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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 325 records · Page 18

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NASA NTRS1990

Spacecraft wall design for increased protection against penetration by space debris impacts

All orbiting spacecraft are susceptible to impacts by meteoroids and pieces of orbital space debris. These impacts occur at extremely high speeds and can damage flight-critical systems, which can in turn lead to catastrophic failure of the spacecraft. The design of a spacecraft for a long-duration mission into the meteoroid and space debris environment must include adequate protection against perforation of pressurized components by such impacts. This paper presents the results of an investigation into the perforation resistance of dual-wall structural systems fabricated with monolithic bumper plates and with corrugated bumper plates of equal weight. A comparative analysis of the impact damage in dual-wall systems with corrugated bumper specimens and that in dual-wall specimens with monolithic bumpers of similar weight is performed to determine the advantages and disadvantages of employing corrugated bumpers in structural wall systems for long-duration spacecraft. The analysis indicates that a significant increase in perforation protection can be achieved if a monolithic bumper is replaced by a corrugated bumper of equal weight. The parameters of the corrugations in the corrugated bumper plates are optimized in a manner that minimizes the potential for the creation of ricochet debris in the event of an oblique hypervelocity impact. Several design examples using the optimization scheme are presented and discussed.

Schonberg, William P.↗

NASA NTRS1997

Analytical Modeling of Pressure Wall Hole Size and Maximum Tip-to-Tip Crack Length for Perforating Normal and Oblique Orbital Debris Impacts

This report presents the results of a study whose objective was to develop first-principles-based models of hole size and maximum tip-to-tip crack length for a spacecraft module pressure wall that has been perforated in an orbital debris particle impact. The hole size and crack length models are developed by sequentially characterizing the phenomena comprising the orbital debris impact event, including the initial impact, the creation and motion of a debris cloud within the dual-wall system, the impact of the debris cloud on the pressure wall, the deformation of the pressure wall due to debris cloud impact loading prior to crack formation, pressure wall crack initiation, propagation, and arrest, and finally pressure wall deformation following crack initiation and growth. The model development has been accomplished through the application of elementary shock physics and thermodynamic theory, as well as the principles of mass, momentum, and energy conservation. The predictions of the model developed herein are compared against the predictions of empirically-based equations for hole diameters and maximum tip-to-tip crack length for three International Space Station wall configurations. The ISS wall systems considered are the baseline U.S. Lab Cylinder, the enhanced U.S. Lab Cylinder, and the U.S. Lab Endcone. The empirical predictor equations were derived from experimentally obtained hole diameters and crack length data. The original model predictions did not compare favorably with the experimental data, especially for cases in which pressure wall petalling did not occur. Several modifications were made to the original model to bring its predictions closer in line with the experimental results. Following the adjustment of several empirical constants, the predictions of the modified analytical model were in much closer agreement with the experimental results.

Schonberg, William P.↗

NASA NTRS2011

Pressure Testing of a Minimum Gauge PRSEUS Panel

Advanced aircraft configurations that have been developed to increase fuel efficiency require advanced, novel structural concepts capable of handling the unique load conditions that arise. One such concept is the Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) developed by the Boeing Company. The PRSEUS concept is being investigated by NASA s Environmentally Responsible Aviation (ERA) Program for use in a hybrid-wing body (HWB) aircraft. This paper summarizes the analysis and test of a PRSEUS panel subjected to internal pressure, the first such pressure test for this structural concept. The pressure panel used minimum gauge skin, with stringer and frame configurations consistent with previous PRSEUS tests. Analysis indicated that for the minimum gauge skin panel, the stringer locations exhibit fairly linear response, but the skin bays between the stringers exhibit nonlinear response. Excellent agreement was seen between nonlinear analysis and test results in the critical portion at the center of the panel. The pristine panel was capable of withstanding the required 18.4 psi pressure load condition without exhibiting any damage. The impacted panel was capable of withstanding a pressure load in excess of 28 psi before initial failure occurred at the center stringer, and the panel was capable of sustaining increased pressure load after the initial failure. This successful PRSEUS panel pressure panel test was a critical step in the building block approach for enabling the use of this advanced structural concept on future aircraft, such as the HWB.

Lovejoy, Andrew J.↗

NASA NTRS2016

Tsunami Generation from Asteroid Airburst and Ocean Impact and Van Dorn Effect

Airburst - In the simulations explored energy from the airburst couples very weakly with the water making tsunami dangerous over a shorter distance than the blast for asteroid sizes up to the maximum expected size that will still airburst (approx.250MT). Future areas of investigation: - Low entry angle airbursts create more cylindrical blasts and might couple more efficiently - Bursts very close to the ground will increase coupling - Inclusion of thermosphere (>80km altitude) may show some plume collapse effects over a large area although with much less pressure center dot Ocean Impact - Asteroid creates large cavity in ocean. Cavity backfills creating central jet. Oscillation between the cavity and jet sends out tsunami wave packet. - For deep ocean impact waves are deep water waves (Phase speed = 2x Group speed) - If the tsunami propagation and inundation calculations are correct for the small (<250MT) asteroids in these simulations where they impact deep ocean basins, the resulting tsunami is not a significant hazard unless particularly close to vulnerable communities. Future work: - Shallow ocean impact. - Effect of continental shelf and beach profiles - Tsunami vs. blast damage radii for impacts close to populated areas - Larger asteroids below presumed threshold of global effects (Ø200 - 800m).

Tsunami↗

NASA NTRS1983

Experimental results of a deflected thrust V/STOL nozzle research program

Four deflected thrust nozzle concepts, designed to operate at the low pressure ratio typical of high bypass-ratio turbofan engines for medium speed (subsonic) V/STOL aircraft, were studied. Maps of overall performance characteristics and exit velocity distributions are used to highlight similarities and differences between the four concepts. Analytically determined secondary flows at the exit of a 90 deg circular pipe bend are compared with the experimental results from the more complex three dimensional geometries. The relative impact of total-pressure losses and secondary flows on nozzle thrust coefficient is addressed by numerical integration of exit velocity measurements.

Burstadt, P. L.↗

NASA NTRS1983

Experimental results of a deflected thrust V/STOL nozzle research program

Burstadt, P. L.↗

NASA NTRS2024

A Diversity of Temperature and Pressure Conditions Recorded by Zircon within Suevite from Ries Crater, Germany

The temperature and pressure conditions experienced by rocks during an impact event can be constrained using petrologic and microstructural analysis and is crucial to providing ground truth to the impact cratering process. Suevite is a polymict, impact melt-bearing breccia, specific to Ries crater in Germany. There are competing models for suevite formation and emplacement, such as clastic flows pushed out of the crater rim or ejecta plume fallback. Knowledge of the temperature and pressure pathways recorded by grains within the suevite can help distinguish between these and other models. The accessory phase zircon (ZrSiO4) and its high-pressure polymorph reidite are particularly useful in such circumstances as they are highly refractory minerals that can record the high-temperature and/or high-pressure conditions of an impact event. Here we present evidence for a wide array of temperature and pressure conditions recorded in zircon grains within a single thin section of suevite. Zircons in this study range from unshocked to highly shocked (>53 GPa), and record temperatures more than 1673 °C. These findings confirm previous studies concluding that suevites contain material exposed to very diverse pressure and temperature conditions during initial shock compression and excavation but do not, as a whole, experience extreme temperatures (>1673 °C) or pressures (>30 GPa).

mineralogy↗

NASA NTRSDate not supplied

Twinned magnetite in granitic samples from the Siljan impact structure, Sweden

Impact cratering is a ubiquitous process throughout the solar system and has played a key role for the geologic evolution of Earth and other planets [1]. Magnetic anomalies are common characteristics of impact craters [2], so understanding how magnetite (Fe23+Fe2+O42-), an important magnetic carrier in both terrestrial and extraterrestrial rocks, is affected by shock waves, especially structurally and magnetically, is crucial. Magnetic minerals have been studied to gain insight into the geologic evolution of Mars, with specific focus including understanding the Martian crustal structure and the oxidization state of Martian rocks (e.g., [3,4,5]). Shock waves permanently alter the intrinsic magnetic properties of rocks (e.g., [6]), as do twinning in natural environments with less extreme P/T conditions [7]. In fact, pressure conditions induced by impacts have been suggested to explain demagnetization signatures observed around Martian impact basins [8]. It is still poorly understood what effects shock has on the crystallographic structure of magnetite and thus it’s intrinsic magnetic properties, and , how that affects the bulk magnetic properties of rocks (e.g., [9]). Limited experimental studies have investigated the effects of shock compression on magnetite, especially with the aim of describing crystallographic deformation (e.g., [9] and references therein). In this work we report preliminary results of an investigation of microstructures in magnetite, an “unconventional” mineral in shock studies, in granitic samples from the ca. 380 Ma ~52 km-in-diameter Siljan impact structure, located in south-central Sweden.

shock metamorphism↗

NASA NTRS2014

Numerical Simulation of Boundary Layer Ingesting (BLI) Inlet-Fan Interaction

Future civil transport designs may incorporate engine inlets integrated into the body of the aircraft to take advantage of efficiency increases due to weight and drag reduction. Additional increases in engine efficiency are predicted if the inlet ingests the lower momentum boundary layer flow. Previous studies have shown, however, that efficiency benefits of Boundary Layer Ingesting (BLI) ingestion are very sensitive to the magnitude of fan and duct losses, and blade structural response to the non-uniform flow field that results from a BLI inlet has not been studied in-depth. This paper presents an effort to extend the modeling capabilities of an existing rotating turbomachinery unsteady analysis code to include the ability to solve the external and internal flow fields of a BLI inlet. The TURBO code has been a successful tool in evaluating fan response to flow distortions for traditional engine/inlet integrations, such as the development of rotating stall and inlet distortion through compressor stages. This paper describes the first phase of an effort to extend the TURBO model to calculate the external and inlet flowfield upstream of fan so that accurate pressure distortions that result from BLI configurations can be computed and used to analyze fan aerodynamics and structural response. To validate the TURBO program modifications for the BLI flowfield, experimental test data obtained by NASA for a flushmounted S-duct with large amounts of boundary layer ingestion was modeled. Results for the flow upstream and in the inlet are presented and compared to experimental data for several high Reynolds number flows to validate the modifications to the solver. Quantitative data is presented that indicates good predictive capability of the model in the upstream flow. A representative fan is attached to the inlet and results are presented for the coupled inlet/fan model. The impact on the total pressure distortion at the AIP after the fan is attached is examined.

Inlet Fan Interactions↗

NASA NTRS1995

Impact damage resistance of carbon/epoxy composite tubes for the DC-XA liquid hydrogen feedline

Low-velocity impacts were inflicted upon two elbow sections of carbon/epoxy feedline that are to be a part of the Delta Clipper-XA flight vehicle. A soap-based liquid leak detector solution was used to inspect the impact sites for leaks of pressurized gas that was pumped into the tube. Visual surface damage was noted and recorded for each impact site. After impact testing of each of the two sections of tubes was completed, the damage zones were disected from the tube and cross sectioned through the impact site. These specimens were polished after potting them in epoxy and were examined for microcracking using a fluorescent dye penetrant technique. The results showed that nonvisible damage could cause microcracking, thereby resulting in leaks through the tube wall.

Nettles, A. T.↗

NASA NTRS2012

Design, Analysis and Testing of a PRSEUS Pressure Cube to Investigate Assembly Joints

Due to its potential to significantly increase fuel efficiency, the current focus of NASA's Environmentally Responsible Aviation Program is the hybrid wing body (HWB) aircraft. Due to the complex load condition that exists in HWB structure, as compared to traditional aircraft configurations, light-weight, cost-effective and manufacturable structural concepts are required to enable the HWB. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) concept is one such structural concept. A building block approach for technology development of the PRSEUS concept is being conducted. As part of this approach, a PRSEUS pressure cube was developed as a risk reduction test article to examine a new integral cap joint concept. This paper describes the design, analysis and testing of the PRSEUS pressure cube test article. The pressure cube was required to withstand a 2P, 18.4 psi, overpressure load requirement. The pristine pressure cube was tested to 2.2P with no catastrophic failure. After the addition of barely visible impact damage, the cube was pressure loaded to 48 psi where catastrophic failure occurred, meeting the scale-up requirement. Comparison of pretest and posttest analyses with the cube test response agree well, and indicate that current analysis methods can be used to accurately analyze PRSEUS structure for initial failure response.

Yovanof, Nicolette↗

DOE OSTI2025

Effects of Water Vapor on the Reactivity of Aluminosilicates in Vapor-Phase Propanal Aldol Condensation

Aluminosilicate materials have been extensively studied as efficient aldol catalysts for C-C coupling reactions due to their acidic nature, high surface area, thermal stability, and porous structure. This work investigated the impact of water vapor pressure on the catalytic reactivity of aluminosilicates for the aldol condensation of propanal to 2-methyl-2-pentenal (MP). The catalytic performance of amorphous SiO2-Al2O3 (A-Si-Al) and aluminated MCM-41 (Al-MCM-41) for the vapor-phase aldol condensation of propanal was evaluated at 200 degrees C as a function of vapor-phase water content at atmospheric pressure. Our findings demonstrate that co-feeding low water vapor pressures (1-18 kPa) with propanal enhances the rates of MP production at 200 degrees C on A-Si-Al. Conversely, water vapor pressures of 25 kPa result in a decrease in aldol dimer formation rates. The rate of MP production evaluated on Al-MCM-41 also increased in the presence of 5 kPa water compared to anhydrous conditions. Propylamine temperature-programmed desorption analyses revealed an increase in Bronsted acid site density when both catalysts were exposed to water, which likely accounts for the observed enhancement in aldol condensation reactivity under hydrous conditions. Reversibility testing of the water vapor effect under reaction conditions, combined with X-ray diffraction analysis of fresh, spent, and regenerated catalysts, revealed no structural changes in either aluminosilicate upon exposure to water or reaction conditions. The rates of aldol condensation and the impact of water vapor were highly consistent across both materials, suggesting that zeolite crystallinity has minimal influence on the catalytic performance.

acid catalysts↗

NASA NTRS2023

Exploration Extra-Vehicular Mobility Unit (xEMU) Composite Hard Upper Torso (CHUT) Development

The xEMU is the Exploration Mobility Unity or space suit designed for microgravity (cislunar and low earth orbit (LEO)) and lunar surface operations. This suit design allows crewmembers to perform extravehicular exploration, science, construction, maintenance, and contingency operations while unattached to a vehicle for life support in pressure and thermal environments that exceed human capability. The xEMU provides life support, environmental protection, and communications capabilities to the EVA crewmember while allowing sufficient mobility and visibility to perform dexterous EVA tasks. The effort documented in this paper, addressed the design, analysis, manufacturing, full-scale test article testing and validation for a Composite Hard Upper Torso(CHUT)unit. Design and analysis of the CHUT was based on measured B-basis properties of the selected S-glass/epoxy composite, and established final geometry, composite layup and interface details that met requirements. A complete manufacturing and assembly protocol was established for the CHUT starting from composite layup in the tool, to final assembly of all interface metal hardware prior to delivery to NASA for suit integration. Full-scale CHUT test articles underwent static and fatigue pressure testing (2 lifetimes), impact testing at critical stress locations for tool drop/microgravity scenarios, followed by post-impact fatigue testing. Effect of manufacturing defects was evaluated by manufacturing a full-scale CHUT with 0.375”/0.5” defects at critical stress locations, followed by static and life-cycle fatigue testing. In all cases, the CHUT design met or exceeded mass, structural, interface and functional requirements. Two (2) complete CHUT articles were delivered to NASA for full-scale suit integration and testing.

spacesuit↗

NASA NTRS2023

Composite Hard Upper Torso (CHUT) for xEMU Space Suit

spacesuit↗

NASA NTRSDate not supplied

Simulation and Modeling of Hypersonic Turbulent Boundary Layers Subject to Adverse Pressure Gradients due to Concave Streamline Curvature

Direct numerical simulations (DNS) of adverse-pressure-gradient turbulent boundary layers over a planar concave wall are presented for a nominal freestream Mach number of 5, with the objective of assessing the limitations of the currently available Reynolds-averaged Navier-Stokes (RANS) models. The wall geometry and flow conditions of the DNS are representative of the experimental data for a Mach 4.9 turbulent boundary layer that was tested on a two-dimensional planar concave wall model in the high-speed blow-down wind tunnel located at the National Aerothermochemistry Laboratory at Texas A&M University (TAMU). The DNS was validated against the experimental results of TAMU for the same flow conditions and wall geometry. An analysis of the DNS datasets was also conducted to provide an assessment of the validity of Morkovin’s hypothesis and the strong Reynolds analog for turbulence subject to mechanical nonequilibrium. In addition to the DNS results, RANS predictions are obtained by using the Baldwin-Lomax (BL), Spalart-Allmaras (SA), and the k - w SST turbulence models. The comparisons between RANS and DNS showed little impact of an adverse pressure gradient on the accuracy of these models, at least up to an incompressible Clauser pressure gradient parameter of beta(sub inc) 1.22. While the Boussinesq assumption provided reasonable predictions for the Reynolds shear stress, it failed to adequately predict the normal components of the Reynolds stress.

turbulent boundary layers↗

NASA NTRS2017

Results of Simulated Galactic Cosmic Radiation (GCR) and Solar Particle Events (SPE) on Spectra Restraint Fabric

Spectra or similar Ultra-high-molecular-weight polyethylene (UHMWPE) fabric is the likely choice for future structural space suit restraint materials due to its high strength-to-weight ratio, abrasion resistance, and dimensional stability. During long duration space missions, space suits will be subjected to significant amounts of high-energy radiation from several different sources. To insure that pressure garment designs properly account for effects of radiation, it is important to characterize the mechanical changes to structural materials after they have been irradiated. White Sands Test Facility (WSFTF) collaborated with the Crew and Thermal Systems Division at the Johnson Space Center (JSC) to irradiate and test various space suit materials by examining their tensile properties through blunt probe puncture testing and single fiber tensile testing after the materials had been dosed at various levels of simulated GCR and SPE Iron and Proton beams at Brookhaven National Laboratories. The dosages were chosen based on a simulation developed by the Structural Engineering Division at JSC for the expected radiation dosages seen by space suit softgoods seen on a Mars reference mission. Spectra fabric tested in the effort saw equivalent dosages at 2x, 10x, and 20x the predicted dose as well as a simulated 50 year exposure to examine the range of effects on the material and examine whether any degradation due to GCR would be present if the suit softgoods were stored in deep space for a long period of time. This paper presents the results of this work and outlines the impact on space suit pressure garment design for long duration deep space missions.

Peters, Benjamin↗

NASA NTRS2014

Analytic Ballistic Performance Model of Whipple Shields

The dual-wall Whipple shield is the shield of choice for lightweight, long-duration flight. The shield uses an initial sacrificial wall to initiate fragmentation and melt an impacting threat that expands over a void before hitting a subsequent shield wall of a critical component. The key parameters to this type of shield are the rear wall and its mass which stops the debris, as well as the minimum pressure generated under threat particle impact of the sacrificial wall and the amount of void that is available for expansion. Ensuring the minimum pressure is sufficiently high to achieve large scale fragmentation/melt of the threat particle enables the expansion of the threat and reduces the momentum flux of the debris on the rear wall. Three key factors in the minimum pressure achieved are the thickness of the sacrificial wall relative to the characteristic dimension of the impacting particle, the density and material cohesion contrast of the sacrificial wall relative to the threat particle and the impact speed. The mass of the rear wall and the sacrificial wall are desirable to minimize for launch costs and dynamic concerns making it important to have an understanding of the effects of density contrast and impact speed. In this paper a fourth key parameter is identified related to fragmentation, which corresponds to the ratio of the size of the projectile relative to the transition from brittle to ductile hole growth in the projectile. Ballistic limit equations have been developed to define the failure limits of a MMOD shield, generally in terms of projectile diameter (or mass), impact velocity, and angle. Within the range of impact velocities relevant for Earth-orbiting spacecraft, three distinct regions of penetration phenomenology have been identified for Whipple shields: center dot Low velocity: the projectile is eroded (and possibly deformed) during its passage through the bumper plate, but is not fragmented. Thus, perforation of the rear wall is by a fragment with a mass and speed equal to or less than the original impactor. center dot Intermediate (shatter) velocity: impact velocities are sufficient to induce projectile fragmentation upon impact with the bumper plate, resulting in a coarse debris cloud with large solid fragments. Increasing velocity within the shatter regime results in increased fragmentation, and eventually melting, of the projectile and bumper fragments, generating a finer and more evenly dispersed debris cloud. Failure of the rear wall is a complicated combination of modes observed at low- and hypervelocity. center dot Hypervelocity: the projectile and holed-out bumper material is completely, or nearly completely, melted and/or vaporized by the initial impact. The resultant debris cloud impacts over a dispersed area of the rear wall, loading it impulsively and inducing failure through rupture or petalling. While each of these regimes are well observed with extensive empirical methods to describe these regions, differences in impactor materials, configurations of shields and questions about the limitations of the attainable impact speeds have left questions that are difficult to answer from completely empirical methods.

Miller, J. E.↗

NASA NTRS1987

Impact on the earth, ocean and atmosphere

On the basis of finite-difference techniques, cratering flow calculations are used to obtain the spatial attenuation of shock pressure with radius along the impact axis for the impact of silicate rock and iron impactors on a silicate half-space at speeds of 5 to 45 km/sec. Upon impact of a 10 to 30 km diameter silicate or water object onto a 5 km deep ocean overlying a silicate half-space planet at 30 km/sec, it is found that from 12 to 15 percent of the incident energy is coupled into the water. The mass of atmosphere lost due to impacts of 1 to 5 km radius projectiles is calculated.

Ahrens, Thomas J.↗