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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 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Thermal stress analysis of ceramic gas-path seal components for aircraft turbines

Stress and temperature distributions were evaluated numerically for a blade-tip seal system proposed for gas turbine applications. The seal consists of an abradable ceramic layer on metallic backing with intermediate layers between the ceramic layer and metal substrate. The most severe stresses in the seal, as far as failure is concerned, are tensile stresses at the top of the ceramic layer and shear and normal stresses at the layer interfaces. All these stresses reach their maximum values during the deceleration phase of a test engine cycle. A parametric study was carried out to evaluate the influence of various design parameters on these critical stress values. The influences of material properties and geometric parameters of the ceramic, intermediate, and backing layers were investigated. After the parametric study was completed, a seal system was designed which incorporated materials with beneficial elastic and thermal properties in each layer of the seal. An analysis of the proposed seal design shows an appreciable decrease in the magnitude of the maximum critical stresses over those obtained with earlier configurations.

Kennedy, F. E.↗
NASA NTRS1988

Application of integrated fluid-thermal-structural analysis methods

Hypersonic vehicles operate in a hostile aerothermal environment which has a significant impact on their aerothermostructural performance. Significant coupling occurs between the aerodynamic flow field, structural heat transfer, and structural response creating a multidisciplinary interaction. Interfacing state-of-the-art disciplinary analysis methods is not efficient, hence interdisciplinary analysis methods integrated into a single aerothermostructural analyzer are needed. The NASA Langley Research Center is developing such methods in an analyzer called LIFTS (Langley Integrated Fluid-Thermal-Structural) analyzer. The evolution and status of LIFTS is reviewed and illustrated through applications.

Wieting, Allan R.↗
NASA NTRS1988

Application of integrated fluid-thermal structural analysis methods

Hypersonic vehicles operate in a hostile aerothermal environment which has a significant impact on their aerothermostructural performance. Significant coupling occurs between the aerodynamic flow field, structural heat transfer, and structural response creating a multidisciplinary interaction. Interfacing state-of-the-art disciplinary analysis methods are not efficient, hence interdisciplinary analysis methods integrated into a single aerothermostructural analyzer are needed. The NASA Langley Research Center is developing such methods in an analyzer called LIFTS (Langley Integrated Fluid-Thermal-Structural) analyzer. The evolution and status of LIFTS is reviewed and illustrated through applications.

Wieting, Allan R.↗
NASA NTRS1994

Thermal Stability Analysis for a Heliocentric Gravitational Radiation Detection Mission

The Laser Interferometer Space Antenna (LISA) mission is designed for detailed studies of low-frequency gravitational radiation. The mission is currently a candidate for ESA's post-Horizon 2000 program. Thermal noise affects the measurement in at least two ways. Thermal variation of the length of the optical cavity to which the lasers are stabilized introduces phase variations in the interferometer signal, which have to be corrected for by using data from the two arms separately.

Laser Interferometer Space Antenna LISA gravitatio↗
NASA NTRS1995

The Sixth Annual Thermal and Fluids Analysis Workshop

The Sixth Annual Thermal and Fluids Analysis Workshop consisted of classes, vendor demonstrations, and paper sessions. The classes and vendor demonstrations provided participants with the information on widely used tools for thermal and fluids analysis. The paper sessions provided a forum for the exchange of information and ideas among thermal and fluids analysis. Paper topics included advances an uses of established thermal and fluids computer codes (such as SINDA and TRASYS) as well as unique modeling techniques and applications.

Source record↗
NASA NTRS1985

Thermal storage analysis for large manned space platforms

High electrical power and waste heat rejection is projected for future manned low earth orbit space platforms, such as Space Station. The high heat rejection, optical coating degradation, long operating life with minimum maintenance requirements pose a challenging thermal management design problem. System optimization, with respect to radiator area and weight, indicate the requirement for thermal storage. This paper examines the thermal storage benefits, determines the characteristics as applied to different TMS concepts (e.g., centralized, decentralized), and examines the similarities and differences of thermal storage integration with single-phase and two-phase systems for a study baseline 75 kWe low earth orbit platform.

Lehtinen, A. M.↗
NASA NTRS2013

Insights into the Sulfur Mineralogy of Martian Soil at Rocknest, Gale Crater, Enabled by Evolved Gas Analyses

The first solid samples analysed by the Chemistry and Mineralogy (CheMin) instrument and Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) consisted of < 150 m fines sieved from aeolian bedform material at a site named Rocknest. All four samples of this material analyzed by SAM s evolved gas analysis mass spectrometry (EGA-MS) released H2O, CO2, O2, and SO2 (Fig. 1), as well as H2S and possibly NO. This is the first time evolved SO2 (and evolved H2S) has been detected from thermal analysis of martian materials. The identity of these evolved gases and temperature (T) of evolution can support mineral detection by CheMin and place constraints on trace volatile-bearing phases present below the CheMin detection limit or difficult to characterize with XRD (e.g., X-ray amorphous phases). Constraints on phases responsible for evolved CO2 and O2 are detailed elsewhere [1,2,3]. Here, we focus on potential constraints on phases that evolved SO2, H2S, and H2O during thermal analysis.

McAdam, A.↗
NASA NTRS1997

A Thermal and Electrical Analysis of Power Semiconductor Devices

The state-of-art power semiconductor devices require a thorough understanding of the thermal behavior for these devices. Traditional thermal analysis have (1) failed to account for the thermo-electrical interaction which is significant for power semiconductor devices operating at high temperature, and (2) failed to account for the thermal interactions among all the levels involved in, from the entire device to the gate micro-structure. Furthermore there is a lack of quantitative studies of the thermal breakdown phenomenon which is one of the major failure mechanisms for power electronics. This research work is directed towards addressing. Using a coupled thermal and electrical simulation, in which the drift-diffusion equations for the semiconductor and the energy equation for temperature are solved simultaneously, the thermo-electrical interactions at the micron scale of various junction structures are thoroughly investigated. The optimization of gate structure designs and doping designs is then addressed. An iterative numerical procedure which incorporates the thermal analysis at the device, chip and junction levels of the power device is proposed for the first time and utilized in a BJT power semiconductor device. In this procedure, interactions of different levels are fully considered. The thermal stability issue is studied both analytically and numerically in this research work in order to understand the mechanism for thermal breakdown.

Vafai, Kambiz↗
NASA NTRS2003

Direct profiling of environmental microbial populations by thermal dissociation analysis of native rRNAs hybridized to oligonucleotide microarrays

Oligonucleotide microarrays were used to profile directly extracted rRNA from environmental microbial populations without PCR amplification. In our initial inspection of two distinct estuarine study sites, the hybridization patterns were reproducible and varied between estuarine sediments of differing salinities. The determination of a thermal dissociation curve (i.e., melting profile) for each probe-target duplex provided information on hybridization specificity, which is essential for confirming adequate discrimination between target and nontarget sequences.

Non-NASA Center↗
DOE OSTI2025

Multiscale Thermal-hydraulic analysis of the MARVEL microreactor using a coupled SAM and SCM simulation. (PPTX)

This is .pptx document presenting a summary of the paper of the same name that has been submitted and accepted to NURETH-21: MARVEL is a natural-convection-cooled sodium-potassium microreactor that is anticipated to generate 85 kilowatts of thermal energy. It will operate within Idaho National Laboratory Transient Reactor Test Facility and is being developed by the DOE Microreactor Program. MARVEL will be used to test microreactor applications, evaluate systems for remote monitoring, and develop autonomous control technologies. A thermal-hydraulic computational model of this facility is a valuable tool to study important transients and calculate the safety limits of the micro-reactor design. For this purpose, the authors have chosen to use a multiscale coupled simulation: SCM for modeling the reactor core and SAM for the reactor's primary cooling system. SCM is MOOSE physics module for subchannel analysis, which was designed to model single-phase flows through liquid-metal cooled, wire-wrapped fuel pin sub-assemblies, ordered in a triangular lattice. The SCM code was modified to be able to model MARVEL?s unique geometry. SAM is a systems analysis module based on the MOOSE framework. It aims to provide fast-running, whole-plant transient analyses capability with improved-fidelity for various advanced reactor types. The coupling between the two SCM and SAM for MARVEL modeling is done implementing a domain over-lapping approach. The resulting coupled simulation can model transients such as reactor startup/shutdown and provide an intermediate fidelity picture of the temperature field and other variables, in the core. Results for the steady-state simulations are presented in the article as well as flow blockage transient.

21 - SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLAN↗
NASA NTRS1992

Phase diagram and electrical behavior of silicon-rich iridium silicide compounds

The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis, metalography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only four distinct compositions: IrSi, Ir3Si4, Ir3Si5 and IrSi sub about 3. The existence of Ir4Si5 could not be confirmed in this study, even though the crystal structure has been previously reported. Differential thermal analysis (DTA) in conjunction with X-ray powder diffraction confirm polymorphism in IrSi sub about 3, determined to have orthorhombic and monoclinic unit cells in the high and low temperature forms. A eutectic composition alloy of 83 +/- 1 atomic percent silicon was observed between IrSi sub about 3 and silicon. Ir3Si4 exhibits distinct metallic behavior while Ir3Si5 is semiconducting. Both and IrSi and IrSi sub about 3 exhibit nearly temperature independent electrical resistivities on the order of 5-10 x 10 exp -6 ohms-m.

Allevato, C. E.↗
NASA NTRS2002

Twelfth Thermal and Fluids Analysis Workshop

The Twelfth Thermal and Fluids Analysis Workshop (TFAWS 01) was held at the Bevill Center, The University of Alabama in Huntsville, Huntsville, Alabama, September 10-14, 2001. The theme for the hands-on training workshop and conference was "Engineering Excellence and Advances in the New Millenium." Forty-five technical papers were presented in four sessions: (1) Thermal Spacecraft/Payloads, (2) Thermal Propulsion/Vehicles, (3) Interdisciplinary Papers, and (4) Fluids Papers. Thirty-nine papers were published in these proceedings. The remaining six papers were not available in electronic format at the time of publication. In addition to the technical papers, there were (a) nine hands-on classes on thermal and flow analyses software, (b) thirteen short courses and product overview lectures, (c) five keynote lectures and, (d) panel discussions consisting of eight presentations. The workshop resulted in participation of 195 persons representing NASA Centers, Government agencies, aerospace industries, academia, software providers, and private corporations.

Majumdar, Alok↗
NASA NTRS2001

The Tenth Thermal and Fluids Analysis Workshop

The Tenth Thermal arid Fluids Analysis Workshop (TFAWS 99) was held at the Bevill Center, University of Alabama in Huntsville, Huntsville, Alabama, September 13-17, 1999. The theme for the hands-on training workshop and conference was "Tools and Techniques Contributing to Engineering Excellence". Forty-seven technical papers were presented in four sessions. The sessions were: (1) Thermal Spacecraft/Payloads, (2) Thermal Propulsion/Vehicles, (3) Interdisciplinary Paper, and (4) Fluids Paper. Forty papers were published in these proceedings. The remaining seven papers were not available in electronic format at the time of publication. In addition to the technical papers, there were (a) nine hands-on classes on thermal and flow analyses software, (b) twelve short courses, (c) thirteen product overview lectures, and (d) three keynote lectures. The workshop resulted in participation of 171 persons representing NASA Centers, Government agencies, aerospace industries, academia, software providers, and private corporations.

Majumdar, Alok↗
DOE OSTI2025

Toward integrating high-fidelity CFD approaches in the thermal-hydraulic analysis of turbulent dry cask systems

Nuclear power plants have been supplying resilient and reliable electricity for decades, contributing to energy independence of the U.S.. However, nuclear waste management remains one of the most significant challenges in the industry. The safety of dry cask storage systems relies heavily on their thermal-hydraulic performance. Computational Fluid Dynamics (CFD) simulations are often used to demonstrate this performance and ensure that the system design meets safety standards. This study presents reduced numerical models for various types of dry cask systems. These numerical models can produce efficient and fast results based on the employed modeling strategies. Additionally, the study uses a novel approach to high-fidelity simulations to evaluate modeling assumptions in dry cask modeling. Large Eddy Simulations (LES) are used for this purpose, particularly in regions where fluid velocity is relatively high and the turbulence characteristics become important. Furthermore, the results of these high-fidelity simulations will enhance the interpretation of outcomes produced from a lower-fidelity CFD model.

CFD↗
DOE OSTI2020

Thermal Design Analysis Supporting a Loss-of-Coolant-Accident Experiment at TREAT

The LOCA-SERTTA experiment vehicle along with the power and flexibility of TREAT allow for the ability to create the temperature profile evolution throughout a LOCA that would be seen in a commercial LWR. Presented in this summary are thermal-hydraulic modeling results for LOCA-SERTTA which are then compared to LOCA simulation results from a commercial LWR.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
NASA NTRS1978

A simple element for multilayer beams in NASTRAN thermal stress analysis

In the application of NASTRAN, structural members are usually represented by bar elements with multipoint constraint cards to enforce the interface conditions. While this is a very powerful method in principle, it was found that in practice the process for specification of constraints became tedious and error prone, unless the geometry was simple and the number of grid points low. An alternative approach was found within the framework of the NASTRAN program. This approach made use of the idea that a thermal distortion in a multilayer beam may be similar to a homogeneous beam with a thermal gradient across the cross section. The exact mathematical derivation for the equivalent beam, and all the necessary formulae for the equivalent parameters in NASTRAN analysis are presented. Some numerical examples illustrate the simplicity and ease of this approach for finite element analysis.

Chen, W. T.↗
DOE OSTI2022

Fundamental Effects of Al and Ta on Microstructure and Phase Transformations in the Al–Cr–Mo–Ta–Ti Refractory Complex Concentrated Alloy System

The effect of aluminum and tantalum concentrations on a refractory metal complex concentrated alloy is reported, particularly with respect to their effect on microstructure and phase composition of the alloy in cast and annealed form. Alloys with an equiatomic composition, (AlCrMoTaTi), an aluminum-lean composition (Al 0.75 CrMoTaTi), and a tantalum-lean composition (AlCrMoTa 0.75 Ti) are produced via arc melting. The alloys exhibit multiphase structures, confirmed by X-ray diffraction, microstructural characterization, and thermal analysis. The minor off-equiatomic adjustments of aluminum and tantalum in this alloy system did not drastically alter the prevalence of the Cr–Ta-based Laves phase. Correlations between thermodynamic predictions and observed phase transformations via thermal analysis are improved upon refinement of calculations removing impractical intermediate phases. As a result, experimental findings provide information for the refinement of thermodynamic modeling and deliver additional insight into the optimization of alloy compositions within this five-component system.

36 MATERIALS SCIENCE↗
NASA NTRS1980

A simulation model of temperature transitory on rocks having different thermal inertia. Analysis of the theoretical capacity of rock discrimination by remote sensing data

The possibility of identifying ground surface material by measuring the surface temperature at two different and significant times of the day was investigated for the case of hypothetical island whose rocky surface contained no vegetation and consisted of dolomite, clay, and granite. The thermal dynamics of the soil surface during a day in which atmospheric conditions were average for a latitude of about 40 deg to 50 deg were numerically simulated. The line of separation between zones of different materials was delineated by the range of temperature variation. Results show that the difference between maximum and minimum value of the temperature of ground surface during the day is linked to the thermal inertia value of the material of which the rock is formed.

Cassinis, R.↗