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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 NTRS2014

Supplemental Information For: Asymmetric Distribution of Lunar Impact Basins Caused by Variations in Target Properties

Maps of crustal thickness derived from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission revealed more large impact basins on the nearside hemisphere of the Moon than on its farside. The enrichment in heat-producing elements and prolonged volcanic activity on the lunar nearside hemisphere indicate that the temperature of the nearside crust and uppermantle was hotter than that of the farside at the time of basin formation. Using the iSALE-2D hydrocode to model impact basin formation, we found that impacts on the hotter nearside would have formed basins up to two times larger than similar impacts on the cooler farside hemisphere. The size distribution of lunar impact basins is thus not representative of the earliest inner Solar system impact bombardment

Lunar↗
NASA NTRS2014

Chemical Zoning of Feldspars in Lunar Granitoids: Implications for the Origins of Lunar Silicic Magmas

Fine-scale chemical and textural measurements of alkali and plagioclase feldspars in the Apollo granitoids (ex. Fig. 1) can be used to address their petrologic origin(s). Recent findings suggest that these granitoids may hold clues of global importance, rather than of only local significance for small-scale fractionation. Observations of morphological features that resemble silicic domes on the unsampled portion of the Moon suggest that local, sizable net-works of high-silica melt (>65 wt % SiO2) were present during crust-formation. Remote sensing data from these regions suggest high concentrations of Si and heat-producing elements (K, U, and Th). To help under-stand the role of high-silica melts in the chemical differentiation of the Moon, three questions must be answered: (1) when were these magmas generated?, (2) what was the source material?, and (3) were these magmas produced from internal differentiation. or impact melting and crystallization? Here we focus on #3. It is difficult to produce high-silica melts solely by fractional crystallization. Partial melting of preexisting crust may therefore also have been important and pos-sibly the primary mechanism that produced the silicic magmas on the Moon. Experimental studies demonstrate that partial melting of gabbroic rock under mildly hydrated conditions can produce high-silica compositions and it has been suggested by that partial melting by basaltic underplating is the mechanism by which high-silica melts were produced on the Moon. TEM and SIMS analyses, coordinated with isotopic dating and tracer studies, can help test whether the minerals in the Apollo granitoids formed in a plutonic setting or were the result of impact-induced partial melting. We analyzed granitoid clasts from 3 Apollo samples: polymict breccia 12013,141, crystalline-matrix breccia 14303,353, and breccia 15405,78

Mills, R. D↗
NASA NTRS2015

Microstructural and Compositional Relations of Granitoid Clasts in Lunar Breccias at the Micrometer to Sub-Micrometer Scale

Lunar granitoid lithologies have long been of interest for the information they provide on processes leading to silicic melt compositions on the Moon. The extraction of such melts over time affects the distribution and budget of incompatible materials (i.e., radiogenic heat producing elements and volatiles) of the lunar interior. We have recently shown that in addition to their high concentrations of incompatible lithophile elements, some granitoid clasts in lunar breccias have significant indigenous water contents in their alkali feldspars. This raises the importance of lunar granitoid materials in the expanding search for mineralogic/petrologic hosts of indigenous lunar water-related species. We are undertaking a detailed survey of the petrologic/mineralogical relations of granitoid clasts in lunar breccias to achieve a better understanding of the potential of these diverse assemblages as hosts for volatiles, and as candidates for additional isotope chronology studies. Our preliminary results reported here based on high-resolution field-emission SEM, EPMA and TEM studies uncover immense complexity in these materials at the micrometer to sub-micrometer scale that heretofore have not been fully documented.

Christoffersen, R.↗
NASA NTRS2019

Lunar Seismometer and Burial System

Beginning in 1969, Apollo successfully deployed a long-lived network of seismometers on the Moon. Seismic studies provide definitive knowledge of internal planetary structure, and analysis of the Apollo seismic data has contributed to the magma ocean hypothesis for initial terrestrial planetary differentiation [Wieczoreket al., 2006]. While the general model is widely accepted, details such as mantle composition, stratification and possible overturn, lateral structure, and thermal inhomogeneities remain unresolved. The Moon experiences moonquakes at varying depths [Nakamura, 1983]. Shallow quakes are relatively large but rare, similar to terrestrial intra-plate earthquakes. Deeper quakes are comparatively smaller but more frequent, occurring periodically according to the tidal cycle. On the Moon, the lack of an atmosphere enables seismic experiments to potentially constrain meteorite impact flux, which informs cratering rates assumed throughout the solar system. The large diurnal temperature variation between day and night also induces thermal moonquakes, which may contribute to regolith production [Duennebier& Sutton, 1974; Weber et al., 2017]. Still, many questions remain regarding the frequency and distribution of natural moonquakes. This translates into an incomplete understanding of the Moon’s hemispherical dichotomies in crustal thickness, mare volcanism, seismicity, and the distribution of heat-producing elements. The Planetary Decadal Survey (National Research Council, 2013) identifies a New Frontiers Lunar Geophysical Network (LGN) mission to answer such questions.

Bailey, S. H.↗
NASA NTRS2018

Europa Clipper Thermal Control Design

This paper details the design developments of the Europa Clipper spacecraft thermal control system and its primary element the Heat Redistribution System (HRS). The Europa Clipper spacecraft will launch in the early 2020s and will have multiple flybys of Jupiter’s icy moon, Europa. The HRS, which utilizes a Mechanically Pumped Fluid Loop (MPFL) to reclaim waste heat from an avionics vault module and redistribute it to the propulsion module and radiator, has become an integral part of the spacecraft architecture both in terms of mechanical configuration and spacecraft operations capability. A walkthrough on the planned implementation of the HRS on the primary spacecraft modules is provided along with a description on thermal control of spacecraft hardware not located on the HRS vault, where thermal isolation and tolerance to extreme thermal environment drives the hardware designs.

Bhandari, Pradeep↗
NASA NTRS1982

Integrated finite element thermal-structural analysis with radiation heat transfer

An integrated approach for efficiently coupling thermal and stress analyses of structures with radiation heat transfer is presented. A new integrated one dimensional element based on a nodeless variable formulation is introduced. Lumped and consistent formulations of the nonlinear radiation heat transfer matrix are presented. The accuracy of the integrated approach is assessed by comparisons with analytical solutions and conventional finite element thermal-structural analyses. Results show that the nodeless variable thermal element yields accuracy equivalent to a higher order element but permits a common discretization with a lower order congruent structural element. The integrated element thus provides improved accuracy and efficiency of thermal stress analysis for structures with complex temperature distributions.

Thornton, E. A.↗
NASA NTRS1995

A probabilistic model of a porous heat exchanger

This paper presents a probabilistic one-dimensional finite element model for heat transfer processes in porous heat exchangers. The Galerkin approach is used to develop the finite element matrices. Some of the submatrices are asymmetric due to the presence of the flow term. The Neumann expansion is used to write the temperature distribution as a series of random variables, and the expectation operator is applied to obtain the mean and deviation statistics. To demonstrate the feasibility of the formulation, a one-dimensional model of heat transfer phenomenon in superfluid flow through a porous media is considered. Results of this formulation agree well with the Monte-Carlo simulations and the analytical solutions. Although the numerical experiments are confined to parametric random variables, a formulation is presented to account for the random spatial variations.

Agrawal, O. P.↗
NASA NTRS1964

Removable preheater elements improve oxide induction furnace

Heat and corrosion resistant preheater elements are used in oxide induction furnaces to raise the temperature to the level for conducting electricity. These preheater elements are then removed and the induction coil energized.

Leipold, M. H.↗
NASA NTRS1993

A p-version finite element method for steady incompressible fluid flow and convective heat transfer

A new p-version finite element formulation for steady, incompressible fluid flow and convective heat transfer problems is presented. The steady-state residual equations are obtained by considering a limiting case of the least-squares formulation for the transient problem. The method circumvents the Babuska-Brezzi condition, permitting the use of equal-order interpolation for velocity and pressure, without requiring the use of arbitrary parameters. Numerical results are presented to demonstrate the accuracy and generality of the method.

Winterscheidt, Daniel L.↗
NASA NTRS2002

Structural Assembly Device

A structural assembly device and method for securing together a pair of surfaces of two fusible materials wherein an electrically conductive thermal element is located between the surfaces which will melt, without substantially degrading, when heated. When the thermal element is heated, it is elevated to a temperature sufficient to melt the first and second elements and then is allowed to cool such that the first and second elements are joined to the thermal element and may be joined to each other as well.

Melvin A Bryant, III↗
NASA NTRS2012

Thermally conductive porous element-based recuperators

A heat exchanger includes at least one hot fluid flow channel comprising a first plurality of open cell porous elements having first gaps there between for flowing a hot fluid in a flow direction and at least one cold fluid flow channel comprising a second plurality of open cell porous elements having second gaps therebetween for flowing a cold fluid in a countercurrent flow direction relative to the flow direction. The thermal conductivity of the porous elements is at least 10 W/mK. A separation member is interposed between the hot and cold flow channels for isolating flow paths associated these flow channels. The first and second plurality of porous elements at least partially overlap one another to form a plurality of heat transfer pairs which transfer heat from respective ones of the first porous elements to respective ones of the second porous elements through the separation member.

Du, Jian Hua↗
NASA NTRS1974

Calculations of the moon's heat history at different concentrations of radioactive elements taking account of the material differentiation with melting

A mathematical procedure for analyzing the heat conductivity of the lunar surface is discussed. The solution is based on homogeneous and laminated moon models and considers the effects of radioactive elements conveyed to the lunar surface by melting. The various parameters which introduce uncertainties into the numerical analysis are identified. The application of data obtained from radio astronomy and from analyses of lunar samples returned by the Apollo flights is explained. Tables of data are included to show the types and amounts of radioactive materials which have been identified.

Arnatskaya, O. I.↗
NASA NTRS1991

Evaluation of a transfinite element numerical solution method for nonlinear heat transfer problems

Laplace transform techniques have been widely used to solve linear, transient field problems. A transform-based algorithm enables calculation of the response at selected times of interest without the need for stepping in time as required by conventional time integration schemes. The elimination of time stepping can substantially reduce computer time when transform techniques are implemented in a numerical finite element program. The coupling of transform techniques with spatial discretization techniques such as the finite element method has resulted in what are known as transfinite element methods. Recently attempts have been made to extend the transfinite element method to solve nonlinear, transient field problems. This paper examines the theoretical basis and numerical implementation of one such algorithm, applied to nonlinear heat transfer problems. The problem is linearized and solved by requiring a numerical iteration at selected times of interest. While shown to be acceptable for weakly nonlinear problems, this algorithm is ineffective as a general nonlinear solution method.

Cerro, J. A.↗
NASA NTRS2010

Self-Validating Thermocouple

Self-Validating Thermocouple (SVT) Systems capable of detecting sensor probe open circuits, short circuits, and unnoticeable faults such as a probe debonding and probe degradation are useful in the measurement of temperatures. SVT Systems provide such capabilities by incorporating a heating or excitation element into the measuring junction of the thermocouple. By heating the measuring junction and observing the decay time for the detected DC voltage signal, it is possible to indicate whether the thermocouple is bonded or debonded. A change in the thermal transfer function of the thermocouple system causes a change in the rise and decay times of the thermocouple output. Incorporation of the excitation element does not interfere with normal thermocouple operation, thus further allowing traditional validation procedures as well.

Perotti, Jose M.↗
NASA NTRS1986

Coupled flow, thermal and structural analysis of aerodynamically heated panels

A finite element approach to coupling flow, thermal and structural analyses of aerodynamically heated panels is presented. The Navier-Stokes equations for laminar compressible flow are solved together with the energy equation and quasi-static structural equations of the panel. Interactions between the flow, panel heat transfer and deformations are studied for thin stainless steel panels aerodynamically heated by Mach 6.6 flow.

Thornton, Earl A.↗
NASA NTRS1987

Coupled flow, thermal and structural analysis of aerodynamically heated panels

A finite element approach for coupling flow, thermal and structural analyses of aerodynamically heated panels is presented. The Navier-Stokes equations for laminar compressible flow are solved together with the energy equation and quasi-static structural equations of the panel. Interactions between the flow, panel heat transfer and deformations are studied for thin stainless steel panels aerodynamically heated by Mach 6.6 flow.

Thornton, Earl A.↗
NASA NTRS1989

Coupled fluid-thermal-structural analysis for aerodynamically heated structures

A finite element approach for integrated fluid-thermal-structural analysis of aerodynamically heated structures is described. The approach is used to solve: (1) the Navier-Stokes equations for the aerodynamic flow, (2) the energy equation of the structure for the temperature response, and (3) the quasi-static equilibrium equations of the structure for the structural response. Coupling between the three disciplines is demonstrated using two applications: Mach 7 flow over a panel and Mach 8 shock-shock interference on a cylinder.

Dechaumphai, Pramote↗
NASA NTRS2006

Accuracy Quantification of the Loci-CHEM Code for Chamber Wall Heat Fluxes in a G02/GH2 Single Element Injector Model Problem

A robust rocket engine combustor design and development process must include tools which can accurately predict the multi-dimensional thermal environments imposed on solid surfaces by the hot combustion products. Currently, empirical methods used in the design process are typically one dimensional and do not adequately account for the heat flux rise rate in the near-injector region of the chamber. Computational Fluid Dynamics holds promise to meet the design tool requirement, but requires accuracy quantification, or validation, before it can be confidently applied in the design process. This effort presents the beginning of such a validation process for the Loci- CHEM CPD code. The model problem examined here is a gaseous oxygen (GO2)/gaseous hydrogen (GH2) shear coaxial single element injector operating at a chamber pressure of 5.42 MPa. The GO2/GH2 propellant combination in this geometry represents one the simplest rocket model problems and is thus foundational to subsequent validation efforts for more complex injectors. Multiple steady state solutions have been produced with Loci-CHEM employing different hybrid grids and two-equation turbulence models. Iterative convergence for each solution is demonstrated via mass conservation, flow variable monitoring at discrete flow field locations as a function of solution iteration and overall residual performance. A baseline hybrid grid was used and then locally refined to demonstrate grid convergence. Solutions were also obtained with three variations of the k-omega turbulence model.

West, Jeff↗