Real-gas effects in the flow of methane and natural gas through critical-flow nozzles
Methane and natural gas flow through critical flow nozzles, calculating real gas effects on mass flow rate
Johnson, R. C.↗
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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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A study of boundary layer transition on outgassing cones in hypersonic flow
Surface heat-transfer rates and pressures were measured at hypersonic speeds on sharp cones at zero angle of attack with and without gas injection. Using the non-injection results for reference data the effects on heating and transition location of surface roughness and injectant rate, distribution and composition were determined. The transition location was sensitive to the injectant distribution. The transition Reynolds numbers were significantly greater when the injectant distribution was constant than with a variable distribution. The measured heat-transfer distribution were also strongly dependent upon the injectant distribution. Transition Reynolds number results obtained during this program with a variable injectant distribution were correlated with a limited amount of data available for a degrading model tested in a different facility. Transitional data with constant injectant distribution were correlated with earlier results. An empirical correlation of heat-transfer reduction due to gas injection in turbulent flow was developed for both distributions tested. Several effects of mass addition on heating and transition, which have been earlier reported, were observed.
Stalmach, C. J., Jr.↗
Computer Programs for Calculating and Plotting the Stability Characteristics of a Balloon Tethered in a Wind
Computer programs for calculating the stability characteristics of a balloon tethered in a steady wind are presented. Equilibrium conditions, characteristic roots, and modal ratios are calculated for a range of discrete values of velocity for a fixed tether-line length. Separate programs are used: (1) to calculate longitudinal stability characteristics, (2) to calculate lateral stability characteristics, (3) to plot the characteristic roots versus velocity, (4) to plot the characteristic roots in root-locus form, (5) to plot the longitudinal modes of motion, and (6) to plot the lateral modes for motion. The basic equations, program listings, and the input and output data for sample cases are presented, with a brief discussion of the overall operation and limitations. The programs are based on a linearized, stability-derivative type of analysis, including balloon aerodynamics, apparent mass, buoyancy effects, and static forces which result from the tether line.
Bennett, R. M.↗
Equation of state of matter at supernuclear densities.
The qualitative features of the equation of state of matter at supernuclear densities are deduced through a careful examination of the nature of particle interactions at short distances and by the introduction of an 'effective baryon mass spectrum.' It is found that the equation of state begins to take on a particularly simple form (the 'asymptotic form') at a relatively low matter density of 100,000 teragrams per cu cm.
Leung, Y. C.↗
Analytical techniques and instrumentation, a compilation
Procedures for conducting materials tests and structural analyses of aerospace components are presented as a part of the NASA technology utilization program. Some of the subjects discussed are as follows: (1) failures in cryogenic tank insulation, (2) friction characteristics of graphite and graphite-metal combinations, (3) evaluation of polymeric products in thermal-vacuum environment, (4) erosion of metals by multiple impacts with water, (5) mass loading effects on vibrated ring and shell structures, (6) nonlinear damping in structures, and (7) method for estimating reliability of randomly excited structures.
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Entry into outer planet environments. I - The radiating shock layer with coupled ablation for carbon and silica
Fully coupled solutions of shock layer equations for the stagnation region are obtained, comprising a set of converged benchmark flowfield solutions for silica and carbon heat shields entering modeled atmospheres of Saturn and Uranus. Model atmospheres and entry trajectories providing significant radiative heating to the entry probes so that the heating environment and effects of mass addition on the heating environment are clearly defined are emphasized. Results referable to the carbon heat shield are questioned because of the high (sublimation) wall temperature assumed and the relatively low shock layer temperature.
Liu, C.-H.↗
Ignition Transients of Large Segmented Solid Rocket Boosters
A model is described which provides a means for analyzing the complexities of ignition transients and pressure peaks of large, high performance, segmented solid rocket boosters. The method accounts for: (1) temporal and spatial development of the flow field set up by the head end igniter discharge, (2) ignition and flame spreading coupled to chamber flow, (3) the steep velocity, pressure, and temperature gradients that occur during the early phases of ignition, and (4) the interactions that produce ignition spikes (i.e., compression of chamber gases during pressurization, erosive burning, and mass added effect of igniter discharge). The technique differs from earlier models in that the flow interactions between the slots and main chamber are accounted for, and the original computer program for monolithic motors is improved. The procedures were used to predict the ignition transients of the current design for the space shuttle booster.
Caveny, L. H.↗
Application of molecular orbital theory to the interpretation of mass spectra study of substituent effect on a series of acetophenones
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Loew, G. H.↗
Theoretical and experimental studies of the deposition of Na2SO4 from seeded combustion gases
A basic point in the hot corrosion of turbine components is the deposition of sodium sulfate from flames containing sodium and sulfur. An experimental study is described which examines a dew point prediction theory based on the local thermochemical equilibrium (LTCE) method, and a means to calculate the deposition rate is suggested. In addition, a convective diffusion theory, based on the assumption of a chemically frozen boundary layer, utilizing the LTCE results, and imposing the additional effects of mass transport, was also successful in predicting dew points for Na2SO4-seeded combustion gases. A multicomponent mass transfer equation was derived to predict NaSO4 deposition rate via vapor transport at temperatures below the deposition onset temperature.
Kohl, F. J.↗
Mass fractionation of the lunar surface by solar wind sputtering
An investigation is conducted concerning the mass-fractionation effects produced in connection with the bombardment of the moon by the solar wind. Most of the material ejected by sputtering escapes the moon's gravity, but some returning matter settles back onto the lunar surface. This material, which is somewhat richer in heavier atoms than the starting surface, is incorporated into the heavily radiation-damaged outer surfaces of grains. The investigation indicates that sputtering of the lunar surface by the solar wind will give rise to significant surface heavy atom enrichments if the grain surfaces are allowed to come into sputtering equilibrium.
Switkowski, Z. E.↗
Rare gases in etched 10084 ilmenite - A search for trapped solar-flare rare gases
Results are presented of rare-gas analyses of 10084 ilmenite samples which have been etched to depths of about 1 micrometer in an attempt to remove the surface layer of trapped solar-wind gases, thereby allowing detection of the more deeply implanted solar-flare ions in the remaining trapped gases. A tendency found for the Ne-20/Ne-22 ratios in the etched ilmenite to reflect the solar-wind ratio measured in the solar-wind composition experiment foils may represent a cancellation of mass-fractionation effects. The Ne-20/Ne-22 ratio in the saturated layer is lowered with respect to the solar wind by preferential diffusive loss, but is raised again in the gas diffusing inward by the same preferential mobilization of Ne-20 relative to Ne-22. Attention is also given to the significance of the findings in the case of argon, krypton, and xenon.
Leich, D. A.↗
Convective heat flux in a laser-heated thruster
An analysis is performed to estimate the convective heating to the wall in a laser-heated thruster on the basis of a solution of the laminar boundary-layer equations with variable transport properties. A local similiarity approximation is used, and it is assumed that the gas phase is in equilibrium. For the thruster described by Wu (1976), the temperature and pressure distributions along the nozzle are obtained from the core calculation. The similarity solutions and heat flux are obtained from the freestream conditions of the boundary layer, in order to determine if it is necessary to couple the boundary losses directly to the core calculation. In addition, the effects of mass injection on the convective heat transfer across the boundary layer with large density-viscosity product gradient are examined.
Wu, P. K. S.↗
A simplified gross thrust computing technique for an afterburning turbofan engine
A simplified gross thrust computing technique extended to the F100-PW-100 afterburning turbofan engine is described. The technique uses measured total and static pressures in the engine tailpipe and ambient static pressure to compute gross thrust. Empirically evaluated calibration factors account for three-dimensional effects, the effects of friction and mass transfer, and the effects of simplifying assumptions for solving the equations. Instrumentation requirements and the sensitivity of computed thrust to transducer errors are presented. NASA altitude facility tests on F100 engines (computed thrust versus measured thrust) are presented, and calibration factors obtained on one engine are shown to be applicable to the second engine by comparing the computed gross thrust. It is concluded that this thrust method is potentially suitable for flight test application and engine maintenance on production engines with a minimum amount of instrumentation.
Hamer, M. J.↗
Altimetry data over trenches and island-arcs and convection in the mantle
Transfer function techniques were developed to calculate the isostatic component of the geoid signal over trench/island arc/back arc systems. Removal of this isostatic component from geoid profiles determined by GEOS 3 radar altimetry leaves a residual geoid that can be attributed to the effect of mass inhomogeneities below the depth of compensation. Efforts are underway to extend the analysis to all the major trench/island arc systems of the world in order to provide more detailed understanding of the dynamic processes occurring beneath island arcs.
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IUE observations of blue halo high luminosity stars
Two high luminosity population II blue stars of high galactic latitude, BD+33 deg 2642 and HD 137569 were observed at high resolution. The stellar spectra show the effect of mass loss in BD+33 deg 2642 and abnormally weak metallic lines in HD 137569. The interstellar lines in the direction of BD+33 deg 2642, which lies at a height z greater than or equal to 6.2 kpc from the galactic plane, are split into two components. No high ionization stages are found at the low velocity component; nor can they be detected in the higher velocity clouds because of mixing with the corresponding stellar/circumstellar lines.
Hack, M.↗
On the physics of Circinus X-1. II - Eccentricity, mass transfer rates, secular orbital effects, possible gamma-ray bursts, and a possible origin for Circinus X-1
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Haynes, R. F.↗
IUE spectra of RS Puppis and HD 20722 - Stars in symmetric dusty nebulae
Spectra obtained by the IUE satellite of the Cepheid variable RS Puppis and the K giant HD 20722, both of which are surrounded by symmetric nebula, are presented. Exposures were made in 1980 with the long wavelength redundant camera and 10 x 20 arcmin focal plane aperture at a spatial resolution of about 5 arcsec and spectral resolution about 6 A. No anomalies are found in the low-dispersion spectra of the stars with nebula with respect to those of apparently similar stars that lack nebulae. It is pointed out, however, that high-resolution studies of the Mg II doublet are still warranted since the doublet profile, which is unresolved in the present studies, is a sensitive indicator of mass loss effects.
Johnson, H. M.↗
Experimental modal analysis of the fuselage panels of an Aero Commander aircraft
The reduction of interior noise in light aircraft was investigated with emphasis the thin fuselage sidewall. The approach used is theoretical and involves modeling of the sidewall panels and stiffeners. Experimental data obtained from tests investigating the effects of mass and stiffness treatments to the sidewalls are presented. The dynamic characteristics of treated panels are contrasted with the untreated sidewall panels using experimental modal analysis techniques. The results include the natural frequencies, modal dampling, and mode shapes of selected panels. Frequency response functions, data relating to the global fuselage response, and acoustic response are also presented.
Geisler, D.↗