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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Computer program of data reduction procedures for facilities using CO2-N2-O2-Ar equilibrium real-gas mixtures

Data reduction procedures for determining free-stream and post-normal-shock flow conditions are presented. These procedures are applicable to flows of CO2, N2, O2, Ar, or mixtures of these gases and include the effects of dissociation and ionization. The assumption of thermochemical equilibrium free-stream and post-normal-shock flow is made. Although derived primarily to meet the immediate needs of an expansion tube of a hot gas radiation research facility, these procedures are applicable to any supersonic or hypersonic test facility using these gases or mixtures thereof. The data reduction procedures are based on combinations of three of the following flow parameters measured in the immediate vicinity of the test section: (1) stagnation pressure behind normal shock, (2) free-stream static pressure, (3) stagnation-point heat-transfer rate, (4) free-stream velocity, and (5) free-stream density. Thus, these procedures do not depend explicitly upon measured or calculated upstream flow parameters. The procedures are incorporated into a single computer program written in FORTRAN IV language. A listing of this computer program is presented, along with a description of the inputs required and a sample of the data printout.

Miller, C. G., III↗
NASA NTRS1972

A program for calculating expansion-tube flow quantities for real-gas mixtures and comparison with experimental results

A computer program written in FORTRAN 4 language is presented which determines expansion-tube flow quantities for real test gases CO2 N2, O2, Ar, He, and H2, or mixtures of these gases, in thermochemical equilibrium. The effects of dissociation and first and second ionization are included. Flow quantities behind the incident shock into the quiescent test gas are determined from the pressure and temperature of the quiescent test gas in conjunction with: (1) incident-shock velocity, (2) static pressure immediately behind the incident shock, or (3) pressure and temperature of the driver gas (imperfect hydrogen or helium). The effect of the possible existence of a shock reflection at the secondary diaphragm of the expansion tube is included. Expansion-tube test-section flow conditions are obtained by performing an isentropic unsteady expansion from the conditions behind the incident shock or reflected shock to either the test-region velocity or the static pressure. Both a thermochemical-equilibrium expansion and a frozen expansion are included. Flow conditions immediately behind the bow shock of a model positioned at the test section are also determined. Results from the program are compared with preliminary experimental data obtained in the Langley 6-inch expansion tube.

Miller, C. G., III↗
NASA NTRS1991

Acoustic composition sensor for cryogenic gas mixtures

An acoustic sensor useful for the determination of the composition of a gaseous binary mixture in cryogenic liquid spills has been characterized. One version of the instrument traps a known mixture of helium and nitrogen at ambient temperature in a tube which is interrogated by sonic pulses to determine the speed of sound and hence the composition. Experimental data shows that this sensor is quite accurate. The second version uses two unconfined microphones which sense sound pulses. Experimental data acquired during mixing when liquid nitrogen is poured into a vessel of gaseous helium is presented. Data during transient cooling of the tubular sensor containing nitrogen when the sensor is dipped into liquid nitrogen and during transient warm-up when the sensor is withdrawn are also presented. This sensor is being developed for use in the mixing of liquid cryogens with gas evolution in the simulation of liquid hydrogen/liquid oxygen explosion hazards.

Shakkottai, P.↗
NASA NTRS1970

Simple method for predicting viscosity of gas mixtures

Method is derived from the Chapman-enskog theory which describes viscosities at low-to-moderate pressures. Mixtures of nonpolar gases require the viscosities and molecular weights of the constituents in addition to the mixture composition. Dipole moments, boiling points and liquid boiling point densities are also needed with polar gases.

Brokaw, R. S.↗
NASA NTRS1971

Laminar or turbulent boundary-layer flows of perfect gases or reacting gas mixtures in chemical equilibrium

Turbulent boundary layer flows of non-reacting gases are predicted for both interal (nozzle) and external flows. Effects of favorable pressure gradients on two eddy viscosity models were studied in rocket and hypervelocity wind tunnel flows. Nozzle flows of equilibrium air with stagnation temperatures up to 10,000 K were computed. Predictions of equilibrium nitrogen flows through hypervelocity nozzles were compared with experimental data. A slender spherically blunted cone was studied at 70,000 ft altitude and 19,000 ft/sec. in the earth's atmosphere. Comparisons with available experimental data showed good agreement. A computer program was developed and fully documented during this investigation for use by interested individuals.

Anderson, E. C.↗
NASA NTRS1971

Preliminary performance of the Brayton 4.25 inch radial compressor operating in a helium xenon gas mixture

Compressor performance was mapped during the Brayton cycle power system testing. The range of testing included three shaft speeds: the design speed of 36,000 rpm, 10 percent overspeed (39,600 rpm), and 10 percent underspeed (32,400 rpm). A range of compressor inlet temperatures from 60 F to 120 F and discharge pressures from 20 to 45 psia were included. The effects of turbine inlet temperatures (from 1200 F to 1600 F) on the compressor were also studied. The data presented include plots of weight flow, compressor pressure ratio, efficiency, and temperature-rise ratio.

Asadourian, A. S.↗
NASA NTRS1972

Computation of pressure effects of inert-gas mixtures on atomic line shapes.

Recent line-shape experiments on the absorption series of cesium pressurized by various concentration ratios of argon and helium provide an opportunity to study the additivity of perturber interactions. Calculations which assume additivity and which assume additive adiabatic collisions agree well with the reported data. The results suggest that a systematic study of such experiments using accurate digitized data can furnish criteria for the valid applications of the additivity approximation.

Jacobson, H. C.↗
NASA NTRS1972

Viscosity and thermal conductivity of moderately dense gas mixtures.

Derivation of a simple, semitheoretical expression for the initial density dependence of the viscosity and thermal conductivity of gaseous mixtures in terms of the appropriate properties of the pure components and of their interaction quantities. The derivation is based on Enskog's theory of dense gases and yields an equation in which the composition dependence of the linear factor in the density expansion is explicit. The interaction quantities are directly related to those of the mixture extrapolated to zero density and to a universal function valid for all gases. The reliability of the formulation is assessed with respect to the viscosity of several binary mixtures. It is found that the calculated viscosities of binary mixtures agree with the experimental data with a precision which is comparable to that of the most precise measurements.

Wakeham, W. A.↗
NASA NTRS1973

Determination of the temperature of gas mixtures by using laser Raman scattering

A theoretical model for the Raman rotational spectrum of air was formulated, yielding the spectral temperature dependence; and an error analysis of temperature measurement accuracies was performed. The theoretical spectra and the predicted temperature measurement error of + or - 20 K (7 percent) compared well with experimental data. These experimental data consisted of Raman spectra of air obtained for temperatures ranging from 243 to 313 K at a pressure of 1 atmosphere. The use of selected lines resulted in an experimental accuracy of + or - 13 K (-5 percent).

Coney, T. A.↗
NASA NTRS1973

Vibrational deactivation of O3/101/ molecules in gas mixtures

The laser excited fluorescence method has been employed to determine rate constants for vibrational relaxation of O3(101) molecules by O3, O2, CO2, H2, D2, CH4, N2, He, and Ar collision partners at 298 K. Excitation of the O3(001) level by absorption of laser transitions on the CO2 9.5-micron band have permitted the first measurements of vibrational relaxation on O3.

Rosen, D. I.↗
NASA NTRS1975

Study of spark chambers filled with various gas mixtures

The performance is reported of the four layer spark chamber filled with alcohol vapors at 45 torr, very pure neon at 1 to 4.6 atm and also filled with only very pure neon at 1 to 2.9 atm. The curves of particles recording efficiency vs. the delay time in the chamber pulse supply and the number of operations are given. This efficiency decreases with an increase in the delay time; any addition of alcohol vapors increases the drop in the efficiency with time. However, alcohol vapors improve the localization of tracks along which the particles move and make them three to four times as narrow compared to the tracks inside the chamber filled with very pure neon.

Akopyan, G. S.↗