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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

An Analytical Model of Erosive Wear of BioMass Comminution Components

An analytical erosion model that relates critical process parameters (speed and impingement angle) to critical material attributes of inorganic mineral species in feedstock (density, size, aspect ratio) and substrate (hardness, toughness, and fatigue ductility) was applied to model wear in pretreatment milling operations. Results of the model were compared to experimental measurements of wear produced using the Accelerated Wear Test (AWT) rig at Idaho National Laboratory (INL). Results showed that there is good agreement between predicted and measured performance, and that a quality-by-design (QbD) tool can be developed to predict component reliability based on scientific engineering principles in lieu of trial-and-error approaches.

09 BIOMASS FUELS↗
NASA NTRS1972

Aeolian processes on Mars - Erosive velocities, settling velocities, and yellow clouds.

Extremely high atmospheric wind velocities are needed to erode particulate matter on Mars. Settling velocities are roughly equivalent to terrestrial settling velocities for clay to fine sand-size particles; suspension transport may be dominant for fine particles on Mars. Yellow clouds suggest that required threshold erosion velocities are reached and that a great deal of fine-grained material is carried in suspension. Yellow cloud origins are concentrated over the southern latitudes and areas of major topographic relief. The cloud distribution pattern suggests that high threshold velocities are attained by transient atmospheric disturbances such as slope winds and dust devils.-

Arvidson, R. E.↗
NASA NTRS1979

The erosion/corrosion of small superalloy turbine rotors operating in the effluent of a PFB coal combustor

The operation of a turbine in the effluent of a pressurized fluidized bed (PFB) coal combustor presents serious materials problems. Synergistic erosion/corrosion and deposition/corrosion interactions may favor the growth of erosion-resistant oxides on blade surfaces, but brittle cracking of these oxides may be an important source of damage along heavy particle paths. Integrally cast alloy 713LC and IN792 + Hf superalloy turbine rotors in a single-stage turbine with 6% partial admittance have been operated in the effluent of a PFB coal combustor for up to 164 hr. The rotor erosion pattern exhibits heavy particle separation with severe erosion at the leading edge, pressure side center, and suction side trailing edge at the tip. The erosion distribution pattern gives a spectrum of erosion/oxidation/deposition as a function of blade position. The data suggest that preferential degradation paths may exist even under the targeted lower loadings (less than 20 ppm).

Zellars, G. R.↗
NASA NTRS1980

Photogeological constraints on lunar and planetary vulcanism, part 2

The use of several simple theoretical modelling approaches in simulating lava erosion were evaluated. Both one dimensional and two dimensional models were used with the two dimensional model being superior. The two dimensional model accounts, in a purely phenomenological way, for the effects of turbulence and mechanical erosion in a flow. Criteria for mechanical erosion was related to the basal stress and the effect of entrained eroded material on fluid properties was parameterized.

Source record↗
NASA NTRS1988

Fluvial processes on Mars: Erosion and sedimentation

One of the most important discoveries of the Mariner 9 and Viking missions to Mars was evidence of change of the Martian surface by the action of liquid water. From the standpoint of a Mars Rover/Sample Return Mission, fluvial activity on Mars is important in two ways: (1) channel formation has deeply eroded the Martian crust, providing access to relatively undisturbed subsurface units; and (2) much of the material eroded from channels may have been deposited in standing bodies of liquid water. The most striking fluvial erosion features on Mars are the outflow channels. A second type of channel apparently caused by flow of liquid water is the valley systems. These are similar to terrestial drainage systems. The sedimentary deposits of outflow channels are often difficult to identfy. No obvious deposits such as deltaic accumulations are visible in Viking images. Another set of deposits that may be water lain and that date approx. from the epoch of outflow channels are the layered deposits in the Valles Marineris. From the standpoint of a Mars Rover/Sample Return mission, the problem with all of these water-lain sediments is their age, or rather the lack of it.

Squyres, Steven W.↗
DOE OSTI2021

Failure Analysis of a New Polyamide-Based Fluoropolymer-Free Backsheet After Combined-Accelerated Stress Testing

The viability of novel coextruded, fluoropolymer-free backsheets for photovoltaic (PV) modules has been questioned as a result of a large number of early-life backsheet failures in PV installations containing one of the earliest co-extruded polyamide (PA)-based backsheet to reach the market, “AAA.” New PV reliability testing protocols have been recently developed and applied to backsheets to reproduce failures observed in the field and evaluate the durability of novel backsheet materials and designs prior to commercialization. A new co-extruded PA-based backsheet was tested using combined-accelerated stress testing (C-AST) and demonstrated a greater lifetime than AAA, and some other fluoropolymer-based backsheets such as polyvinylidene fluoride. The improved PA-based backsheet also eventually failed by through-thickness cracking. Using surface and bulk material characterization techniques, we performed a comprehensive study of material properties before and after the stress testing. Aging of the backsheet resulted in an increase of surface roughness by erosion of the outer PA layer. However the failure is more likely related to an increase in crystallinity of the polyolefin core layer reducing the backsheet tearing energy. The analysis can ultimately inform on the specific weaknesses of the materials so that the manufacturer can improve the backsheet design to extend its lifetime.

14 SOLAR ENERGY↗
DOE OSTI2023

Computational exploration of DIII-D QH-mode with extended MHD

This work will enable improved understanding of the scientific basis for DIII-D Quiescent H-mode (QH-mode) by leveraging recent computational developments of the NIMROD code. Experimentally, it is established that the QH-mode tokamak operation regime is free of edge-localized modes (ELMs) with good energy confinement. ELMs produce an impulsive heat-flux on the divertor that is unacceptable under burning-plasma conditions. Beyond DIII-D in future high-power-density tokamaks, accommodation of a high heat flux at the divertor represents a key challenge to overcome. Proposed solutions involve operation at high divertor density to achieve divertor detachment, operation with a liquid lithium wall and/or introduction of impurities to enhance radiative losses. Additionally, the first wall material is likely to be a high-Z material such as Tungsten in future devices as materials such as graphite tiles restrict the lifetime of the first wall due to a high erosion rate. While the atomic species composition of the plasma is known to impact the edge-pedestal structure and stability, the specifics of the underlying physics basis for this interaction is not firm. Studying this interaction is the goal of this proposal without focusing specifically on the fine details of the first wall and divertor solution. It is the goal is to lay the ground work to establish the compatibility of the divertor solutions and wall material with pedestal solutions that eliminate ELMs by leveraging present DIII-D experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1978

Development of a plasma sprayed ceramic gas path seal for high pressure turbine application

Development of the plasma sprayed graded, layered ZRO2/CoCrAlY seal system for gas turbine engine blade tip seal applications up to 1589 K (2400 F) surface temperature was continued. The effect of changing ZRO2/CoCrAlY ratios in the intermediate layers on thermal stresses was evaluated analytically with the goal of identifying the materials combinations which would minimize thermal stresses in the seal system. Three methods of inducing compressive residual stresses in the sprayed seal materials to offset tensile thermal stresses were analyzed. The most promising method, thermal prestraining, was selected based upon potential, feasibility and complexity considerations. The plasma spray equipment was modified to heat, control and monitor the substrate temperature during spraying. Specimens were fabricated and experimentally evaluated to: (1) substantiate the capability of the thermal prestrain method to develop compressive residual stresses in the sprayed structure and (2) define the effect of spraying on a heated substate on abradability, erosion and thermal shock characteristics of the seal system. Thermal stress analysis, including residual stresses and material properties variations, was performed and correlated with thermal shock test results. Seal system performance was assessed and recommendations for further development were made.

Shiembob, L. T.↗
NASA NTRS2015

Use of a Tantalum Liner to Reduce Bore Erosion and Increase Muzzle Velocity in Two-Stage Light Gas Guns

Muzzle velocities and gun erosion predicted by earlier numerical simulations of two stage light gas guns with steel gun tubes were in good agreement with experimental values. In a subsequent study, simulations of high performance shots were repeated with rhenium (Re) gun tubes. Large increases in muzzle velocity (2 - 4 km/sec) were predicted for Re tubes. In addition, the hydrogen-produced gun tube erosion was, in general, predicted to be zero with Re tubes. Tantalum (Ta) has some mechanical properties superior to those of Re. Tantalum has a lower modulus of elasticity than Re for better force transmission from the refractory metal liner to an underlying thick wall steel tube. Tantalum also has greater ductility than Re for better survivability during severe stress/strain cycles. Also, tantalum has been used as a coating or liner in military powder guns with encouraging results. Tantalum has, however, somewhat inferior thermal properties to those of rhenium, with a lower melting point and lower density and thermal conductivity. The present study was undertaken to see to what degree the muzzle velocity gains of rhenium gun tubes (over steel tubes) could be achieved with tantalum gun tubes. Nine high performance shots were modeled with a new version of our CFD gun code for steel, rhenium and tantalum gun tubes. For all except the highest velocity shot, the results with Ta tubes were nearly identical with those for Re tubes. Even for the highest velocity shot, the muzzle velocity gain over a steel tube using Ta was 82% of the gain obtained using Re. Thus, the somewhat inferior thermal properties of Ta (when compared to those of Re) translate into only very slightly poorer overall muzzle velocity performance. When this fact is combined with the superior mechanical properties of Ta and the encouraging performance of Ta liners/coatings in military powder guns, tantalum is to be preferred over Re as a liner/coating material for two stage light gas guns to increase muzzle velocity and reduce bore erosion.

Launchers↗
DOE OSTI2021

Melting and Ejecta Produced by High Velocity Microparticle Impacts of Steel on Tin

At sufficiently high velocities, a microparticle impacting a metal substrate can cause ejection of material from the substrate and impact-induced melting, both of which can result in erosion. Here, we directly image the impact of individual hard steel microparticles on soft tin substrates, at controlled impact velocities in the range of ~100 to 1000 m/s. By using scanning electron and laser scanning confocal microscopy, we characterize the surface morphology, depth, and volume of each impact crater. We observe a gradual onset of impact-induced melting in the craters, as well as the production of increasing amounts of ejecta from the target metal. By comparing measurements of impact and rebound velocity to an elastic-plastic model, we observe that at a high enough impact velocity, melting and ejection begin to consume additional kinetic energy beyond that expected by plastic deformation of the target material alone. By calculating the excess energy dissipation using this elastic-plastic model, we show that although this divergent behavior is associated with the onset of melting, the majority of the ejected volume must be solid rather than liquid.

Mechanics↗
NASA NTRS1993

ASRM nozzle thermal analysis

This report describes results from the nozzle thermal analysis contract which has been performed to support NASA/Marshall Space Flight Center in the development of the Advanced Solid Rocket Motor (ASRM). The emphasis of this study has been directed to four potential problem areas of the nozzle. These areas are the submerged nozzle region containing the flex seal, the nozzle entrance region, the material interface region in the nozzle exit cone, and the aft region of the exit cone. This study was limited throughout by inadequate material response models, especially for the polyisoprene flex seal and the low density carbon phenolic used in the exit cone. Thermal response and particle erosion calculations were performed for each of the potential problem areas. Results from these studies showed excessive erosion (large negative safety margins) to occur in the flex seal and nozzle entrance regions. The exit cone was found to be marginally adequate (near zero safety margins) and the material interface region was found not to be a problem.

Strobel, Forrest↗
DOE OSTI2022

5.1.6 Demo #6: NanoStitch (NAWAStitch) Multifunctional Composites Trade Validation

The overall objective of the NanoStitch Multifunctional Composites Trade Validation Demonstration project was to determine the value proposition of adding NanoStitch to rapid-cure composite systems for structures used in the expanding sector of advanced air mobility (AAM) and specifically electric vertical take-off and landing (eVTOL) aircraft. The expected value proposition was stronger composite parts, with new multifunctional attributes, that are lower cost to fabricate and maintain. NanoStitch is a new composite innovation where a contiguous vertically aligned carbon nanotube (VACNT) forest is located between each ply of a laminate composite resulting in improved mechanical properties as well as other multifunctional properties such as enhanced thermal and electrical conductivity. NanoStitch was originally distributed by N12, later acquired by NAWA Technologies, now called NAWAStitch, and henceforth referred to in this document as NAWAStitch. Two significant evaluations were framed to help meet the overall objective. First, was Task 1 to evaluate the effects that adding NAWAStitch to a rapid cure material system would have on the mechanical and processing properties of the material. Second, was Task 2 to evaluate the workability of adding NAWAStitch to practical flight demonstration articles. From previous research, it was already known that the application of NAWAStitch to a composite structure can enhance the mechanical properties of that structure. However, this project will help the engineering community understand those benefits and the basic structural strength values to apply when incorporating NAWAStitch material into composite structure that utilizes a rapid-cure resin system, which is novel. Testing showed that by adding NAWAStitch to the prepreg, most material properties were improved because the VACNTs strengthened the resin to fiber interface, and the interface itself, between plies. For example compression strength improved by more than 20%, and erosion resistance by more than 50%. The UDRI team identified two flight demonstration articles through discussions with Aurora Flight Sciences (Aurora) and reviewing literature on air mobility and the eVTOL market. The demonstration articles were a thin skin honeycomb panel and a section from an eVTOL propeller blade. The manufacturing and testing trials of the demonstration articles were as follows: • NAWAStitch added no manufacturing complexity or detriment to the article physical qualities, while at the same time added multifunctional properties such as enhanced rain erosion and electrothermal de-icing besides enhanced mechanical properties • VACNTs did not increase or hurt the mechanical properties of the interface between honeycomb core materials and the thin skin face sheet • Demonstrated successful de-icing function in an eVTOL propeller meeting real-world specifications in uniformity and endurance • Multifunctional eVTOL propeller cost analysis showed a cost savings of at least 67 % for a single propeller blade with multifunctional de-icing capability and improved mechanical properties which equates to a potential savings of $10,116 per eVTOL aircraft with six three-bladed propellers Overall, the results of this project can provide additional tools for the composite industry to optimize energy efficiency through faster and stronger composite parts that are lower cost to fabricate and maintain. Additionally, the results of this effort can help US industry like NAWA America set the stage for rapid growth and establishment of a manufacturing facility in Ohio. The project has given NAWA America the basic understanding of how the addition of VACNTs to a composite structure can affect the mechanical properties and hence point them to potential commercial applications. The project has also provided Teijin Carbon US with another potential material application for their rapid cure materials that are manufactured at the Renegade facility in Miamisburg, OH.

36 MATERIALS SCIENCE↗
NASA NTRS1987

Effect of long-term exposure to Low Earth Orbit (LEO) space environment

Data obtained from components and materials from the Solar Maximum Mission satellite are presented and compared to data for similar materials obtained from the Advanced Composite Materials Exposure to Space Experiment (ACOMEX) flown on Shuttle mission STS-41G. In addition to evaluation of surface erosion and mass loss that may be of importance to very long-term missions, comparisons of solar absorptance and thermal emittance measurements for both long and short term exposures were made. Although the ratio of absorptance over emittance can be altered by proper choice of materials to ensure a proper operating environment for the spacecraft, once the thermal design is established, it is important that the material properties not change in order to maintain the operating environment for many payload and bus items such as electronics, batteries, fuel, etc. However, data presented show significant changes after short exposure in low Earth environment. Moreover, the measured changes are shown to differ according to the manner of exposure, i.e., normal or oblique, which also affects the resultant eroded surface morphology. These results identify constraints to be considered in development of flight experiments or laboratory testing.

Zimcik, D. G.↗
NASA NTRS1991

Wrinkle ridges in the floor material of Kasei Valles, Mars: Nature and origin

Wrinkle ridges on Mars occur almost exclusively in smooth plains material referred to as ridged plains. One of the largest contiguous units of ridged plains occurs on Lunae Planum on the eastern flank of the Tharsis rise. The eastern, western, and northern margins of the ridged plains of Lunae Planum suffered extensive erosion in early Amazonian channel-forming events. The most dramatic example of erosion in early Amazonian plains is in Kasei Valles. The nature an origin of the wrinkle ridges in the floor material of Kasei Valles are discussed.

Watters, Thomas R.↗
NASA NTRS1991

Preliminary performance and life evaluations of a 2-kW arcjet

The first results of a program to expand the operational envelope of low-power arcjets to higher specific impulse and power levels are presented. The performance of a kW-class laboratory model arcjet thruster was characterized at three mass flow rates of a 2:1 mixture of hydrogen and nitrogen at power levels ranging from 1.0 to 2.0 kW. This same thruster was then operated for a total of 300 h at a specific impulse and power level of 550 s and 2.0 kW, respectively, in three continuous 100-h sessions. Thruster operation during the three test segments was stable, and no measurable performance degradation was observed during the test series. Substantial cathode erosion was observed during an inspection following the second 100-h test segment. Most notable was the migration of material from the center of the cathode tip to a ring around a large crater. The anode sustained no significant damage during the endurance test segments. Some difficulty was encountered during start-up after disassembly and inspection following the second 100-h test segment, which caused constrictor erosion. This resulted in a reduced flow restriction and arc chamber pressure, which in turn caused a reduction in the arc impedance.

Morren, W. Earl↗
NASA NTRS1991

Preliminary performance and life evaluation of a 2-kW arcjet

The first results of a program to expand the operational envelope of low-power arcjets to higher specific impulse and power levels are presented. The performance of a kW-class laboratory model arcjet thruster was characterized at three mass flow rates of a 2:1 mixture of hydrogen and nitrogen at power levels ranging from 1.0 to 2.0 kW. This same thruster was then operated for a total of 300 h at a specific impulse and power level of 550 s and 2.0 kW, respectively, in three continuous 100-h sessions. Thruster operation during the three test segments was stable, and no measurable performance degradation was observed during the test series. Substantial cathode erosion was observed during an inspection following the second 100-h test segment. Most notable was the migration of material from the center of the cathode tip to a ring around a large crater. The anode sustained no significant damage during the endurance test segments. Some difficulty was encountered during start-up after disassembly and inspection following the second 100-h test segment, which caused constrictor erosion. This resulted in a reduced flow restriction and arc chanber pressure, which in turn caused a reduction in the arc impedance.

Morren, W. E.↗
DOE OSTI2023

Final Design of the Material Plasma Exposure eXperiment

The Material Plasma Exposure eXperiment (MPEX) has completed its design phase. MPEX will be a unique facility to investigate plasma material interactions (PMIs) under fusion prototypic divertor conditions in steady state. This includes plasma exposure conditions expected in a fusion reactor divertor. Materials to be investigated will include solids, liquids, and neutron pre-irradiated materials. Electron and ion heating will allow for a large operational domain ranging from erosion-dominated PMI conditions to deposition-dominated PMI conditions. An overview of the final design for all MPEX systems is given. Here, in particular, it is shown how mission-driven project requirements have led to detailed design choices with innovative solutions. Examples are the water-cooled helicon window, the electron cyclotron heating launcher, the target holder and manipulator, and the autonomous decouplers.

Fusion reactor↗
NASA NTRS2008

NASA Subsonic Rotary Wing Project - Structures and Materials Discipline

The Structures & Materials Discipline within the NASA Subsonic Rotary Wing Project is focused on developing rotorcraft technologies. The technologies being developed are within the task areas of: 5.1.1 Life Prediction Methods for Engine Structures & Components 5.1.2 Erosion Resistant Coatings for Improved Turbine Blade Life 5.2.1 Crashworthiness 5.2.2 Methods for Prediction of Fatigue Damage & Self Healing 5.3.1 Propulsion High Temperature Materials 5.3.2 Lightweight Structures and Noise Integration The presentation will discuss rotorcraft specific technical challenges and needs as well as details of the work being conducted in the six task areas.

Halbig, Michael C.↗