplitude of a step using a theoretical 1D model of the shock tube. Heat transfer, other actual effects and effects of the shock tube imperfections are not taken into account. The amplitude of the pressure step is then used to determine the sensitivity in dynamic conditions. The second method uses a frequency bandwidth comparison to determine pressure at frequencies from quasi-static conditions, traceable to static pressure standards, to higher frequencies (up to 10 kHz). The measurand is also a step of pressure generated by a supposed ideal shock tube or a fast-opening device. The results are provided as a transfer function with an uncertainty budget assigned to a frequency range, also deliverable frequency by frequency. The largest uncertainty in the bandwidth of comparison is used to trace the final pressure step level measured in dynamic conditions, owing that this pressure is not measurable in a steady state on a shock tube. A reference sensor thereby calibrated can be used in a comparison measurement process. At high frequencies the most important component of the uncertainty in this method is due to actual shock tube complex effects not already functionalized nowadays or thought not to be functionalized in this kind of direct method. After a brief review of both methods and a brief review of the determination of the transfer function of pressure transducers, and the budget of associated uncertainty for the dynamic calibration of a pressure transducer in gas, this paper presents a comparison of the results obtained with the ‘ideal shock tube’ and the ‘collective standard’ methods.

Analysis of foot structure in athletes sustaining proximal fifth metatarsal stress fracture.

PubMed

Hetsroni, Iftach; Nyska, Meir; Ben-Sira, David; Mann, Gideon; Segal, Ofer; Maoz, Guy; Ayalon, Moshe

2010-03-01

In the past, several studies provided anecdotal descriptions of high-arched feet in individuals sustaining proximal fifth metatarsal stress fractures. This relationship has never been supported by scientific evidence. Our objective was to examine whether athletes who sustained this injury had an exceptional static foot structure or dynamic loading pattern. Ten injured professional soccer players who regained full professional activity following a unilateral proximal fifth metatarsal stress fracture and ten control soccer players were examined. Independent variables included static evaluation of foot and arch structure, followed by dynamic plantar foot pressure evaluation. Each variable was compared between injured, contra-lateral uninjured, and control feet. Static measurements of foot and arch structure did not reveal differences among the groups. However, plantar pressure evaluation revealed relative unloading of the fourth metatarsal in injured and uninjured limbs of injured athletes compared with control, while the fifth metatarsal revealed pressure reduction only in the injured limbs of injured athletes. Athletes who sustained proximal fifth metatarsal stress fracture were not characterized by an exceptional static foot structure. Dynamically, lateral metatarsal unloading during stance may either play a role in the pathogenesis of the injury, or alternately represent an adaptive process. Footwear fabrication for previously injured athletes should not categorically address cushioning properties designed for high-arch feet, but rather focus on individual dynamic evaluation of forefoot loading, with less attention applied to static foot and arch characteristics.

Measurements and predictions of flyover and static noise of an afterburning turbofan engine in an F-111 airplane

NASA Technical Reports Server (NTRS)

Burcham, F. W., Jr.

1979-01-01

The noise of the TF30 afterburning turbofan engine in an F-111 airplane was determined from static (ground) and flyover tests. Exhaust temperatures and velocity profiles were measured for a range of power settings. Comparisons were made between predicted and measured jet mixing, internal, and shock noise. It was found that the noise produced at static conditions was dominated by jet mixing noise, and was adequately predicted by current methods. The noise produced during flyovers exhibited large contributions from internally generated noise in the forward arc. For flyovers with the engine at nonafterburning power, the internal noise, shock noise, and jet mixing noise were accurately predicted. During flyovers with afterburning power settings, however, additional internal noise believed to be due to the afterburning process was evident; its level was as much as 8 decibels above the nonafterburning internal noise.

Investigation of Shock Diffusers at Mach Number 1.85. 2 - Projecting Double-Shock Cones

DTIC Science & Technology

1947-06-17

pitot - static rake located as shown in figure 1(a). Total-pressure recoveries were measured for a series of tip projections varied in minimum steps...is shown. The position of the pitot -static rake with which these distributions were .measured is shown in figure 1(a). The data points correspond...Schroeder SUMMARY An Investigation has "been undertaken in the Cleveland 18- by 18-Inch, supersonic tunnel to determine the total-pressure

Results of a jet plume effects test on Rockwell International integrated space shuttle vehicle using a vehicle 5 configuration 0.02-scale model (88-OTS) in the 11 by 11 foot leg of the NASA/Ames Research Center unitary plan wind tunnel (IA19), volume 1

NASA Technical Reports Server (NTRS)

Nichols, M. E.

1975-01-01

Results are presented of jet plume effects test IA19 using a vehicle 5 configuration integrated space shuttle vehicle 0.02-scale model in the NASA/Ames Research Center 11 x 11-foot leg of the unitary plan wind tunnel. The jet plume power effects on the integrated vehicle static pressure distribution were determined along with elevon, main propulsion system nozzle, and solid rocket booster nozzle effectiveness and elevon hinge moments.

Space Shuttle propulsion performance reconstruction from flight data

NASA Technical Reports Server (NTRS)

Rogers, Robert M.

1989-01-01

The aplication of extended Kalman filtering to estimating Space Shuttle Solid Rocket Booster (SRB) performance, specific impulse, from flight data in a post-flight processing computer program. The flight data used includes inertial platform acceleration, SRB head pressure, and ground based radar tracking data. The key feature in this application is the model used for the SRBs, which represents a reference quasi-static internal ballistics model normalized to the propellant burn depth. Dynamic states of mass overboard and propellant burn depth are included in the filter model to account for real-time deviations from the reference model used. Aerodynamic, plume, wind and main engine uncertainties are included.

Static and dynamic stress analyses of the prototype high head Francis runner based on site measurement

NASA Astrophysics Data System (ADS)

Huang, X.; Oram, C.; Sick, M.

2014-03-01

More efforts are put on hydro-power to balance voltage and frequency within seconds for primary control in modern smart grids. This requires hydraulic turbines to run at off-design conditions. especially at low load or speed-no load. Besides. the tendency of increasing power output and decreasing weight of the turbine runners has also led to the high level vibration problem of the runners. especially high head Francis runners. Therefore. it is important to carry out the static and dynamic stress analyses of prototype high head Francis runners. This paper investigates the static and dynamic stresses on the prototype high head Francis runner based on site measurements and numerical simulations. The site measurements are performed with pressure transducers and strain gauges. Based on the measured results. computational fluid dynamics (CFD) simulations for the flow channel from stay vane to draft tube cone are performed. Static pressure distributions and dynamic pressure pulsations caused by rotor-stator interaction (RSI) are obtained under various operating conditions. With the CFD results. static and dynamic stresses on the runner at different operating points are calculated by means of the finite element method (FEM). The agreement between simulation and measurement is analysed with linear regression method. which indicates that the numerical result agrees well with that of measurement. Furthermore. the maximum static and dynamic stresses on the runner blade are obtained at various operating points. The relations of the maximum stresses and the power output are discussed in detail. The influences of the boundary conditions on the structural behaviour of the runner are also discussed.

Prevention of pressure ulcers with a static air support surface: A systematic review.

PubMed

Serraes, Brecht; van Leen, Martin; Schols, Jos; Van Hecke, Ann; Verhaeghe, Sofie; Beeckman, Dimitri

2018-06-01

The aims of this study were to identify, assess, and summarise available evidence about the effectiveness of static air mattress overlays to prevent pressure ulcers. The primary outcome was the incidence of pressure ulcers. Secondary outcomes included costs and patient comfort. This study was a systematic review. Six electronic databases were consulted: Cochrane Library, EMBASE, PubMed (Medline), CINAHL (EBSCOhost interface), Science direct, and Web of Science. In addition, a hand search through reviews, conference proceedings, and the reference lists of the included studies was performed to identify additional studies. Potential studies were reviewed and assessed by 2 independent authors based on the title and abstract. Decisions regarding inclusion or exclusion of the studies were based on a consensus between the authors. Studies were included if the following criteria were met: reporting an original study; the outcome was the incidence of pressure ulcer categories I to IV when using a static air mattress overlay and/or in comparison with other pressure-redistribution device(s); and studies published in English, French, and Dutch. No limitation was set on study setting, design, and date of publication. The methodological quality assessment was evaluated using the Critical Appraisal Skills Program Tool. Results were reported in a descriptive way to reflect the exploratory nature of the review. The searches included 13 studies: randomised controlled trials (n = 11) and cohort studies (n = 2). The mean pressure ulcer incidence figures found in the different settings were, respectively, 7.8% pressure ulcers of categories II to IV in nursing homes, 9.06% pressure ulcers of categories I to IV in intensive care settings, and 12% pressure ulcers of categories I to IV in orthopaedic wards. Seven comparative studies reported a lower incidence in the groups of patients on a static air mattress overlay. Three studies reported a statistical (P < .1) lower incidence compared with a standard hospital mattress (10 cm thick, density 35 kg/m 3 ), a foam mattress (15 cm thick), and a viscoelastic foam mattress (15 cm thick). No significant difference in incidence, purchase costs, and patient comfort was found compared with dynamic air mattresses. This review focused on the effectiveness of static air mattress overlays to prevent pressure ulcers. There are indications that these mattress overlays are more effective in preventing pressure ulcers compared with the use of a standard mattress or a pressure-reducing foam mattress in nursing homes and intensive care settings. However, interpretation of the evidence should be performed with caution due to the wide variety of methodological and/or reporting quality levels of the included studies. © 2018 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Validation of the Beneware model ABP-021 ambulatory blood pressure monitor according to the revised 2010 European Society of hypertension international protocol.

PubMed

Pereira, Telmo; Guimarães, João

2018-06-11

This study aimed to evaluate the accuracy of the Beneware model ABP-021 oscillometric blood pressure monitor in the general population according to the European Society of Hypertension International Protocol (ESH-IP). The accuracy of the device was assessed in relation to various clinical variables, including age, sex, BMI, and arm circumference. Thirty-three individuals (18 men and 15 women), with a mean age of 36±14 years (age range: 20-68 years), were studied according to the recommendations of the ESH-IP. Sequential same-arm blood pressure measurements were performed, alternating between a mercury standard and the automatic device. The differences among the test-control measurements were assessed and divided into categorization zones of 5, 10, and 15 mmHg discrepancy. The device complied with the quality requirements of the ESH-IP. The device-observer disagreement was -1.2±4.7 mmHg for systolic blood pressure (SBP) and -1.7±4.3 mmHg for diastolic blood pressure (DBP). The device produced 77, 93, and 98 measurements, respectively, within the 5, 10, and 15 mmHg discrepancy limits for SBP. For DBP, 80, 97, and 99 measurements were observed within the 5, 10, and 15 mmHg discrepancy limits. The number of participants with two or three of the device-observer differences within 5 mmHg was 26 for SBP and 29 for DBP, whereas there were only two participants with no device-observer differences within 5 mmHg for DBP. These data show that the Beneware model ABP-021 monitor meets the requirements of the ESH-IP, in static conditions, indicating its suitability for measuring blood pressure in the general adult population.

Flowfield measurements in the NASA Lewis Research Center 9- by 15-foot low-speed wind tunnel

NASA Technical Reports Server (NTRS)

Hughes, Christopher E.

1989-01-01

An experimental investigation was conducted in the NASA Lewis 9- by 15-Foot Low-Speed Wind Tunnel to determine the flow characteristics in the test section during wind tunnel operation. In the investigation, a 20-probe horizontally-mounted Pitot-static flow survey rake was used to obtain cross-sectional total and static pressure surveys at four axial locations in the test section. At each axial location, the cross-sectional flowfield surveys were made by repositioning the Pitot-static flow survey rake vertically. In addition, a calibration of the new wind tunnel rake instrumentation, used to determine the wind tunnel operating conditions, was performed. Boundary laser surveys were made at three axial locations in the test section. The investigation was conducted at tunnel Mach numbers 0.20, 0.15, 0.10, and 0.05. The test section profile results from the investigation indicate that fairly uniform total pressure profiles (outside the test section boundary layer) and fairly uniform static pressure and Mach number profiles (away from the test section walls and downstream of the test section entrance) exist throughout in the wind tunnel test section.

Potential uses of vacuum bubbles in noise and vibration control

NASA Technical Reports Server (NTRS)

Ver, Istvan L.

1989-01-01

Vacuum bubbles are new acoustic elements which are dynamically more compliant than the gas volume they replace, but which are statically robust. They are made of a thin metallic shell with vacuum in their cavity. Consequently, they pose no danger in terms of contamination or fire hazard. The potential of the vacuum bubble concept for noise and vibration control was assessed with special emphases on spacecraft and aircraft applications. The following potential uses were identified: (1) as a cladding, to reduce sound radiation of vibrating surfaces and the sound excitation of structures, (2) as a screen, to reflect or absorb an incident sound wave, and (3) as a liner, to increase low frequency sound transmission loss of double walls and to increase the low frequency sound attenuation of muffler baffles. It was found that geometric and material parameters must be controlled to a very high accuracy to obtain optimal performance and that performance is highly sensitive to variations in static pressure. Consequently, it was concluded that vacuum bubbles have more potential in spacecraft applications where static pressure is controlled more than in aircraft applications where large fluctuations in static pressure are common.

Boiling regimes of impacting drops on a heated substrate under reduced pressure

NASA Astrophysics Data System (ADS)

van Limbeek, Michiel A. J.; Hoefnagels, Paul B. J.; Shirota, Minori; Sun, Chao; Lohse, Detlef

2018-05-01

We experimentally investigate the boiling behavior of impacting ethanol drops on a heated smooth sapphire substrate at pressures ranging from P =0.13 bar to atmospheric pressure. We employ frustrated total internal reflection imaging to study the wetting dynamics of the contact between the drop and the substrate. The spreading drop can be in full contact (contact boiling), it can partially touch (transition boiling), or the drop can be fully levitated (Leidenfrost boiling). We show that the temperature of the boundary between contact and transition boiling shows at most a weak dependence on the impact velocity, but a significant decrease with decreasing ambient gas pressure. A striking correspondence is found between the temperature of this boundary and the static Leidenfrost temperature for all pressures. We therefore conclude that both phenomena share the same mechanism and are dominated by the dynamics taking place at the contact line. On the other hand, the boundary between transition boiling and Leidenfrost boiling, i.e., the dynamic Leidenfrost temperature, increases for increasing impact velocity for all ambient gas pressures. Moreover, the dynamic Leidenfrost temperature coincides for pressures between P =0.13 and 0.54 bar, whereas for atmospheric pressure the dynamic Leidenfrost temperature is slightly elevated. This indicates that the dynamic Leidenfrost temperature is at most weakly dependent on the enhanced evaporation by the lower saturation temperature of the liquid.

Influence of gas law on ultrasonic behaviour of porous media under pressure.

PubMed

Griffiths, S; Ayrault, C

2010-06-01

This paper deals with the influence of gas law on ultrasonic behaviour of porous media when the saturating fluid is high pressured. Previous works have demonstrated that ultrasonic transmission through a porous sample with variations of the static pressure (up to 18 bars) of the saturating fluid allows the characterization of high damping materials. In these studies, the perfect gas law was used to link static pressure and density, which is disputable for high pressures. This paper compares the effects of real and perfect gas laws on modeled transmission coefficient for porous foams at these pressures. Direct simulations and a mechanical parameters estimation from minimization show that results are very similar in both cases. The real gas law is thus not necessary to describe the acoustic behaviour of porous media at low ultrasonic frequencies (100 kHz) up to 20 bars. 2010 Elsevier B.V. All rights reserved.

A Nonlinear Modal Aeroelastic Solver for FUN3D

NASA Technical Reports Server (NTRS)

Goldman, Benjamin D.; Bartels, Robert E.; Biedron, Robert T.; Scott, Robert C.

2016-01-01

A nonlinear structural solver has been implemented internally within the NASA FUN3D computational fluid dynamics code, allowing for some new aeroelastic capabilities. Using a modal representation of the structure, a set of differential or differential-algebraic equations are derived for general thin structures with geometric nonlinearities. ODEPACK and LAPACK routines are linked with FUN3D, and the nonlinear equations are solved at each CFD time step. The existing predictor-corrector method is retained, whereby the structural solution is updated after mesh deformation. The nonlinear solver is validated using a test case for a flexible aeroshell at transonic, supersonic, and hypersonic flow conditions. Agreement with linear theory is seen for the static aeroelastic solutions at relatively low dynamic pressures, but structural nonlinearities limit deformation amplitudes at high dynamic pressures. No flutter was found at any of the tested trajectory points, though LCO may be possible in the transonic regime.

Postural control and low back pain in elite athletes comparison of static balance in elite athletes with and without low back pain.

PubMed

Oyarzo, Claudio A; Villagrán, Claudio R; Silvestre, Rony E; Carpintero, Pedro; Berral, Francisco J

2014-01-01

Although current research findings suggest that postural control or static balance is impaired in subjects with low back pain, few studies have specifically addressed the effect of low back pain on static balance in elite athletes. Forty-four athletes belonging to Chilean national teams took part in this study; 20 had low back pain and the remaining 24 were healthy controls. Displacement of the centre of pressure was analyzed by computerized platform posturography, using a standardized protocol; subjects were required to stand upright on both feet, with eyes first open then closed. The results showed that, athletes with low back pain used significantly more energy (p< 0.0182) and had a greater displacement of the centre of pressure (p< 0.005) with open eyes to control posture than healthy athletes. It may be concluded that static balance is impaired in elite athletes with low back pain and that analysis of two-footed stance provides a sensitive assessment of static balance in athletes.

Enrichment desired quality chitosan fraction and advance yield by sequential static and static-dynamic supercritical CO2.

PubMed

Hsieh, Yi-Yin; Chin, Hui Yen; Tsai, Min-Lang

2015-11-20

This study aimed to establish the sequential static and static-dynamic supercritical carbon dioxide (SDCO2) fractionation conditions to obtain a higher yield and desired chitosan with lower polydispersity index (PDI) and higher degree of deacetylation (DD). The yield increased with increasing DD of used chitosan and amount of cosolvent. The yield of acetic acid cosolvent was higher than those of malic and citric acid cosolvents. SDCO2, compared to static supercritical carbon dioxide, has higher yield. The yield of extracted chitosan was 5.82-14.70% by SDCO2/acetic acid, which increases with increasing pressure. The DD of fractionated chitosan increased from 66.1% to 70.81-85.33%, while the PDI decreased from 3.97 to 1.69-3.16. The molecular weight changed from 622kDa to 412-649kDa, which increased as density of supercritical carbon dioxide increases. Hence, higher DD and lower PDI extracted chitosan can be obtained through controlling the temperature and pressure of SDCO2. Copyright © 2015 Elsevier Ltd. All rights reserved.

Role of central command in carotid baroreflex resetting in humans during static exercise

NASA Technical Reports Server (NTRS)

Ogoh, S.; Wasmund, W. L.; Keller, D. M.; O-Yurvati, A.; Gallagher, K. M.; Mitchell, J. H.; Raven, P. B.

2002-01-01

The purpose of the experiments was to examine the role of central command in the exercise-induced resetting of the carotid baroreflex. Eight subjects performed 30 % maximal voluntary contraction (MVC) static knee extension and flexion with manipulation of central command (CC) by patellar tendon vibration (PTV). The same subjects also performed static knee extension and flexion exercise without PTV at a force development that elicited the same ratings of perceived exertion (RPE) as those observed during exercise with PTV in order to assess involvement of the exercise pressor reflex. Carotid baroreflex (CBR) function curves were modelled from the heart rate (HR) and mean arterial pressure (MAP) responses to rapid changes in neck pressure and suction during steady state static exercise. Knee extension exercise with PTV (decreased CC activation) reset the CBR-HR and CBR-MAP to a lower operating pressure (P < 0.05) and knee flexion exercise with PTV (increased CC activation) reset the CBR-HR and CBR-MAP to a higher operating pressure (P < 0.05). Comparison between knee extension and flexion exercise at the same RPE with and without PTV found no difference in the resetting of the CBR-HR function curves (P > 0.05) suggesting the response was determined primarily by CC activation. However, the CBR-MAP function curves were reset to operating pressures determined by both exercise pressor reflex (EPR) and central command activation. Thus the physiological response to exercise requires CC activation to reset the carotid-cardiac reflex but requires either CC or EPR to reset the carotid-vasomotor reflex.

The Seismic Design of Waterfront Retaining Structures

DTIC Science & Technology

1993-01-01

of elastic backfill behind a rigid wall .... .......... .. 134 5.2 Pressure distributions on smooth rigid wall for l-g static horizontal body force...135 5.3 Resultant force and resultant moment on smooth rigid wall for l-g static horizontal body force...distributions on smooth rigid wall for 1-g static horizontal body force clearly showed the limitations of Woods simplified procedure when this condi- tion is not

Comparison of Space Shuttle Hot Gas Manifold analysis to air flow data

NASA Technical Reports Server (NTRS)

Mcconnaughey, P. K.

1988-01-01

This paper summarizes several recent analyses of the Space Shuttle Main Engine Hot Gas Manifold and compares predicted flow environments to air flow data. Codes used in these analyses include INS3D, PAGE, PHOENICS, and VAST. Both laminar (Re = 250, M = 0.30) and turbulent (Re = 1.9 million, M = 0.30) results are discussed, with the latter being compared to data for system losses, outer wall static pressures, and manifold exit Mach number profiles. Comparison of predicted results for the turbulent case to air flow data shows that the analysis using INS3D predicted system losses within 1 percent error, while the PHOENICS, PAGE, and VAST codes erred by 31, 35, and 47 percent, respectively. The INS3D, PHOENICS, and PAGE codes did a reasonable job of predicting outer wall static pressure, while the PHOENICS code predicted exit Mach number profiles with acceptable accuracy. INS3D was approximately an order of magnitude more efficient than the other codes in terms of code speed and memory requirements. In general, it is seen that complex internal flows in manifold-like geometries can be predicted with a limited degree of confidence, and further development is necessary to improve both efficiency and accuracy of codes if they are to be used as design tools for complex three-dimensional geometries.

LSENS: A General Chemical Kinetics and Sensitivity Analysis Code for homogeneous gas-phase reactions. Part 3: Illustrative test problems

NASA Technical Reports Server (NTRS)

Bittker, David A.; Radhakrishnan, Krishnan

1994-01-01

LSENS, the Lewis General Chemical Kinetics and Sensitivity Analysis Code, has been developed for solving complex, homogeneous, gas-phase chemical kinetics problems and contains sensitivity analysis for a variety of problems, including nonisothermal situations. This report is part 3 of a series of three reference publications that describe LSENS, provide a detailed guide to its usage, and present many example problems. Part 3 explains the kinetics and kinetics-plus-sensitivity analysis problems supplied with LSENS and presents sample results. These problems illustrate the various capabilities of, and reaction models that can be solved by, the code and may provide a convenient starting point for the user to construct the problem data file required to execute LSENS. LSENS is a flexible, convenient, accurate, and efficient solver for chemical reaction problems such as static system; steady, one-dimensional, inviscid flow; reaction behind incident shock wave, including boundary layer correction; and perfectly stirred (highly backmixed) reactor. In addition, the chemical equilibrium state can be computed for the following assigned states: temperature and pressure, enthalpy and pressure, temperature and volume, and internal energy and volume. For static problems the code computes the sensitivity coefficients of the dependent variables and their temporal derivatives with respect to the initial values of the dependent variables and/or the three rate coefficient parameters of the chemical reactions.

Analysis of stratified and closely spaced jets exhausting into a crossflow. [aerodynamic characteristics of lift-jet, vectored thrust, and lift fan V/STOL aircraft

NASA Technical Reports Server (NTRS)

Ziegler, H.; Woller, P. T.

1973-01-01

Procedures have been developed for determining the flow field about jets with velocity stratification exhausting into a crossflow. Jets with three different types of exit velocity stratification have been considered: (1) jets with a relatively high velocity core; (2) jets with a relatively low velocity core; and (3) jets originating from a vaned nozzle. The procedure developed for a jet originating from a high velocity core nozzle is to construct an equivalent nozzle having the same mass flow and thrust but having a uniform exit velocity profile. Calculations of the jet centerline and induced surface static pressures have been shown to be in good agreement with test data for a high velocity core nozzle. The equivalent ideal nozzle has also been shown to be a good representation for jets with a relatively low velocity core and for jets originating from a vaned nozzle in evaluating jet-induced flow fields. For the singular case of a low velocity core nozzle, namely a nozzle with a dead air core, and for the vaned nozzle, an alternative procedure has been developed. The internal mixing which takes place in the jet core has been properly accounted for in the equations of motion governing the jet development. Calculations of jet centerlines and induced surface static pressures show good agreement with test data these nozzles.

Measured pressure distributions inside nonaxisymmetric nozzles with partially deployed thrust reversers

NASA Technical Reports Server (NTRS)

Green, Robert S.; Carson, George T., Jr.

1987-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel at static conditions to measure the pressure distributions inside a nonaxisymmetric nozzle with simultaneous partial thrust reversing (50-percent deployment) and thrust vectoring of the primary (forward-thrust) nozzle flow. Geometric forward-thrust-vector angles of 0 and 15 deg. were tested. Test data were obtained at static conditions while nozzle pressure ratio was varied from 2.0 to 4.0. Results indicate that, unlike the 0 deg. vector angle nozzle, a complicated, asymmetric exhaust flow pattern exists in the primary-flow exhaust duct of the 15 deg. vectored nozzle.

Design of on line detection system for static evaporation rate of LNG vehicle cylinders

NASA Astrophysics Data System (ADS)

Tang, P.; Wang, M.; Tan, W. H.; Ling, Z. W.; Li, F.

2017-06-01

In order to solve the problems existing in the regular inspection of LNG vehicle cylinders, the static evaporation rate on line detection system of LNG cylinders is discussed in this paper. A non-disassembling, short-term and high-efficiency on line detection system for LNG vehicle cylinders is proposed, which can meet the requirement of evaporation rate test under different media and different test pressures. And then test methods under the experimental conditions, atmospheric pressure and pressure are given respectively. This online detection system designed in this paper can effectively solve the technical problems during the inspection of the cylinder.

Sensing characteristics of long period gratings in hollow core fiber fabricated via electrode arc discharge

NASA Astrophysics Data System (ADS)

Iadicicco, Agostino; Cutolo, A.; Campopiano, Stefania

2014-05-01

This paper reports on the fabrication of Long Period Gratings (LPGs) in hollow-core air-silica photonic bandgap fibers (HC-PCFs) by using pressure assisted Electrode Arc Discharge (EAD) technique. In particular, the fabrication procedure relies on the combined use of EAD step, to locally heat the HC fiber, and of a static pressure (slightly higher than the external one) inside the fiber holes, to modify the holes. Here, the experimental fabrication of LPG prototypes with different periods and lengths are discussed. And, the sensitivity of LPGs in HC-PCF to environmental parameters such as strain, temperature and static pressure are presented and discussed.

Performance Characteristics of Plane-Wall Two-Dimensional Diffusers

NASA Technical Reports Server (NTRS)

Reid, Elliott G

1953-01-01

Experiments have been made at Stanford University to determine the performance characteristics of plane-wall, two-dimensional diffusers which were so proportioned as to insure reasonable approximation of two-dimensional flow. All of the diffusers had identical entrance cross sections and discharged directly into a large plenum chamber; the test program included wide variations of divergence angle and length. During all tests a dynamic pressure of 60 pounds per square foOt was maintained at the diffuser entrance and the boundary layer there was thin and fully turbulent. The most interesting flow characteristics observed were the occasional appearance of steady, unseparated, asymmetric flow - which was correlated with the boundary-layer coalescence - and the rapid deterioration of flow steadiness - which occurred as soon as the divergence angle for maximum static pressure recovery was exceeded. Pressure efficiency was found to be controlled almost exclusively by divergence angle, whereas static pressure recovery was markedly influenced by area ratio (or length) as well as divergence angle. Volumetric efficiency. diminished as area ratio increased, and at a greater rate with small lengths than with large ones. Large values of the static-pressure-recovery coefficient were attained only with long diffusers of large area ratio; under these conditions pressure efficiency was high and. volumetric efficiency low. Auxiliary tests with asymmetric diffusers demonstrated that longitudinal pressure gradient, rather than wall divergence angle, controlled flow separation. Others showed that the addition of even a short exit duct of uniform section augmented pressure recovery. Finally, it was found that the installation of a thin, central, longitudinal partition suppressed flow separation in short diffusers and thereby improved pressure recovery

Investigation Leads to Improved Understanding of Space Shuttle RSRM Internal Insulation Joints

NASA Technical Reports Server (NTRS)

McWhorter, Bruce B.; Bolton, Doug E.; Hicken, Steve V.; Allred, Larry D.; Cook, Dave J.

2003-01-01

The Space Shuttle Reusable Solid Rocket Motor (RSRM) uses an internal insulation J-joint design for the mated insulation interface between two assembled RSRM segments. In this assembled (mated) segment configuration, this J-joint design serves as a thermal barrier to prevent hot gases from affecting the case field joint metal surfaces and O-rings. A pressure sensitive adhesive (PSA) provides some adhesion between the two mated insulation surfaces. In 1995, after extensive testing, a new ODC-free PSA (free of ozone depleting chemicals) was selected for flight on RSRM-55 (STS-78). Post-flight inspection revealed that the J-joint, equipped with the new ODC-free PSA, did not perform well. Hot gas seeped inside the J-joint interface. Although not a flight safety threat, the J-joint hot gas intrusion on RSRM-55 was a mystery to the investigators since the PSA had previously worked well on a full-scale static test. A team was assembled to study the J-joint and PSA further. All J-joint design parameters, measured data, and historical performance data were re-reviewed and evaluated by subscale testing and analysis. Although both the ODC-free and old PSA were weakened by humidity, the ODC-free PSA strength was lower to start with. Another RSRM full-scale static test was conducted in 1998 and intentionally duplicated the gas intrusion. This test, along with many concurring tests, showed that if a J-joint was 1) mated with the new ODC-free PSA, 2) exposed to a history of high humidity (Kennedy Space Center levels), and 3) also a joint which experienced significant but normal joint motion (J-joint deformation resulting from motor pressurization dynamics) then that J-joint would open (allow gas intrusion) during motor operation. When all of the data from the analyses, subscale tests, and full-scale tests were considered together, a theory emerged. Most of the joint motion on the RSRM occurs early in motor operation at which point the J-joints are pulled into tension. If the new PSA has been weakened due to humidity, then the J-joint will partially pull apart (inboard side), and the J-joint surfaces will be charred by exposure to hot gases. After early operation, a J-joint that has been pulled apart will come back together as the J-joint deformation decreases. This J-joint heating event is relatively short and occurs only during the first part of motor operation. Internal instrumentation was developed for another full-scale static test in February 2000. The static test instrumentation did indeed prove this theory to be correct. Post-test inspection revealed very similar charring characteristics as observed on RSRM-55. This experience of the development of a new PSA, its testing, the RSRM-55 flight, followed by the J-joint investigation led to good 'lessons learned' and to an additional fundamental understanding of the RSRM J-joint function.

An investigation to determine the static pressure distribution of the 0.00548 scale shuttle solid rocket booster (MSFC model number 468) during reentry in the NASA/MSFC 14 inch trisonic wind tunnel (SA28F)

NASA Technical Reports Server (NTRS)

Braddock, W. F.; Streby, G. D.

1977-01-01

The results of a pressure test of a .00548 scale 146 inch Space Shuttle Solid Rocket Booster (SRB) with and without protuberances, conducted in a 14 x 14 inch trisonic wind tunnel are presented. Static pressure distributions for the SRB at reentry attitudes and flight conditions were obtained. Local longitudinal and ring pressure distributions are presented in tabulated form. Integration of the pressure data was performed. The test was conducted at Mach numbers of 0.40 to 4.45 over an angle of attack range from 60 to 185 degrees. Roll angles of 0, 45, 90 and 315 degrees were investigated. Reynolds numbers per foot varied for selected Mach numbers.

Protecting the Turkish Straits from Maritime Terrorism: A Scheme to Impede Propeller Efficiency

DTIC Science & Technology

2012-06-01

electric fence, fire nozzle with pressurized water, optical laser distracter (a dazzle gun), Long Range Acoustic Device (LRAD) and other types of non...are easily ignited by machinery, cigarettes, and static electricity . Static electricity discharged when one walks on a carpet or brushes his/her hair...formed in the first tank car due to the impact with a signaling stake. The pressurized LPG was released as a two-phase jet: the liquid phase formed a

Turbine Engine Control Synthesis. Volume 1. Optimal Controller Synthesis and Demonstration

DTIC Science & Technology

1975-03-01

Nomenclature (Continued) Symbol Deseription M Matrix (of Table 12) M Mach number N Rotational speed, rpm N ’ Nonlinear rotational speed, rpm P Power lever... P Pressure, N /m 2; bfh/ft 2 PLA Power lever angle PR = PT3/PT2 Pressure ratio ( P Power, ft-lbf/sec Q Matrix (of Table 30) R Universal gas constant, 53...function, i = 1, 2, 3, ... in Inlet n Stage number designation out Outlet p Variable associated with particle s Static condition _se Static condition

Probe systems for measuring static pressure and turbulence intensity in fluid streams

NASA Technical Reports Server (NTRS)

Rossow, Vernon J. (Inventor)

1993-01-01

A method and an apparatus for measuring time-averaged static or ambient pressure and turbulence intensity in a turbulent stream are discussed. The procedure involves placing a plurality of probes in the stream. Each probe responds in a different manner to characteristics of the fluid stream, preferably as a result of having varying cross sections. The responses from the probes are used to eliminate unwanted components in the measured quantities for accurate determination of selected characteristics.

A comparison study of brachial blood pressure recorded with Spacelabs 90217A and Mobil-O-Graph NG devices under static and ambulatory conditions.

PubMed

Sarafidis, P A; Lazaridis, A A; Imprialos, K P; Georgianos, P I; Avranas, K A; Protogerou, A D; Doumas, M N; Athyros, V G; Karagiannis, A I

2016-12-01

Ambulatory blood pressure monitoring is an important tool in hypertension diagnosis and management. Although several ambulatory devices exist, comparative studies are scarce. This study aimed to compare for the first time brachial blood pressure levels of Spacelabs 90217A and Mobil-O-Graph NG, under static and ambulatory conditions. We examined 40 healthy individuals under static (study A) and ambulatory (study B) conditions. In study A, participants were randomized into two groups that included blood pressure measurements with mercury sphygmomanometer, Spacelabs and Mobil-O-Graph devices with reverse order of recordings. In study B, simultaneous 6-h recordings with both devices were performed with participants randomized in two sequences of device positioning with arm reversal at 3 h. Finally, all the participants filled in a questionnaire rating their overall preference for a device. In study A, brachial systolic blood pressure (117.2±10.3 vs 117.1±9.8 mm Hg, P=0.943) and diastolic blood pressure (73.3±9.4 mm Hg vs 74.1±9.4 mm Hg, P=0.611) did not differ between Spacelabs and Mobil-O-Graph or vs sphygmomanometer (117.8±11.1 mm Hg, P=0.791 vs Spacelabs, P=0.753 vs Mobil-O-Graph). Similarly, no differences were found in ambulatory systolic blood pressure (117.9±11.4 vs 118.3±11.0 mm Hg, P=0.864), diastolic blood pressure (73.7±7.4 vs 74.7±8.0 mm Hg, P=0.571), mean blood pressure and heart rate between Spacelabs and Mobil-O-Graph. Correlation analyses and Bland-Altman plots showed agreement between the monitors. Overall, the participants showed a preference for the Mobil-O-Graph. Spacelabs 90217A and Mobil-O-Graph NG provide practically identical measurements during the static and ambulatory conditions in healthy individuals and can be rather used interchangeably in clinical practice.

Dynamic Cerebrovascular and Intracranial Pressure Reactivity Assessment of Impaired Cerebrovascular Autoregulation in Intracranial Hypertension.

PubMed

Bragin, Denis E; Statom, Gloria; Nemoto, Edwin M

2016-01-01

We previously suggested that the discrepancy between a critical cerebral perfusion pressure (CPP) of 30 mmHg, obtained by increasing intracranial pressure (ICP), and 60 mmHg, obtained by decreasing arterial pressure, was due to pathological microvascular shunting at high ICP [1], and that the determination of the critical CPP by the static cerebral blood flow (CBF) autoregulation curve is not valid with intracranial hypertension. Here, we demonstrated that induced dynamic ICP reactivity (iPRx), and cerebrovascular reactivity (CVRx) tests accurately identify the critical CPP in the hypertensive rat brain, which differs from that obtained by the static autoregulation curve. Step changes in CPP from 70 to 50 and 30 mmHg were made by increasing ICP using an artificial cerebrospinal fluid reservoir connected to the cisterna magna. At each CPP, a transient 10-mmHg increase in arterial pressure was induced by bolus intravenous dopamine. iPRx and iCVRx were calculated as ΔICP/Δ mean arterial pressure (MAP) and as ΔCBF/ΔMAP, respectively. The critical CPP at high ICP, obtained by iPRx and iCVRx, is 50 mmHg, where compromised capillary flow, transition of blood flow to nonnutritive microvascular shunts, tissue hypoxia, and brain-blood barrier leakage begin to occur, which is higher than the 30 mmHg determined by static autoregulation.

Global Pressure- and Temperature-Measurements in 1.27-m JAXA Hypersonic Wind Tunnel

NASA Astrophysics Data System (ADS)

Yamada, Y.; Miyazaki, T.; Nakagawa, M.; Tsuda, S.; Sakaue, H.

Pressure-sensitive paint (PSP) technique has been widely used in aerodynamic measurements. A PSP is a global optical sensor, which consists of a luminophore and binding material. The luminophore gives a luminescence related to an oxygen concentration known as oxygen quenching. In an aerodynamic measurement, the oxygen concentration is related to a partial pressure of oxygen and a static pressure, thus the luminescent signal can be related to a static pressure [1]. The PSP measurement system consists of a PSP coated model, an image acquisition unit, and an image processing unit (Fig. 1). For the image acquisition, an illumination source and a photo-detector are required. To separate the illumination and PSP emission detected by a photo-detector, appropriate band-pass filters are placed in front of the illumination and photo-detector. The image processing unit includes the calibration and computation. The calibration relates the luminescent signal to pressures and temperatures. Based on these calibrations, luminescent images are converted to a pressure map.

An investigation of transient pressure and plasma properties in a pinched plasma column. M.S. Thesis

NASA Technical Reports Server (NTRS)

Stover, E. K.; York, T. M.

1971-01-01

The transient pinched plasma column generated in a linear Z-pinch was studied experimentally and analytically. The plasma column was investigated experimentally with the following plasma diagnostics: a special rapid response pressure transducer, a magnetic field probe, a voltage probe and discharge luminosity. Axial pressure profiles on the discharge chamber axis were used to identify three characteristic regions of plasma column behavior; they were in temporal sequence: strong axial pressure asymmetry noted early in plasma column lifetime followed by plasma heating in which there is a rapid rise in static pressure and a slight decrease static pressure before plasma column breakup. Plasma column lifetime was approximately 5 microseconds. The axial pressure asymmetry was attributed to nonsimultaneous pinching of the imploding current sheet along the discharge chamber axis. The rapid heating is attributed in part to viscous effects introduced by radial gradients in the axial streaming velocity. Turbulent heating arising from discharge current excitation of the ion acoustic wave instability is also considered a possible heating mechanism.

Measuring Blast-Related Intracranial Pressure Within the Human Head

DTIC Science & Technology

2010-08-01

an d stagnation pressures; stagnation pr essure , also called incident pre ssure, consists of static and dynamic pressure combined and subsequent da...represent a n oticeable decrease in IC pr essure that happened before the IC pressure started to increase. This behavior is very noticeable in all

Porous media fracturing dynamics: stepwise crack advancement and fluid pressure oscillations

NASA Astrophysics Data System (ADS)

Cao, Toan D.; Hussain, Fazle; Schrefler, Bernhard A.

2018-02-01

We present new results explaining why fracturing in saturated porous media is not smooth and continuous but is a distinct stepwise process concomitant with fluid pressure oscillations. All exact solutions and almost all numerical models yield smooth fracture advancement and fluid pressure evolution, while recent experimental results, mainly from the oil industry, observation from geophysics and a very few numerical results for the quasi-static case indeed reveal the stepwise phenomenon. We summarize first these new experiments and these few numerical solutions for the quasi-static case. Both mechanical loading and pressure driven fractures are considered because their behaviours differ in the direction of the pressure jumps. Then we explore stepwise crack tip advancement and pressure fluctuations in dynamic fracturing with a hydro-mechanical model of porous media based on the Hybrid Mixture Theory. Full dynamic analyses of examples dealing with both hydraulic fracturing and mechanical loading are presented. The stepwise fracture advancement is confirmed in the dynamic setting as well as in the pressure fluctuations, but there are substantial differences in the frequency contents of the pressure waves in the two loading cases. Comparison between the quasi-static and fully dynamic solutions reveals that the dynamic response gives much more information such as the type of pressure oscillations and related frequencies and should be applied whenever there is a doubt about inertia forces playing a role - the case in most fracturing events. In the absence of direct relevant dynamic tests on saturated media some experimental results on dynamic fracture in dry materials, a fast hydraulic fracturing test and observations from geophysics confirm qualitatively the obtained results such as the type of pressure oscillations and the substantial difference in the behaviour under the two loading cases.

Hydrodynamic comparison of the Penumbra system and commonly available syringes in forced-suction thrombectomy.

PubMed

Simon, Scott Douglas; Grey, Casey Paul

2014-04-01

The Penumbra system uses a coaxial separator and continuous extracorporeal suction to remove a clot from a cerebral artery. Forced-suction thrombectomy (FST) involves aspirating clots through the same reperfusion catheter using only a syringe, decreasing the procedure time and supplies needed. To evaluate multiple combinations of catheters and syringes to determine the optimal pairing for use in FST. Tests were performed using both the Penumbra system and syringes to aspirate water through Penumbra 0.041 inch (041), 4Max, 0.054 inch (054) and 5Max reperfusion catheters and a shuttle sheath. Dynamic pressure and flow at the catheter tip were calculated from the fill times for each system. Static pressure and force for each aspiration source were determined with a vacuum gauge. All syringes provided significantly higher dynamic pressure at the catheter tip than the Penumbra system (p<0.001). Increasing syringe volume significantly increased static pressure (p<0.001). Both flow and aspiration force significantly increased with catheter size (p<0.001). Cases are presented to demonstrate the clinical value of the laboratory principles. Maximizing static and dynamic pressure when performing FST is achieved by aspirating with a syringe possessing both the largest volume and the largest inlet diameter available. Maximizing aspiration force and flow rate is achieved by using the largest catheter possible.

Effect of Sweep on Cavity Flow Fields at Subsonic and Transonic Speeds

NASA Technical Reports Server (NTRS)

Tracy, Maureen B.; Plentovich, Elizabeth B.; Hemsch, Michael J.; Wilcox, Floyd J.

2012-01-01

An experimental investigation was conducted in the NASA Langley 7 x 10-Foot High Speed Tunnel (HST) to study the effect of leading- and trailing-edge sweep on cavity flow fields for a range of cavity length-to-height (l/h) ratios. The free-stream Mach number was varied from 0.2 to 0.8. The cavity had a depth of 0.5 inches, a width of 2.5 inches, and a maximum length of 12.0 inches. The leading- and trailing-edge sweep was adjusted using block inserts to achieve leading edge sweep angles of 65 deg, 55 deg, 45 deg, 35 deg, and 0 deg. The fore and aft cavity walls were always parallel. The aft wall of the cavity was remotely positioned to achieve a range of length-to-depth ratios. Fluctuating- and static-pressure data were obtained on the floor of the cavity. The fluctuating pressure data were used to determine whether or not resonance occurred in the cavity rather than to provide a characterization of the fluctuating pressure field. Qualitative surface flow visualization was obtained using a technique in which colored water was introduced into the model through static-pressure orifices. A complete tabulation of the mean static-pressure data for the swept leading edge cavities is included.

78 FR 35645 - Certain Static Random Access Memories and Products Containing Same; Commission Determination...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-13

... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-792] Certain Static Random Access Memories and Products Containing Same; Commission Determination Affirming a Final Initial Determination..., and the sale within the United States after importation of certain static random access memories and...

Flow analysis for the nacelle of an advanced ducted propeller at high angle-of-attack and at cruise with boundary layer control

NASA Technical Reports Server (NTRS)

Hwang, D. P.; Boldman, D. R.; Hughes, C. E.

1994-01-01

An axisymmetric panel code and a three dimensional Navier-Stokes code (used as an inviscid Euler code) were verified for low speed, high angle of attack flow conditions. A three dimensional Navier-Stokes code (used as an inviscid code), and an axisymmetric Navier-Stokes code (used as both viscous and inviscid code) were also assessed for high Mach number cruise conditions. The boundary layer calculations were made by using the results from the panel code or Euler calculation. The panel method can predict the internal surface pressure distributions very well if no shock exists. However, only Euler and Navier-Stokes calculations can provide a good prediction of the surface static pressure distribution including the pressure rise across the shock. Because of the high CPU time required for a three dimensional Navier-Stokes calculation, only the axisymmetric Navier-Stokes calculation was considered at cruise conditions. The use of suction and tangential blowing boundary layer control to eliminate the flow separation on the internal surface was demonstrated for low free stream Mach number and high angle of attack cases. The calculation also shows that transition from laminar flow to turbulent flow on the external cowl surface can be delayed by using suction boundary layer control at cruise flow conditions. The results were compared with experimental data where possible.

Vibrational Spectroscopic Studies of Reduced-Sensitivity RDX under Static Compression

NASA Astrophysics Data System (ADS)

Wong, Chak

2005-07-01

Explosives formulations with Reduced- Sensitivity RDX showed reduced shock sensitivity using NOL Large Scale Gap Test, compared with similar formulations using normal RDX. Molecular processes responsible for the reduction of sensitivity are unknown and are crucial for formulation development. Vibrational spectroscopy at static high pressure may shed light to the mechanisms responsible for the reduced shock sensitivity as shown by the NOL Large Scale Gap Test. SIRDX, a form of Reduced- Sensitivity RDX, was subjected to static compression at ambient temperature in a Merrill-Bassett sapphire cell from ambient to about 6 GPa. The spectroscopic techniques used were Raman and Fourier-Transformed IR (FTIR). The pressure dependence of the Raman mode frequencies of SIRDX was determined and compared with that of normal RDX. The behavior of SIRDX near the pressure at which normal RDX, at ambient temperature, undergoes a phase transition from the α to the γ polymorph will be presented. Implications to the reduction in sensitivity will be discussed.

First-principles study of the structural, elastic, vibrational, thermodynamic and electronic properties of the Mo2B intermetallic under pressure

NASA Astrophysics Data System (ADS)

Escamilla, R.; Carvajal, E.; Cruz-Irisson, M.; Romero, M.; Gómez, R.; Marquina, V.; Galván, D. H.; Durán, A.

2016-12-01

The structural, elastic, vibrational, thermodynamic and electronic properties of the Mo2B intermetallic under pressure are assessed using first-principles calculations based on the generalized gradient approximation (GGA) proposed by Perdew-Wang (PW91). Our results show that the calculated structural parameters at a pressure of zero GPa are in good agreement with the available experimental data. The effect of high pressures on the lattice constants shows that the compression along the c-axis and along the a-axis are similar. The elastic constants were calculated using the static finite strain technique, and the bulk shear moduli are derived from the ideal polycrystalline aggregate. We find that the elastic constants, elastic modulus and hardness monotonically increase as a function of pressure; consequently, the structure is dynamically stable and tends from brittle to ductile behavior under pressure. The Debye temperature θD increases and the so-called Gru¨ neisen constant γ decreases due to stiffening of the crystal structure. The phonon dispersion curves were obtained using the direct method. Additionally, the internal energy (ΔE), the Helmholtz free energy (ΔF), the entropy (S) and the lattice contribution to the heat capacity Cv were calculated and analyzed with the help of the phonon dispersion curves. The N(EF) and the electron transfer between the B and Mo atoms increase as a function of pressure.

Measurement and Computation of Supersonic Flow in a Lobed Diffuser-Mixer for Trapped Vortex Combustors

NASA Technical Reports Server (NTRS)

Brankovic, Andreja; Ryder, Robert C., Jr.; Hendricks, Robert C.; Liu, Nan-Suey; Gallagher, John R.; Shouse, Dale T.; Roquemore, W. Melvyn; Cooper, Clayton S.; Burrus, David L.; Hendricks, John A.

2002-01-01

The trapped vortex combustor (TVC) pioneered by Air Force Research Laboratories (AFRL) is under consideration as an alternative to conventional gas turbine combustors. The TVC has demonstrated excellent operational characteristics such as high combustion efficiency, low NO(x) emissions, effective flame stabilization, excellent high-altitude relight capability, and operation in the lean-burn or rich burn-quick quench-lean burn (RQL) modes of combustion. It also has excellent potential for lowering the engine combustor weight. This performance at low to moderate combustor mach numbers has stimulated interest in its ability to operate at higher combustion mach number, and for aerospace, this implies potentially higher flight mach numbers. To this end, a lobed diffuser-mixer that enhances the fuel-air mixing in the TVC combustor core was designed and evaluated, with special attention paid to the potential shock system entering the combustor core. For the present investigation, the lobed diffuser-mixer combustor rig is in a full annular configuration featuring sixfold symmetry among the lobes, symmetry within each lobe, and plain parallel, symmetric incident flow. During hardware cold-flow testing, significant discrepancies were found between computed and measured values for the pitot-probe-averaged static pressure profiles at the lobe exit plane. Computational fluid dynamics (CFD) simulations were initiated to determine whether the static pressure probe was causing high local flow-field disturbances in the supersonic flow exiting the diffuser-mixer and whether shock wave impingement on the pitot probe tip, pressure ports, or surface was the cause of the discrepancies. Simulations were performed with and without the pitot probe present in the modeling. A comparison of static pressure profiles without the probe showed that static pressure was off by nearly a factor of 2 over much of the radial profile, even when taking into account potential axial displacement of the probe by up to 0.25 in. (0.64 cm). Including the pitot probe in the CFD modeling and data interpretation lead to good agreement between measurement and prediction. Graphical inspection of the results showed that the shock waves impinging on the probe surface were highly nonuniform, with static pressure varying circumferentially among the pressure ports by over 10 percent in some cases. As part of the measurement methodology, such measurements should be routinely supplemented with CFD analyses that include the pitot probe as part of the flow-path geometry.

Incidence loss for a core turbine rotor blade in a two-dimensional cascade

NASA Technical Reports Server (NTRS)

Stabe, R. G.; Kline, J. F.

1974-01-01

The effect of incidence angle on the aerodynamic performance of an uncooled core turbine rotor blade was investigated experimentally in a two-dimensional cascade. The cascade test covered a range of incidence angles from minus 15 deg to 15 deg in 5-degree increments and a range of pressure ratios corresponding to ideal exit critical velocity ratios of 0.6 to 0.95. The principal measurements were blade-surface static pressures and cross-channel surveys of exit total pressure, static pressure, and flow angle. The results of the investigation include blade-surface velocity distribution and overall performance in terms of weight flow and loss for the range of incidence angles and exit velocity ratios investigated. The measured losses are also compared with two common methods of predicting incidence loss.

Analysis of Fluctuating Static Pressure Measurements in the National Transonic Facility

NASA Technical Reports Server (NTRS)

Igoe, William B.

1996-01-01

Dynamic measurements of fluctuating static pressure levels were taken with flush-mounted, high-frequency response pressure transducers at 11 locations in the circuit of the National Transonic Facility (NTF) across the complete operating range of this wind tunnel. Measurements were taken at test-section Mach numbers from 0.1 to 1.2, at pressures from 1 to 8.6 atm, and at temperatures from ambient to -250 F, which resulted in dynamic flow disturbance measurements at the highest Reynolds numbers available in a transonic ground test facility. Tests were also made by independent variation of the Mach number, the Reynolds number, or the fan drive power while the other two parameters were held constant, which for the first time resulted in a distinct separation of the effects of these three important parameters.

Numerical analysis of flow interaction of turbine system in two-stage turbocharger of internal combustion engine

NASA Astrophysics Data System (ADS)

Liu, Y. B.; Zhuge, W. L.; Zhang, Y. J.; Zhang, S. Y.

2016-05-01

To reach the goal of energy conservation and emission reduction, high intake pressure is needed to meet the demand of high power density and high EGR rate for internal combustion engine. Present power density of diesel engine has reached 90KW/L and intake pressure ratio needed is over 5. Two-stage turbocharging system is an effective way to realize high compression ratio. Because turbocharging system compression work derives from exhaust gas energy. Efficiency of exhaust gas energy influenced by design and matching of turbine system is important to performance of high supercharging engine. Conventional turbine system is assembled by single-stage turbocharger turbines and turbine matching is based on turbine MAP measured on test rig. Flow between turbine system is assumed uniform and value of outlet physical quantities of turbine are regarded as the same as ambient value. However, there are three-dimension flow field distortion and outlet physical quantities value change which will influence performance of turbine system as were demonstrated by some studies. For engine equipped with two-stage turbocharging system, optimization of turbine system design will increase efficiency of exhaust gas energy and thereby increase engine power density. However flow interaction of turbine system will change flow in turbine and influence turbine performance. To recognize the interaction characteristics between high pressure turbine and low pressure turbine, flow in turbine system is modeled and simulated numerically. The calculation results suggested that static pressure field at inlet to low pressure turbine increases back pressure of high pressure turbine, however efficiency of high pressure turbine changes little; distorted velocity field at outlet to high pressure turbine results in swirl at inlet to low pressure turbine. Clockwise swirl results in large negative angle of attack at inlet to rotor which causes flow loss in turbine impeller passages and decreases turbine efficiency. However negative angle of attack decreases when inlet swirl is anti-clockwise and efficiency of low pressure turbine can be increased by 3% compared to inlet condition of clockwise swirl. Consequently flow simulation and analysis are able to aid in figuring out interaction mechanism of turbine system and optimizing turbine system design.

In-ground optical fibre Bragg grating pressure switch for security applications

NASA Astrophysics Data System (ADS)

Allwood, Gary; Wild, Graham; Hinckley, Steven

2012-02-01

In this study, a fibre Bragg grating (FBG) was embedded beneath three common flooring materials acting as a pressure switch for in-ground intrusion detection. This is achieved using an intensiometric detection system, where a laser diode and FBG were optically mismatched so that there was a static dc offset from the transmitted and reflected optical power signals. As pressure was applied, in the form of a footstep, a strain induced wavelength shift occurred that could then be detected by converting the wavelength shift into an intensity change. The change in intensity caused a significant change in the DC offset which behaved as on optical switch. This switch could easily be configured to trigger an alarm if required. The intention is to use the FBG sensor as an in-ground intrusion detection pressure switch to detect an intruder walking within range of the sensor. This type of intrusion detection system can be applied to both external (in soil, etc) and internal (within the foundations or flooring of the home) security systems. The results show that a person's footstep can clearly be detected through solid wood flooring, laminate flooring, and ceramic floor tiles.

Scale model test results of several STOVL ventral nozzle concepts

NASA Technical Reports Server (NTRS)

Meyer, B. E.; Re, R. J.; Yetter, J. A.

1991-01-01

Short take-off and vertical landing (STOVL) ventral nozzle concepts are investigated by means of a static cold flow scale model at a NASA facility. The internal aerodynamic performance characteristics of the cruise, transition, and vertical lift modes are considered for four ventral nozzle types. The nozzle configurations examined include those with: butterfly-type inner doors and vectoring exit vanes; circumferential inner doors and thrust vectoring vanes; a three-port segmented version with circumferential inner doors; and a two-port segmented version with cylindrical nozzle exit shells. During the testing, internal and external pressure is measured, and the thrust and flow coefficients and resultant vector angles are obtained. The inner door used for ventral nozzle flow control is found to affect performance negatively during the initial phase of transition. The best thrust performance is demonstrated by the two-port segmented ventral nozzle due to the elimination of the inner door.

78 FR 25767 - Certain Static Random Access Memories and Products Containing Same; Commission Determination To...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-02

... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-792] Certain Static Random Access Memories and Products Containing Same; Commission Determination To Review in Part a Final Initial... States after importation of certain static random access memories and products containing the same by...

Turbine airfoil with ambient cooling system

DOEpatents

Campbell, Jr, Christian X.; Marra, John J.; Marsh, Jan H.

2016-06-07

A turbine airfoil usable in a turbine engine and having at least one ambient air cooling system is disclosed. At least a portion of the cooling system may include one or more cooling channels configured to receive ambient air at about atmospheric pressure. The ambient air cooling system may have a tip static pressure to ambient pressure ratio of at least 0.5, and in at least one embodiment, may include a tip static pressure to ambient pressure ratio of between about 0.5 and about 3.0. The cooling system may also be configured such that an under root slot chamber in the root is large to minimize supply air velocity. One or more cooling channels of the ambient air cooling system may terminate at an outlet at the tip such that the outlet is aligned with inner surfaces forming the at least one cooling channel in the airfoil to facilitate high mass flow.

High Temperature Dynamic Pressure Measurements Using Silicon Carbide Pressure Sensors

NASA Technical Reports Server (NTRS)

Okojie, Robert S.; Meredith, Roger D.; Chang, Clarence T.; Savrun, Ender

2014-01-01

Un-cooled, MEMS-based silicon carbide (SiC) static pressure sensors were used for the first time to measure pressure perturbations at temperatures as high as 600 C during laboratory characterization, and subsequently evaluated in a combustor rig operated under various engine conditions to extract the frequencies that are associated with thermoacoustic instabilities. One SiC sensor was placed directly in the flow stream of the combustor rig while a benchmark commercial water-cooled piezoceramic dynamic pressure transducer was co-located axially but kept some distance away from the hot flow stream. In the combustor rig test, the SiC sensor detected thermoacoustic instabilities across a range of engine operating conditions, amplitude magnitude as low as 0.5 psi at 585 C, in good agreement with the benchmark piezoceramic sensor. The SiC sensor experienced low signal to noise ratio at higher temperature, primarily due to the fact that it was a static sensor with low sensitivity.

Numerical modeling and characterization of blast waves for application in blast-induced mild traumatic brain injury research

NASA Astrophysics Data System (ADS)

Phillips, Michael G.

Human exposure to blast waves, including blast-induced traumatic brain injury, is a developing field in medical research. Experiments with explosives have many disadvantages including safety, cost, and required area for trials. Shock tubes provide an alternative method to produce free field blast wave profiles. A compressed nitrogen shock tube experiment instrumented with static and reflective pressure taps is modeled using a numerical simulation. The geometry of the numerical model is simplified and blast wave characteristics are derived based upon static and pressure profiles. The pressure profiles are analyzed along the shock tube centerline and radially away from the tube axis. The blast wave parameters found from the pressure profiles provide guidelines for spatial location of a specimen. The location could be based on multiple parameters and provides a distribution of anticipated pressure profiles experience by the specimen.

Frictionless bead packs have macroscopic friction, but no dilatancy.

PubMed

Peyneau, Pierre-Emmanuel; Roux, Jean-Noël

2008-07-01

The statement of the title is shown by numerical simulation of homogeneously sheared assemblies of frictionless, nearly rigid beads in the quasistatic limit. Results coincide for steady flows at constant shear rate gamma[over ] in the limit of small gamma[over ] and static approaches, in which packings are equilibrated under growing deviator stresses. The internal friction angle phi , equal to 5.76 degrees +/-0.22 degrees in simple shear, is independent of average pressure P in the rigid limit and stems from the ability of stable frictionless contact networks to form stress-induced anisotropic fabrics. No enduring strain localization is observed. Dissipation at the macroscopic level results from repeated network rearrangements, similar to the effective friction of a frictionless slider on a bumpy surface. Solid fraction Phi remains equal to the random close packing value approximately 0.64 in slowly or statically sheared systems. Fluctuations of stresses and volume are observed to regress in the large system limit. Defining the inertial number as I=gamma radical m/(aP), with m the grain mass and a its diameter, both internal friction coefficient mu*=tan phi and volume 1/Phi increase as powers of I in the quasistatic limit of vanishing I , in which all mechanical properties are determined by contact network geometry. The microstructure of the sheared material is characterized with a suitable parametrization of the fabric tensor and measurements of coordination numbers.

Dynamic analysis of solid propellant grains subjected to ignition pressurization loading

NASA Astrophysics Data System (ADS)

Chyuan, Shiang-Woei

2003-11-01

Traditionally, the transient analysis of solid propellant grains subjected to ignition pressurization loading was not considered, and quasi-elastic-static analysis was widely adopted for structural integrity because the analytical task gets simplified. But it does not mean that the dynamic effect is not useful and could be neglected arbitrarily, and this effect usually plays a very important role for some critical design. In order to simulate the dynamic response for solid rocket motor, a transient finite element model, accompanied by concepts of time-temperature shift principle, reduced integration and thermorheologically simple material assumption, was used. For studying the dynamic response, diverse ignition pressurization loading cases were used and investigated in the present paper. Results show that the dynamic effect is important for structural integrity of solid propellant grains under ignition pressurization loading. Comparing the effective stress of transient analysis and of quasi-elastic-static analysis, one can see that there is an obvious difference between them because of the dynamic effect. From the work of quasi-elastic-static and transient analyses, the dynamic analysis highlighted several areas of interest and a more accurate and reasonable result could be obtained for the engineer.

Raman Doppler velocimetry - A unified approach for measuring molecular flow velocity, temperature, and pressure

NASA Technical Reports Server (NTRS)

Exton, R. J.; Hillard, M. E.

1986-01-01

Molecular flow velocity (one component), translational temperature, and static pressure of N2 are measured in a supersonic wind tunnel using inverse Raman spectroscopy. For velocity, the technique employs the large Doppler shift exhibited by the molecules when the pump and probe laser beams are counterpropagating (backward scattering). A retrometer system is employed to yield an optical configuration insensitive to mechanical vibration, which has the additional advantage of simultaneously obtaining both the forward and backward scattered spectra. The forward and backward line breadths and their relative Doppler shift can be used to determine the static pressure, translational temperature, and molecular flow velocity. A demonstration of the technique was performed in a continuous airflow supersonic wind tunnel in which data were obtained under the following conditions: (1) free-stream operation at five set Mach number levels over the 2.50-4.63 range; (2) free-stream operation over a range of Reynolds number (at a fixed Mach number) to vary systematically the static pressure; and (3) operation in the flow field of a simple aerodynamic model to assess beam steering effects in traversing the attached shock layer.

Astrophysical and Cosmological Consequences of the Dynamical Localization of Gravity

NASA Astrophysics Data System (ADS)

Germani, Cristiano

2003-11-01

In this thesis I review cosmological and astrophysical exact models for Randall-Sundrum-type braneworlds and their physical implications. I present new insights and show their analogies with quantum theories via the holographic idea. In astrophysics I study the two fundamental models of a spherically symmetric static star and spherically symmetric collapsing objects. I show how matching for the pressure of a static star encodes braneworld effects. In addition I study the problem of the vacuum exterior conjecturing a uniqueness theorem. Furthermore I show that a collapsing dust cloud in the braneworld has a non-static exterior, in contrast to the General Relativistic case. This non-static behaviour is linked to the presence of a "surplus potential energy" that must be released, producing a non-zero flux of energy. Via holography this can be connected with the Hawking process, giving an indirect measure of the brane tension. In cosmology I investigate the generalization of the Randall-Sundrum-type model obtained by introducing the Gauss-Bonnet combination into the action. I elucidate the junction conditions necessary to study the brane model and obtain the cosmological dynamics, showing that, even in the thin shell limit for the brane, the Gauss-Bonnet term implies a non-trivial internal structure for the matter and geometry distributions. Independently of the gravitational theory used, I show how to derive the modified Friedman equation and how it is related to the black hole solution of the theory. Via holography I also show how to interpret quantum mechanically the mass of this black hole from a four-dimensional perspective in the simplest Randall-Sundrum-type scenario.

Static Air Support Surfaces to Prevent Pressure Injuries: A Multicenter Cohort Study in Belgian Nursing Homes.

PubMed

Serraes, Brecht; Beeckman, Dimitri

2016-01-01

The aim of this study was to investigate the incidence and risk factors for developing pressure injuries (PIs) in patients placed on a static air support surfaces: mattress overlay, heel wedge, and seat cushion. Multicenter cohort study. The sample comprised 176 residents; their mean age was 87 (SD = 6.76) years; their mean Braden Scale score was 14 (SD = 2.54). The study was performed on a convenience sample of 6 nursing homes in Belgium. Data were collected on 23 care units. The primary outcome measure, cumulative PI incidence (category [stage] II-IV) over a 30-day observation period, was calculated. Pressure injury occurrence was defined according to the 2014 European and US National Pressure Injury Advisory panels, Pan Pacific Pressure Injury Alliance classification system. The PI incidence for category (stage) II-IV was 5.1%. Six residents (3.4%) developed a category II PI, and 3 (1.7%) developed a category III PI; no category IV ulcers occurred. No significant risk factors for category II-IV PIs were identified using multivariate logistic regression. Time of sitting in a chair was found to be a risk factor for development of nonblanchable erythema (category I PI) (odds ratio = 21.608; 95% confidence interval [CI], 20.510-22.812; P = .013). The median time to develop a category II-IV PI was 16 days (interquartile range = 2-26). The interrater reliability between the observations of the researcher and nurses on-site was almost perfect (0.86; 95% CI, 0.81-0.91). We found a low incidence of PIs when using a static air overlay mattress for patients at risk in a nursing home population. Static air support surfaces, alongside patient-tailored patient repositioning protocols, should be considered to prevent PIs in this patient population.

How do surgeons treat haemorrhoids? A study with special reference to Lord's procedure.

PubMed Central

Hancock, B. D.

1982-01-01

Forty-eight patients treated for haemorrhoids by Lord's procedure have been followed up for 5 years. Preoperative anal pressure and motility studies suggest that the best long-term results occur in patients with an active internal sphincter. Anal pressure was reduced by dilatation and remained static over the next 5 years. It was not possible to predict which patients would have later recurrence of symptoms from anal pressures measured one year after dilatation. Excellent clinical results were obtained in patients with first- and second-degree haemorrhoids, but in those with third-degree haemorrhoids a completely satisfactory outcome occurred in just under half the patients. Members of the Manchester Regional Association of Surgeons completed a questionnaire concerning their methods of treating haemorrhoids. Lord's procedure was the method used most frequently, but only 11% of surgeons used it regularly for patients with third-degree haemorrhoids. One-third of the surgeons still used haemorrhoidectomy for 25% of more of all their patients. Outpatient cryosurgery and rubber-band ligation were not popular, but treatment by dietary advice alone was common. PMID:7137830

Study of vapor flow into a capillary acquisition device. [for cryogenic rocket propellants

NASA Technical Reports Server (NTRS)

Dodge, F. T.; Bowles, E. B.

1982-01-01

An analytical model was developed that prescribes the conditions for vapor flow through the window screen of a start basket. Several original submodels were developed as part of this model. The submodels interrelate such phenomena as the effect of internal evaporation of the liquid, the bubble point change of a screen in the presence of wicking, the conditions for drying out of a screen through a combination of evaporation and pressure difference, the vapor inflow rate across a wet screen as a function of pressure difference, and the effect on wicking of a difference between the static pressure of the liquid reservoir and the surrounding vapor. Most of these interrelations were verified by a series of separate effects tests, which were also used to determine certain empirical constants in the models. The equations of the model were solved numerically for typical start basket designs, and a simplified start basket was constructed to verify the predictions, using both volatile and nonvolatile test liquids. The test results verified the trends predicted by the model.

Measuring Small Leak Holes

NASA Technical Reports Server (NTRS)

Koch, D. E.; Stephenson, J. G.

1983-01-01

Hole sizes deduced from pressure measurements. Measuring apparatus consists of pitot tube attached to water-filled manometer. Compartment tested is pressurized with air. Pitot probe placed at known distance from leak. Dynamic pressure of jet measured at that point and static pressure measured in compartment. Useful in situations in which small leaks are tolerable but large leaks are not.

Fracture toughness of Ti-Al3Ti-Al-Al3Ti laminate composites under static and cyclic loading conditions

NASA Astrophysics Data System (ADS)

Patselov, A. M.; Gladkovskii, S. V.; Lavrikov, R. D.; Kamantsev, I. S.

2015-10-01

The static and cyclic fracture toughnesses of a Ti-Al3Ti-Al-Al3Ti laminate composite material containing at most 15 vol % intermetallic compound are studied. Composite specimens are prepared by terminating reaction sintering of titanium and aluminum foils under pressure. The fracture of the titanium layers is quasi-cleavage during cyclic crack growth and is ductile during subsequent static loading.

Static investigation of two STOL nozzle concepts with pitch thrust-vectoring capability

NASA Technical Reports Server (NTRS)

Mason, M. L.; Burley, J. R., II

1986-01-01

A static investigation of the internal performance of two short take-off and landing (STOL) nozzle concepts with pitch thrust-vectoring capability has been conducted. An axisymmetric nozzle concept and a nonaxisymmetric nozzle concept were tested at dry and afterburning power settings. The axisymmetric concept consisted of a circular approach duct with a convergent-divergent nozzle. Pitch thrust vectoring was accomplished by vectoring the approach duct without changing the nozzle geometry. The nonaxisymmetric concept consisted of a two dimensional convergent-divergent nozzle. Pitch thrust vectoring was implemented by blocking the nozzle exit and deflecting a door in the lower nozzle flap. The test nozzle pressure ratio was varied up to 10.0, depending on model geometry. Results indicate that both pitch vectoring concepts produced resultant pitch vector angles which were nearly equal to the geometric pitch deflection angles. The axisymmetric nozzle concept had only small thrust losses at the largest pitch deflection angle of 70 deg., but the two-dimensional convergent-divergent nozzle concept had large performance losses at both of the two pitch deflection angles tested, 60 deg. and 70 deg.

Detecting damage in full-scale honeycomb sandwich composite curved fuselage panels through frequency response

NASA Astrophysics Data System (ADS)

Leone, Frank A., Jr.; Ozevin, Didem; Mosinyi, Bao; Bakuckas, John G., Jr.; Awerbuch, Jonathan; Lau, Alan; Tan, Tein-Min

2008-03-01

Preliminary tests were conducted using frequency response (FR) characteristics to determine damage initiation and growth in a honeycomb sandwich graphite/epoxy curved panel. This investigation was part of a more general study investigating the damage tolerance characteristics of several such panels subjected to quasi-static internal pressurization combined with hoop and axial loading. The panels were tested at the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center in Atlantic City, NJ. The overall program objective was to investigate the damage tolerance characteristics of full-scale composite curved aircraft fuselage panels and the evolution of damage under quasi-static loading up to failure. This paper focuses on one aspect of this comprehensive investigation: the effect of state-of-damage on the characteristics of the frequency response of the subject material. The results presented herein show that recording the frequency response could be used for real-time monitoring of damage growth and in determining damage severity in full-scale composites fuselage aircraft structures.

Compression asphyxia in upright suspended position.

PubMed

Tumram, Nilesh Keshav; Ambade, Vipul Namdeorao; Dixit, Pradeep Gangadhar

2014-06-01

In compression asphyxia, the respiration is prevented by external pressure on the body. It is usually due to external force compressing the trunk due to heavy weight over chest/abdomen and is associated with internal injuries. In the present case, the victim was suspended in an upright position owing to wedging of the chest and the abdomen in the gap between 2 parallel bridges undergoing construction. There was neither any heavy weight over the body, nor was any external force applied over the trunk. Moreover, there was neither any severe blunt force injury nor any significant pathological natural disease contributing to the cause of death. The body was wedged in the gap between 2 static hard surfaces. The victim was unable to extricate himself from the position owing to impairment of cognitive responses and coordination due to influence of alcohol. The victim died as a result of "static" asphyxia due to compression of the chest and the abdomen. Compression asphyxia in upright suspended position under this circumstance is very rare and not reported previously to the best of our knowledge.

14 CFR 23.1323 - Airspeed indicating system.

Code of Federal Regulations, 2010 CFR

2010-01-01

... instrument calibration error when the corresponding pitot and static pressures are applied. (b) Each airspeed... positive drainage of moisture from the pitot static plumbing. (d) If certification for instrument flight rules or flight in icing conditions is requested, each airspeed system must have a heated pitot tube or...

Dynamic loads on human and animal surrogates at different test locations in compressed-gas-driven shock tubes

NASA Astrophysics Data System (ADS)

Alay, E.; Skotak, M.; Misistia, A.; Chandra, N.

2018-01-01

Dynamic loads on specimens in live-fire conditions as well as at different locations within and outside compressed-gas-driven shock tubes are determined by both static and total blast overpressure-time pressure pulses. The biomechanical loading on the specimen is determined by surface pressures that combine the effects of static, dynamic, and reflected pressures and specimen geometry. Surface pressure is both space and time dependent; it varies as a function of size, shape, and external contour of the specimens. In this work, we used two sets of specimens: (1) anthropometric dummy head and (2) a surrogate rodent headform instrumented with pressure sensors and subjected them to blast waves in the interior and at the exit of the shock tube. We demonstrate in this work that while inside the shock tube the biomechanical loading as determined by various pressure measures closely aligns with live-fire data and shock wave theory, significant deviations are found when tests are performed outside.

Development of Dynamic Flow Field Pressure Probes Suitable for Use in Large Scale Supersonic Wind Tunnels

NASA Technical Reports Server (NTRS)

Porro, A. Robert

2000-01-01

A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10-by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor staff and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

Finite-Element Modeling of a Damaged Pipeline Repaired Using the Wrap of a Composite Material

NASA Astrophysics Data System (ADS)

Lyapin, A. A.; Chebakov, M. I.; Dumitrescu, A.; Zecheru, G.

2015-07-01

The nonlinear static problem of FEM modeling of a damaged pipeline repaired by a composite material and subjected to internal pressure is considered. The calculation is carried out using plasticity theory for the pipeline material and considering the polymeric filler and the composite wrap. The level of stresses in various zones of the structure is analyzed. The most widespread alloy used for oil pipelines is selected as pipe material. The contribution of each component of the pipeline-filler-wrap system to the level of stresses is investigated. The effect of the number of composite wrap layers is estimated. The results obtained allow one to decrease the costs needed for producing test specimens.

Thermodynamic Properties of Low-Density {}^{132}Xe Gas in the Temperature Range 165-275 K

NASA Astrophysics Data System (ADS)

Akour, Abdulrahman

2018-01-01

The method of static fluctuation approximation was used to calculate selected thermodynamic properties (internal energy, entropy, energy capacity, and pressure) for xenon in a particularly low-temperature range (165-270 K) under different conditions. This integrated microscopic study started from an initial basic assumption as the main input. The basic assumption in this method was to replace the local field operator with its mean value, then numerically solve a closed set of nonlinear equations using an iterative method, considering the Hartree-Fock B2-type dispersion potential as the most appropriate potential for xenon. The results are in very good agreement with those of an ideal gas.

Relationship of planter pressure and glycemic control in type 2 diabetic patients with and without neuropathy.

PubMed

Halawa, Mohammed R; Eid, Yara M; El-Hilaly, Rana A; Abdelsalam, Mona M; Amer, Amr H

Foot disease is a common complication of type 2 diabetes that can have tragic consequences. Abnormal plantar pressures are considered to play a major role in the pathologies of neuropathic ulcers in the diabetic foot. To examine Relationship of Planter Pressure and Glycemic Control in Type 2 Diabetic Patients with and without Neuropathy. The study was conducted on 50 type 2 diabetic patients and 30 healthy volunteers. BMI calculation, disease duration, Hemoglobin A1c and presence of neuropathy (by history, foot examination and DN4 questionnaire) were recorded. Plantar pressure was recorded for all patients using the Mat-scan (Tekscan, Inc.vers. 6.34 Boston USA) in static conditions (standing) and dynamic conditions (taking a step on the Mat-scan). Plantar pressures (kPa) were determined at the five metatarsal areas, mid foot area, medial and lateral heel areas and medial three toes. Static and dynamic plantar pressures in both right and left feet were significantly higher in diabetic with neuropathy group than in control group in measured areas (P<0.05). Static and dynamic pressures in right and left feet were significantly higher in diabetic with neuropathy group than in diabetic without neuropathy group in measured areas (P<0.05). On comparison between controls and diabetic without neuropathy group there was a significant difference in plantar pressures especially in metatarsal areas (P<0.05). No significant correlations were present between the studied variables age, disease duration, BMI and HbA1c and plantar pressures in all studied areas. Persons with diabetic neuropathy have elevated peak plantar pressure (PPP) compared to patients without neuropathy and control group. HbA1c% as a surrogate for glycemic control had no direct impact on peak planter pressure, yet it indirectly impacts neuropathy evolution through out disease duration eventually leading to the drastic planter pressure and gait biomechanics changes. Copyright © 2017 Diabetes India. Published by Elsevier Ltd. All rights reserved.

Static Posturography: A New Perspective in the Assessment of Lameness in a Canine Model

PubMed Central

Manera, Maria E.; Carrillo, José M.; Batista, Miguel; Rubio, Monica; Sopena, Joaquin; Santana, Angelo

2017-01-01

The aim of this study was to assess the static posturography in dogs as a useful tool for diagnosis of lameness by means of the use of a pressure platform. For this purpose, a series of different parameters (pressure distribution, area of support, mean pressure, maximum pressure and statokinesiograms) were obtained from five lame dogs with unilateral elbow osteoarthritis treated with plasma rich in growth factors. Data were obtained before and 3 months after treatment, and results were compared with a control group of sound dogs of similar conformation. Significant differences were found in the above mentioned parameters between sound and lame limbs. Improvement after 3 months of treatment was also detected, demonstrating that this multi-parametric technique is an effective and reliable method for the assessment of lameness in dogs. PMID:28114312

Static Posturography: A New Perspective in the Assessment of Lameness in a Canine Model.

PubMed

Manera, Maria E; Carrillo, José M; Batista, Miguel; Rubio, Monica; Sopena, Joaquin; Santana, Angelo; Vilar, José M

2017-01-01

The aim of this study was to assess the static posturography in dogs as a useful tool for diagnosis of lameness by means of the use of a pressure platform. For this purpose, a series of different parameters (pressure distribution, area of support, mean pressure, maximum pressure and statokinesiograms) were obtained from five lame dogs with unilateral elbow osteoarthritis treated with plasma rich in growth factors. Data were obtained before and 3 months after treatment, and results were compared with a control group of sound dogs of similar conformation. Significant differences were found in the above mentioned parameters between sound and lame limbs. Improvement after 3 months of treatment was also detected, demonstrating that this multi-parametric technique is an effective and reliable method for the assessment of lameness in dogs.

Variation with Mach Number of Static and Total Pressures Through Various Screens

NASA Technical Reports Server (NTRS)

Adler, Alfred A

1946-01-01

Tests were conducted in the Langley 24-inch highspeed tunnel to ascertain the static-pressure and total-pressure losses through screens ranging in mesh from 3 to 12 wires per inch and in wire diameter from 0.023 to 0.041 inch. Data were obtained from a Mach number of approximately 0.20 up to the maximum (choking) Mach number obtainable for each screen. The results of this investigation indicate that the pressure losses increase with increasing Mach number until the choking Mach number, which can be computed, is reached. Since choking imposes a restriction on the mass rate of flow and maximum losses are incurred at this condition, great care must be taken in selecting the screen mesh and wire dimmeter for an installation so that the choking Mach number is

Flat Feet, Happy Feet? Comparison of the Dynamic Plantar Pressure Distribution and Static Medial Foot Geometry between Malawian and Dutch Adults

PubMed Central

Stolwijk, Niki M.; Duysens, Jacques; Louwerens, Jan Willem K.; van de Ven, Yvonne HM.; Keijsers, Noël LW.

2013-01-01

In contrast to western countries, foot complaints are rare in Africa. This is remarkable, as many African adults walk many hours each day, often barefoot or with worn-out shoes. The reason why Africans can withstand such loading without developing foot complaints might be related to the way the foot is loaded. Therefore, static foot geometry and dynamic plantar pressure distribution of 77 adults from Malawi were compared to 77 adults from the Netherlands. None of the subjects had a history of foot complaints. The plantar pressure pattern as well as the Arch Index (AI) and the trajectory of the center of pressure during the stance phase were calculated and compared between both groups. Standardized pictures were taken from the feet to assess the height of the Medial Longitudinal Arch (MLA). We found that Malawian adults: (1) loaded the midfoot for a longer and the forefoot for a shorter period during roll off, (2) had significantly lower plantar pressures under the heel and a part of the forefoot, and (3) had a larger AI and a lower MLA compared to the Dutch. These findings demonstrate that differences in static foot geometry, foot loading, and roll off technique exist between the two groups. The advantage of the foot loading pattern as shown by the Malawian group is that the plantar pressure is distributed more equally over the foot. This might prevent foot complaints. PMID:23468936

Research on viscosity of metal at high pressure

NASA Astrophysics Data System (ADS)

Li, Y.; Liu, F.; Ma, X.; Zhang, M.

2016-11-01

A new experimental technique, the flyer-impact method, is proposed in this article to investigate the viscosity coefficient of shocked metals. In this technique, a shock wave with a sinusoidal perturbation on the front is induced by the sinusoidal profile of the impact surface of the sample by use of a two-stage light-gas gun, and the oscillatory damping process of the perturbation amplitude is monitored by electric pins. The damping processes of aluminum at 78 and 101 GPa and iron at 159 and 103 GPa are obtained by this technique, which supplement the existing data by measuring the viscosity coefficient via a dynamic high-pressure method. Applying the formula of Miller and Ahrens to fit the experimental data, the shear viscosity coefficients of aluminum at 78 and 101 GPa are 1350 ± 500 and 1200 ± 500 Pa s, respectively, and those of iron at 159 and 103 GPa are 1150 ± 1000 and 4800 ± 1000 Pa s, respectively. The values measured by the flyer-impact method, approximately 103 Pa s, are consistent with those measured by Sakharov's method, while still greatly differing from those measured by static high-pressure methods. In dynamic high-pressure experiments, the shear viscosity is related to dislocation motion in the solid material, while that in static high-pressure experiments is related to the diffusion motion of atoms or molecules in liquids. Therefore, there are different physical meanings of shear viscosity in dynamic and static high-pressure experiments, and there is no comparability among these results.

DYNAMIC CEREBROVASCULAR AND INTRACRANIAL PRESSURE REACTIVITY ASSESMENT OF IMPAIRED CEREBROVASCULAR AUTOREGULATION IN INTRACRANIAL HYPERTENSION

PubMed Central

Bragin, Denis E.; Statom, Gloria; Nemoto, Edwin M.

2016-01-01

SUMMARY We previously suggested that the discrepancy between the critical cerebral perfusion pressures (CPP) of 30 mmHg, obtained by increasing intracranial pressure (ICP), and 60 mmHg, obtained by decreasing arterial pressure, was due to pathological microvascular shunting at high ICP [1] and that the determination of the critical CPP by the static cerebral blood flow (CBF) autoregulation curve is not valid with intracranial hypertension. Here we demonstrated that critical CPP, measured by induced dynamic ICP reactivity (iPRx) and cerebrovascular reactivity (CVRx), accurately identifies the critical CPP in the hypertensive rat brain which differs from that obtained by the static autoregulation curve. Step changes in CPP from 70 to 50 and 30 mmHg were made by increasing ICP using an artificial cerebrospinal fluid reservoir connected to the cisterna magna. At each CPP, a transient 10-mmHg rise in arterial pressure was induced by bolus i.v. dopamine. iPRx and iCVRx were calculated as ΔICP/ΔMAP and as ΔCBF/ΔMAP, respectively. The critical CPP at high ICP, obtained by iPRx and iCVRx, is 50 mmHg, where compromised capillary flow, transition of blood flow to non-nutritive microvascular shunts, tissue hypoxia and BBB leakage begin to occur, which is higher than the 30 mmHg determined by static autoregulation. PMID:27165917

Characterization of cavity flow fields using pressure data obtained in the Langley 0.3-Meter Transonic Cryogenic Tunnel

NASA Technical Reports Server (NTRS)

Tracy, M. B.; Plentovich, E. B.

1993-01-01

Static and fluctuating pressure distributions were obtained along the floor of a rectangular-box cavity in an experiment performed in the LaRC 0.3-Meter Transonic Cryogenic Tunnel. The cavity studied was 11.25 in. long and 2.50 in. wide with a variable height to obtain length-to-height ratios of 4.4, 6.7, 12.67, and 20.0. The data presented herein were obtained for yaw angles of 0 deg and 15 deg over a Mach number range from 0.2 to 0.9 at a Reynolds number of 30 x 10(exp 6) per ft with a boundary-layer thickness of approximately 0.5 in. The results indicated that open and transitional-open cavity flow supports tone generation at subsonic and transonic speeds at Mach numbers of 0.6 and above. Further, pressure fluctuations associated with acoustic tone generation can be sustained when static pressure distributions indicate that transitional-closed and closed flow fields exist in the cavity. Cavities that support tone generation at 0 deg yaw also supported tone generation at 15 deg yaw when the flow became transitional-closed. For the latter cases, a reduction in tone amplitude was observed. Both static and fluctuating pressure data must be considered when defining cavity flow fields, and the flow models need to be refined to accommodate steady and unsteady flows.

Investigation of Shock Diffusers at Mach Number 1.85. 1 - Projecting Single Shock Cones

DTIC Science & Technology

1947-06-17

cylindrical simulated combustion chamber was used to vary the outlet area of the flow through the diffuser. The pitot -static rake , located as shown in the...Simulated combustion u chamber A 90° W •—Conical damper S Static-pressure orifice ps pitot -static "" rake ’ NATIONAL ADVISORY...recoveries were obtained with subsonic entrance flow. INTRODCJCTION For efficient conversion of the kinetic energy of a supersonic air stream into ram

Pressure Probe Designs for Dynamic Pressure Measurements in a Supersonic Flow Field. [conducted in the Glenn Supersonic Wind Tunnel (SWT)

NASA Technical Reports Server (NTRS)

Porro, A. Robert

2001-01-01

A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10- by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor stall and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

Hydrostatic pressure modulates mRNA expressions for matrix proteins in human meniscal cells.

PubMed

Suzuki, Toru; Toyoda, Takashi; Suzuki, Hiroshi; Hisamori, Noriyuki; Matsumoto, Hideo; Toyama, Yoshiaki

2006-01-01

There have been few reports describing the effects of mechanical loading on the metabolism of meniscal cells. The aim of this study was to investigate the effects of hydrostatic pressure on meniscal cell metabolism. Human meniscal cells were cultured in alginate beads for 3 days. They were then subjected to 4 MPa hydrostatic pressure for 4 hours in either a static or cyclic (1 Hz) mode using a specially designed and constructed system. Immediately after the pressure application, the messenger RNA levels for aggrecan, type I collagen, matrix metalloproteinases (MMP) -1, -3, -9, -13 and tissue inhibitors of metalloproteinases (TIMP) -1 and -2 were measured. It was found that the application of static hydrostatic pressure caused a significant decrease in mRNA expression for MMP-1 and -13 (p<0.05). In contrast, the application of cyclic hydrostatic pressure was associated with a significant increase in type I collagen (p<0.01), TIMP-1 and -2 mRNA expression (p<0.01). These results would suggest that hydrostatic pressure in isolation can modulate mRNA expressions for matrix proteins in meniscal cells.

Porous plug for reducing orifice induced pressure error in airfoils

NASA Technical Reports Server (NTRS)

Plentovich, Elizabeth B. (Inventor); Gloss, Blair B. (Inventor); Eves, John W. (Inventor); Stack, John P. (Inventor)

1988-01-01

A porous plug is provided for the reduction or elimination of positive error caused by the orifice during static pressure measurements of airfoils. The porous plug is press fitted into the orifice, thereby preventing the error caused either by fluid flow turning into the exposed orifice or by the fluid flow stagnating at the downstream edge of the orifice. In addition, the porous plug is made flush with the outer surface of the airfoil, by filing and polishing, to provide a smooth surface which alleviates the error caused by imperfections in the orifice. The porous plug is preferably made of sintered metal, which allows air to pass through the pores, so that the static pressure measurements can be made by remote transducers.

Effects of intermittent pressure imitating rolling manipulation on calcium ion homeostasis in human skeletal muscle cells.

PubMed

Zhang, Hong; Liu, Howe; Lin, Qing; Zhang, Guohui; Mason, David C

2016-08-26

Homeostasis imbalance of intracellular Ca(2+) is one of the key pathophysiological factors in skeletal muscle injuries. Such imbalance can cause significant change in the metabolism of Ca(2+)-related biomarkers in skeletal muscle, such as superoxide dismutase (SOD), malondialdehyde (MDA) and creatine kinase (CK). Measurements of these biomarkers can be used to evaluate the degree of damage to human skeletal muscle cells (HSKMCs) injury. Rolling manipulation is the most popular myofascial release technique in Traditional Chinese Medicine. The mechanism of how this technique works in ameliorating muscle injury is unknown. This study aimed to investigate the possible Ca(2+) mediated effects of intermittent pressure imitating rolling manipulation (IPIRM) of Traditional Chinese Medicine in the injured HSKMCs. The normal HSKMCs was used as control normal group (CNG), while the injured HSKMCs were further divided into five different groups: control injured group (CIG), Rolling manipulation group (RMG), Rolling manipulation-Verapamil group (RMVG), static pressure group (SPG) and static pressure-Verapamil group (SPVG). RMG and RMVG cells were cyclically exposed to 9.5-12.5 N/cm(2) of IPIRM at a frequency of 1.0 Hz for 10 min. SPG and SPVG were loaded to a continuous pressure of 12.5 N/cm(2) for 10 min. Verapamil, a calcium antagonist, was added into the culture mediums of both RMVG and SPVG groups to block the influx of calcium ion. Compared with the CNG (normal cells), SOD activity was remarkably decreased while both MDA content and CK activity were significantly increased in the CIG (injured cells). When the injured cells were treated with the intermittent rolling manipulation pressure (RMG), the SOD activity was significantly increased and MDA content and CK activity were remarkably decreased. These effects were suppressed by adding the calcium antagonist Verapamil into the culture medium in RMVG. On the other hand, exposure to static pressure in SPG and SPVG affected neither the SOD activity nor the MDA content and CK activity in the injured muscle cells regardless of the presence of verapamil or not in the culture medium. These data suggest that the intermittent rolling pressure with the manipulation could ameliorate HSKMCs injury through a Ca(2+) dependent pathway. Static pressure did not lead to the same results.

Mean curvature model for a quasi-static advancing meniscus: a drop tower test

NASA Astrophysics Data System (ADS)

Chen, Yongkang; Tavan, Noel; Weislogel, Mark

A critical geometric wetting condition resulting in a significant shift of a capillary fluid from one region of a container to another was recently demonstrated during experiments performed aboard the International Space Station (the Capillary Flow Experiments, Vane Gap test units, bulk shift phenomena). Such phenomena are of interest for advanced methods of control for large quantities of liquids aboard spacecraft. The dynamics of the flows are well understood, but analytical models remain qualitative without the correct capillary pressure driving force for the shifting bulk fluid—where one large interface (meniscus) advances while another recedes. To determine this pressure an investigation of the mean curvature of the advancing meniscus is presented which is inspired by earlier studies of receding bulk menisci in non-circular cylindrical containers. The approach is permissible only in the quasi-static limit. It will be shown that the mean curvature of the advancing bulk meniscus is related to that of the receding bulk meniscus, both of which are highly sensitive to container geometry and wetting conditions. The two meniscus curvatures are identical for any control parameter at the critical value identified by the Concus-Finn analysis. However, they differ when the control parameter is below its critical value. Experiments along these lines are well suited for drop towers and comparisons with the analytical predictions implementing the mean curvature model are presented. The validation opens a pathway to the analysis of such flows in containers of great geometric complexity.

An improved method for predicting brittleness of rocks via well logs in tight oil reservoirs

NASA Astrophysics Data System (ADS)

Wang, Zhenlin; Sun, Ting; Feng, Cheng; Wang, Wei; Han, Chuang

2018-06-01

There can be no industrial oil production in tight oil reservoirs until fracturing is undertaken. Under such conditions, the brittleness of the rocks is a very important factor. However, it has so far been difficult to predict. In this paper, the selected study area is the tight oil reservoirs in Lucaogou formation, Permian, Jimusaer sag, Junggar basin. According to the transformation of dynamic and static rock mechanics parameters and the correction of confining pressure, an improved method is proposed for quantitatively predicting the brittleness of rocks via well logs in tight oil reservoirs. First, 19 typical tight oil core samples are selected in the study area. Their static Young’s modulus, static Poisson’s ratio and petrophysical parameters are measured. In addition, the static brittleness indices of four other tight oil cores are measured under different confining pressure conditions. Second, the dynamic Young’s modulus, Poisson’s ratio and brittleness index are calculated using the compressional and shear wave velocity. With combination of the measured and calculated results, the transformation model of dynamic and static brittleness index is built based on the influence of porosity and clay content. The comparison of the predicted brittleness indices and measured results shows that the model has high accuracy. Third, on the basis of the experimental data under different confining pressure conditions, the amplifying factor of brittleness index is proposed to correct for the influence of confining pressure on the brittleness index. Finally, the above improved models are applied to formation evaluation via well logs. Compared with the results before correction, the results of the improved models agree better with the experimental data, which indicates that the improved models have better application effects. The brittleness index prediction method of tight oil reservoirs is improved in this research. It is of great importance in the optimization of fracturing layer and fracturing construction schemes and the improvement of oil recovery.

46 CFR 153.940 - Standards for marking of cargo hose.

Code of Federal Regulations, 2012 CFR

2012-10-01

... abnormally distort under static liquid pressure at least as great as the recommended working pressure. [CGD... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Marking of... manufacture; (2) Working pressure discribed in paragraph (d) of this section; (3) Date of the last test made...

46 CFR 153.940 - Standards for marking of cargo hose.

Code of Federal Regulations, 2011 CFR

2011-10-01

... abnormally distort under static liquid pressure at least as great as the recommended working pressure. [CGD... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Marking of... manufacture; (2) Working pressure discribed in paragraph (d) of this section; (3) Date of the last test made...

46 CFR 153.940 - Standards for marking of cargo hose.

Code of Federal Regulations, 2013 CFR

2013-10-01

... abnormally distort under static liquid pressure at least as great as the recommended working pressure. [CGD... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Marking of... manufacture; (2) Working pressure discribed in paragraph (d) of this section; (3) Date of the last test made...

46 CFR 153.940 - Standards for marking of cargo hose.

Code of Federal Regulations, 2010 CFR

2010-10-01

... abnormally distort under static liquid pressure at least as great as the recommended working pressure. [CGD... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Marking of... manufacture; (2) Working pressure discribed in paragraph (d) of this section; (3) Date of the last test made...

46 CFR 153.940 - Standards for marking of cargo hose.

Code of Federal Regulations, 2014 CFR

2014-10-01

... abnormally distort under static liquid pressure at least as great as the recommended working pressure. [CGD... SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Marking of... manufacture; (2) Working pressure described in paragraph (d) of this section; (3) Date of the last test made...

A Simple Experiment for Teaching Process Intensification by Static Mixing in Chemical Reaction Engineering

ERIC Educational Resources Information Center

Baz-Rodríguez, Sergio; Herrera-Soberanis, Natali; Rodríguez-Novelo, Miguel; Guillén-Francisc, Juana; Rocha-Uribe, José

2016-01-01

An experiment for teaching mixing intensification in reaction engineering is described. For this, a simple tubular reactor was constructed; helical static mixer elements were fabricated from stainless steel strips and inserted into the reactor. With and without the internals, the equipment operates as a static mixer reactor or a laminar flow…

Static investigation of the circulation control wing/upper surface blowing concept applied to the quiet short haul research aircraft

NASA Technical Reports Server (NTRS)

Eppel, J. C.; Shovlin, M. D.; Jaynes, D. N.; Englar, R. J.; Nichols, J. H., Jr.

1982-01-01

Full scale static investigations were conducted on the Quiet Short Haul Research Aircraft (QSRA) to determine the thrust deflecting capabilities of the circulation control wing/upper surface blowing (CCW/USB) concept. This scheme, which combines favorable characteristics of both the A-6/CCW and QSRA, employs the flow entrainment properties of CCW to pneumatically deflect engine thrust in lieu of the mechanical USB flap system. Results show that the no moving parts blown system produced static thrust deflections in the range of 40 deg to 97 deg (depending on thrust level) with a CCW pressure of 208,900 Pa (30.3 psig). In addition, the ability to vary horizontal forces from thrust to drag while maintaining a constant vertical (or lift) value was demonstrated by varying the blowing pressure. The versatility of the CCW/USB system, if applied to a STOL aircraft, was confirmed, where rapid conversion from a high drag approach mode to a thrust recovering waveoff or takeoff configuration could be achieved by nearly instantaneous blowing pressure variation.

PREFACE: 23rd International Conference on High Pressure Science and Technology (AIRAPT-23)

NASA Astrophysics Data System (ADS)

Gupta, Satish C.

2012-07-01

The 23rd AIRAPT International Conference on High Pressure Science and Technology was held at Bhabha Atomic Research Centre, Mumbai, from 25-30 September 2011. This conference is part of the series of AIRAPT International Conferences which are held biennially. AIRAPT is an acronym for the French title which translates as 'International Association for the Advancement of High Pressure Science and Technology'. This was the second time the AIRAPT Conference was organized in India. The first was held 20 years ago at the National Aeronautical Laboratory, Bangalore in 1991. The 23rd Conference covered many important topics in the area of both static and dynamic high pressures including theoretical and experimental investigations on the response of materials under high pressures, new developments using neutron and synchrotron sources, investigations on superconductivity under high pressure, studies of geophysical and planetary sciences, biosciences, and the synthesis of new materials. The conference program included Bridgman award lecture, Jemieson award lecture, seven plenary talks, 85 invited talks, 83 oral presentations and about 195 posters. In all there were 372 presentations. 285 scientists from 19 countries participated in the conference. The countries represented included Austria, Canada, China, Estonia, France, Germany, India, Israel, Italy, Japan, Nepal, New Zealand, Poland, Russia, South Korea, Spain, Sweden, Switzerland, Turkey, UK, Ukraine and USA. Many new developments were presented, for example, measurement techniques using the new generation synchrotron sources, more powerful neutron sources and much brighter laser sources; integration of gas-gun with synchrotron source; the achievement of multi-megabar pressures in shock-less dynamic compressions; and capabilities to synthesize centimeter size diamonds with better quality. All these developments have opened up new opportunities for understanding the physics of materials under high pressures. I would like to thank all those who have made valuable contributions to the success of the conference, which include the members of the AIRAPT executive committee, the International Advisory Committee and National Advisory Committee, the plenary speakers, invited speakers, the chairmen of various sessions, all the participants, and the authors of the papers in this volume. All the papers accepted for the proceedings have been reviewed by two independent referees. I am extremely thankful to all the anonymous referees, who have spent their valuable time to ensure the quality of the papers of this volume. I wish to express my gratitude to the members of the Local Organizing Committee for their help and hard work for the success of the conference. Finally, I convey my special thanks to Dr T C Kaushik and Dr K D Joshi, who worked tirelessly and enthusiastically towards making this conference a success. I am confident that this volume of the Conference proceedings will provide an excellent source of information on the current trends in the field of High Pressure Science and Technology. Satish C Gupta Conference Chairman 25-30 September 2011 Conference logo Conference photograph

Quasi-static acoustic tweezing thromboelastometry.

PubMed

Holt, R G; Luo, D; Gruver, N; Khismatullin, D B

2017-07-01

Essentials Blood coagulation measurement during contact with an artificial surface leads to unreliable data. Acoustic tweezing thromboelastometry is a novel non-contact method for coagulation monitoring. This method detects differences in the blood coagulation state within 10 min. Coagulation data were obtained using a much smaller sample volume (4 μL) than currently used. Background Thromboelastography is widely used as a tool to assess the coagulation status of critical care patients. It allows observation of changes in material properties of whole blood, beginning with early stages of clot formation and ending with clot lysis. However, the contact activation of the coagulation cascade at surfaces of thromboelastographic systems leads to inherent variability and unreliability in predicting bleeding or thrombosis risks. Objectives To develop acoustic tweezing thromboelastometry as a non-contact method for perioperative assessment of blood coagulation. Methods Acoustic tweezing is used to levitate microliter drops of biopolymer and human blood samples. By quasi-statically changing the acoustic pressure we control the sample drop location and deformation. Sample size, deformation and location are determined by digital imaging at each pressure. Results Simple Newtonian liquid solutions maintain a constant, reversible location vs. deformation curve. In contrast, the location/deformation curves for gelatin, alginate, whole blood and blood plasma uniquely change as the samples solidify. Increasing elasticity causes the sample to deform less, leading to steeper stress/strain curves. By extracting a linear regime slope, we show that whole blood or blood plasma exhibits a unique slope profile as it begins to clot. By exposing blood samples to pro- or antithrombotic agents, the slope profile changes, allowing detection of hyper- or hypocoagulable states. Conclusions We demonstrate that quasi-static acoustic tweezing can yield information about clotting onset, maturation and strength. The advantages of small sample size, non-contact and rapid measurement make this technique desirable for real-time monitoring of blood coagulation. © 2017 International Society on Thrombosis and Haemostasis.

Aerodynamic characteristics of the National Launch System (NLS) 1 1/2 stage launch vehicle

NASA Technical Reports Server (NTRS)

Springer, A. M.; Pokora, D. C.

1994-01-01

The National Aeronautics and Space Administration (NASA) is studying ways of assuring more reliable and cost effective means to space. One launch system studied was the NLS which included the l l/2 stage vehicle. This document encompasses the aerodynamic characteristics of the 1 l/2 stage vehicle. To support the detailed configuration definition two wind tunnel tests were conducted in the NASA Marshall Space Flight Center's 14x14-Inch Trisonic Wind Tunnel during 1992. The tests were a static stability and a pressure test, each utilizing 0.004 scale models. The static stability test resulted in the forces and moments acting on the vehicle. The aerodynamics for the reference configuration with and without feedlines and an evaluation of three proposed engine shroud configurations were also determined. The pressure test resulted in pressure distributions over the reference vehicle with and without feedlines including the reference engine shrouds. These pressure distributions were integrated and balanced to the static stability coefficients resulting in distributed aerodynamic loads on the vehicle. The wind tunnel tests covered a Mach range of 0.60 to 4.96. These ascent flight aerodynamic characteristics provide the basis for trajectory and performance analysis, loads determination, and guidance and control evaluation.

Examining the role of Coulomb static stress transfer in injection-induced seismicity: a generic modeling approach

NASA Astrophysics Data System (ADS)

Brown, M. R. M.; Ge, S.

2017-12-01

Increased pore pressure decreasing the effective stress on a critically stressed fault has been the accepted mechanism for injection-induced seismicity. This, however, is an over simplified approach that does not take into account the coupled hydro-mechanical effects. In addition, this approach leaves out a possible key stressor in the system, the earthquakes. Earthquakes are known to interact with each other by Coulomb static stress transfer, the process of permanent stress change caused by movement on a fault. In areas of induced seismicity, many small to moderate earthquakes can occur adding to the stress in the system via Coulomb static stress transfer. Here we ask: Is the Coulomb static stress transfer from the earthquakes as important as the pore pressure increase or stress changes caused by coupled hydro-mechanical processes? Is there a point where the Coulomb static stress transfer from the earthquakes becomes the controlling process for inducing future earthquakes? How does the effect of many small earthquakes compare to a few larger events in terms of Coulomb static stress transfer? In this study, we use hydrologic and coupled hydro-mechanical models and USGS Coulomb 3 to assess the importance of induced earthquakes in terms of the stress change in the system. Realistic scenarios of wastewater injection and earthquake magnitude-frequency distributions are used to develop generic models. Model variables and data are varied to evaluate the range of possible outcomes. Preliminary results show that the stress change associated with injection is of the same order of magnitude as the cumulative Coulomb static stress change of a series of small (1

Flight-test data on the static fore-and-aft stability of various German airplanes

NASA Technical Reports Server (NTRS)

Hubner, Walter

1933-01-01

The static longitudinal stability of an airplane with locked elevator is usually determined by analysis and model tests. The present report proposes to supply the results of such measurements. The method consisted of recording the dynamic pressure versus elevator displacement at different center-of-gravity positions in unaccelerated flight.

Supersonic Pitch Damping Predictions of Blunt Entry Vehicles from Static CFD Solutions

NASA Technical Reports Server (NTRS)

Schoenenberger, Mark

2013-01-01

A technique for predicting supersonic pitch damping of blunt axisymmetric bodies from static CFD data is presented. The contributions to static pitching moment due to forebody and aftbody pressure distributions are broken out and considered separately. The one-dimension moment equation is cast to model the separate contributions from forebody and aftbody pressures with no traditional damping term included. The aftbody contribution to pitching moment is lagged by a phase angle of the natural oscillation period. This lag represents the time for aftbody wake structures to equilibrate while the body is oscillation. The characteristic equation of this formulation indicates that the lagged backshell moment adds a damping moment equivalent in form to a constant pitch damping term. CFD calculations of the backshell's contribution to the static pitching moment for a range of angles-of-attack is used to predict pitch damping coefficients. These predictions are compared with ballistic range data taken of the Mars Exploration Rover (MER) capsule and forced oscillation data of the Mars Viking capsule. The lag model appears to capture dynamic stability variation due to backshell geometry as well as Mach number.

Experimental measurements of hydrodynamic stiffness matrices for a centrifugal pump impeller

NASA Technical Reports Server (NTRS)

Chamieh, D. S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.; Franz, R.

1982-01-01

The objective of the Rotor Force Test Facility at the California Institute of Technology is to artificially orbit the center of rotation of an impeller enclosed within a volute over a range of frequencies from zero to synchronous and to measure the resulting forces on the impeller. Preliminary data from the first stage experiments in which the shaft is orbited at low frequency is reported. Steady volute forces along with stiffness matrices due to the change in position of the rotor center are measured. Static pressure taps around the volute are used to obtain volute pressure distributions for various fixed positions of the impeller center and for various flow rates. Static pressure forces are calculated from these pressure distributions allowing a more complete analysis of the components of the impeller forces. Comparison is made with various existing theoretical and experimental results.

Cold flow testing of the Space Shuttle Main Engine high pressure fuel turbine model

NASA Technical Reports Server (NTRS)

Hudson, Susan T.; Gaddis, Stephen W.; Johnson, P. D.; Boynton, James L.

1991-01-01

In order to experimentally determine the performance of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump (HPFTP) turbine, a 'cold' air flow turbine test program was established at NASA's Marshall Space Flight Center. As part of this test program, a baseline test of Rocketdyne's HPFTP turbine has been completed. The turbine performance and turbine diagnostics such as airfoil surface static pressure distributions, static pressure drops through the turbine, and exit swirl angles were investigated at the turbine design point, over its operating range, and at extreme off-design points. The data was compared to pretest predictions with good results. The test data has been used to improve meanline prediction codes and is now being used to validate various three-dimensional codes. The data will also be scaled to engine conditions and used to improve the SSME steady-state performance model.

Evaluation of water cooled supersonic temperature and pressure probes for application to 1366 K flows

NASA Technical Reports Server (NTRS)

Lagen, Nicholas; Seiner, John M.

1990-01-01

Water cooled supersonic probes are developed to investigate total pressure, static pressure, and total temperature in high-temperature jet plumes and thereby determine the mean flow properties. Two probe concepts, designed for operation at up to 1366 K in a Mach 2 flow, are tested on a water cooled nozzle. The two probe designs - the unsymmetric four-tube cooling configuration and the symmetric annular cooling design - take measurements at 755, 1089, and 1366 K of the three parameters. The cooled total and static pressure readings are found to agree with previous test results with uncooled configurations. The total-temperature probe, however, is affected by the introduction of water coolant, and effect which is explained by the increased heat transfer across the thermocouple-bead surface. Further investigation of the effect of coolant on the temperature probe is proposed to mitigate the effect and calculate more accurate temperatures in jet plumes.

Static Aeroelastic Predictions for a Transonic Transport Model Using an Unstructured-Grid Flow Solver Coupled With a Structural Plate Technique

NASA Technical Reports Server (NTRS)

Allison, Dennis O.; Cavallo, Peter A.

2003-01-01

An equivalent-plate structural deformation technique was coupled with a steady-state unstructured-grid three-dimensional Euler flow solver and a two-dimensional strip interactive boundary-layer technique. The objective of the research was to assess the extent to which a simple accounting for static model deformations could improve correlations with measured wing pressure distributions and lift coefficients at transonic speeds. Results were computed and compared to test data for a wing-fuselage model of a generic low-wing transonic transport at a transonic cruise condition over a range of Reynolds numbers and dynamic pressures. The deformations significantly improved correlations with measured wing pressure distributions and lift coefficients. This method provided a means of quantifying the role of dynamic pressure in wind-tunnel studies of Reynolds number effects for transonic transport models.

A design method for entrance sections of transonic wind tunnels with rectangular cross sections

NASA Technical Reports Server (NTRS)

Lionel, L.; Mcdevitt, J. B.

1975-01-01

A mathematical technique developed to design entrance sections for transonic or high-speed subsonic wind tunnels with rectangular cross sections is discribed. The transition from a circular cross-section setting chamber to a rectangular test section is accomplished smoothly so as not to introduce secondary flows (vortices or boundary-layer separation) into a uniform test stream. The results of static-pressure measurements in the transition region and of static and total-pressure surveys in the test section of a pilot model for a new facility at the Ames Research Center are presented.

Poroelastic metamaterials with negative effective static compressibility

NASA Astrophysics Data System (ADS)

Qu, Jingyuan; Kadic, Muamer; Wegener, Martin

2017-04-01

We suggest a three-dimensional metamaterial structure exhibiting an isotropic expansion in response to an increased hydrostatic pressure imposed by a surrounding gas or liquid. We show that this behavior corresponds to a negative absolute (rather than only differential) effective compressibility under truly static and stable conditions. The poroelastic metamaterial is composed of only a single ordinary constituent solid. By detailed numerical parameter studies, we find that a pressure increase of merely one bar can lead to a relative increase in the effective volume exceeding one percent for geometrical structure parameters that should be accessible to fabrication by 3D printing.

Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions

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

Kraus, D.; Vorberger, J.; Pak, A.

The effects of hydrocarbon reactions and diamond precipitation on the internal structure and evolution of icy giant planets such as Neptune and Uranus have been discussed for more than three decades. Inside these celestial bodies, simple hydrocarbons such as methane, which are highly abundant in the atmospheres, are believed to undergo structural transitions that release hydrogen from deeper layers and may lead to compact stratified cores. Indeed, from the surface towards the core, the isentropes of Uranus and Neptune intersect a temperature–pressure regime in which methane first transforms into a mixture of hydrocarbon polymers, whereas, in deeper layers, a phasemore » separation into diamond and hydrogen may be possible. Here in this paper, we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene (C 8H 8) n samples dynamically compressed to conditions around 150 GPa and 5,000 K; these conditions resemble the environment around 10,000 km below the surfaces of Neptune and Uranus. Our findings demonstrate the necessity of high pressures for initiating carbon–hydrogen separation and imply that diamond precipitation may require pressures about ten times as high as previously indicated by static compression experiments. In conclusion, our results will inform mass–radius relationships of carbon-bearing exoplanets, provide constraints for their internal layer structure and improve evolutionary models of Uranus and Neptune, in which carbon–hydrogen separation could influence the convective heat transport.« less

Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions

DOE PAGES

Kraus, D.; Vorberger, J.; Pak, A.; ...

2017-08-21

The effects of hydrocarbon reactions and diamond precipitation on the internal structure and evolution of icy giant planets such as Neptune and Uranus have been discussed for more than three decades. Inside these celestial bodies, simple hydrocarbons such as methane, which are highly abundant in the atmospheres, are believed to undergo structural transitions that release hydrogen from deeper layers and may lead to compact stratified cores. Indeed, from the surface towards the core, the isentropes of Uranus and Neptune intersect a temperature–pressure regime in which methane first transforms into a mixture of hydrocarbon polymers, whereas, in deeper layers, a phasemore » separation into diamond and hydrogen may be possible. Here in this paper, we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene (C 8H 8) n samples dynamically compressed to conditions around 150 GPa and 5,000 K; these conditions resemble the environment around 10,000 km below the surfaces of Neptune and Uranus. Our findings demonstrate the necessity of high pressures for initiating carbon–hydrogen separation and imply that diamond precipitation may require pressures about ten times as high as previously indicated by static compression experiments. In conclusion, our results will inform mass–radius relationships of carbon-bearing exoplanets, provide constraints for their internal layer structure and improve evolutionary models of Uranus and Neptune, in which carbon–hydrogen separation could influence the convective heat transport.« less

Afterbody/nozzle pressure distributions of a twin-tail twin-engine fighter with axisymmetric nozzles at Mach numbers from 0.6 to 1.2

NASA Technical Reports Server (NTRS)

Wing, David J.

1995-01-01

Distributions of static pressure coefficient over the afterbody and axisymmetric nozzles of a generic, twin-tail twin-engine fighter were obtained in the Langley 16-Foot Transonic Tunnel. The longitudinal positions of the vertical and horizontal tails were varied for a total of six aft-end configurations. Static pressure coefficients were obtained at Mach numbers between 0.6 and 1.2, angles of attack between 0 deg and 8 deg, and nozzle pressure ratios ranging from jet-off to 8. The results of this investigation indicate that the influence of the vertical and horizontal tails extends beyond the vicinity of the tail-afterbody juncture. The pressure distribution affecting the aft-end drag is influenced more by the position of the vertical tails than by the position of the horizontal tails. Transonic tail-interference effects are seen at lower free-stream Mach numbers at positive angles of attack than at an angle of attack of 0 deg.

Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar

PubMed Central

Dubrovinsky, Leonid; Dubrovinskaia, Natalia; Prakapenka, Vitali B; Abakumov, Artem M

2012-01-01

Since invention of the diamond anvil cell technique in the late 1950s for studying materials at extreme conditions, the maximum static pressure generated so far at room temperature was reported to be about 400 GPa. Here we show that use of micro-semi-balls made of nanodiamond as second-stage anvils in conventional diamond anvil cells drastically extends the achievable pressure range in static compression experiments to above 600 GPa. Micro-anvils (10–50 μm in diameter) of superhard nanodiamond (with a grain size below ∼50 nm) were synthesized in a large volume press using a newly developed technique. In our pilot experiments on rhenium and gold we have studied the equation of state of rhenium at pressures up to 640 GPa and demonstrated the feasibility and crucial necessity of the in situ ultra high-pressure measurements for accurate determination of material properties at extreme conditions. PMID:23093199

Measurements of Flow Turbulence in the NASA Langley Transonic Dynamics Tunnel

NASA Technical Reports Server (NTRS)

Wiesman, Carol D.; Sleeper, Robert K.

2005-01-01

An assessment of the flow turbulence in the NASA Langley Transonic Dynamics Tunnel (TDT) was conducted during calibration activities following the facility conversion from a Freon-12 heavy-gas test medium to an R134a heavy-gas test medium. Total pressure, static pressure, and acoustic pressure levels were measured at several locations on a stingmounted rake. The test measured wall static pressures at several locations although this paper presents only those from one location. The test used two data acquisition systems, one sampling at 1000 Hz and the second sampling at 125 000 Hz, for acquiring time-domain data. This paper presents standard deviations and power spectral densities of the turbulence points throughout the wind tunnel envelope in air and R134a. The objective of this paper is to present the turbulence characteristics for the test section. No attempt is made to assess the causes of the turbulence. The present paper looks at turbulence in terms of pressure fluctuations. Reference 1 looked at tunnel turbulence in terms of velocity fluctuations.

Survival of Shewanella Oneidensis MR-1 to GPa pressures

NASA Astrophysics Data System (ADS)

Hazael, Rachael; Foglia, Fabrizia; Leighs, James; Appleby-Thomas, Gareth; Daniel, Isabelle; Eakins, Daniel; Meersman, Filip; McMillian, Paul

2013-06-01

Most life on Earth is thought to occupy near-surface environments under relatively mild conditions of temperature, pressure, pH, salinity etc. That view is changing following discovery of extremophile organisms that prefer environments based on high or low T, extreme chemistries, or very high pressures. Over the past three decades, geomicrobiologists have discovered an extensive subsurface biosphere, that may account for between 1/10 to 1/3 of Earth's living biomass. We subjected samples of Shewanella oneidensis to several pressure cycles to examine its survival to static high pressures to above 1.5 GPa. Shewanella forms part of a genus that contains several piezophile species like S. violacea and S. benthica. We have obtained growth curves for populations recovered from high P conditions and cultured in the laboratory, before being subjected to even higher pressures. We have also carried out dynamic shock experiments using a specially designed cell to maintain high-P, low-T conditions during shock-recovery experiments and observe colony formation among the survivors. Colony counts, shape and growth curves allow us to compare the static vs dynamic pressure resistance of wild type vs pressure-adapted strains. Leverhulme

Static and Dynamic Moduli of Malm Carbonate: A Poroelastic Correlation

NASA Astrophysics Data System (ADS)

Hassanzadegan, Alireza; Guérizec, Romain; Reinsch, Thomas; Blöcher, Guido; Zimmermann, Günter; Milsch, Harald

2016-08-01

The static and poroelastic moduli of a porous rock, e.g., the drained bulk modulus, can be derived from stress-strain curves in rock mechanical tests, and the dynamic moduli, e.g., dynamic Poisson's ratio, can be determined by acoustic velocity and bulk density measurements. As static and dynamic elastic moduli are different, a correlation is often required to populate geomechanical models. A novel poroelastic approach is introduced to correlate static and dynamic bulk moduli of outcrop analogues samples, representative of Upper-Malm reservoir rock in the Molasse basin, southwestern Germany. Drained and unjacketed poroelastic experiments were performed at two different temperature levels (30 and 60°C). For correlating the static and dynamic elastic moduli, a drained acoustic velocity ratio is introduced, corresponding to the drained Poisson's ratio in poroelasticity. The strength of poroelastic coupling, i.e., the product of Biot and Skempton coefficients here, was the key parameter. The value of this parameter decreased with increasing effective pressure by about 56 ~% from 0.51 at 3 MPa to 0.22 at 73 MPa. In contrast, the maximum change in P- and S-wave velocities was only 3 % in this pressure range. This correlation approach can be used in characterizing underground reservoirs, and can be employed to relate seismicity and geomechanics (seismo-mechanics).

Results of investigations on an 0.015-scale model (49-0) of the Rockwell International Space Shuttle orbiter in the NASA-Ames Research Center 3.5-foot hypersonic wind tunnel (0A98)

NASA Technical Reports Server (NTRS)

Milam, M. D.; Dzuibala, T. J.

1975-01-01

The results of a wind tunnel test are presented; the model used for this test was 0.015-scale 140 A/B hybrid configuration of the space shuttle orbiter. The primary test objectives were to obtain incremental data on the effects of a sting mount on base pressures and force and moment data. The increments obtained included the addition of MPS nozzles as well as the deletion of the simulated sting mount. Six-component aerodynamic force and moment data were recorded over an angle of attack range from 12 to 42 degrees at 0 and 5 degrees angles of sideslip. The testing was accomplished at Mach 5.3 and Mach 10.3. The effects of various elevon, body flap, and speed brake settings were investigated, and static pressures were measured at the fuselage base for use in force-data reduction.

Effects of Temperature and Method of Solution Preparation on the Performance of a Typical Red Mud Flocculent

NASA Astrophysics Data System (ADS)

Ferland, Pierre; Malito, John T.; Phillips, Everett C.

Alcan International Ltd. in collaboration with Ondeo Nalco Company have carried out a fundamental study on the dissolution and performance of a 100% anionic polymer. The effects of method of preparation, solvent composition, temperature and exposure time on flocculent activity under conditions relevant to both atmospheric and pressure decantation were investigated. Flocculent activity was determined using static and dynamic settling tests, and the results were correlated with the reduced specific viscosity (RSV). For any given method of preparation of the flocculent solutions (makeup/dilution) the RSV tended to decrease with increasing solution ionic strength, independent of ionic speciation. While a significant loss in flocculent activity occurred with long exposure of the solution to high temperature, only a minor loss occurred in the short time required to flocculate and settle the mud in a decanter operating at 150 °C. Recent results in an actual plant pressure decanter appear to validate this conclusion.

Aerodynamic Synthesis of a Centrifugal Impeller Using CFD and Measurements

NASA Technical Reports Server (NTRS)

Larosiliere, L. M.; Skoch, G. J.; Prahst, P. S.

1997-01-01

The performance and flow structure in an unshrouded impeller of approximately 4:1 pressure ratio is synthesized on the basis of a detailed analysis of 3D viscous CFD results and aerodynamic measurements. A good data match was obtained between CFD and measurements using laser anemometry and pneumatic probes. This solidified the role of the CFD model as a reliable representation of the impeller internal flow structure and integrated performance. Results are presented showing the loss production and secondary flow structure in the impeller. The results indicate that while the overall impeller efficiency is high, the impeller shroud static pressure recovery potential is underdeveloped leading to a performance degradation in the downstream diffusing element. Thus, a case is made for a follow-on impeller parametric design study to improve the flow quality. A strategy for aerodynamic performance enhancement is outlined and an estimate of the gain in overall impeller efficiency that might be realized through improvements to the relative diffusion process is provided.

Preliminary 2-D shell analysis of the space shuttle solid rocket boosters

NASA Technical Reports Server (NTRS)

Knight, Norman F., Jr.; Gillian, Ronnie E.; Nemeth, Michael P.

1987-01-01

A two-dimensional shell model of an entire solid rocket booster (SRB) has been developed using the STAGSC-1 computer code and executed on the Ames CRAY computer. The purpose of these analyses is to calculate the overall deflection and stress distributions for the SRB when subjected to mechanical loads corresponding to critical times during the launch sequence. The mechanical loading conditions for the full SRB arise from the external tank (ET) attachment points, the solid rocket motor (SRM) pressure load, and the SRB hold down posts. The ET strut loads vary with time after the Space Shuttle main engine (SSME) ignition. The SRM internal pressure varies axially by approximately 100 psi. Static analyses of the full SRB are performed using a snapshot picture of the loads. The field and factory joints are modeled by using equivalent stiffness joints instead of detailed models of the joint. As such, local joint behavior cannot be obtained from this global model.

Space shuttle propulsion estimation development verification

NASA Technical Reports Server (NTRS)

Rogers, Robert M.

1989-01-01

The application of extended Kalman filtering to estimating the Space Shuttle Propulsion performance, i.e., specific impulse, from flight data in a post-flight processing computer program is detailed. The flight data used include inertial platform acceleration, SRB head pressure, SSME chamber pressure and flow rates, and ground based radar tracking data. The key feature in this application is the model used for the SRB's, which is a nominal or reference quasi-static internal ballistics model normalized to the propellant burn depth. Dynamic states of mass overboard and propellant burn depth are included in the filter model to account for real-time deviations from the reference model used. Aerodynamic, plume, wind and main engine uncertainties are also included for an integrated system model. Assuming uncertainty within the propulsion system model and attempts to estimate its deviations represent a new application of parameter estimation for rocket powered vehicles. Illustrations from the results of applying this estimation approach to several missions show good quality propulsion estimates.

Multicenter comparison of the efficacy on prevention of pressure ulcer in postoperative patients between two types of pressure-relieving mattresses in China

PubMed Central

Jiang, Qixia; Li, Xiaohua; Zhang, Aiqin; Guo, Yanxia; Liu, Yahong; Liu, Haiying; Qu, Xiaolong; Zhu, Yajun; Guo, Xiujun; Liu, Li; Zhang, Liyan; Bo, Suping; Jia, Jing; Chen, Yuejuan; Zhang, Rui; Wang, Jiandong

2014-01-01

Objective: Present study is designed to evaluate the effects of preventing pressure ulcer in surgical patients with two types of pressure-relieving mattresses. Methods: 1074 surgical patients from 12 hospitals in China were divided into A group (static air mattress with repositioning every 2 hours, n = 562) and B group (power pressure air mattress with repositioning every 2 hours, n = 512). The patient was subjected to a pressure-relieving mattress and observed from 0-5 days after surgery. Indications include the Braden scores, hospital-acquired pressure ulcers (HAPU) incidence and stage. Results: The Braden scores between two groups in five days after surgery were no significant (P > 0.05). The incidence of HAPU between two groups in same days also was no significant (1.07% vs. 0.98%, P > 0.05). The incidence of Stage I and stage II pressure ulcers in group A and B were 1.07% (6/562) and 0.98% (5/512), respectively (χ2 = 0.148, P = 0.882). Conclusion: The effects of preventing pressure ulcer in surgical patients with two types of pressure-relieving mattresses are similar, but the protocol by static air mattress with repositioning every 2 hours is benefit when no power. PMID:25356144

The Relationships between Foot Arch Volumes and Dynamic Plantar Pressure during Midstance of Walking in Preschool Children

PubMed Central

Chang, Hsun-Wen; Chieh, Hsiao-Feng; Lin, Chien-Ju; Su, Fong-Chin; Tsai, Ming-June

2014-01-01

Objectives The purpose of this study was to examine the correlation between the foot arch volume measured from static positions and the plantar pressure distribution during walking. Methods A total of 27 children, two to six years of age, were included in this study. Measurements of static foot posture were obtained, including navicular height and foot arch volume in sitting and standing positions. Plantar pressure, force and contact areas under ten different regions of the foot were obtained during walking. Results The foot arch index was correlated (r = 0.32) with the pressure difference under the midfoot during the foot flat phase. The navicular heights and foot arch volumes in sitting and standing positions were correlated with the mean forces and pressures under the first (r = −0.296∼−0.355) and second metatarsals (r = −0.335∼−0.504) and midfoot (r = −0.331∼−0.496) during the stance phase of walking. The contact areas under the foot were correlated with the foot arch parameters, except for the area under the midfoot. Conclusions The foot arch index measured in a static position could be a functional index to predict the dynamic foot functions when walking. The foot arch is a factor which will influence the pressure distribution under the foot. Children with a lower foot arch demonstrated higher mean pressure and force under the medial forefoot and midfoot, and lower contact areas under the foot, except for the midfoot region. Therefore, children with flatfoot may shift their body weight to a more medial foot position when walking, and could be at a higher risk of soft tissue injury in this area. PMID:24736650

Experimental investigation of generic three-dimensional sidewall-compression scramjet inlets at Mach 6 in tetrafluoromethane

NASA Technical Reports Server (NTRS)

Holland, Scott D.

1993-01-01

Three-dimensional sidewall-compression scramjet inlets with leading-edge sweeps of 30 deg and 70 deg were tested in the Langley Hypersonic CF4 Tunnel at Mach 6 and with a ratio of specific heats of 1.2. The parametric effects of leading-edge sweep, cowl position, contraction ratio, and Reynolds number were investigated. The models were instrumented with 42 static pressure orifices that were distributed on the sidewalls, base plate, and cowl. Schlieren movies were made of each test for flow visualization of the effects of the internal flow spillage on the external flow field. To obtain an approximate characterization of the flow field, a modification to two-dimensional, inviscid, oblique shock theory was derived to accommodate the three-dimensional effects of leading-edge sweep. This theory qualitatively predicted the reflected shock structure (i.e., sidewall impingement locations) and the observed increase in spillage with increasing leading-edge sweep. The primary effect of moving the cowl forward was capturing the flow that would have otherwise spilled out ahead of the cowl. Increasing the contraction ratio increases the number of internal shock reflections and hence incrementally increases the sidewall pressure distribution. Significant Reynolds number effects were noted over a small range of Reynolds number.

Fuselage and nozzle pressure distributions on a 1/12-scale F-15 propulsion model at transonic speeds. [conducted in langley 16 foot transonic tunnel

NASA Technical Reports Server (NTRS)

Pendergraft, O. C., Jr.

1979-01-01

Static pressure coefficient distributions on the forebody, afterbody, and nozzles of a 1/12 scale F-15 propulsion model were determined. The effects of nozzle power setting and horizontal tail deflection angle on the pressure coefficient distributions were investigated.

40 CFR 60.274 - Monitoring of operations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... that is important to the performance of the total capture system (i.e., pressure sensors, dampers, and... under paragraph (d) of this section; and (4) All pressure data obtained under paragraph (f) of this... provisions of this subpart shall check and record on a once-per-shift basis furnace static pressure (if a DEC...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2012 CFR

2012-10-01

... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2012-10-01 2012-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2013 CFR

2013-10-01

... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2013-10-01 2013-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2014 CFR

2014-10-01

... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... 42 Public Health 1 2014-10-01 2014-10-01 false Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2010 CFR

2010-10-01

... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic...

42 CFR 84.157 - Airflow resistance test; Type C supplied-air respirator, pressure-demand class; minimum...

Code of Federal Regulations, 2011 CFR

2011-10-01

... respirator, pressure-demand class; minimum requirements. 84.157 Section 84.157 Public Health PUBLIC HEALTH... test; Type C supplied-air respirator, pressure-demand class; minimum requirements. (a) The static... the facepiece shall not fall below atmospheric at inhalation airflows less than 115 liters (4 cubic...

Unsteady loads due to propulsive lift configurations. Part C: Development of experimental techniques for investigation of unsteady pressures behind a cold model jet

NASA Technical Reports Server (NTRS)

Haviland, J. K.; Schroeder, J. C.

1978-01-01

As part of an overall study of the scaling laws for the fluctuating pressures induced on the wings and flaps of STOL aircraft by jet engine impingement, an experimental investigation was made of the near field fluctuating pressures behind a cold circular jet, both when it was free and when it was impinging on a flat plate. Miniature static pressure probes were developed for measurements in the free jet and on the flat plate which were connected by plastic tubing to 1/8 inch microphones and acted as pressure transducers. Using a digital correlator together with an FFT program on the CDC 6400 computer, spectral densities, relative amplitudes, phase lags, and coherences were also obtained for the signals from pairs of these probes, and were used to calibrate these probes directly against microphones. This system of instrumentation was employed to obtain single point rms and third octave surveys of the static pressures in the free jet and on the surface of the plate.

Atomization, drop size, and penetration for cross-stream water injection at high-altitude reentry conditions with application to the RAM C-1 and C-3 flights

NASA Technical Reports Server (NTRS)

Gooderum, P. B.; Bushnell, D. M.

1972-01-01

Atomization, drop size, and penetration data are presented for cross stream water injection at conditions simulating high altitude reentry (low Weber number, high static temperature, high Knudsen number, and low static pressure). These results are applied to the RAM C-1 and C-3 flights. Two primary breakup modes are considered, vapor pressure or flashing and aerodynamic atomization. Results are given for breakup boundaries and mean drop size for each of these atomization mechanisms. Both standard and flight orifice geometries are investigated. The data were obtained in both a static environment and in conventional aerodynamic facilities at Mach numbers of 4.5 and 8. The high temperature aspects of reentry were simulated in a Mach 5.5 cyanogen-oxygen tunnel with total temperature of 4500 K.

Magma degassing triggered by static decompression at Kīlauea Volcano, Hawai‘i

USGS Publications Warehouse

Poland, Michael P.; Jeff, Sutton A.; Gerlach, Terrence M.

2009-01-01

During mid-June 2007, the summit of Kīlauea Volcano, Hawai‘i, deflated rapidly as magma drained from the subsurface to feed an east rift zone intrusion and eruption. Coincident with the deflation, summit SO2 emission rates rose by a factor of four before decaying to background levels over several weeks. We propose that SO2 release was triggered by static decompression caused by magma withdrawal from Kīlauea's shallow summit reservoir. Models of the deflation suggest a pressure drop of 0.5–3 MPa, which is sufficient to trigger exsolution of the observed excess SO2 from a relatively small volume of magma at the modeled source depth beneath Kīlauea's summit. Static decompression may also explain other episodes of deflation accompanied by heightened gas emission, including the precursory phases of Kīlauea's 2008 summit eruption. Hazards associated with unexpected volcanic gas emission argue for increased awareness of magma reservoir pressure fluctuations.

Orthostatic symptoms, blood pressure and working postures of factory and service workers over an observed workday.

PubMed

Ngomo, Suzy; Messing, Karen; Perrault, Hélène; Comtois, Alain

2008-11-01

North American workers usually stand while working, and prolonged standing is associated with discomfort and cardiovascular problems. Moving may alleviate the problems, but optimum mobility is unknown. The effects of variations in mobility were explored among (1) 34 health care workers whose symptoms of orthostatic intolerance (OI) were recorded after work; (2) 45 factory and laundry workers. Postures were observed over a workday and blood pressure (BP) and heart rate (HR) of both groups were recorded before and after work. Among health care workers, 65% manifested OI symptoms. In a multiple logistic regression, presence of >or= 1 symptom of OI was associated with static postures and being female (p=0.001). More static standing was associated with a larger drop in BP (p=0.04) in both populations. The results suggest that more static standing postures are associated with OI and musculoskeletal symptoms and with a subclinical drop in BP.

Structural Modeling of a Five-Meter Thin Film Inflatable Antenna/Concentrator With Rigidized Support Struts

NASA Technical Reports Server (NTRS)

Smalley, Kurt B.; Tinker, Michael L.

2001-01-01

Dynamic characterization of a non-rigidized thin film inflatable antenna/solar concentrator structure with rigidized composite support struts is described in detail. A two-step finite element modeling approach in MSC/NASTRAN is utilized, consisting of: (1) a nonlinear static pressurization procedure used to obtain the updated stiffness matrix, and (2) a modal "restart" eigen solution that uses the modified stiffness matrix. Unique problems encountered in modeling of this large 5-m lightweight inflatable are identified, including considerable difficulty in obtaining convergence in the nonlinear pressurization solution. It was found that the extremely thin polyimide film material (.001 in or I mil) presents tremendous problems in obtaining a converged solution when internal pressure loading is applied. It was concluded that the ratios of film thickness to other geometric dimensions such as torus cross-sectional and ring diameter and lenticular diameter are the critical parameters for convergence of the pressurization procedure. Comparison of finite element predictions for frequency and mode shapes with experimental results indicated reasonable agreement considering the complexity of the structure, the film-to-air interaction, and the nonlinear material properties of the film. It was also concluded that analysis should be done using different finite element to codes to determine if a more robust and stable solution can be obtained.

Flow Control Device Evaluation for an Internal Flow with an Adverse Pressure Gradient

NASA Technical Reports Server (NTRS)

Jenkins, Luther N.; Gorton, Susan Althoff; Anders, Scott G.

2002-01-01

The effectiveness of several active and passive devices to control flow in an adverse pressure gradient with secondary flows present was evaluated in the 15 Inch Low Speed Tunnel at NASA Langley Research Center. In this study, passive micro vortex generators, micro bumps, and piezoelectric synthetic jets were evaluated for their flow control characteristics using surface static pressures, flow visualization, and 3D Stereo Digital Particle Image Velocimetry. Data also were acquired for synthetic jet actuators in a zero flow environment. It was found that the micro vortex generator is very effective in controlling the flow environment for an adverse pressure gradient, even in the presence of secondary vortical flow. The mechanism by which the control is effected is a re-energization of the boundary layer through flow mixing. The piezoelectric synthetic jet actuators must have sufficient velocity output to produce strong longitudinal vortices if they are to be effective for flow control. The output of these devices in a laboratory or zero flow environment will be different than the output in a flow environment. In this investigation, the output was higher in the flow environment, but the stroke cycle in the flow did not indicate a positive inflow into the synthetic jet.

[Analysis of the distribution of VOCs concentration field with oil static breathing loss in internal floating roof tank].

PubMed

Wu, Hong-Zhang; Huang, Wei-Qiu; Yang, Guang; Zhao, Chen-Lu; Wang, Ying-Xia; Cai, Dao-Fei

2013-12-01

Internal floating roof tank has the advantages of external floating roof tank and fixed roof tank and has its own evaporation loss properties. The influences of volatile organic compounds (VOCs) distribution gradient, molecular diffusion, thermal diffusion and forced convection on the evaporation loss of oil were studied in the space of the homemade platform of an internal floating roof tank. The results showed that thermal diffusion with temperature change was the main cause for the static loss in the internal floating roof tank. On this basis, there were some measures for reduction of the evaporation loss and formulas to calculate the evaporation loss of the internal floating roof tank in this research.

Results of test IA137 in the NASA/ARC 14 foot transonic wind tunnel of the 0.07 scale external tank forebody (model 68-T) to determine auxiliary aerodynamic data system feasibility

NASA Technical Reports Server (NTRS)

Thornton, D. E.

1976-01-01

Tests were conducted in a 14 foot transonic wind tunnel to examine the feasibility of the auxiliary aerodynamic data system (AADS) for determining angles of attack and sideslip during boost flight. The model used was a 0.07 scale replica of the external tank forebody consisting of the nose portion and a 60 inch (full scale) cylindrical section of the ogive cylinder tangency point. The model terminated in a blunt base with a 320.0 inch diameter at external tank (ET) station 1120.37. Pressure data were obtained from five pressure orifices (one total and four statics) on the nose probe, and sixteen surface static pressure orifices along the ET forebody.

Incidence loss for fan turbine rotor blade in two-dimensional cascade

NASA Technical Reports Server (NTRS)

Kline, J. F.; Moffitt, T. P.; Stabe, R. G.

1983-01-01

The effect of incidence angle on the aerodynamic performance of a fan turbine rotor blade was investigated experimentally in a two dimensional cascade. The test covered a range of incidence angles from -15 deg to 10 deg and exit ideal critical velocity ratios from 0.75 to 0.95. The principal measurements were blade-surface static pressures and cross-channel survey of exit total pressure, static pressure, and flow angle. Flow adjacent to surfaces was examined using a visualization technique. The results of the investigation include blade-surface velocity distribution and overall kinetic energy loss coefficients for the incidence angles and exit velocity ratios tested. The measured losses are compared with those from a reference core turbine rotor blade and also with two common analytical methods of predicting incidence loss.

Expressions to Rayleigh circumferential phase velocity and dispersion relation for a cylindrical surface under mechanical pressure

NASA Astrophysics Data System (ADS)

Sebold, Jean Eduardo; de Lacerda, Luiz Alkimin

2018-04-01

This paper describes a substantiated mathematical theory for Rayleigh waves propagated on some types of metal cylinders. More specifically, it presents not only a new way to express the dispersion relation of Rayleigh waves propagated on the cylindrical surface, but also how it can be used to construct a mathematical equation showing that the applied static mechanical pressure affects the shear modulus of the metal cylinder. All steps, required to conclude the process, consider the equation of motion as a function of radial and circumferential coordinates only, while the axial component can be overlooked without causing any problems. Some numerical experiments are done to illustrate the changes in the Rayleigh circumferential phase velocity in a metal cylindrical section due to static mechanical pressure around its external surface.

The 1991 International Aerospace and Ground Conference on Lightning and Static Electricity, volume 1

NASA Technical Reports Server (NTRS)

1991-01-01

The proceedings of the 1991 International Aerospace and Ground Conference on Lightning and Static Electricity are reported. Some of the topics covered include: lightning, lightning suppression, aerospace vehicles, aircraft safety, flight safety, aviation meteorology, thunderstorms, atmospheric electricity, warning systems, weather forecasting, electromagnetic coupling, electrical measurement, electrostatics, aircraft hazards, flight hazards, meteorological parameters, cloud (meteorology), ground effect, electric currents, lightning equipment, electric fields, measuring instruments, electrical grounding, and aircraft instruments.

Predictive equations for respiratory muscle strength according to international and Brazilian guidelines.

PubMed

Pessoa, Isabela M B S; Houri Neto, Miguel; Montemezzo, Dayane; Silva, Luisa A M; Andrade, Armèle Dornelas De; Parreira, Verônica F

2014-01-01

The maximum static respiratory pressures, namely the maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP), reflect the strength of the respiratory muscles. These measures are simple, non-invasive, and have established diagnostic and prognostic value. This study is the first to examine the maximum respiratory pressures within the Brazilian population according to the recommendations proposed by the American Thoracic Society and European Respiratory Society (ATS/ERS) and the Brazilian Thoracic Association (SBPT). To establish reference equations, mean values, and lower limits of normality for MIP and MEP for each age group and sex, as recommended by the ATS/ERS and SBPT. We recruited 134 Brazilians living in Belo Horizonte, MG, Brazil, aged 20-89 years, with a normal pulmonary function test and a body mass index within the normal range. We used a digital manometer that operationalized the variable maximum average pressure (MIP/MEP). At least five tests were performed for both MIP and MEP to take into account a possible learning effect. We evaluated 74 women and 60 men. The equations were as follows: MIP=63.27-0.55 (age)+17.96 (gender)+0.58 (weight), r(2) of 34% and MEP= - 61.41+2.29 (age) - 0.03(age(2))+33.72 (gender)+1.40 (waist), r(2) of 49%. In clinical practice, these equations could be used to calculate the predicted values of MIP and MEP for the Brazilian population.

Parametric investigation of single-expansion-ramp nozzles at Mach numbers from 0.60 to 1.20

NASA Technical Reports Server (NTRS)

Capone, Francis J.; Re, Richard J.; Bare, E. Ann

1992-01-01

An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of varying six nozzle geometric parameters on the internal and aeropropulsive performance characteristics of single-expansion-ramp nozzles. This investigation was conducted at Mach numbers from 0.60 to 1.20, nozzle pressure ratios from 1.5 to 12, and angles of attack of 0 deg +/- 6 deg. Maximum aeropropulsive performance at a particular Mach number was highly dependent on the operating nozzle pressure ratio. For example, as the nozzle upper ramp length or angle increased, some nozzles had higher performance at a Mach number of 0.90 because of the nozzle design pressure was the same as the operating pressure ratio. Thus, selection of the various nozzle geometric parameters should be based on the mission requirements of the aircraft. A combination of large upper ramp and large lower flap boattail angles produced greater nozzle drag coefficients at Mach number greater than 0.80, primarily from shock-induced separation on the lower flap of the nozzle. A static conditions, the convergent nozzle had high and nearly constant values of resultant thrust ratio over the entire range of nozzle pressure ratios tested. However, these nozzles had much lower aeropropulsive performance than the convergent-divergent nozzle at Mach number greater than 0.60.

Structural analysis of the space shuttle solid rocket booster/external tank attach ring

NASA Technical Reports Server (NTRS)

Dorsey, John T.

1988-01-01

An External Tank (ET) attach ring is used in the Space Shuttle System to transfer lateral loads between the ET and the Solid Rocket Booster (SRB). Following the Challenger (51-L) accident, the flight performance of the ET attach ring was reviewed, and negative margins of safety and failed bolts in the attach ring were subsequently identified. The analyses described in this report were performed in order to understand the existing ET attach ring structural response to motor case internal pressurization as well as to aid in an ET attach ring redesign effort undertaken by NASA LaRC. The finite element model as well as the results from linear and nonlinear static structural analyses are described.

Nitrogen nucleation in a cryogenic supersonic nozzle

NASA Astrophysics Data System (ADS)

Bhabhe, Ashutosh; Wyslouzil, Barbara

2011-12-01

We follow the vapor-liquid phase transition of N2 in a cryogenic supersonic nozzle apparatus using static pressure measurements. Under our operating conditions, condensation always occurs well below the triple point. Mean field kinetic nucleation theory (MKNT) does a better job of predicting the conditions corresponding to the estimated maximum nucleation rates, Jmax = 1017±1 cm-3 s-1, than two variants of classical nucleation theory. Combining the current results with the nucleation pulse chamber measurements of Iland et al. [J. Chem. Phys. 130, 114508-1 (2009)], we use nucleation theorems to estimate the critical cluster properties. Both the theories overestimate the size of the critical cluster, but MKNT does a good job of estimating the excess internal energy of the clusters.

From relief to development: the long-term effects of 'temporary' accommodation on refugees and displaced persons in the Republic of Croatia.

PubMed

Ellis, S; Barakat, S

1996-06-01

The increasing scale of international intervention in conflict is generating new pressures on the humanitarian community. Increased expenditure on emergency relief, static levels of overseas development aid and subsequent lack of funds for development are dictating that agencies design relief projects that positively effect developmental reconstruction. This paper examines the provision of shelter for refugees and displaced persons in the Republic of Croatia and identifies ways in which it has encouraged and discouraged sustainable reconstruction. It argues that to promote lasting reconstruction, programmes must focus on saving livelihoods as well as lives, thus minimising the long-term psychological and physical impacts of aid on refugees, displaced persons and host communities.

Computational Methods for Frictional Contact With Applications to the Space Shuttle Orbiter Nose-Gear Tire

NASA Technical Reports Server (NTRS)

Tanner, John A.

1996-01-01

A computational procedure is presented for the solution of frictional contact problems for aircraft tires. A Space Shuttle nose-gear tire is modeled using a two-dimensional laminated anisotropic shell theory which includes the effects of variations in material and geometric parameters, transverse-shear deformation, and geometric nonlinearities. Contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with both contact and friction conditions. The contact-friction algorithm is based on a modified Coulomb friction law. A modified two-field, mixed-variational principle is used to obtain elemental arrays. This modification consists of augmenting the functional of that principle by two terms: the Lagrange multiplier vector associated with normal and tangential node contact-load intensities and a regularization term that is quadratic in the Lagrange multiplier vector. These capabilities and computational features are incorporated into an in-house computer code. Experimental measurements were taken to define the response of the Space Shuttle nose-gear tire to inflation-pressure loads and to inflation-pressure loads combined with normal static loads against a rigid flat plate. These experimental results describe the meridional growth of the tire cross section caused by inflation loading, the static load-deflection characteristics of the tire, the geometry of the tire footprint under static loading conditions, and the normal and tangential load-intensity distributions in the tire footprint for the various static vertical loading conditions. Numerical results were obtained for the Space Shuttle nose-gear tire subjected to inflation pressure loads and combined inflation pressure and contact loads against a rigid flat plate. The experimental measurements and the numerical results are compared.

Computational methods for frictional contact with applications to the Space Shuttle orbiter nose-gear tire: Comparisons of experimental measurements and analytical predictions

NASA Technical Reports Server (NTRS)

Tanner, John A.

1996-01-01

A computational procedure is presented for the solution of frictional contact problems for aircraft tires. A Space Shuttle nose-gear tire is modeled using a two-dimensional laminated anisotropic shell theory which includes the effects of variations in material and geometric parameters, transverse-shear deformation, and geometric nonlinearities. Contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the stress resultants, the generalized displacements, and the Lagrange multipliers associated with both contact and friction conditions. The contact-friction algorithm is based on a modified Coulomb friction law. A modified two-field, mixed-variational principle is used to obtain elemental arrays. This modification consists of augmenting the functional of that principle by two terms: the Lagrange multiplier vector associated with normal and tangential node contact-load intensities and a regularization term that is quadratic in the Lagrange multiplier vector. These capabilities and computational features are incorporated into an in-house computer code. Experimental measurements were taken to define the response of the Space Shuttle nose-gear tire to inflation-pressure loads and to inflation-pressure loads combined with normal static loads against a rigid flat plate. These experimental results describe the meridional growth of the tire cross section caused by inflation loading, the static load-deflection characteristics of the tire, the geometry of the tire footprint under static loading conditions, and the normal and tangential load-intensity distributions in the tire footprint for the various static vertical-loading conditions. Numerical results were obtained for the Space Shuttle nose-gear tire subjected to inflation pressure loads and combined inflation pressure and contact loads against a rigid flat plate. The experimental measurements and the numerical results are compared.

Comprehensive Forced Response Analysis of J2X Turbine Bladed-Discs with 360 Degree Variation in CFD Loading

NASA Technical Reports Server (NTRS)

Elrod, David; Christensen, Eric; Brown, Andrew

2011-01-01

The temporal frequency content of the dynamic pressure predicted by a 360 degree computational fluid dynamics (CFD) analysis of a turbine flow field provides indicators of forcing function excitation frequencies (e.g., multiples of blade pass frequency) for turbine components. For the Pratt and Whitney Rocketdyne J-2X engine turbopumps, Campbell diagrams generated using these forcing function frequencies and the results of NASTRAN modal analyses show a number of components with modes in the engine operating range. As a consequence, forced response and static analyses are required for the prediction of combined stress, high cycle fatigue safety factors (HCFSF). Cyclically symmetric structural models have been used to analyze turbine vane and blade rows, not only in modal analyses, but also in forced response and static analyses. Due to the tortuous flow pattern in the turbine, dynamic pressure loading is not cyclically symmetric. Furthermore, CFD analyses predict dynamic pressure waves caused by adjacent and non-adjacent blade/vane rows upstream and downstream of the row analyzed. A MATLAB script has been written to calculate displacements due to the complex cyclically asymmetric dynamic pressure components predicted by CFD analysis, for all grids in a blade/vane row, at a chosen turbopump running speed. The MATLAB displacements are then read into NASTRAN, and dynamic stresses are calculated, including an adjustment for possible mistuning. In a cyclically symmetric NASTRAN static analysis, static stresses due to centrifugal, thermal, and pressure loading at the mode running speed are calculated. MATLAB is used to generate the HCFSF at each grid in the blade/vane row. When compared to an approach assuming cyclic symmetry in the dynamic flow field, the current approach provides better assurance that the worst case safety factor has been identified. An extended example for a J-2X turbopump component is provided.

Temporal static stress drop variations due to injection activity at The Geysers geothermal field, California

NASA Astrophysics Data System (ADS)

Staszek, M.; Orlecka-Sikora, B.; Leptokaropoulos, K.; Kwiatek, G.; Martínez-Garzón, P.

2017-07-01

We use a high-quality data set from the NW part of The Geysers geothermal field to determine statistical significance of temporal static stress drop variations and their relation to injection rate changes. We use a group of 322 seismic events which occurred in the proximity of Prati-9 and Prati-29 injection wells to examine the influence of parameters such as moment magnitude, focal mechanism, hypocentral depth, and normalized hypocentral distances from open-hole sections of injection wells on static stress drop changes. Our results indicate that (1) static stress drop variations in time are statistically significant, (2) statistically significant static stress drop changes are inversely related to injection rate fluctuations. Therefore, it is highly expected that static stress drop of seismic events is influenced by pore pressure in underground fluid injection conditions and depends on the effective normal stress and strength of the medium.

Blast-Induced Acceleration in a Shock Tube: Distinguishing Primary and Tertiary Blast Injury

DTIC Science & Technology

2015-10-01

these well-defined exposure conditions, anesthetized rats are used to simultaneously record intracranial pressure (ICP), intravascular pressure , and...blast flow conditions (e.g. peak static and total pressure , positive phase duration, and impulse) and acceleration and displacement of a wide range of...resultant pressure responses in varied compartments in concert with the neuropathological, neurochemical, and neurobehavioral consequences of exposures

A model investigation of turbulence-driven pressure-pumping effects on the rate of diffusion of CO2, N2O, and CH4 through layered snowpacks

Treesearch

W. J. Massman; R. A. Sommerfeld; A. R. Mosier; K. F. Zeller; T.J . Hehn; S. G. Rochelle

1997-01-01

Pressure pumping at the Earth's surface is caused by short-period atmospheric turbulence, longer-period barometric changes, and quasi-static pressure fields induced by wind blowing across irregular topography. These naturally occurring atmospheric pressure variations induce periodic fluctuations in airflow through snowpacks, soils, and any other porous media at...

Development of a primary standard for dynamic pressure based on drop weight method covering a range of 10 MPa-400 MPa

NASA Astrophysics Data System (ADS)

Salminen, J.; Högström, R.; Saxholm, S.; Lakka, A.; Riski, K.; Heinonen, M.

2018-04-01

In this paper we present the development of a primary standard for dynamic pressures that is based on the drop weight method. At the moment dynamic pressure transducers are typically calibrated using reference transducers, which are calibrated against static pressure standards. Because dynamic and static characteristics of pressure transducers may significantly differ from each other, it is important that these transducers are calibrated against dynamic pressure standards. In a method developed in VTT Technical Research Centre of Finland Ltd, Centre for Metrology MIKES, a pressure pulse is generated by impact between a dropping weight and a piston of a liquid-filled piston-cylinder assembly. The traceability to SI-units is realized through interferometric measurement of the acceleration of the dropping weight during impact, the effective area of the piston-cylinder assembly and the mass of the weight. Based on experimental validation and an uncertainty evaluation, the developed primary standard provides traceability for peak pressures in the range from 10 MPa to 400 MPa with a few millisecond pulse width and a typical relative expanded uncertainty (k  =  2) of 1.5%. The performance of the primary standard is demonstrated by test calibrations of two dynamic pressure transducers.

Preliminary Drag Tests in Flight of Low-Drag Wing on the Curtiss XP-60 Airplane

DTIC Science & Technology

1941-12-01

y () Ho T Y absolute free q abaolute weke HI absolute wake Ho absolute free stream static p~. essure position static ~ essure position totel ~ressure...t’hetotal .hetidlev61- The stream stagnation ,pressure .Ho is found ay ‘addingthe .~ essure corresponding to the indicated deflection of “fourthtube 142..3

Orifice-induced pressure error studies in Langley 7- by 10-foot high-speed tunnel

NASA Technical Reports Server (NTRS)

Plentovich, E. B.; Gloss, B. B.

1986-01-01

For some time it has been known that the presence of a static pressure measuring hole will disturb the local flow field in such a way that the sensed static pressure will be in error. The results of previous studies aimed at studying the error induced by the pressure orifice were for relatively low Reynolds number flows. Because of the advent of high Reynolds number transonic wind tunnels, a study was undertaken to assess the magnitude of this error at high Reynolds numbers than previously published and to study a possible method of eliminating this pressure error. This study was conducted in the Langley 7- by 10-Foot High-Speed Tunnel on a flat plate. The model was tested at Mach numbers from 0.40 to 0.72 and at Reynolds numbers from 7.7 x 1,000,000 to 11 x 1,000,000 per meter (2.3 x 1,000,000 to 3.4 x 1,000,000 per foot), respectively. The results indicated that as orifice size increased, the pressure error also increased but that a porous metal (sintered metal) plug inserted in an orifice could greatly reduce the pressure error induced by the orifice.

Static performance investigation of a skewed-throat multiaxis thrust-vectoring nozzle concept

NASA Technical Reports Server (NTRS)

Wing, David J.

1994-01-01

The static performance of a jet exhaust nozzle which achieves multiaxis thrust vectoring by physically skewing the geometric throat has been characterized in the static test facility of the 16-Foot Transonic Tunnel at NASA Langley Research Center. The nozzle has an asymmetric internal geometry defined by four surfaces: a convergent-divergent upper surface with its ridge perpendicular to the nozzle centerline, a convergent-divergent lower surface with its ridge skewed relative to the nozzle centerline, an outwardly deflected sidewall, and a straight sidewall. The primary goal of the concept is to provide efficient yaw thrust vectoring by forcing the sonic plane (nozzle throat) to form at a yaw angle defined by the skewed ridge of the lower surface contour. A secondary goal is to provide multiaxis thrust vectoring by combining the skewed-throat yaw-vectoring concept with upper and lower pitch flap deflections. The geometric parameters varied in this investigation included lower surface ridge skew angle, nozzle expansion ratio (divergence angle), aspect ratio, pitch flap deflection angle, and sidewall deflection angle. Nozzle pressure ratio was varied from 2 to a high of 11.5 for some configurations. The results of the investigation indicate that efficient, substantial multiaxis thrust vectoring was achieved by the skewed-throat nozzle concept. However, certain control surface deflections destabilized the internal flow field, which resulted in substantial shifts in the position and orientation of the sonic plane and had an adverse effect on thrust-vectoring and weight flow characteristics. By increasing the expansion ratio, the location of the sonic plane was stabilized. The asymmetric design resulted in interdependent pitch and yaw thrust vectoring as well as nonzero thrust-vector angles with undeflected control surfaces. By skewing the ridges of both the upper and lower surface contours, the interdependency between pitch and yaw thrust vectoring may be eliminated and the location of the sonic plane may be further stabilized.

Flight Investigation at High Mach Numbers of Several Methods of Measuring Static Pressure on an Airplane Wing

DTIC Science & Technology

1944-11-01

SS SUBJECT HEADIN6S: Pressure distribution - Flow research - Methods (40950) Wings (74500); DMiion, Intolilfjonco Air Kkrtcricl Command AIQ TECHNICAL INDGK Wrl0ht- Patto *son Air Forco ( Dayton, Ohio ///¥

Modeling of Propagation of Interacting Cracks Under Hydraulic Pressure Gradient

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

Huang, Hai; Mattson, Earl Douglas; Podgorney, Robert Karl

A robust and reliable numerical model for fracture initiation and propagation, which includes the interactions among propagating fractures and the coupling between deformation, fracturing and fluid flow in fracture apertures and in the permeable rock matrix, would be an important tool for developing a better understanding of fracturing behaviors of crystalline brittle rocks driven by thermal and (or) hydraulic pressure gradients. In this paper, we present a physics-based hydraulic fracturing simulator based on coupling a quasi-static discrete element model (DEM) for deformation and fracturing with conjugate lattice network flow model for fluid flow in both fractures and porous matrix. Fracturingmore » is represented explicitly by removing broken bonds from the network to represent microcracks. Initiation of new microfractures and growth and coalescence of the microcracks leads to the formation of macroscopic fractures when external and/or internal loads are applied. The coupled DEM-network flow model reproduces realistic growth pattern of hydraulic fractures. In particular, simulation results of perforated horizontal wellbore clearly demonstrate that elastic interactions among multiple propagating fractures, fluid viscosity, strong coupling between fluid pressure fluctuations within fractures and fracturing, and lower length scale heterogeneities, collectively lead to complicated fracturing patterns.« less

Closed-loop helium circulation system for actuation of a continuously operating heart catheter pump.

PubMed

Karabegovic, Alen; Hinteregger, Markus; Janeczek, Christoph; Mohl, Werner; Gföhler, Margit

2017-06-09

Currently available, pneumatic-based medical devices are operated using closed-loop pulsatile or open continuous systems. Medical devices utilizing gases with a low atomic number in a continuous closed loop stream have not been documented to date. This work presents the construction of a portable helium circulation addressing the need for actuating a novel, pneumatically operated catheter pump. The design of its control system puts emphasis on the performance, safety and low running cost of the catheter pump. Static and dynamic characteristics of individual elements in the circulation are analyzed to ensure a proper operation of the system. The pneumatic circulation maximizes the working range of the drive unit inside the catheter pump while reducing the total size and noise production.Separate flow and pressure controllers position the turbine's working point into the stable region of the pressure creation element. A subsystem for rapid gas evacuation significantly decreases the duration of helium removal after a leak, reaching subatmospheric pressure in the intracorporeal catheter within several milliseconds. The system presented in the study offers an easy control of helium mass flow while ensuring stable behavior of its internal components.

Internal Flow Simulation of Enhanced Performance Solid Rocket Booster for the Space Transportation System

NASA Technical Reports Server (NTRS)

Ahmad, Rashid A.; McCool, Alex (Technical Monitor)

2001-01-01

An enhanced performance solid rocket booster concept for the space shuttle system has been proposed. The concept booster will have strong commonality with the existing, proven, reliable four-segment Space Shuttle Reusable Solid Rocket Motors (RSRM) with individual component design (nozzle, insulator, etc.) optimized for a five-segment configuration. Increased performance is desirable to further enhance safety/reliability and/or increase payload capability. Performance increase will be achieved by adding a fifth propellant segment to the current four-segment booster and opening the throat to accommodate the increased mass flow while maintaining current pressure levels. One development concept under consideration is the static test of a "standard" RSRM with a fifth propellant segment inserted and appropriate minimum motor modifications. Feasibility studies are being conducted to assess the potential for any significant departure in component performance/loading from the well-characterized RSRM. An area of concern is the aft motor (submerged nozzle inlet, aft dome, etc.) where the altered internal flow resulting from the performance enhancing features (25% increase in mass flow rate, higher Mach numbers, modified subsonic nozzle contour) may result in increased component erosion and char. To assess this issue and to define the minimum design changes required to successfully static test a fifth segment RSRM engineering test motor, internal flow studies have been initiated. Internal aero-thermal environments were quantified in terms of conventional convective heating and discrete phase alumina particle impact/concentration and accretion calculations via Computational Fluid Dynamics (CFD) simulation. Two sets of comparative CFD simulations of the RSRM and the five-segment (IBM) concept motor were conducted with CFD commercial code FLUENT. The first simulation involved a two-dimensional axi-symmetric model of the full motor, initial grain RSRM. The second set of analyses included three-dimensional models of the RSRM and FSM aft motors with four-degree vectored nozzles.

Static cardiomyoplasty with synthetic elastic net suppresses ventricular dilatation and dysfunction after myocardial infarction in the rat: a chronic study.

PubMed

Kato, Nobusuke; Kawaguchi, Akira T; Kishida, Akio; Yamaoka, Tetsuji

2013-07-01

Although static cardiomyoplasty prevents the left ventricle (LV) from dilatation, it may interfere with diastolic relaxation, or cause restriction. We developed a synthetic net with dual elasticity and tested its effect late after myocardial infarction in the rat. LV pressure-volume relationships (PVR) were successively analyzed before, after intravenous volume load, and 10 minutes after occlusion of the left anterior descending artery. Rats were then randomized into groups receiving synthetic net wrapping around the heart (NET+, n = 8) and only partially behind LV (NET-, n = 9), and they underwent the same PVR studies 6 weeks later. End-diastolic and end-systolic PVR were defined, and LV size and function were compared under standardized loading conditions. Although there was no difference in Day 0, increase in LV end-diastolic and end-systolic volumes were significantly attenuated in NET+ rats 6 weeks later when there was a significant correlation between LV volumes by PVR estimation and actual measurements, with significant differences in both measures between the groups: NET+ < NET-. The presence or absence of net did not show restrictive hemodynamics under acute volume load. Static cardiomyoplasty using a synthetic elastic net significantly attenuated LV dilatation and dysfunction without restriction late after myocardial infarction in the rat. © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Vertical thermal structure of the Venus atmosphere from temperature and pressure measurements

NASA Technical Reports Server (NTRS)

Linkin, V. M.; Blamon, Z.; Lipatov, A. P.; Devyatkin, S. I.; Dyachkov, A. V.; Ignatova, S. I.; Kerzhanovich, V. V.; Malyk, K.; Stadny, V. I.; Sanotskiy, Y. V.

1986-01-01

Accurate temperature and pressure measurements were made on the Vega-2 lander during its entire descent. The temperature and pressure at the surface were 733 K and 89.3 bar, respectively. A strong temperature inversion was found in the upper troposphere. Several layers with differing static stability were visible in the atmospheric structure.

Comparison of experiment with calculations using curvature-corrected zero and two equation turbulence models for a two-dimensional U-duct

NASA Astrophysics Data System (ADS)

Monson, D. J.; Seegmiller, H. L.; McConnaughey, P. K.

1990-06-01

In this paper experimental measurements are compared with Navier-Stokes calculations using seven different turbulence models for the internal flow in a two-dimensional U-duct. The configuration is representative of many internal flows of engineering interst that experience strong curvature. In an effort to improve agreement, this paper tests several versions of the two-equation k-epsilon turbulence model including the standard version, an extended version with a production range time scale, and a version that includes curvature time scales. Each is tested in its high and low Reynolds number formulations. Calculations using these new models and the original mixing length model are compared here with measurements of mean and turbulence velocities, static pressure and skin friction in the U-duct at two Reynolds numbers. The comparisons show that only the low Reynolds number version of the extended k-epsilon model does a reasonable job of predicting the important features of this flow at both Reynolds numbers tested.

Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow baseline and suppressor nozzles. Volume 1: Noise source locations and extrapolation of static free-field jet noise data

NASA Technical Reports Server (NTRS)

Jaeck, C. L.

1976-01-01

A test was conducted in the Boeing Large Anechoic Chamber to determine static jet noise source locations of six baseline and suppressor nozzle models, and establish a technique for extrapolating near field data into the far field. The test covered nozzle pressure ratios from 1.44 to 2.25 and jet velocities from 412 to 594 m/s at a total temperature of 844 K.

Tests Of Array Of Flush Pressure Sensors

NASA Technical Reports Server (NTRS)

Larson, Larry J.; Moes, Timothy R.; Siemers, Paul M., III

1992-01-01

Report describes tests of array of pressure sensors connected to small orifices flush with surface of 1/7-scale model of F-14 airplane in wind tunnel. Part of effort to determine whether pressure parameters consisting of various sums, differences, and ratios of measured pressures used to compute accurately free-stream values of stagnation pressure, static pressure, angle of attack, angle of sideslip, and mach number. Such arrays of sensors and associated processing circuitry integrated into advanced aircraft as parts of flight-monitoring and -controlling systems.

Transient Pressure Test Article (TPTA) 1.1 and 1.1A, volume 1

NASA Technical Reports Server (NTRS)

Rebells, Clarence A.

1988-01-01

This final test report presents the results obtained during the static hot firing and cold-gas high Q tests of the first Transient Pressure Test Article (TPTA) 1.1. The TPTA consisted of field test joints A and B, which were the original RSRM J-insulation configuration, with a metal capture feature. It also consisted of a flight configuration nozzle-to-case test joint (Joint D) with shorter vent slots. Fluorocarbon O-rings were used in all the test joints. The purpose of the TPTA tests is to evaluate and characterize the RSMR field and nozzle-to-case joints under the influence of ignition and strut loads during liftoff anf high Q. All objectives of the cold-gas high Q (TPTA 1.1A) test were met and all measurements were close to predicted values. During the static hot-firing test (TPTA 1.1), the motor was inadvertently plugged by the quench injector plug, making it a more severe test, although no strut loads were applied. The motor was depressurized after approximately 11 min using an auxiliary system, and no anomalies were noted. In the static hot-firing test, pressure was incident on the insulation and the test joint gaps were within the predicted range. During the static hot-firing test, no strut loads were applied because the loading system malfunctioned. For this test, all measurements were within range of similar tests performed without strut loads.

Free-jet feasibility study of a thermal acoustic shield concept for AST/VCE application-dual stream nozzles. Comprehensive data report. Volume 2: Laser velocimeter and suppressor. Base pressure data

NASA Technical Reports Server (NTRS)

Janardan, B. A.; Brausch, J. F.; Price, A. O.

1984-01-01

Acoustic and diagnostic data that were obtained to determine the influence of selected geometric and aerodynamic flow variables of coannular nozzles with thermal acoustic shields are summarized in this comprehensive data report. A total of 136 static and simulated flight acoustic test points were conducted with 9 scale-model nozzles. Aerodynamic laser velocimeter measurements were made for four selected plumes. In addition, static pressure data in the chute base region of the suppressor configurations were obtained to assess the influence of the shield stream on the suppressor base drag.

Portable wastewater flow meter

DOEpatents

Hunter, Robert M.

1999-02-02

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under fill pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

Portable wastewater flow meter

DOEpatents

Hunter, Robert M.

1990-01-01

A portable wastewater flow meter particularly adapted for temporary use at a single location in measuring the rate of liquid flow in a circular entrance conduit of a sewer manhole both under free flow and submerged, open channel conditions and under full pipe, surcharged conditions, comprising an apparatus having a cylindrical external surface and an inner surface that constricts the flow through the apparatus in such a manner that a relationship exists between (1) the difference between the static pressure head of liquid flowing through the entrance of the apparatus and the static pressure head of liquid flowing through the constriction, and (2) the rate of liquid flow through the apparatus.

Aero-thermal investigation of a highly loaded transonic linear turbine guide vane cascade. A test case for inviscid and viscous flow computations

NASA Astrophysics Data System (ADS)

Arts, T.; Lambertderouvroit, M.; Rutherford, A. W.

1990-09-01

An experimental aerothermal investigation of a highly loaded transonic turbine nozzle guide vane mounted in a linear cascade arrangement is presented. The measurements were performed in a short duration isentropic light piston compression tube facility, allowing a correct simulation of Mach and Reynolds numbers as well as of the gas to wall temperature ratio compared to the values currently observed in modern aeroengines. The experimental program consisted of the following: (1) flow periodicity checks by means of wall static pressure measurements and Schlieren flow visualizations; (2) blade velocity distribution measurements by means of static pressure tappings; (3) blade convective heat transfer measurements by means of static pressure tappings; (4) blade convective heat transfer measurements by means of platinium thin films; (5) downstream loss coefficient and exit flow angle determinations by using a new fast traversing mechanism; and (6) free stream turbulence intensity and spectrum measurements. These different measurements were performed for several combinations of the free stream flow parameters looking at the relative effects on the aerodynamic blade performance and blade convective heat transfer of Mach number, Reynolds number, and freestream turbulence intensity.

A review of wave celerity in frictionless and axisymmetrical steel-lined pressure tunnels

NASA Astrophysics Data System (ADS)

Hachem, F. E.; Schleiss, A. J.

2011-02-01

Generally applicable approaches for estimating the “quasi-static”, which means without fluid-structure interaction and frequency-dependent water-hammer wave speed in steel-lined pressure tunnels are analyzed. The external constraints and assumptions of these approaches are discussed in detail. The reformulated formulas are then compared to commonly used expressions. Some special cases of wave speed calculation such as unlined pressure tunnels and open-air penstocks are investigated. The quasi-static wave speed is significantly influenced by the state of the backfill concrete and the near-field rock zone (cracked or uncracked). In the case when these two layers are cracked, the quasi-static wave speed is overestimated in between 1% and 8% compared to uncracked concrete and near-field rock layers. Depending on the stiffness of steel liner and penstock, the fluid-structure interaction leads to significant difference in wave speeds values. Compared to the quasi-static case, the fluid-structure interaction approach, applied to steel-lined tunnels, results up to 13% higher wave speed values in the high-frequency range (higher than 600 Hz) and up to 150% lower values for frequencies between 150 and 300 Hz in the considered test case.

A GPS-Based Pitot-Static Calibration Method Using Global Output-Error Optimization

NASA Technical Reports Server (NTRS)

Foster, John V.; Cunningham, Kevin

2010-01-01

Pressure-based airspeed and altitude measurements for aircraft typically require calibration of the installed system to account for pressure sensing errors such as those due to local flow field effects. In some cases, calibration is used to meet requirements such as those specified in Federal Aviation Regulation Part 25. Several methods are used for in-flight pitot-static calibration including tower fly-by, pacer aircraft, and trailing cone methods. In the 1990 s, the introduction of satellite-based positioning systems to the civilian market enabled new inflight calibration methods based on accurate ground speed measurements provided by Global Positioning Systems (GPS). Use of GPS for airspeed calibration has many advantages such as accuracy, ease of portability (e.g. hand-held) and the flexibility of operating in airspace without the limitations of test range boundaries or ground telemetry support. The current research was motivated by the need for a rapid and statistically accurate method for in-flight calibration of pitot-static systems for remotely piloted, dynamically-scaled research aircraft. Current calibration methods were deemed not practical for this application because of confined test range size and limited flight time available for each sortie. A method was developed that uses high data rate measurements of static and total pressure, and GPSbased ground speed measurements to compute the pressure errors over a range of airspeed. The novel application of this approach is the use of system identification methods that rapidly compute optimal pressure error models with defined confidence intervals in nearreal time. This method has been demonstrated in flight tests and has shown 2- bounds of approximately 0.2 kts with an order of magnitude reduction in test time over other methods. As part of this experiment, a unique database of wind measurements was acquired concurrently with the flight experiments, for the purpose of experimental validation of the optimization method. This paper describes the GPS-based pitot-static calibration method developed for the AirSTAR research test-bed operated as part of the Integrated Resilient Aircraft Controls (IRAC) project in the NASA Aviation Safety Program (AvSP). A description of the method will be provided and results from recent flight tests will be shown to illustrate the performance and advantages of this approach. Discussion of maneuver requirements and data reduction will be included as well as potential applications.

Static Performance of a Fixed-Geometry Exhaust Nozzle Incorporating Porous Cavities for Shock-Boundary Layer Interaction Control

NASA Technical Reports Server (NTRS)

Asbury, Scott C.; Hunter, Craig A.

1999-01-01

An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to determine the internal performance of a fixed-geometry exhaust nozzle incorporating porous cavities for shock-boundary layer interaction control. Testing was conducted at static conditions using a sub-scale nozzle model with one baseline and 27 porous configurations. For the porous configurations, the effects of percent open porosity, hole diameter, and cavity depth were determined. All tests were conducted with no external flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable, shock-induced, boundary-layer separation at over-expanded conditions. Porous configurations were capable of controlling off-design separation in the nozzle by either alleviating separation or encouraging stable separation of the exhaust flow. The ability of the porous nozzle concept to alternately alleviate separation or encourage stable separation of exhaust flow through shock-boundary layer interaction control offers tremendous off-design performance benefits for fixed-geometry nozzle installations. In addition, the ability to encourage separation on one divergent flap while alleviating it on the other makes it possible to generate thrust vectoring using a fixed-geometry nozzle.

Focused RBCC Experiments: Two-Rocket Configuration Experiments and Hydrocarbon/Oxygen Rocket Ejector Experiments

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh

2003-01-01

This addendum report documents the results of two additional efforts for the Rocket Based Combined Cycle (RBCC) rocket-ejector mode research work carried out at the Penn State Propulsion Engineering Research Center in support of NASA s technology development efforts for enabling 3 d generation Reusable Launch Vehicles (RLV). The tasks reported here build on an earlier NASA MSFC funded research program on rocket ejector investigations. The first task investigated the improvements of a gaseous hydrogen/oxygen twin thruster RBCC rocket ejector system over a single rocket system. The second task investigated the performance of a hydrocarbon (liquid JP-7)/gaseous oxygen single thruster rocket-ejector system. To gain a systematic understanding of the rocket-ejector s internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static diffusion and afterburning (DAB) configurations for a range of rocket operating conditions. For all experimental conditions, overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust. Detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (gaseous oxygen, hydrogen, nitrogen and water vapor) for the gaseous hydrogen/oxygen rocket ejector experiments.

Space Shuttle Main Engine structural analysis and data reduction/evaluation. Volume 7: High pressure fuel turbo-pump third stage impeller analysis

NASA Technical Reports Server (NTRS)

Pool, Kirby V.

1989-01-01

This volume summarizes the analysis used to assess the structural life of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbo-Pump (HPFTP) Third Stage Impeller. This analysis was performed in three phases, all using the DIAL finite element code. The first phase was a static stress analysis to determine the mean (non-varying) stress and static margin of safety for the part. The loads involved were steady state pressure and centrifugal force due to spinning. The second phase of the analysis was a modal survey to determine the vibrational modes and natural frequencies of the impeller. The third phase was a dynamic response analysis to determine the alternating component of the stress due to time varying pressure impulses at the outlet (diffuser) side of the impeller. The results of the three phases of the analysis show that the Third Stage Impeller operates very near the upper limits of its capability at full power level (FPL) loading. The static loading alone creates stresses in some areas of the shroud which exceed the yield point of the material. Additional cyclic loading due to the dynamic force could lead to a significant reduction in the life of this part. The cyclic stresses determined in the dynamic response phase of this study are based on an assumption regarding the magnitude of the forcing function.

Flight Calibration of four airspeed systems on a swept-wing airplane at Mach numbers up to 1.04 by the NACA radar-phototheodolite method

NASA Technical Reports Server (NTRS)

Thompson, Jim Rogers; Bray, Richard S; COOPER GEORGE E

1950-01-01

The calibrations of four airspeed systems installed in a North American F-86A airplane have been determined in flight at Mach numbers up to 1.04 by the NACA radar-phototheodolite method. The variation of the static-pressure error per unit indicated impact pressure is presented for three systems typical of those currently in use in flight research, a nose boom and two different wing-tip booms, and for the standard service system installed in the airplane. A limited amount of information on the effect of airplane normal-force coefficient on the static-pressure error is included. The results are compared with available theory and with results from wind-tunnel tests of the airspeed heads alone. Of the systems investigated, a nose-boom installation was found to be most suitable for research use at transonic and low supersonic speeds because it provided the greatest sensitivity of the indicated Mach number to a unit change in true Mach number at very high subsonic speeds, and because it was least sensitive to changes in airplane normal-force coefficient. The static-pressure error of the nose-boom system was small and constant above a Mach number of 1.03 after passage of the fuselage bow shock wave over the airspeed head.

The phase diagram of solid hydrogen at high pressure: A challenge for first principles calculations

NASA Astrophysics Data System (ADS)

Azadi, Sam; Foulkes, Matthew

2015-03-01

We present comprehensive results for the high-pressure phase diagram of solid hydrogen. We focus on the energetically most favorable molecular and atomic crystal structures. To obtain the ground-state static enthalpy and phase diagram, we use semi-local and hybrid density functional theory (DFT) as well as diffusion quantum Monte Carlo (DMC) methods. The closure of the band gap with increasing pressure is investigated utilizing quasi-particle many-body calculations within the GW approximation. The dynamical phase diagram is calculated by adding proton zero-point energies (ZPE) to static enthalpies. Density functional perturbation theory is employed to calculate the proton ZPE and the infra-red and Raman spectra. Our results clearly demonstrate the failure of DFT-based methods to provide an accurate static phase diagram, especially when comparing insulating and metallic phases. Our dynamical phase diagram obtained using fully many-body DMC calculations shows that the molecular-to-atomic phase transition happens at the experimentally accessible pressure of 374 GPa. We claim that going beyond mean-field schemes to obtain derivatives of the total energy and optimize crystal structures at the many-body level is crucial. This work was supported by the UK engineering and physics science research council under Grant EP/I030190/1, and made use of computing facilities provided by HECTOR, and by the Imperial College London high performance computing centre.

Experimental Investigation on Design Enhancement of Axial Fan Using Fixed Guide Vane

NASA Astrophysics Data System (ADS)

Munisamy, K. M.; Govindasamy, R.; Thangaraju, S. K.

2015-09-01

Airflow passes through the rotating blade in an axial flow fan will experience a helical flow pattern. This swirling effect leads the system to experience swirl energy losses or pressure drop yet reducing the total efficiency of the fan system. A robust tool to encounter this air spin past the blade is by introducing guide vane to the system. Owing to its importance, a new approach in designing outlet guide vane design for a commercial usage 1250mm diameter axial fan with a 30° pitch angle impeller has been introduced in this paper. A single line metal of proper curvature guide vane design technique has been adopted for this study. By choosing fan total efficiency as a target variable to be improved, the total and static pressure on the design point were set to be constraints. Therefore, the guide vane design was done based on the improvement target on the static pressure in system. The research shows that, with the improvement in static pressure by 29.63% through guide vane installation, the total fan efficiency is increased by 5.12%, thus reduces the fan power by 5.32%. Good agreement were found, that when the fan total efficiency increases, the power consumption of the fan is reduced. Therefore, this new approach of guide vane design can be applied to improve axial fan performance.

Wind pressure testing of tornado safe room components made from wood

Treesearch

Robert Falk; Deepak Shrestha

2016-01-01

To evaluate the ability of a wood tornado safe room to resist wind pressures produced by a tornado, two safe room com-ponents were tested for wind pressure strength. A tornado safe room ceiling panel and door were static-pressure-tested according to ASTM E 330 using a vacuum test system. Re-sults indicate that the panels had load capacities from 2.4 to 3.5 times that...

Manufacturing Diamond Under Very High Pressure

NASA Technical Reports Server (NTRS)

Voronov, Oleg

2007-01-01

A process for manufacturing bulk diamond has been made practical by the invention of the High Pressure and Temperature Apparatus capable of applying the combination of very high temperature and high pressure needed to melt carbon in a sufficiently large volume. The apparatus includes a reaction cell wherein a controlled static pressure as high as 20 GPa and a controlled temperature as high as 5,000 C can be maintained.

The Ames 12-Foot Pressure Tunnel: Tunnel Empty Flow Calibration Results and Discussion

NASA Technical Reports Server (NTRS)

Zell, Peter T.; Banducci, David E. (Technical Monitor)

1996-01-01

An empty test section flow calibration of the refurbished NASA Ames 12-Foot Pressure Tunnel was recently completed. Distributions of total pressure, dynamic pressure, Mach number, flow angularity temperature, and turbulence are presented along with results obtained prior to facility demolition. Axial static pressure distributions along tunnel centerline are also compared. Test section model support geometric configurations will be presented along with a discussion of the issues involved with different model mounting schemes.

Prevalence of graduated compression stocking-associated pressure injuries in surgical intensive care units.

PubMed

Hobson, Deborah B; Chang, Tracy Y; Aboagye, Jonathan K; Lau, Brandyn D; Shihab, Hasan M; Fisher, Betsy; Young, Samantha; Sujeta, Nancy; Shaffer, Dauryne L; Popoola, Victor O; Kraus, Peggy S; Knorr, Gina; Farrow, Norma E; Streiff, Michael B; Haut, Elliott R

2017-08-01

This study aimed to determine the prevalence of static graduated compression stocking (sGCS)-associated pressure injury among patients in surgical intensive care units (ICUs). We retrospectively reviewed data from wound care rounds between April 2011 and June 2012 at 3 surgical ICUs at an urban, tertiary care hospital. Patients with sGCS-associated pressure injury were identified and descriptive analysis was performed on their demographic, perioperative, and postoperative characteristics. We examined 1787 individual patients during 2391 patient encounters. A total of 129 (7.2%) of patients developed pressure injuries. Forty patients (2.2%) developed sGCS-associated pressure injury. Static GCS-associated pressure injury accounted for 31% (40/129) of all pressure injuries and 74% (40/54) of all medical device-related pressure injury. Eighteen (45%) and 6 (15%) developed stage 1 and 2 pressure injury, respectively, and 16 (40%) developed deep tissue injuries. The mean age of our patients was 64.7 years, about half (47.5%) were male, and their mean Acute Physiology and Chronic Health Evaluation II score was 18.8. Many had comorbid conditions, including obesity (44.5%) and diabetes (42.5%), and required mechanical ventilation (45%). Pressure injuries are a notable complication of sGCS in surgical ICU patients. Appropriate measures are required to help avoid this potentially preventable harm. Copyright © 2017 Elsevier Inc. All rights reserved.

Pressure ulcer risk assessment and prevention: a systematic comparative effectiveness review.

PubMed

Chou, Roger; Dana, Tracy; Bougatsos, Christina; Blazina, Ian; Starmer, Amy J; Reitel, Katie; Buckley, David I

2013-07-02

Pressure ulcers are associated with substantial health burdens but may be preventable. To review the clinical utility of pressure ulcer risk assessment instruments and the comparative effectiveness of preventive interventions in persons at higher risk. MEDLINE (1946 through November 2012), CINAHL, the Cochrane Library, grant databases, clinical trial registries, and reference lists. Randomized trials and observational studies on effects of using risk assessment on clinical outcomes and randomized trials of preventive interventions on clinical outcomes. Multiple investigators abstracted and checked study details and quality using predefined criteria. One good-quality trial found no evidence that use of a pressure ulcer risk assessment instrument, with or without a protocolized intervention strategy based on assessed risk, reduces risk for incident pressure ulcers compared with less standardized risk assessment based on nurses' clinical judgment. In higher-risk populations, 1 good-quality and 4 fair-quality randomized trials found that more advanced static support surfaces were associated with lower risk for pressure ulcers compared with standard mattresses (relative risk range, 0.20 to 0.60). Evidence on the effectiveness of low-air-loss and alternating-air mattresses was limited, with some trials showing no clear differences from advanced static support surfaces. Evidence on the effectiveness of nutritional supplementation, repositioning, and skin care interventions versus usual care was limited and had methodological shortcomings, precluding strong conclusions. Only English-language articles were included, publication bias could not be formally assessed, and most studies had methodological shortcomings. More advanced static support surfaces are more effective than standard mattresses for preventing ulcers in higher-risk populations. The effectiveness of formal risk assessment instruments and associated intervention protocols compared with less standardized assessment methods and the effectiveness of other preventive interventions compared with usual care have not been clearly established.

Global surface pressure measurements of static and dynamic stall on a wind turbine airfoil at low Reynolds number

NASA Astrophysics Data System (ADS)

Disotell, Kevin J.; Nikoueeyan, Pourya; Naughton, Jonathan W.; Gregory, James W.

2016-05-01

Recognizing the need for global surface measurement techniques to characterize the time-varying, three-dimensional loading encountered on rotating wind turbine blades, fast-responding pressure-sensitive paint (PSP) has been evaluated for resolving unsteady aerodynamic effects in incompressible flow. Results of a study aimed at demonstrating the laser-based, single-shot PSP technique on a low Reynolds number wind turbine airfoil in static and dynamic stall are reported. PSP was applied to the suction side of a Delft DU97-W-300 airfoil (maximum thickness-to-chord ratio of 30 %) at a chord Reynolds number of 225,000 in the University of Wyoming open-return wind tunnel. Static and dynamic stall behaviors are presented using instantaneous and phase-averaged global pressure maps. In particular, a three-dimensional pressure topology driven by a stall cell pattern is detected near the maximum lift condition on the steady airfoil. Trends in the PSP-measured pressure topology on the steady airfoil were confirmed using surface oil visualization. The dynamic stall case was characterized by a sinusoidal pitching motion with mean angle of 15.7°, amplitude of 11.2°, and reduced frequency of 0.106 based on semichord. PSP images were acquired at selected phase positions, capturing the breakdown of nominally two-dimensional flow near lift stall, development of post-stall suction near the trailing edge, and a highly three-dimensional topology as the flow reattaches. Structural patterns in the surface pressure topologies are considered from the analysis of the individual PSP snapshots, enabled by a laser-based excitation system that achieves sufficient signal-to-noise ratio in the single-shot images. The PSP results are found to be in general agreement with observations about the steady and unsteady stall characteristics expected for the airfoil.

Ground effect for V/STOL aircraft configurations and its simulation in the wind tunnel. Part 1: Introduction and theoretical studies

NASA Technical Reports Server (NTRS)

Hackett, J. E.; Praytor, E. B.

1972-01-01

Theoretical studies are made of three dimensional turbulent boundary layer behavior on fixed grounds and on moving grounds of the type used in wind tunnel tests. It is shown that, for several widely-varying STOL configurations, the ground static pressure distributions possess a remarkable degree of fore-aft symmetry about the center of lift. At low Renolds number, corresponding to small-tunnel testing, the boundary layer displacement surface reflects to a large degree the symmetry of the pressure distribution. For this reason, induced incidence at the model is small for unseparated ground flow. At high Reynolds number, the displacement thickness decrease aft of the static pressure maximum is noticeably more rapid than the corresponding rise. This is attributed to trailing-vortex-induced spanwise pumping within the boundary layer.

Dynamic XRD, Shock and Static Compression of CaF2

NASA Astrophysics Data System (ADS)

Kalita, Patricia; Specht, Paul; Root, Seth; Sinclair, Nicholas; Schuman, Adam; White, Melanie; Cornelius, Andrew; Smith, Jesse; Sinogeikin, Stanislav

2017-06-01

The high-pressure behavior of CaF2 is probed with x-ray diffraction (XRD) combined with both dynamic compression, using a two-stage light gas gun, and static compression, using diamond anvil cells. We use XRD to follow the unfolding of a shock-driven, fluorite to cotunnite phase transition, on the timescale of nanoseconds. The dynamic behavior of CaF2 under shock loading is contrasted with that under static compression. This work leverages experimental capabilities at the Advanced Photon Source: dynamic XRD and shock experiments at the Dynamic Compression Sector, as well as XRD and static compression in diamond anvil cell at the High-Pressure Collaborative Access Team. These experiments and cross-platform comparisons, open the door to an unprecedented understanding of equations of state and phase transitions at the microstructural level and at different time scales and will ultimately improve our capability to simulate the behavior of materials at extreme conditions. Sandia National Laboratories is a multi-mission laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

In situ determination of the static inductance and resistance of a plasma focus capacitor bank.

PubMed

Saw, S H; Lee, S; Roy, F; Chong, P L; Vengadeswaran, V; Sidik, A S M; Leong, Y W; Singh, A

2010-05-01

The static (unloaded) electrical parameters of a capacitor bank are of utmost importance for the purpose of modeling the system as a whole when the capacitor bank is discharged into its dynamic electromagnetic load. Using a physical short circuit across the electromagnetic load is usually technically difficult and is unnecessary. The discharge can be operated at the highest pressure permissible in order to minimize current sheet motion, thus simulating zero dynamic load, to enable bank parameters, static inductance L(0), and resistance r(0) to be obtained using lightly damped sinusoid equations given the bank capacitance C(0). However, for a plasma focus, even at the highest permissible pressure it is found that there is significant residual motion, so that the assumption of a zero dynamic load introduces unacceptable errors into the determination of the circuit parameters. To overcome this problem, the Lee model code is used to fit the computed current trace to the measured current waveform. Hence the dynamics is incorporated into the solution and the capacitor bank parameters are computed using the Lee model code, and more accurate static bank parameters are obtained.

In situ determination of the static inductance and resistance of a plasma focus capacitor bank

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

Saw, S. H.; Institute for Plasma Focus Studies, 32 Oakpark Drive, Chadstone, Victoria 3148; Lee, S.

2010-05-15

The static (unloaded) electrical parameters of a capacitor bank are of utmost importance for the purpose of modeling the system as a whole when the capacitor bank is discharged into its dynamic electromagnetic load. Using a physical short circuit across the electromagnetic load is usually technically difficult and is unnecessary. The discharge can be operated at the highest pressure permissible in order to minimize current sheet motion, thus simulating zero dynamic load, to enable bank parameters, static inductance L{sub 0}, and resistance r{sub 0} to be obtained using lightly damped sinusoid equations given the bank capacitance C{sub 0}. However, formore » a plasma focus, even at the highest permissible pressure it is found that there is significant residual motion, so that the assumption of a zero dynamic load introduces unacceptable errors into the determination of the circuit parameters. To overcome this problem, the Lee model code is used to fit the computed current trace to the measured current waveform. Hence the dynamics is incorporated into the solution and the capacitor bank parameters are computed using the Lee model code, and more accurate static bank parameters are obtained.« less

Experimental Investigation of Unsteady Shock Wave Turbulent Boundary Layer Interactions About a Blunt Fin

NASA Technical Reports Server (NTRS)

Barnhart, Paul J.; Greber, Isaac

1997-01-01

A series of experiments were performed to investigate the effects of Mach number variation on the characteristics of the unsteady shock wave/turbulent boundary layer interaction generated by a blunt fin. A single blunt fin hemicylindrical leading edge diameter size was used in all of the experiments which covered the Mach number range from 2.0 to 5.0. The measurements in this investigation included surface flow visualization, static and dynamic pressure measurements, both on centerline and off-centerline of the blunt fin axis. Surface flow visualization and static pressure measurements showed that the spatial extent of the shock wave/turbulent boundary layer interaction increased with increasing Mach number. The maximum static pressure, normalized by the incoming static pressure, measured at the peak location in the separated flow region ahead of the blunt fin was found to increase with increasing Mach number. The mean and standard deviations of the fluctuating pressure signals from the dynamic pressure transducers were found to collapse to self-similar distributions as a function of the distance perpendicular to the separation line. The standard deviation of the pressure signals showed initial peaked distribution, with the maximum standard deviation point corresponding to the location of the separation line at Mach number 3.0 to 5.0. At Mach 2.0 the maximum standard deviation point was found to occur significantly upstream of the separation line. The intermittency distributions of the separation shock wave motion were found to be self-similar profiles for all Mach numbers. The intermittent region length was found to increase with Mach number and decrease with interaction sweepback angle. For Mach numbers 3.0 to 5.0 the separation line was found to correspond to high intermittencies or equivalently to the downstream locus of the separation shock wave motion. The Mach 2.0 tests, however, showed that the intermittent region occurs significantly upstream of the separation line. Power spectral densities measured in the intermittent regions were found to have self-similar frequency distributions when compared as functions of a Strouhal number for all Mach numbers and interaction sweepback angles. The maximum zero-crossing frequencies were found to correspond with the peak frequencies in the power spectra measured in the intermittent region.