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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Effects of Random Micron-Sized Roughness on Swept-Wing Transition

This study examines the effect of random micron-sized distributed roughness on stationary crossflow instabilities. The roughness parameters are varied by creating nanoparticle coatings of various formulations and applying them to inserts that cover approximately the first 14% of the model. In addition to the baseline configuration (no added roughness, root-mean-square (RMS) ≈ 0.42 𝜇m), panels with RMS roughness values of 4.8 and 8.6 𝜇m were tested, with correlation lengths of 1029 and 385 𝜇m, respectively. Despite the significant roughness levels tested, the transition location was found to be only mildly impacted by the additional roughness, and the roughness panel with lower RMS amplitude caused a larger upstream movement of transition, on average. However, the stationary crossflow amplitudes and wavelength content were found to vary substantially depending on the roughness input. In particular, the panel with higher RMS roughness amplitude resulted in significantly larger amplitudes in the 7.5-9 mm wavelength range at the farthest upstream measurement station, while the lower roughness panel resulted in mildly larger amplitudes at 10 mm and wavelengths larger than 15 mm. Nonlinear Parabolized Stability Equations (PSE) computations were performed to attempt to estimate the initial amplitudes of the stationary crossflow instabilities. Wavelength spectra were matched at the most upstream measurement location, but large discrepancies exist between the predicted and measured growth behavior farther downstream, thus, more work is required to improve confidence in initial amplitude estimates.

boundary-layer transition↗
NASA NTRSDate not supplied

Effects of Random Micron-Sized Roughness on Swept-Wing Transition

This study examines the effect of random micron-sized distributed roughness on stationary crossflow instabilities. The roughness parameters are varied by creating nanoparticle coatings of various formulations and applying them to inserts that cover approximately the first 14% of the model. In addition to the baseline configuration (no added roughness, root-mean-square (RMS) ≈ 0.42 𝜇m), panels with RMS roughness values of 4.8 and 8.6 𝜇m were tested, with correlation lengths of 1029 and 385 𝜇m, respectively. Despite the significant roughness levels tested, the transition location was found to be only mildly impacted by the additional roughness, and the roughness panel with lower RMS amplitude caused a larger upstream movement of transition, on average. However, the stationary crossflow amplitudes and wavelength content were found to vary substantially depending on the roughness input. In particular, the panel with higher RMS roughness amplitude resulted in significantly larger amplitudes in the 7.5-9 mm wavelength range at the farthest upstream measurement station, while the lower roughness panel resulted in mildly larger amplitudes at 10 mm and wavelengths larger than 15 mm. Nonlinear Parabolized Stability Equations (PSE) computations were performed to attempt to estimate the initial amplitudes of the stationary crossflow instabilities. Wavelength spectra were matched at the most upstream measurement location, but large discrepancies exist between the predicted and measured growth behavior farther downstream, thus, more work is required to improve confidence in initial amplitude estimates.

boundary-layer transition↗
NASA NTRSDate not supplied

Effects of Random Micron-Sized Roughness on Swept-Wing Transition

This study examines the effect of random micron-sized distributed roughness on stationary crossflow instabilities. The roughness parameters are varied by creating nanoparticle coatings of various formulations and applying them to inserts that cover approximately the first 14% of the model. In addition to the baseline configuration (no added roughness, root-mean-square (RMS) ≈ 0.42 𝜇m), panels with RMS roughness values of 4.8 and 8.6 𝜇m were tested, with correlation lengths of 1029 and 385 𝜇m, respectively. Despite the significant roughness levels tested, the transition location was found to be only mildly impacted by the additional roughness, and the roughness panel with lower RMS amplitude caused a larger upstream movement of transition, on average. However, the stationary crossflow amplitudes and wavelength content were found to vary substantially depending on the roughness input. In particular, the panel with higher RMS roughness amplitude resulted in significantly larger amplitudes in the 7.5-9 mm wavelength range at the farthest upstream measurement station, while the lower roughness panel resulted in mildly larger amplitudes at 10 mm and wavelengths larger than 15 mm. Nonlinear Parabolized Stability Equations (PSE) computations were performed to attempt to estimate the initial amplitudes of the stationary crossflow instabilities. Wavelength spectra were matched at the most upstream measurement location, but large discrepancies exist between the predicted and measured growth behavior farther downstream, thus, more work is required to improve confidence in initial amplitude estimates.

boundary-layer transition↗
NASA NTRS1997

Correlation of Chemical and Physical Test Data for the Environmental Ageing of Tefzel (ETFE)

In a similar approach to that used for the previously issued correlation report for Coflon (CAPP/M.10), this report aims to identify any correlations between mechanical property changes and chemical/morphological changes for Tefzel, using information supplied in other MERL and TRI project reports. Differences identified with Coflon behaviour will be of scientific interest as well as appropriate to project applications, as Tefzel and Coflon are chemical isomers. Owing to the considerable chemical resistance of Tefzel, much of its testing so far has been based on mechanical properties. Where changes have occurred, chemical analysis can now be targeted more effectively. Relevant test data collated here include: tensile modulus and related properties, permeation coefficients, % crystallinity, some crack growth resistance measurements, and other observations where significant. Fluids based on methanol and amine (Fluid G), a mixture of methane, carbon dioxide and hydrogen sulphide gases plus an aqueous amine solution (Fluid F), and an aromatic oil mix of heptane, cyclohexane, toluene and 1-propanol (Fluid I) have affected Tefzel to varying degrees, and are discussed in some detail herein.

Morgan, G. J.↗
NASA NTRS1996

Correlation of Chemical and Physical Test Data for the Environmental Ageing of Tefzel (ETFE)

In a similar approach to that used for the previously issued correlation report for Coflon (CAPP/M.10), this report aims to identify any correlations between mechanical property changes and chemical/morphological changes for Tefzel, using information supplied in other MERL and TRI project reports (plus latest data which will be included in final reports for Phase 1). Differences identified with Coflon behaviour will be of scientific interest as well as appropriate to project applications, as Tefzel and Coflon are chemical isomers. Owing to the considerable chemical resistance of Tefzel, much of its testing so far has been based on mechanical properties. Where changes have occurred, chemical analysis can now be targeted more effectively. Relevant test data collated here include: tensile modulus and related properties, permeation coefficients, % crystallinity, and other observations where significant. Fluids based on methanol and amine (Fluid G), a mixture of methane, carbon dioxide and hydrogen sulphide gases plus an aqueous amine solution (Fluid F), and an aromatic oil mix of heptane, cyclohexane, toluene and I-propanol (Fluid 1) have affected Tefzel to varying degrees, and are discussed in some detail herein.

Morgan, G. J.↗
NASA NTRS1983

Design and true Reynolds number 2-D testing of an advanced technology airfoil

A NASA-industry program has been conducted to determine the accuracy of available 2-D airfoil analysis procedures over a wide range of Reynolds numbers. The program also served to develop and demonstrate effective wind tunnel model designs for use in a cryogenic environment. A Lockheed design, CRYO 12X, supercritical, shockfree airfoil was configured using a continuous curvature analytical definition of the ordinates. Test results show a very close ordinate tolerance was necessary to realize the intended pressure distribution. Correlation of test with Korn-Garabedian 2-D analysis pressure data were generally good. GRUMFOIL analysis with a sidewall correction gave a better correlation.

Reaser, J. S.↗
NASA NTRS1975

Thermal scale modeling of a manned spacecraft

A manned spacecraft thermal scale modeling program is described. The program consisted of the design, construction, instrumentation, testing, data correlation, and associated analysis of a transient thermal scale model (TSM) of the Subsystem Test Bed (STB). The STB was chosen as a representative manned spacecraft for which detailed thermal vacuum test data were available. The STB is a cylindrical vehicle (15 ft diameter by 8.3 ft high) with four docking hatches and six windows. The pressure shell is insulated with multilayer insulation and protected by meteoroid shields. Four truss assemblies were used to support the STB during testing. It was concluded that thermal scale modeling can be used as an effective thermal design/verification tool for manned spacecraft. Thermal analysis can be used in conjunction with scale model testing to provide a verified math model that can be applied to the prototype manned spacecraft.

Shannon, R. L.↗
NASA NTRS1994

Sapphire reinforced alumina matrix composites

Unidirectionally reinforced A1203 matrix composites have been fabricated by hot pressing. Approximately 30 volume % of either coated or uncoated sapphire fiber was used as reinforcement. Unstabilized ZrO2 was applied as the fiber coating. Composite mechanical behavior was analyzed both after fabrication and after additional heat treatment. The results of composite tensile tests were correlated with fiber-matrix interfacial shear strengths determined from fiber push-out tests. Substantially higher strength and greater fiber pull-out were observed for the coated fiber composites for all processing conditions studied. The coated fiber composites retained up to 95% and 87% of their as-fabricated strength when heat treated at 14000C for 8 or 24 hours, respectively. Electron microscopy analysis of the fracture surfaces revealed extensive fiber pull-out both before and after heat treatment.

Jaskowiak, Martha H.↗
NASA NTRS2012

Design, Analysis and Fabrication of Secondary Structural Components for the Habitat Demonstration Unit-Deep Space Habitat

In support of NASA s Habitat Demonstration Unit - Deep Space Habitat Prototype, a number of evolved structural sections were designed, fabricated, analyzed and installed in the 5 meter diameter prototype. The hardware consisted of three principal structural sections, and included the development of novel fastener insert concepts. The articles developed consisted of: 1) 1/8th of the primary flooring section, 2) an inner radius floor beam support which interfaced with, and supported (1), 3) two upper hatch section prototypes, and 4) novel insert designs for mechanical fastener attachments. Advanced manufacturing approaches were utilized in the fabrication of the components. The structural components were developed using current commercial aircraft constructions as a baseline (for both the flooring components and their associated mechanical fastener inserts). The structural sections utilized honeycomb sandwich panels. The core section consisted of 1/8th inch cell size Nomex, at 9 lbs/cu ft, and which was 0.66 inches thick. The facesheets had 3 plys each, with a thickness of 0.010 inches per ply, made from woven E-glass with epoxy reinforcement. Analysis activities consisted of both analytical models, as well as initial closed form calculations. Testing was conducted to help verify analysis model inputs, as well as to facilitate correlation between testing and analysis. Test activities consisted of both 4 point bending tests as well as compressive core crush sequences. This paper presents an overview of this activity, and discusses issues encountered during the various phases of the applied research effort, and its relevance to future space based habitats.

Smith, Russell W.↗
NASA NTRS1985

Sensitivities of Soap Solutions in Leak Detection

Document describes method for determining minimum leak rate to which soap-solution leak detectors sensitive. Bubbles formed at smaller leak rates than previously assumed. In addition to presenting test results, document discusses effects of joint-flange configurations, properties of soap solutions, and correlation of test results with earlier data.

Stuck, D.↗
NASA NTRS2003

Evaluation of a Singular Value Decomposition Approach for Impact Dynamic Data Correlation

Impact dynamic tests are used in the automobile and aircraft industries to assess survivability of occupants during crash, to assert adequacy of the design, and to gain federal certification. Although there is no substitute for experimental tests, analytical models are often developed and used to study alternate test conditions, to conduct trade-off studies, and to improve designs. To validate results from analytical predictions, test and analysis results must be compared to determine the model adequacy. The mathematical approach evaluated in this paper decomposes observed time responses into dominant deformation shapes and their corresponding contribution to the measured response. To correlate results, orthogonality of test and analysis shapes is used as a criterion. Data from an impact test of a composite fuselage is used and compared to finite element predictions. In this example, the impact response was decomposed into multiple shapes but only two dominant shapes explained over 85% of the measured response

Horta, Lucas G.↗
NASA NTRS2003

Correlating Flammability of Materials with FTIR Analysis Test Results

The purpose of this experiment was to correlate flammability data with FTIR test results. Kydex 100 is a blend of chlorinated polyvinyl chloride and polymethylmethacrylate, with some filler materials. Samples supplied were 0.125 in. thick. 10 samples were taken from a sheet of Kydex and analyzed for flammability and by FTIR spectroscopy. This material was utilized as a round robin sample for flammability testing. The flammability test results were found to vary across the same sheet.

Moore, Robin↗
NASA NTRS1979

Study of liquid and vapor flow into a Centaur capillary device

The following areas of liquid and vapor flow were analyzed and experimentally evaluated; 1) the refilling of capillary devices with settled liquid, and 2) vapor flow across wetted screens. These investigations resulted in: 1) the development of a versatile computer program that was successfully correlated with test data and used to predict Centaur D-1S LO2 and LH2 start basket refilling; 2) the development of a semi-empirical model that was only partially correlated with data due to difficulties in obtaining repeatable test results. Also, a comparison was made to determine the best propellant management system for the Centaur D-1S vehicle. The comparison identified the basline Centaur D-1S system (using pressurization, boost pumps and propellant settling) as the best candidate based on payload weight penalty. However, other comparison criteria and advanced mission condition were identified where pressure fed systems, thermally subcooled boost pumps and capillary devices would be selected as attractive alternatives.

Blatt, M. H.↗
NASA NTRS1983

Microstructural evolution in the HAZ of Inconel 718 and correlation with the hot ductility test

The nickel-base alloy 718 was evaluated to study the role of preweld heat treatment in reducing or eliminating heat-affected zone hot cracking. Three heat treatments were studied using the Gleeble hot ductility test. A modified hot ductility test was also used to follow the evolution of microstructure during simulated welding thermal cycles. The microstructural evolution was correlated with the hot ductility data in order to evaluate the mechanism of hot cracking in alloy 718. The correlation of hot ductility with microstructure showed that recrystallization, grain growth, and dissolution of precipitates did not in themselves cause any loss of ductility during cooling. Ductility loss during cooling was not initiated until the constitutional liquation of NbC particles was observed in the microstructure. Laves-type phases were found precipitated in the solidified grain boundaries but were not found to correlate with any ductility loss parameter. Mechanisms are reviewed which help to explain how heat treatment controls the hot crack susceptibility of alloy 718 as measured in the hot ductility test.

Thompson, R. G.↗
NASA NTRS1992

Application of piezoelectric devices to vibration suppression - From modeling and controller designs to implementation

Embedded piezoelectric devices may be ideally suited for vibration control of space structures, which lack an inertial ground. When subjected to an input voltage, an embedded piezoelectric actuator changes its dimensions, which in turn generates a pair of forces exerted on adjacent structural members. From the direct piezoelectric effect, an embedded piezoelectric transducer generates an electric charge proportional to the structural dynamic response. In this paper, the implementation, testing and modeling of an active truss structure consisting of piezoelectric sensors and actuators are described. Linear quadratic Gaussian (LQG), second-order, and direct rate feedback control schemes are designed to suppress the vibrations of the active structure. Simulation and test results are presented. It is shown that special model reduction considerations are required to achieve good correlation between test and analysis.

Won, Chin C.↗
NASA NTRS1988

Correlation of SA349/2 Helicopter Flight Test Data with a Comprehensive Rotorcraft Model

A comprehensive rotorcraft analysis model, CAMRAD, was used to predict blade aerodynamic and structural loads and performance for comparison with flight test data. The data were obtained from an SA349/2 helicopter with an advanced geometry rotor. Sensitivity of the correlation to wake geometry, blade dynamics, and blade aerodynamic effects was investigated. Blade chordwise pressure coefficients were predicted for the transonic regimes near the blade tip using the model coupled with two finite-difference codes.

Yamauchi, Gloria K.↗
NASA NTRS2006

Performance of AEA 80 Ah Battery Under GEO Profile

To date completed three Solar Dynamic Observatory SDO real-time eclipse seasons. Sony 18650HC has a low rate of capacity fade under GEO cycling regime. Real time test results correlate with accelerated GEO lifetest data and AEA capacity fade prediction tool. This data, together with other AEA test data, justify the SDO Project decision to baseline Lithium-Ion chemistry for the spacecraft battery.

Russel, N.↗