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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Dynamic gas temperature measurement system. Volume 2: Operation and program manual

The hot section technology (HOST) dynamic gas temperature measurement system computer program acquires data from two type B thermocouples of different diameters. The analysis method determines the in situ value of an aerodynamic parameter T, containing the heat transfer coefficient from the transfer function of the two thermocouples. This aerodynamic parameter is used to compute a fequency response spectrum and compensate the dynamic portion of the signal of the smaller thermocouple. The calculations for the aerodynamic parameter and the data compensation technique are discussed. Compensated data are presented in either the time or frequency domain, time domain data as dynamic temperature vs time, or frequency domain data.

Purpura, P. T.↗
NASA NTRS1974

Method of calculating gas dynamics and heat transfer in single stage refrigeration units

A generalized mathematical model of gas-dynamic and heat transfer processes in single-stage regenerative installations operating in Stirling, MacMahon, Gifford-MacMahon, and pulsating tube cycles is proposed. A numerical method os solving initial equations on a digital computer is given. This makes it possible to calculate the change in the thermodynamic parameters in the working cycle in different machine components, as well as the dependence of cold productivity on the temperature level in the steady regime.

Zhitomirskiy, I. S.↗
NASA NTRS1977

Closed-cycle gas dynamic laser design investigation

A conceptual design study was made of a closed cycle gas-dynamic laser to provide definition of the major components in the laser loop. The system potential application is for long range power transmission by way of high power laser beams to provide satellite propulsion energy for orbit changing or station keeping. A parametric cycle optimization was conducted to establish the thermodynamic requirements for the system components. A conceptual design was conducted of the closed cycle system and the individual components to define physical characteristics and establish the system size and weight. Technology confirmation experimental demonstration programs were outlined to develop, evaluate, and demonstrate the technology base needed for this closed cycle GDL system.

Ketch, G. W.↗
NASA NTRS1978

A well posed boundary value problem in transonic gas dynamics

A boundary value problem for the Tricomi equation was studied in connection with transonic gas dynamics. The transformed equation delta u plus 1/3Y u sub Y equals 0 in canonical coordinates was considered in the complex domain of two independent complex variables. A boundary value problem was then set by prescribing the real part of the solution on the boundary of the real unit circle. The Dirichlet problem in the upper unit semicircle with vanishing values of the solution at Y = 0 was solved explicitly in terms of the hypergeometric function for the more general Euler-Poisson-Darboux equation. An explicit representation of the solution was also given for a mixed Dirichlet and Neumann problem for the same equation and domain.

Sanz, J. M.↗
NASA NTRS1993

Dynamic gas temperature measurements using a personal computer for data acquisition and reduction

This report describes a dynamic gas temperature measurement system. It has frequency response to 1000 Hz, and can be used to measure temperatures in hot, high pressure, high velocity flows. A personal computer is used for collecting and processing data, which results in a much shorter wait for results than previously. The data collection process and the user interface are described in detail. The changes made in transporting the software from a mainframe to a personal computer are described in appendices, as is the overall theory of operation.

Fralick, Gustave C.↗
NASA NTRS2021

Streaming Instability with Multiple Dust Species – II. Turbulence and Dust–Gas Dynamics at Non-Linear Saturation

The streaming instability is a fundamental process that can drive dust–gas dynamics and ultimately planetesimal formation inprotoplanetary discs. As a linear instability, it has been shown that its growth with a distribution of dust sizes can be classifiedinto two distinct regimes, fast- and slow-growth, depending on the dust-size distribution and the total dust-to-gas density ratio. Using numerical simulations of an unstratified disc, we bring three cases in different regimes into non-linear saturation. Wefind that the saturation states of the two fast-growth cases are similar to its single-species counterparts. The one with maximumdimensionless stopping timeτs,max=0.1 and=2 drives turbulent vertical dust–gas vortices, while the other withτs,max=2and=0.2 leads to radial traffic jams and filamentary structures of dust particles. The dust density distribution for the former isflat in low densities, while the one for the latter has a low-end cut-off. By contrast, the one slow-growth case results in a virtuallyquiescent state. Moreover, we find that in the fast-growth regime, significant dust segregation by size occurs, with large particlesmoving towards dense regions while small particles remain in the diffuse regions, and the mean radial drift of each dust speciesis appreciably altered from the (initial) drag-force equilibrium. The former effect may skew the spectral index derived frommultiwavelength observations and change the initial size distribution of a pebble cloud for planetesimal formation. The latteralong with turbulent diffusion may influence the radial transport and mixing of solid materials in young protoplanetary discs.

Chao-chin Yang↗
NASA NTRS1983

Microcomputer numerical analysis system for gas dynamics application

The original objective (scope) of the effort was to deliver a microcomputer version of the Continuum gas dynamic numerical analysis on existing NASA equipment. It became apparent during the course of the contract that the interests of NASA would be much better served by the delivery of a dedicated system designed and developed by Continuum, which would provide NASA with additional hardware ideally suited to the specific task at no increase in cost. Accordingly, the contract was modified to reflect this new development. The details of the modification and the delivered capability will be discussed in greater detail in the ensuing technical discussion.

Prozan, R. J.↗
NASA NTRS1991

Vectorization of a Monte Carlo simulation scheme for nonequilibrium gas dynamics

Significant improvement has been obtained in the numerical performance of a Monte Carlo scheme for the analysis of nonequilibrium gas dynamics through an implementation of the algorithm which takes advantage of vector hardware, as presently demonstrated through application to three different problems. These are (1) a 1D standing-shock wave; (2) the flow of an expanding gas through an axisymmetric nozzle; and (3) the hypersonic flow of Ar gas over a 3D wedge. Problem (3) is illustrative of the greatly increased number of molecules which the simulation may involve, thanks to improved algorithm performance.

Boyd, Iain D.↗
NASA NTRS1986

A gas dynamic magnetosheath field model for unsteady interplanetary fields - Application to the solar wind interaction with Venus

The steady state gas dynamic model of magnetosheath magnetic fields previously developed by Spreiter and Stahara (1980) is generalized for the common situation of a temporally varying interplanetary field orientation. Examples for the particular case of Venus in the solar wind illustrate the application of the model to the passage of rotational discontinuities and MHD waves through planetary magnetosheaths. The results of this model illustrate how the field structure near a planetary magnetopause or ionopause can be affected by interplanetary field variations rather than by local processes because of the 'pile up' of magnetosheath fields from a sequence of upstream fields. Changes in the spectrum of interplanetary waves on their transmission to the magnetopause are also indicated.

Luhmann, J. G.↗
NASA NTRS1985

Application of TVD schemes for the Euler equations of gas dynamics

Highly accurate and yet stable shock-capturing finite difference schemes have been designed for the computation of the Euler equations of gas dynamics. Four different principles for the construction of high resolution total variation diminishing (TVD) schemes are available, including hybrid schemes, a second-order extension of Godunov's scheme by van Leer (1979), the modified flux approach of Harten (1983, 1984), and the numerical fluctuation approach of Roe (1985). The present paper has the objective to review the class of second-order TVD schemes via the modified flux approach. Attention is given to first-order TVD schemes, a second-order accurate explicit TVD scheme, the global order of accuracy of the second-order TVD scheme, extensions to systems and two-dimensional conservation laws, numerical experiments with a second-order explicit TVD scheme, implicit TVD schemes, and second-order implicit TVD schemes.

Yee, H. C.↗
NASA NTRS1986

Comments on 'The magnetic field of Mars - Implications from gas dynamic modeling' by C. T. Russell, J. C. Luhmann, J. R. Spreiter, and S. S. Stahara

The Russell et al. (1984) claim that gas dynamic modeling allows a determination of interplanetary and magnetosheath field configurations resembling the Mars 3 magnetic field observations during the January 21, 1972 encounter, and their proposal of a draped magnetic field pattern model for these data, are presently disputed. Extensive use is made of Martian magnetic field analyses undertaken by Dolginov between 1973 and 1984, which are held to prove the existence of an intrinsic Martian magnetic field. Russell replies that the Russell et al. analysis of the variation in the Mars 2, 3, and 5 data suggests the presence of both zero-level and sensor polarity errors in these data. The rejection of an intrinsic Martian magnetic field is accordingly reaffirmed, pending the availability of less ambiguous data.

Dolginov, Sh. SH.↗
NASA NTRS1984

Gas dynamics in the impulsive phase of solar flares. I Thick-target heating by nonthermal electrons

A numerical investigation is carried out of the gas dynamical response of the solar atmosphere to a flare energy input in the form of precipitating nonthermal electrons. Rather than discussing the origin of these electrons, the spectral and temporal characteristics of the injected flux are inferred through a thick-target model of hard X-ray bremsstrahlung production. It is assumed that the electrons spiral about preexisting magnetic field lines, making it possible for a one-dimensional spatial treatment to be performed. It is also assumed that all electron energy losses are due to Coulomb collisions with ambient particles; that is, return-current ohmic effects and collective plasma processes are neglected. The results are contrasted with earlier work on conductive heating of the flare atmosphere. A local temperature peak is seen at a height of approximately 1500 km above the photosphere. This derives from a spatial maximum in the energy deposition rate from an electron beam. It is noted that such a feature is not present in conductively heated models. The associated localized region of high pressure drives material both upward and downward.

Nagai, F.↗
NASA NTRS1991

Particle-gas dynamics in the protoplanetary nebula

In the past year we made significant progress in improving our fundamental understanding of the physics of particle-gas dynamics in the protoplanetary nebula. Having brought our code to a state of fairly robust functionality, we devoted significant effort to optimizing it for running long cases. We optimized the code for vectorization to the extent that it now runs eight times faster than before. The following subject areas are covered: physical improvements to the model; numerical results; Reynolds averaging of fluid equations; and modeling of turbulence and viscosity.

Cuzzi, Jeffrey N.↗
NASA NTRS2000

Thermal-Flow Code for Modeling Gas Dynamics and Heat Transfer in Space Shuttle Solid Rocket Motor Joints

A new, thermal-flow simulation code, called SFLOW. has been developed to model the gas dynamics, heat transfer, as well as O-ring and flow path erosion inside the space shuttle solid rocket motor joints by combining SINDA/Glo, a commercial thermal analyzer. and SHARPO, a general-purpose CFD code developed at Thiokol Propulsion. SHARP was modified so that friction, heat transfer, mass addition, as well as minor losses in one-dimensional flow can be taken into account. The pressure, temperature and velocity of the combustion gas in the leak paths are calculated in SHARP by solving the time-dependent Navier-Stokes equations while the heat conduction in the solid is modeled by SINDA/G. The two codes are coupled by the heat flux at the solid-gas interface. A few test cases are presented and the results from SFLOW agree very well with the exact solutions or experimental data. These cases include Fanno flow where friction is important, Rayleigh flow where heat transfer between gas and solid is important, flow with mass addition due to the erosion of the solid wall, a transient volume venting process, as well as some transient one-dimensional flows with analytical solutions. In addition, SFLOW is applied to model the RSRM nozzle joint 4 subscale hot-flow tests and the predicted pressures, temperatures (both gas and solid), and O-ring erosions agree well with the experimental data. It was also found that the heat transfer between gas and solid has a major effect on the pressures and temperatures of the fill bottles in the RSRM nozzle joint 4 configuration No. 8 test.

Wang, Qunzhen↗