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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
DOE OSTI2022

Cross-correlation of Dark Energy Survey Year 3 lensing data with ACT and P l a n c k thermal Sunyaev-Zel’dovich effect observations. II. Modeling and constraints on halo pressure profiles

Hot, ionized gas leaves an imprint on the cosmic microwave background via the thermal Sunyaev-Zel’dovich (tSZ) effect. The cross-correlation of gravitational lensing (which traces the projected mass) with the tSZ effect (which traces the projected gas pressure) is a powerful probe of the thermal state of ionized baryons throughout the Universe and is sensitive to effects such as baryonic feedback. In a companion paper (Gatti et al. Phys. Rev. D 105, 123525 (2022)), we present tomographic measurements and validation tests of the cross-correlation between Galaxy shear measurements from the first three years of observations of the Dark Energy Survey and tSZ measurements from a combination of Atacama Cosmology Telescope and Planck observations. In this work, we use the same measurements to constrain models for the pressure profiles of halos across a wide range of halo mass and redshift. We find evidence for reduced pressure in low-mass halos, consistent with predictions for the effects of feedback from active Galactic nuclei. We infer the hydrostatic mass bias (B ≡ M 500c /M SZ from our measurements, finding B = 1.8 ± 0.1 when adopting the Planck-preferred cosmological parameters. We additionally find that our measurements are consistent with a nonzero redshift evolution of B, with the correct sign and sufficient magnitude to explain the mass bias necessary to reconcile cluster count measurements with the Planck-preferred cosmology. Our analysis introduces a model for the impact of intrinsic alignments (IAs) of galaxy shapes on the shear-tSZ correlation. We show that IA can have a significant impact on these correlations at current noise levels.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Androgynous { 10 1 ¯ 2 } twin in zinc

Under ambient conditions, Zn is a hexagonal metal with a large c / a ratio of 1.856. Plastic deformation is predominantly accommodated by basal 〈 a 〉 slip and compression twins on the { 10 1 ¯ 2 } planes. Increasing hydrostatic pressure drastically reduces the c / a ratio of Zn and, when a critical threshold of c / a = 3 at about 10 GPa is crossed, the { 10 1 ¯ 2 } twins are predicted to change from compressive to tensile in nature. What happens at the transition point, when c / a = 3 , remains unknown. Here, we strain-cycle a textured polycrystalline sample of pure Zn at uniform hydrostatic pressures ranging between 2 and 17 GPa, over which the c / a ratio crosses the c / a = 3 compressive-tensile transition for { 10 1 ¯ 2 } twins. During deformation, the state of the sample is monitored through x-ray diffraction to extract texture and internal strain evolution. By comparing the experimental results with the predictions of an elastoviscoplastic polycrystal simulation, we confirm the androgynous nature of { 10 1 ¯ 2 } twin response at low and high pressures. When c / a = 3 , polycrystalline Zn does not display any evidence of twinning and its plastic behavior is controlled by mostly basal and pyramidal 〈 c + a 〉 slip activity, with a very small contribution of prismatic 〈 a 〉 slip. Evidence for the activity of other { 10 1 ¯ n } twinning modes, which have been suggested for Zn under high pressure, are not observed. Published by the American Physical Society 2024

Merkel, Sébastien (ORCID:000000032767581X)↗
DOE OSTI2021

Additively Manufactured Compliant Hybrid Gas Thrust Bearing for Supercritical Carbon Dioxide Turbomachinery: Design and Proof of Concept Testing

The following paper presents a new type of gas lubricated thrust bearing that utilizes additive manufacturing or also known as direct metal laser melting (DMLM) to fabricate the bearing. The motivation for the new bearing concept is derived from the need for highly efficient supercritical carbon dioxide (sCO2) turbomachinery in the mega-watt power range. The paper provides a review of existing gas thrust-bearing technology, outlines the need for the new DMLM concept, and discusses proof-of-concept testing results. The new concept combines hydrostatic pressurization with individual tilting pads that are flexibly mounted using hermetic squeeze film dampers (HSFD) in the bearing-pad support. This paper describes the thrust-bearing concept and discusses the final design approach. Proof-of-concept testing in air for a 6.8 in. (173 mm) outer diameter thrust gas bearing was performed; with thrust loading, up to 1500 lbs (6.67 kN) and a thrust runner speed of 10krpm (91 m/s tip speed). The experiments were performed with a bent shaft resulting in thrust runner axial vibration magnitudes of 2.9 mils (74 μm) p-p and dynamic thrust loads of 270 lbs (1.2 kN) p-p. In addition, force deflection characteristics and stiffness coefficients of the bearing system are presented for an inlet hydrostatic pressure of 380 psi (2.62 MPa). Results at 10 krpm show that the pad support architecture was able to sustain high levels of dynamic misalignment equaling 6 times the nominal film clearance while demonstrating a unit load-carrying capacity of 55 psi (0.34 Mpa). Gas-film force deflection tests portrayed nonlinear behavior like a hardening spring, while the bearing pad support stiffness was measured to be linear and independent of gas film thickness.

Engineering↗
DOE OSTI2021

Evaluating the Conservation of Energy Variables in Simulations of Deep Moist Convection

Abstract It is often assumed in parcel theory calculations, numerical models, and cumulus parameterizations that moist static energy (MSE) is adiabatically conserved. However, the adiabatic conservation of MSE is only approximate because of the assumption of hydrostatic balance. Two alternative variables are evaluated here: MSE − IB and MSE + KE, wherein IB is the path integral of buoyancy ( B ) and KE is kinetic energy. Both of these variables relax the hydrostatic assumption and are more precisely conserved than MSE. This article quantifies the errors that result from assuming that the aforementioned variables are conserved in large-eddy simulations (LES) of both disorganized and organized deep convection. Results show that both MSE − IB and MSE + KE better predict quantities along trajectories than MSE alone. MSE − IB is better conserved in isolated deep convection, whereas MSE − IB and MSE + KE perform comparably in squall-line simulations. These results are explained by differences between the pressure perturbation behavior of squall lines and isolated convection. Errors in updraft B diagnoses are universally minimized when MSE − IB is assumed to be adiabatically conserved, but only when moisture dependencies of heat capacity and temperature dependency of latent heating are accounted for. When less accurate latent heat and heat capacity formulae were used, MSE − IB yielded poorer B predictions than MSE due to compensating errors. Our results suggest that various applications would benefit from using either MSE − IB or MSE + KE instead of MSE with properly formulated heat capacities and latent heats.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Improved Compaction Experiments and Modeling of Waste Isolation Pilot Plant Standard, Non-degraded, Waste Containers

A credible simulation of disposal room porosity at the Waste Isolation Pilot Plant (WIPP) requires a tenable compaction model for the 55-gallon waste containers within the room. A review of the legacy waste material model, however, revealed several out-of-date and untested assumptions that could affect the model’s compaction behavior. For example, the legacy model predicted non-physical tensile out-of-plane stresses under plane strain compression. (Plane strain compression is similar to waste compaction in the middle of a long drift.) Consequently, a suite of new compaction experiments were performed on containers filled with surrogate, non-degraded, waste. The new experiments involved uniaxial, triaxial, and hydrostatic compaction tests on quarter-scale and full-scale containers. Special effort was made to measure the volume strain during uniaxial and triaxial tests, so that the lateral strain could be inferred from the axial and volume strain. These experimental measurements were then used to calibrate a pressure dependent, viscoplastic, constitutive model for the homogenized compaction behavior of the waste containers. This new waste material model’s predictions agreed far better with the experimental measurements than the legacy model’s predictions, especially under triaxial and hydrostatic conditions. Under plane strain compression, the new model predicted reasonable compressive out-of-plane stresses, instead of tensile stresses. Moreover, the new model’s plane strain behavior was substantially weaker for the same strain, yet substantially stronger for the same porosity, than the legacy model’s behavior. Although room for improvement exists, the new model appears ready for prudent engineering use.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Sizing and Selection of Pressure Relief Valves for High-Pressure Thermal–Hydraulic Systems

This study covers the critical concerns related to the sizing, selection, installation, maintenance, and testing of pressure safety valves (PSVs). The aim is to ensure the safety of pressurized systems, hydrostatic transmission systems, and hydraulic plants, including process plants, thermal power plants, and nuclear reactor systems. PSVs are devices that ensure the safety and reliability of pressurized vessels, lines, and systems during overpressure events. The task of selecting which PSV features are of greatest value for a specific purpose is complex—especially in the design of a high-pressure experimental thermal–hydraulic facility for hydrostatic and transient testing of the reactor system—when the systems are in the design and development phases and require qualification and demonstration to prove that they have reached a given level of technological readiness. The present study highlights the required steps for users to follow the associated rules, guidelines, and recommendations. As a part of this research, case studies are presented to help readers better understand the applicable strategy and standards. A discussion and a review of PSV performance degradation and failure are summarized to provide a better understanding of varied process applications and conditions, including fluid flow dynamics, boundary-layer formation and pressure drops, gas bubble formation and collapse, geometric configurations, inlet/outlet piping, abrupt pressure fluctuations, and acoustic resonance. Moreover, this study discusses the servicing and testing of PSVs in a multiphase pressurized system. Overall, it provides a basic overview of how PSVs ensure the safety of pressurized systems, supported by case studies and industrial practices.

02 PETROLEUM↗
NASA NTRS1972

Composite overwrapped metallic tanks

Work is reported for fabricating and testing the fiberglass overwrapped titanium pressure vessel for cryogenic service. Difficulties encountered in the tank liner fabrication phase involved explosive forming, vacuum annealing, chemical milling and electron beam welding. While each of these processes and the nondestructive test methods employed are normally considered to be individually reliable, the combination of poor material together with fabrication and development reversals prevented the full achievement of the desired end results. Eight tanks plus a prototype and tool proofing article were produced. Six of the vessels failed during the hydrostatic sizing operation. One of the remaining tanks was hydrostatically pressurized to burst and the other was pressurized repeatedly at 75 F from 100 psi to the operating pressure until failure occurred. As a result, it is not possible to draw firm conclusions as to the true value of the design concept due to the problems encountered in the program.

Caudill, C. L.↗
NASA NTRS1972

Development of boron epoxy rocket motor chambers.

A 71 cm diameter 74 cm length boron/epoxy composite rocket motor chamber was designed based on the geometric configuration of the JPL Applications Technology Satellite titanium alloy apogee motor chamber. Because analyses showed large stress concentrations in the domes, the configuration was modified using the same basic constraints for openings and attachments. The rocket motor chamber was then fabricated by filament winding with boron/epoxy tape and hydrostatically tested to failure at 264 N/sq cm, 57.2 N/sq cm above the design value. Two more rocket motor chambers were fabricated with the same basic constraints, but shortened to 57.6 cm for a smaller propellant load. The first of these short chambers failed in proof because of filament winding fabrication difficulties. The second chamber was successfully fabricated and passed the hydrostatic proof test.

Jensen, W. M.↗
NASA NTRS1974

Intrathoracic and venous pressure relationships during responses to changes in body position

Simultaneous end-expiratory pressures, referred to midthoracic level, in the superior and abdominal venae cavae, pericardial space, and right and left heart, were recorded without thoracotomy in three anesthetized dogs during sudden changes from supine to vertical head-up or head-down body positions. Intrathoracic and dependent great vein pressures referred to midchest level (sixth thoracic vertebra) decreased and showed simple hydrostatic gradients in either vertical position. However, a discontinuity in the large vein hydrostatic gradient occurred just distal to the superior margin of the thorax in either body position and was resumed again above this level. It is concluded that, just as the cerebrospinal fluid and intraperitoneal pressures minimize the effects of gravitational and inertial forces on the cerebral and visceral circulations, the pericardial and pleural pressures have a similar role for the heart proper.

Avasthey, P.↗
NASA NTRS1975

Means and methods of physical conditioning of man in long space flights

Methods of prophylaxis for disorders caused predominantly by reduction or absence of hydrostatic blood pressure in weightlessness and in experimental stimulation of it (readjustment of the watersalt metabolism, relative dehydration, disruption of competence of the cardiovascular system with respect to orthostatic loads, etc.), are adequately substantiated. Two theoretically possible approaches to prophylaxis of this type of disorder are examined: The use of methods of simulation of the effect of hydrostatic blood pressure in flight and the decrease in the gravitational redistribution of blood to the lower part of the body in the postflight period. In particular, the method of negative pressure in the lower region of the body gave favorable results. A significant decrease in orthostatic disorders after completion of such experiments was achieved by use of g-suits or other types of special clothing.

Stepantsov, V. I.↗
NASA NTRS1974

Calculations of the early evolution of Jupiter

The evolution of the protoplanet Jupiter is followed, using a hydrodynamic computer code with radiative energy transport. Jupiter is assumed to have formed as a subcondensation in the primitive solar nebula at a density just high enough for gravitational collapse to occur. The initial state has a density of 0.0015 nanograms per cu cm and a temperature of 43 K; the calculations are carried to an equilibrium state where the central density reaches 0.5 g per cu cm and the central temperature reaches 25,000 K. During the early part of the evolution the object contracts in quasi-hydrostatic equilibrium; later on hydrodynamic collapse occurs, induced by the dissociation of hydrogen molecules. After dissociation is complete, the planet regains hydrostatic equilibrium with a radius of a few times the present value. Further evolution beyond this point is not treated here; however the results are consistent with the existence of a high-luminosity phase shortly after the planet settles into its final quasi-static contraction.-

Bodenheimer, P.↗
NASA NTRS1974

Depth of immersion as a determinant of the natriuresis of water immersion

The current study was undertaken to further assess the contribution of an immersion-induced hydrostatic pressure gradient on the redistribution of blood volume. The rate of sodium excretion by seated subjects was significantly increased by water immersion up to the chest and neck compared to waist immersion and controls. These results are consistent with the hypothesis that whereas immersion to the level of the diaphragm merely cancels the intravascular hydrostatic pressure gradient by providing an identical external gradient, immersion above the diaphragm level results in increased water pressure which tends to favor a shift in blood volume from the lower extremities.

Epstein, M.↗
NASA NTRS1976

Cardiorespiratory deconditioning with static and dynamic leg exercise during bed rest

Results are presented for an experimental study designed to compare the effects of heavy static and dynamic exercise training during 14 days of bed rest on the cardiorespiratory responses to submaximal and maximal exercise performed by seven healthy men aged 19-22 yr. The parameters measured were submaximal and maximal oxygen uptake, minute ventilation, heart rate, and plasma volume. The results indicate that exercise alone during bed rest reduces but does not eliminate the reduction in maximal oxygen uptake. An additional positive hydrostatic effect is therefore necessary to restore maximal oxygen uptake to ambulatory control levels. The greater protective effect of static exercise on maximal oxygen uptake is probably due to a greater hydrostatic component from the isometric muscular contraction. Neither the static nor the dynamic exercise training regimes are found to minimize the changes in all the variables studied, thereby suggesting a combination of static and dynamic exercises.

Stremel, R. W.↗
NASA NTRS1977

A review of the thermonuclear runaway model of a nova outburst

Kraft's (1963) model for a nova outburst caused by a thermonuclear runaway in the hydrogen-rich matter accreted onto the white dwarf in a binary system is reviewed. Hydrostatic and hydrodynamic studies of this phenomenon are summarized, analyses of shock ejection based on hydrodynamic computer codes are discussed, and one specific hydrodynamic code is outlined. Results obtained with this code are presented and evaluated for an initial model containing a white dwarf with a hydrogen-rich envelope of 0.0001 to 0.001 solar mass in hydrostatic and thermal equilibrium. It is shown that an implicit hydrodynamic computer code is required in order to study the thermonuclear-runaway phenomenon. The early evolution of three models with different intrinsic luminosities is illustrated, and enhancement of CNO nuclei at the bottom of the hydrogen-rich envelope is investigated. It is suggested that the concentration of C-13, N-15, and O-17 should be greatly enhanced in nova ejecta.

Sparks, W. M.↗
NASA NTRS1977

Radio and EUV observations of a coronal hole

Current ideas and modeling assumptions concerning the structure of the transition region and corona are summarized. Observations of a specific coronal hole are reported which were made with the EUV spectroheliometer aboard Skylab and with high-resolution radio telescopes in Australia and West Germany. Theoretical EUV line intensities and radio brightness temperatures are calculated, and an attempt is made to analyze the observations on the basis of standard one-dimensional plane-parallel hydrostatic-equilibrium models for the transition region and corona. It is found that any given standard model predicts either higher radio brightnesses or lower EUV line intensities than are observed. Several potential problem areas are examined in order to resolve this conflict. It is concluded that a model involving departures from hydrostatic equilibrium, varying conductive flux, mass outflow, as well as effects of thermal diffusion and nonequilibrium ionization should be investigated in more detail.

Dulk, G. A.↗
NASA NTRS1978

Internal friction Q factor measurements in lunar rocks

In order to better interpret recently reported values for the variation of seismic Q as a function of depth below the lunar surface, we have developed apparatus and made laboratory measurements of Q as a function of hydrostatic pressure, temperature and frequency. Our measurements of the Q associated with shear deformations have demonstrated that the large difference in Q between well outgassed and volatile rich rocks persists to pressures corresponding to a depth of at least 50 km. Here we report new measurements of Q as a function of temperature, on the development of techniques to measure the Q associated with extensional deformations under hydrostatic pressure, on the derivation of theoretical relations between our laboratory Q values and the attenuation coefficient of seismic waves, and on the development of a model for mechanism of adsorption.

Tittmann, B. R.↗
NASA NTRS1978

Possible flyby measurements of Galilean satellite interior structure

Flyby encounters of the Galilean satellites from a Jupiter orbiter spacecraft could yield information about the second-degree gravity harmonics of these satellites. The expected values of these harmonics have been calculated for a range of plausible interior models in hydrostatic equilibrium. Because the satellites respond to comparable perturbations from rotation and tides, an independent test of hydrostatic equilibrium is feasible. For Io and Ganymede, the expected measurement accuracy from a nominal encounter should make possible an excellent discrimination from the ensemble of interior models. For Europa, a qualitative distinction between near-uniform and centrally condensed models seems feasible. Only for Callisto is the proposed experiment of marginal value.

Hubbard, W. B.↗
NASA NTRS1978

Dynamics of the quiescent solar corona

An analytical model for the quiescent inhomogeneous solar corona is developed on the basis of the hypothesis that looplike structures are the basic coronal building blocks. By assuming that quiescent loop structures observed in X-rays are in hydrostatic equilibrium, it is demonstrated that such loops must have their temperature maximum located near their apex and that substantial nonradiative energy deposition must occur along most of their length. The calculations yield a unique relation among loop temperature, pressure, and size, which fits the X-ray observations of quiescent structures well and is consistent with the initial assumption of hydrostatic equilibrium. The results suggest that the coronal loops visible in X-rays represent a relatively steady-state equilibrium of the confined plasmas and that fluctuations in such quantities as the local heating rate can lead to dynamically unstable states in which the loop plasma does not attain a temperature sufficient for X-ray emission. A parameterization of various proposed coronal heating theories is also developed within the context of the analytical model.

Rosner, R.↗