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DOE OSTI2022

NorthStar Facility Target Fab and Flow Testing - FY 21

The facility target fabrication and flow testing activity will consist of flow tests using the blower system at LANL to test the disk holder and target, both redesigned by the NorthStar prime contractor. The housing and transition system delivering helium cooling to the disc holder and target will be fabricated and tested at LANL facilities. The tests will include pressure drop versus flow measurements through the target and housing, optical flow diagnostics and fiber optic imaging of the disc stack. The pressure drop measurements will be compared to CFD simulations to verify the latter, the optical flow diagnostics will be used to determine whether modifications made to the housing and target holder allow sufficient flow through the bottom of the housing to adequately cool it and the fiber optics will be used to image the discs during operation as a proof of concept of the diagnostic, to be used at NorthStar facilities during preproduction testing. The work is a Partial Fulfillment of the Deliverable Requirement for NorthStar Facility Target Fab and Flow Testing and Production Target Testing Support by LANL

42 ENGINEERING↗
NASA NTRS1978

Effect of inlet temperature on the performance of a catalytic reactor

A 12-cm-diameter by 15-cm-long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 300,000 and 600,000 Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range from 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions and, therefore, the combustion efficiency were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount of fuel-bound nitrogen in the fuel. Up to 90% conversion was observed with no apparent effect of any of the test variables. For typical gas-turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

Anderson, D. N.↗
NASA NTRS1982

A ceramic nozzle for the NASA-Langley 2.4-m /8.0-ft/ high temperature structures tunnel

Two materials, a refractory castable ceramic and a SiO2-SiO2 composite, were fabricated as nozzle inserts for the Langley Research Center's 2.4-m (8.0-ft) high temperature structures tunnel. The high pressure and intense heat of the CH4-air products of the combustion-gas stream limits the materials that can be used in this tunnel. The castable-ceramic material showed good resistance to erosion and the thermal loads imposed on it by the gas stream but failed in tension when subjected to high hoop stresses. The SiO2-SiO2-composite nozzle insert withstood the thermomechanical loads but eroded unacceptably with increasing test temperature and pressure.

Buckley, J. D.↗
NASA NTRS2009

A Theoretical Investigation of Composite Overwrapped Pressure Vessel (COPV) Mechanics Applied to NASA Full Scale Tests

A theoretical investigation of the factors controlling the stress rupture life of the National Aeronautics and Space Administration's (NASA) composite overwrapped pressure vessels (COPVs) continues. Kevlar (DuPont) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of a load sharing liner, the manufacturing induced residual stresses and the complex mechanical response, the state of actual fiber stress in flight hardware and test articles is not clearly known. This paper is a companion to a previously reported experimental investigation and develops a theoretical framework necessary to design full-scale pathfinder experiments and accurately interpret the experimentally observed deformation and failure mechanisms leading up to static burst in COPVs. The fundamental mechanical response of COPVs is described using linear elasticity and thin shell theory and discussed in comparison to existing experimental observations. These comparisons reveal discrepancies between physical data and the current analytical results and suggest that the vessel s residual stress state and the spatial stress distribution as a function of pressure may be completely different from predictions based upon existing linear elastic analyses. The 3D elasticity of transversely isotropic spherical shells demonstrates that an overly compliant transverse stiffness relative to membrane stiffness can account for some of this by shifting a thin shell problem well into the realm of thick shell response. The use of calibration procedures are demonstrated as calibrated thin shell model results and finite element results are shown to be in good agreement with the experimental results. The successes reported here have lead to continuing work with full scale testing of larger NASA COPV hardware.

Thesken, John C.↗
NASA NTRS2006

A Theoretical Investigation of Composite Overwrapped Pressure Vessel (COPV) Mechanics Applied to NASA Full Scale Tests

A theoretical investigation of the factors controlling the stress rupture life of the National Aeronautics and Space Agency's (NASA) composite overwrapped pressure vessels (COPVs) continues. Kevlar(TradeMark) fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar(TradeMark) filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However, due to the presence of a load sharing liner, the manufacturing induced residual stresses and the complex mechanical response, the state of actual fiber stress in flight hardware and test articles is not clearly known. This paper is a companion to the experimental investigation reported in [1] and develops a theoretical framework necessary to design full-scale pathfinder experiments and accurately interpret the experimentally observed deformation and failure mechanisms leading up to static burst in COPVs. The fundamental mechanical response of COPVs is described using linear elasticity and thin shell theory and discussed in comparison to existing experimental observations. These comparisons reveal discrepancies between physical data and the current analytical results and suggest that the vessel's residual stress state and the spatial stress distribution as a function of pressure may be completely different from predictions based upon existing linear elastic analyses. The 3D elasticity of transversely isotropic spherical shells demonstrates that an overly compliant transverse stiffness relative to membrane stiffness can account for some of this by shifting a thin shell problem well into the realm of thick shell response. The use of calibration procedures are demonstrated as calibrated thin shell model results and finite element results are shown to be in good agreement with the experimental results. The successes reported here have lead to continuing work with full scale testing of larger NASA COPV hardware.

Greene, N.↗
NASA NTRS1999

Low LBNP Tolerance in Men is Associated With Attenuated Activation of The Renin-Angiotensin System

Vasoactive hormone concentrations [epinephrine (pE), norepinephrine (pNE), angiotensin II (pATII), vasopressin (pVP), endothelin 1 (pET1)] and plasma renin activity (pRA) were measured during lower body negative pressure (LBNP) to test the hypothesis that responsiveness of the renin-angiotensin system is related to LBNP tolerance. Healthy men (2,822 cal/day(exp -1), 2 mmol*kg(exp -1)*day(exp -1)) Na(+)) were exposed to 30 minutes of progressive LBNP to -50 mmHg. LBNP was uneventful for seven men (25 +/- 2 years, HiTol group), but eight men (26 +/- 3 years) reached pre-syncope after 11 +/- 1 minutes (P < 0.001, LoTol group). Mean arterial pressure was unchanged. Central venous pressure and left atrial diameter decreased in both groups (5-6 mmHg by approx. 30%, P < 0.05). Control [hormone] were similar but, pRA differed between groups (LoTol 0.6 +/- 0.1, HiTol 1.2 +/- 0.1 ng Ang1/(ml(exp -1)*h(exp -1)), P < 0.05). LBNP increased (P < 0.05) pRA and pATII more in HiTol (9.9 +/- 2.2 ng Ang1/(ml(exp -1)*h(exp -1)) and 58 +/- 12 pg/ml(exp -1)) than LoTol (4.3 +/- 0.9 ng Ang1/(ml*h) and 28 +/- 6 pg/ml(exp -1)). In contrast, pVP was higher (P < 0.05) in LoTol than in HiTol. The response of the renin-angiotensin system seems linked to the occurrence of pre-syncope, and measurement of resting pRA may be predictive.

Greenleaf, J. E.↗
NASA NTRS1985

Longitudinal mode combustion instabilities of a high-pressure fuel-rich LOX/RP-1 preburner

During the hot-fire testing of a high-pressure fuel-rich LOX/RP-1 preburner, longitudinal mode combustion instabilities were observed. This paper presents the experimental data showing how the instability varied with the chamber pressure, mixture ratio, chamber length and turbulence ring. Technical rationales are given for the test-to-test hardware configuration changes that eventually led to the stable result.

Fang, J. J.↗
NASA NTRS1978

Effect of inlet temperature on the performance of a catalytic reactor

A 12 cm diameter by 15 cm long catalytic reactor was tested with No. 2 diesel fuel in a combustion test rig at inlet temperatures of 700, 800, 900, and 1000 K. Other test conditions included pressures of 3 and 6 x 10 to the 5th power Pa, reference velocities of 10, 15, and 20 m/s, and adiabatic combustion temperatures in the range 1100 to 1400 K. The combustion efficiency was calculated from measurements of carbon monoxide and unburned hydrocarbon emissions. Nitrogen oxide emissions and reactor pressure drop were also measured. At a reference velocity of 10 m/s, the CO and unburned hydrocarbons emissions, and, therefore, the combustion efficiency, were independent of inlet temperature. At an inlet temperature of 1000 K, they were independent of reference velocity. Nitrogen oxides emissions resulted from conversion of the small amount (135 ppm) of fuel-bound nitrogen in the fuel. Up to 90 percent conversion was observed with no apparent effect of any of the test variables. For typical gas turbine operating conditions, all three pollutants were below levels which would permit the most stringent proposed automotive emissions standards to be met.

Anderson, D. N.↗
NASA NTRS1973

Analysis of ground tests of a microwave, earth-occultation, pressure-reference-level system.

A two-satellite, microwave, earth-occultation system can supplement an infrared sensor by providing an accurate altitude reference that will serve to fix, as a function of height, the derived temperature profile of the infrared sounder. The results of ground tests made in Hawaii to estimate the likely effects of scintillation and fading on an occultation system are described. It was found that the microwave signal suffered periods of intense fading; extensive computer analyses of the data were performed in which aircraft-generated refractivity profiles were subjected to ray tracing. Results of these analyses indicate that the probable cause of the observed fading was multipath, a low-altitude phenomenon usually attributed to water vapor inhomogeneities. It is maintained that multipath will therefore have minimal effect on the pressure-reference microwave occultation system, which would operate at a relatively high closest-approach altitude (about 8 km).

Ungar, S. G.↗
NASA NTRS1999

Low LBNP Tolerance in Men is Associated With Attenuated Activation of Renin-Angiotensin System

Vasoactive hormone concentrations (epinephrine (pE), norepinephrine (pNE), angiotensin II (pATII), vasopressin (pVP), endothelin 1 (pET1)] and plasma renin activity (pRA) were measured during lower body negative pressure (LBNP) to test the hypothesis that responsiveness of the reninangiotensin system is related to LBNP tolerance. Healthy men (2,822 cal per day, 2 mmol per kilogram per day Na (+)) were exposed to 30 min of progressive LBNP to -50mmHg. LBNP was uneventful for 7 men (2512 yr, HiTol group), but 8 men (26 plus or minus 3 yr) reached pre-syncope after 11 plus or minus 1 min (P less than 0.001, LoTol group). Mean arterial pressure was unchanged. Central venous pressure and left atrial diameter decreased in both groups (5-6 mmHg by 30%, P less than 0.05). Control [hormone] were similar but, pRA differed between groups (LoTol 0.6 plus or minus 0.1, HiTol 1.2 plus or minus 0.1 ng Ang1 per milliliter per hour, per hour, P less than 0.05). LBNP increased (P less than 0.05) pRA and pATII more in HiTol (9.9 plus or minus 2.2 ng Ang1 per milliliter per hour and 58 plus or minus 12 pg per milliliter) than LoTol (4.3 plus or minus 0.9 ng Angl per milliliter per hour and 28 plus or minus 6 pg per milliliter). In contrast, pVP was higher (P less than 0.05) in LoTol than in HiTol. The response of the renin-angiotensin system seems linked to the occurrence of pre-syncope, and measurement of resting pRA may be predictive.

Greenleaf, John E.↗
NASA NTRS2022

Semispan Test Results of an Active Flow Control Enabled High-Lift Common Research Model in Landing Configuration

A 10%-scale semispan, Active Flow Control (AFC) enabled, simplified high-lift version of the Common Research Model (CRM-SHL-AFC) was tested in the 14- by 22-Foot Subsonic Tunnel at the NASA Langley Research Center. The main objective of the test was to develop an AFC system that can provide the necessary lift recovery on a simple-hinged flap high-lift system while minimizing its pneumatic power requirement. Three new types of AFC approaches were examined: Double-Row Sweeping Jets (DRSWJ), Alternating Pulsed Jets (APJ), and High Efficiency Low Power (HELP) actuators. The DRSWJ and the APJ actuators used two rows of unsteady jets, whereas the HELP actuators used an upstream row of sweeping jets combined with a downstream row of steady jets to overcome strong adverse pressure gradients. The test was conducted mostly at a freestream Mach number of 0.20. For exploration purposes, a limited number of runs were made at lower Mach numbers or using vortex generators (VGs). Minimal sensitivity to Mach number or VGs, for the cases evaluated, were observed. The AFC-induced lift coefficient increment was maintained over the AFC-off case for most flow-control cases examined. The CRM-SHL-AFC configuration equipped with HELP actuation was the only actuator configuration able to match or exceed the targeted lift performance of a reference conventional high-lift configuration. The presented aerodynamic data include lift, drag, and pitching moment coefficients as a function of angle of attack, with and without the Transonic Wall Interference Correction System (TWICS) method applied. Lift increments as a function of AFC pneumatic power usage (i.e., nozzle pressure ratio, mass flow, momentum coefficient, and power coefficient) are also presented at a lower angle of attack (α = 8.9°) and at maximum lift (α= 17.1°). At the two angles of attack, the surface pressure distributions and autospectral densities from the unsteady pressure transducers for the AFC-off case and the best HELP actuation case are compared.

high-lift↗
NASA NTRS2003

High Frequency Adaptive Instability Suppression Controls in a Liquid-Fueled Combustor

This effort extends into high frequency (>500 Hz), an earlier developed adaptive control algorithm for the suppression of thermo-acoustic instabilities in a liquidfueled combustor. The earlier work covered the development of a controls algorithm for the suppression of a low frequency (~280 Hz) combustion instability based on simulations, with no hardware testing involved. The work described here includes changes to the simulation and controller design necessary to control the high frequency instability, augmentations to the control algorithm to improve its performance, and finally hardware testing and results with an experimental combustor rig developed for the high frequency case. The Adaptive Sliding Phasor Averaged Control (ASPAC) algorithm modulates the fuel flow in the combustor with a control phase that continuously slides back and forth within the phase region that reduces the amplitude of the instability. The results demonstrate the power of the method - that it can identify and suppress the instability even when the instability amplitude is buried in the noise of the combustor pressure. The successful testing of the ASPAC approach helped complete an important NASA milestone to demonstrate advanced technologies for low-emission combustors.

Kopasakis, George↗
NASA NTRS2008

Miniature, Lightweight, One-Time-Opening Valve

The figure depicts the main parts of a prototype miniature, lightweight, onetime- opening valve. Like some other miniature one-time-opening valves reported in previous issues of NASA Tech Briefs, this valve is opened by melting a material that blocks the flow path. This valve is designed to remain closed at some temperature between room temperature and cryogenic temperature until the time of opening. The prototype valve includes a 1/8-in. (3-mm) aluminum tube, one end of which is plugged with a solder comprising about 37 weight percent of lead and 63 weight percent of tin. The tube and the solder both have a coefficient of thermal expansion of 23 micron/m-K at room temperature. Before plugging, the interior surface of the plug end of the tube is cleaned with a commercial flux paste developed specifically for preparing aluminum for bonding with lead/tin solder. The solder is then melted into the cleaned end of the tube, forming the plug. In a test, the plugged tube was pressurized to 1,000 psi (6.9 MPa) with helium and leak-tested. It was then cooled to a temperature of 77 K (about 196 C) and again leak-tested at the same pressure. Finally, at a lower pressure, the plugged end of the tube was heated to about 200 C (the melting temperature of the solder is 183 C), causing the solder plug to be ejected (see figure). It has been estimated that in a subsequent version of the valve, the plug could be melted by electrical heating, using a nichrome wire having a mass of only 10 g.

Jones, Jack↗
NASA NTRS2010

High Pressure Angle Gears: Comparison to Typical Gear Designs

A preliminary study has been completed to determine the feasibility of using high-pressure angle gears in aeronautic and space applications. Tests were conducted in the NASA Glenn Research Center (GRC) Spur Gear Test Facility at speeds up to 10,000 rpm and 73 N*m (648 in.*lb) for 3.18, 2.12, and 1.59 module gears (8, 12, and 16 diametral pitch gears), all designed to operate in the same test facility. The 3.18 module (8-diametral pitch), 28 tooth, 20deg pressure angle gears are the GRC baseline test specimen. Also, 2.12 module (12-diametral pitch), 42 tooth, 25deg pressure angle gears were tested. Finally 1.59 module (16-diametral pitch), 56 tooth, 35deg pressure angle gears were tested. The high-pressure angle gears were the most efficient when operated in the high-speed aerospace mode (10,000 rpm, lubricated with a synthetic turbine engine oil), and produced the lowest wear rates when tested with a perfluoroether-based grease. The grease tests were conducted at 150 rpm and 71 N*m (630 in.*lb).

Handschuh, Robert F.↗
NASA NTRS1992

Application of elastic and elastic-plastic fracture mechanics methods to surface flaws

Fuel tanks that are a part of the External Tank assembly for the Space Shuttle are made of relatively thin 2219-T87 aluminum plate. These tanks contain about 917 m of fusion weld seam, all of which is nondestructively inspected for flaws and all those found are repaired. The tanks are subsequently proof-tested to a pressure that is sufficiently severe to cause weld metal yielding in a few local regions of the weld seam. The work undertaken in the present project was to develop a capability to predict flaw growth from undetected surface flaws that are assumed to be located in the highly stressed regions. The technical challenge was to develop R-curve prediction capability for surface cracks in specimens that contain the flaws of unusual sizes and shapes deemed to be of interest. The test techniques developed and the elastic-plastic analysis concepts adopted are presented. The flaws of interest were quite small surface cracks that were narrow-deep ellipses that served to exacerbate the technical difficulties involved.

Mccabe, Donald E.↗
NASA NTRS1986

Thermal barrier coating life-prediction model development

The program focuses on predicting the lives of two types of strain-tolerant and oxidation-resistant thermal barrier coating (TBC) systems that are produced by commercial coating suppliers to the gas turbine industry. The plasma-sprayed TBC system, composed of a low-pressure plasma-spray (LPPS) or an argon shrouded plasma-spray (ASPS) applied oxidation resistant NiCrAlY or (CoNiCrAlY) bond coating and an air-plasma-sprayed yttria partially stabilized zirconia insulative layer, is applied by both Chromalloy, Klock, and Union Carbide. The second type of TBS is applied by the electron beam-physical vapor deposition (EB-PVD) process by Temescal. The second year of the program was focused on specimen procurement, TMC system characterization, nondestructive evaluation methods, life prediction model development, and TFE731 engine testing of thermal barrier coated blades. Materials testing is approaching completion. Thermomechanical characterization of the TBC systems, with toughness, and spalling strain tests, was completed. Thermochemical testing is approximately two-thirds complete. Preliminary materials life models for the bond coating oxidation and zirconia sintering failure modes were developed. Integration of these life models with airfoil component analysis methods is in progress. Testing of high pressure turbine blades coated with the program TBS systems is in progress in a TFE731 turbofan engine. Eddy current technology feasibility was established with respect to nondestructively measuring zirconia layer thickness of a TBC system.

Strangman, T. E.↗
NASA NTRSDate not supplied

Testing of Two Mars Powered Descent Vehicle Concepts in the Langley Unitary Plan Wind Tunnel

Testing was conducted in the NASA Langley Unitary Plan Wind Tunnel in order to investigate the aerodynamic interference of sub-scale versions of two Mars powered descent vehicle concepts at supersonic Mach numbers (2.4 and 3.5): a model based on a blunt hypersonic inflatable aerodynamic decelerator (HIAD) and the second representing a more slender rigid vehicle with body flaps (CobraMRV). Each model was designed to accommodate up to eight nozzles, with the HIAD model having five different nozzle configurations to investigate the effects of nozzle location, cant angle, and area ratio. The models were tested with high pressure air as the nozzle plume gas, and included the following instrumentation: high-speed video, discrete steady state and high-frequency pressure, pressure sensitive paint, and a new flow-through force and moment balance for the HIAD model. The high-speed imagery showed the overall expected growth of the shock layer to increasing thrust levels. The discrete stagnation pressure data on the HIAD model with four and eight blowing nozzles was sensitive to thrust coefficient with the nozzles canted at 0 degrees, whereas having nozzles canted outward 20 degrees and/or being located closer to the heatshield shoulder largely removed that sensitivity. The CobraMRV model stagnation pressure was more sensitive to tunnel Mach number and sideslip angle, due to the nozzle arrangement and plume interference. Pressure sensitive paint data quality was compromised by paint damage from frequent model changes, especially for the HIAD model. However, pressure coefficient data on the CobraMRV model showed the same trends as the discrete pressure measurements, as well as a sensitivity to non-zero sideslip angles. The aerodynamic force coefficients were derived from the pressure sensitive paint data. On the HIAD models, the primary force coefficient decreased with increasing thrust due to the nozzle plumes blocking flow to the heatshield area surrounding the nozzle exist. On the CobraMRV model, the force coefficient was relatively insensitive to thrust coefficient at the lower Mach number when sideslip angle was 0 degrees The force coefficient decreases with increasing thrust coefficient when the sideslip angle is 10 degrees. Balance data quality was negatively impacted by thermal drift issues that were not apparent in pre-test calibration measurements, thus preventing usable test data. Results and lessons learned will be used to take further technology development steps, including more advanced ground test techniques and flight testing.

Karl T Edquist↗
NASA NTRSDate not supplied

Testing of Two Mars Powered Descent Vehicle Concepts in the Langley Unitary Plan Wind Tunnel

Testing was conducted in the NASA Langley Unitary Plan Wind Tunnel in order to investigate the aerodynamic interference of sub-scale versions of two Mars powered descent vehicle concepts at supersonic Mach numbers (2.4 and 3.5): a model based on a blunt hypersonic inflatable aerodynamic decelerator (HIAD) and the second representing a more slender rigid vehicle with body flaps (CobraMRV). Each model was designed to accommodate up to eight nozzles, with the HIAD model having five different nozzle configurations to investigate the effects of nozzle location, cant angle, and area ratio. The models were tested with high pressure air as the nozzle plume gas, and included the following instrumentation: high-speed video, discrete steady state and high-frequency pressure, pressure sensitive paint, and a new flow-through force and moment balance for the HIAD model. The high-speed imagery showed the overall expected growth of the shock layer to increasing thrust levels. The discrete stagnation pressure data on the HIAD model with four and eight blowing nozzles was sensitive to thrust coefficient with the nozzles canted at 0 degrees, whereas having nozzles canted outward 20 degrees and/or being located closer to the heatshield shoulder largely removed that sensitivity. The CobraMRV model stagnation pressure was more sensitive to tunnel Mach number and sideslip angle, due to the nozzle arrangement and plume interference. Pressure sensitive paint data quality was compromised by paint damage from frequent model changes, especially for the HIAD model. However, pressure coefficient data on the CobraMRV model showed the same trends as the discrete pressure measurements, as well as a sensitivity to non-zero sideslip angles. The aerodynamic force coefficients were derived from the pressure sensitive paint data. On the HIAD models, the primary force coefficient decreased with increasing thrust due to the nozzle plumes blocking flow to the heatshield area surrounding the nozzle exist. On the CobraMRV model, the force coefficient was relatively insensitive to thrust coefficient at the lower Mach number when sideslip angle was 0 degrees The force coefficient decreases with increasing thrust coefficient when the sideslip angle is 10 degrees. Balance data quality was negatively impacted by thermal drift issues that were not apparent in pre-test calibration measurements, thus preventing usable test data. Results and lessons learned will be used to take further technology development steps, including more advanced ground test techniques and flight testing.

Supersonic Retropropulsion↗