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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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Neutron and photon transport properties in liquid hydrogen obtained from measuring radiation environment in propellant tank mockup suspended above NERVA reactor
Molecular theory, quantum mechanics, transport properties, perturbation theory, and related research
Thermal conductivity of thin metallic films and wires at cryogenic temperatures, discussing electron transport properties
Near critical heat transfer in cryogenic fluids, discussing thermodynamic and transport properties
Monte Carlo evaluation of molecular transport property integrals temperature dependence
Turbulent shear flows transport properties, computing atmospheric and vortex motions by invariant modeling of Reynolds stress term in boundary layer momentum equation
Fluctuations in electron density and temperature coupled through Ohm's law are studied for an ionizable medium. The nonlinear effects are considered in the limit of a third order quasi-linear treatment. Equations are derived for the amplitude of the fluctuation. Conditions under which a steady state can exist in the presence of the fluctuation are examined and effective transport properties are determined. A comparison is made to previously considered second order theory. The effect of third order terms indicates the possibility of fluctuations existing in regions predicted stable by previous analysis.
Flucturations in electron density and temperature coupled through OHM's Law are studied for MHD power generator and MPD arc thruster applications. The dispersion relation based on linear theory is derived, and the two limiting cases of infinite ionization rate and frozen flow are examined. The nonlinear effects of the frozen flow case are then studied in the quasilinear limit. Equations are derived for the amplitude of the fluctuation and its effect upon Ohm's Law and the electron temperature equation. Conditions under which a steady state can exist in the presence of the fluctuation are examined, and effective transport properties are determined.
A cylindrical one-dimensional model of the Apollo cyrogenic oxygen storage tank has been developed to study the effect of stratification in the tank. Zero gravity was assumed, and only the thermally induced motions were considered. The governing equations were derived from conservation laws and solved on a digital computer. Realistic thermodynamic and transport properties were used. Calculations were made for a wide range of conditions. The results show the fluid behavior to be dependent on the quantity in the tank or equivalently the bulk fluid temperature. For high quantities (low temperatures) the tank pressure rose rapidly with heat addition, the heater temperature remained low, and significant pressure drop potentials accrued. For low quantities the tank pressure rose more slowly with heat addition and the heater temperature became high. A high degree of stratification resulted for all conditions; however, the stratified region extended appreciably into the tank only for the lowest tank quantity.
Fluctuations in electron density and temperature coupled through Ohm's law are studied for an ionizable medium. The nonlinear effects are considered in the limit of a third order quasi-linear treatment. Equations are derived for the amplitude of the fluctuation. Conditions under which a steady state can exist in the presence of the fluctuation are examined and effective transport properties are determined. A comparison is made to previously considered second order theory. The effect of third order terms indicates the possibility of fluctuations existing in regions predicted stable by previous analysis.
Observation that in situ measurements of ambient electron densities with satellite-borne cylindrical probes exhibit periodic variations synchronous with the satellite spin cycle. Representing these fluctuations as a superposition of effects attributable to both the presence of the satellite wake and the geomagnetic field leads to a model of the modulations of accelerated electron current to cylindrical probes in which one modulation component displays current variations dependent on the probe velocity angle (psi), and the other displays variations dependent on the angle between the probe axis and the geomagnetic-field lines (beta). The modulations produce an electron current decrease whenever the probe axis rotates into the satellite wake or whenever the probe axis rotates toward alignment with the geomagnetic-field lines. As altitude increases, the modulation dependent on psi decreases, whereas the modulation dependent on beta increases. The psi-dependent modulation component can be associated with the presence of a wake structure, and the beta-dependent component can be associated with the magnetic influence on the transport properties of thermal electrons, assuming that the electron fluxes are predominant along the field lines. The analysis results imply that the most accurate determinations of atmospheric electron densities by satellite-borne cylindrical probes come from measurements taken out of the wake of the satellite when the probe axis is within 20 deg of being perpendicular to the geomagnetic-field lines.
Semiempirical correlations have been developed between solubility parameters and refractive indices for series of model hydrocarbon compounds and organic polymers. Measurement of intermolecular forces is useful for assessment of material compatibility, glass-transition temperature, and transport properties.
An experimental investigation was conducted to determine the coolant-side, heat transfer coefficients for a liquid cooled, hydrogen-oxygen rocket thrust chamber. Heat transfer rates were determined from measurements of local hot gas wall temperature, local coolant temperature, and local coolant pressure. A correlation incorporating an integration technique for the transport properties needed near the pseudocritical temperature of liquid hydrogen gives a satisfactory prediction of hot gas wall temperatures.
Hypersonic flow of a chemically nonequilibrium multicomponent mixture past an axisymmetric blunt body is considered on the basis of the exact Navier-Stokes and chemical rate equations. The flowfield, characterized by a sharp shock and a boundary layer, is solved numerically in the region between the shock and the body. The governing equations are first formulated in generalized orthogonal coordinates, and then recast in computational coordinates in which both the shock and the body are two straight lines and one coordinate is stretched to allow higher space resolution near the body. The thermodynamic and transport properties are obtained from the most rigorous theories and reliable data for each component and for the mixture itself. A time-marching second-order finite-difference method is used to solve the equations.
New calculations of the viscosity of atomic hydrogen were carried out, and excellent agreement between these values and recent experimental results (Cheng and Blackshear, 1972) is pointed out. They made measurements of the viscosity of atomic hydrogen at four temperatures, using an iterative technique. Theoretical values for the transport properties of atomic hydrogen may be predicted reliably over a wide range of temperatures by use of Kolos and Wolniewicz potential energy functions (1965).
An electrohydrodynamic heat pipe of radical design is proposed which substitutes polarization electrohydrodynamic force effects for capillarity in collecting, guiding, and pumping a condensate liquid phase. The discussed device is restricted to the use of dielectric liquids as working fluids. Because of the relatively poor thermal transport properties of these liquids, capillary heat pipes using these liquids have not been high performance devices. The employment of the electrohydrodynamic concept should enhance this performance and help fill the performance gap that exists in the temperature range from 250 F to 750 F for 'conventional' capillary heat pipes.
An analysis for viscous radiating shock layer flow over a blunt body with massive blowing is presented. Detailed equilibrium computations for the thermodynamics and transport properties are included in the solution. Molecular band and atomic line, as well as continuum radiation are included. For a typical Jovian entry problem, a 40% reduction in total radiative flux at stagnation point, due to the injection of carbon gas, was found. The reduction increases to about 70% at about four body nose radii downstream. The increase of flux reduction indicates that most of the radiative energy is absorbed by the injected carbon gas and dumped into the wake. An examination of the spectral distribution of the surface radiative flux reveals that most of the flux reduction occurs in molecular bands of C2.
The turbulence structure of weakly ionized, continuum plasma is analyzed with emphasis on the turbulent fluctuation and the transport properties of the ionized species. The mean gradients of the velocity and ionized-species concentrations are considered to be uniform. It is assumed that the turbulence Reynolds number is small and that the turbulence field is homogeneous in order to close the dynamic equations of turbulence. It was found that the ratio of the Debye shielding length to the local integral scale of turbulence must be sufficiently small in order for the detailed quasi-neutrality to prevail. The condition of the detailed quasi-neutrality is necessary, in addition to the equal mean concentrations of electrons and ions, in order for the turbulence properties involving the electrons to be the same as those involving the ions.