Search NASA⌕ Search

SEARCH · Search NASA

Results for “Transport Properties”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

A review of reaction rates and thermodynamic and transport properties for the 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

Reaction rate coefficients and thermodynamic and transport properties are provided for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in such environments.

Gupta, Roop N.↗
NASA NTRS2003

Radiation Transport Properties of Potential In Situ-Developed Regolith-Epoxy Materials for Martian Habitats

Mission crews in space outside the Earth s magnetic field will be exposed to high energy heavy charged particles in the galactic cosmic radiation (GCR). These highly ionizing particles will be a source of radiation risk to crews on extended missions to the Moon and Mars, and the biological effects of and countermeasures to the GCR have to be investigated as part of the planning of exploration-class missions. While it is impractical to shield spacecraft and planetary habitats against the entire GCR spectrum, biological and physical studies indicate that relatively modest amounts of shielding are effective at reducing the radiation dose. However, nuclear fragmentation in the shielding materials produces highly penetrating secondary particles, which complicates the problem: in some cases, some shielding is worse than none at all. Therefore the radiation transport properties of potential shielding materials need to be carefully investigated. One intriguing option for a Mars mission is the use of material from the Martian surface, in combination with chemicals carried from Earth and/or fabricated from elements found in the Martian atmosphere, to construct crew habitats. We have measured the transmission properties of epoxy-Martian regolith composites with respect to heavy charged particles characteristic of the GCR ions which bombard the Martian surface. The composites were prepared at NASA Langley Research Center using simulated Martian regolith, in the process also evaluating fabrication methods which could lead to technologies for in situ fabrication on Mars. Initial evaluation of the radiation shielding properties is made using radiation transport models developed at NASA-LaRC, and the results of these calculations are used to select the composites with the most favorable radiation transmission properties. These candidates are then evaluated at particle accelerators which produce beams of heavy charged particles representative in energy and charge of the radiation at the surface of Mars. The ultimate objective is to develop the models into a design tool for use by mission planners, flight surgeons and radiation health specialists.

Miller, Jack↗
NASA NTRS1978

Computer program for obtaining thermodynamic and transport properties of air and products of combustion of ASTM-A-1 fuel and air

A computer program for determining desired thermodynamic and transport property values by means of a three-dimensional (pressure, fuel-air ratio, and either enthalpy or temperature) interpolation routine was developed. The program calculates temperature (or enthalpy), molecular weight, viscosity, specific heat at constant pressure, thermal conductivity, isentropic exponent (equal to the specific heat ratio at conditions where gases do not react), Prandtl number, and entropy for air and a combustion gas mixture of ASTM-A-1 fuel and air over fuel-air ratios from zero to stoichiometric, pressures from 1 to 40 atm, and temperatures from 250 to 2800 K.

Hippensteele, S. A.↗
NASA NTRS2001

Effective Potential Energies and Transport Properties for Nitrogen and Oxygen

The results of recent theoretical studies for N--N2, O--O2, N2--N2 interactions are applied to the transport properties of nitrogen and oxygen gases. The theoretical results are used to select suitable oxygen interaction energies from previous work for determining the diffusion and viscosity coefficients at high temperatures. A universal formulation is applied to determine the collision integrals for O2--O2 interactions at high temperatures and to calculate certain ratios for determining higher-order collision integrals.

Stallcop, James R.↗
NASA NTRS1961

Alignment Charts for Transport Properties Viscosity, Thermal Conductivity, and Diffusion Coefficients for Nonpolar Gases and Gas Mixtures at Low Density

Alignment charts (nomographs) designed to permit rapid calculations of the low-pressure transport properties of nonpolar gases and gas mixtures are presented. Calculations for pure gases are based on the rigorous kinetic theory of gases as applied to a realistic intermolecular force law. Mixture viscosities and conductivities are calculated from good approximations derived from rigorous theory. The properties are calculable with a precision of 2 percent or better. Accuracy depends on how well the constants characterizing the Intermolecular force law are known; if constants are derived from experimental data, results should be accurate to 5 percent or better. Force constants are tabulated for 65 gases.

Brokaw, Richard S.↗
NASA NTRS1975

GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide

A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

Hendricks, R. C.↗
NASA NTRS1988

High temperature transport properties of air - N-O interaction energies and collision integrals

Potential curves for the higher-lying states of NO are used together with a general scattering code to compute accurate values of transport collision integrals for N(4S/0/)-O(3P) interactions. It is found that the major contribution to the collision integrals comes from these higher-lying states of NO. New values of the collision integrals for N(4S/0/)-N(4S/0/) and O(3P)-O(3P) interactions are computed as well. The tabulations of the collision integrals cover a broad range of temperatures from 250 to 100,000 K and can be used to determine transport properties such as viscosity, thermal conductivity, and the diffusion coefficient to the second order.

Levin, E.↗
NASA NTRS1987

Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

Baldwin, Richard S.↗
NASA NTRS1977

The phase diagram and transport properties for hydrogen-helium fluid planets

The properties of pure hydrogen and helium are examined, taking into account metallic hydrogen, molecular hydrogen, and the molecular-metallic transition. Metallic hydrogen-helium mixtures are considered along with molecular hydrogen-helium mixtures, the total phase diagram, and minor constituents, including deuterium. The transport properties of the metallic and the molecular phase are also discussed, giving attention to electrical conductivity, thermal conductivity, viscosity, self-diffusion, interdiffusion, radiative opacity, and second-order transport coefficients.

Stevenson, D. J.↗
NASA NTRS1973

Thermodynamic and transport properties of cryogenic propellants and related fluids

Significant advances have been made in recent years in the quality and range of thermophysical data for the cryogenic propellants, pressurants, and inertants. A review of recently completed and current data compilation projects for helium, hydrogen, argon, nitrogen, oxygen, fluorine, and methane is given together with recommended references for thermodynamic and transport property data tables for these fluids. Modern techniques in the plotting of thermodynamic charts from tabular data (or from functions such as the equation of state) have greatly improved their precision and value. A list of such charts is included.

Johnson, V. J.↗
NASA NTRS2003

Radiation Transport Properties of Polyethylene-Fiber Composites

Composite materials that can both serve as effective shielding materials against cosmic-ray and energetic solar particles in deep space as well as structural materials for habitat and spacecraft remain a critical and mission enabling piece in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density coupled with high hydrogen content. Polyethylene fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of Polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at NASA's Marshall Space Flight Center and tested against 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

Kaul, Raj K.↗
NASA NTRS2004

Space radiation transport properties of polyethylene-based composites

Composite materials that can serve as both effective shielding materials against cosmic-ray and energetic solar particles in deep space, as well as structural materials for habitat and spacecraft, remain a critical and mission enabling component in mission planning and exploration. Polyethylene is known to have excellent shielding properties due to its low density, coupled with high hydrogen content. Polyethylene-fiber reinforced composites promise to combine this shielding effectiveness with the required mechanical properties of structural materials. Samples of polyethylene-fiber reinforced epoxy matrix composite 1-5 cm thick were prepared at the NASA Marshall Space Flight Center and tested against a 500 MeV/nucleon Fe beam at the HIMAC facility of NIRS in Chiba, Japan. This paper presents measured and calculated results for the radiation transport properties of these samples.

Polyethylene/chemistry↗
NASA NTRS2003

Topography and transport properties of oligo(phenylene ethynylene) molecular wires studied by scanning tunneling microscopy

Conjugated phenylene(ethynylene) molecular wires are of interest as potential candidates for molecular electronic devices. Scanning tunneling microscopic study of the topography and current-voltage (I-V) characteristics of self-assembled monolayers of two types of molecular wires are presented here. The study shows that the topography and I-Vs, for small scan voltages, of the two wires are quite similar and that the electronic and structural changes introduced by the substitution of an electronegative N atom in the central phenyl ring of these wires does not significantly alter the self-assembly or the transport properties.

Polymers/chemistry↗