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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 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Aerodynamic characteristics of a monoplanar missile concept with bodies of circular and elliptical cross sections

Experimental aerodynamic characteristics of a low-drag missile concept with a body of circular cross section were compared to one with a body of 3:1 elliptical cross section, the bodies having identical cross section area distributions. The concepts were of monowing design with constant wing span. Tail surfaces were located flush at the body base with plus or minus 30 deg dihedral. Wind tunnel tests were performed at Mach numbers from 0.5 to 4.63 and at angles of attack from about -5 deg to 28 deg.

Graves, E. B.↗
NASA NTRS1978

The effect of over-the-wing nacelles on wing-body aerodynamics

An investigation was conducted in the Langley 16-foot transonic tunnel to further study benefits in climb and cruise performance due to blowing the jet over the wing for a transport-type wing-body configuration. In this investigation a wing-body model/powered-nacelle test rig combination was tested at Mach numbers of 0.5 and 0.8 at angles of attack from -2 to 4 deg and jet total-pressure ratios from jet off to 3 or 4 (depending on Mach number) for a variety of nacelle locations relative to the wing. Results from this investigation show that positioning of the nacelles can have very large effects on the wing-body drag (nacelles were nonmetric). Some positions yielded much higher drag than the baseline wing-body while others yielded drag which was somewhat lower than the baseline.

Reubush, D. E.↗
NASA NTRS1978

Canard-body-tail missile test at angles of attack to 50 deg in the Ames 11-foot transonic wind tunnel

Blunted ogive cylinder missile models with a length-to-diameter ratio of 10.4 were tested at transonic speeds and large angles of attack in an 11 foot transonic wind tunnel. The configurations are: body, body with tail panels, body with canards, and body with canards and tails. Forces and moments from the entire model and each of the eight fins were measured over the pitch range of 20 deg to 50 deg, and roll angles of 0 deg to 45 deg and canard deflection angles between 0 deg and 15 deg. The Reynolds number ranged from 3.9 x 10 to the 6th power per meter. Large side forces and yawing moments were observed for some of the test cases involving a symmetric geometry.

Allen, C. Q.↗
NASA NTRS1974

Design specification for the whole-body algorithm

The necessary requirements and guidelines for the construction of a computer program of the whole-body algorithm are presented. The minimum subsystem models required to effectively simulate the total body response to stresses of interest are (1) cardiovascular (exercise/LBNP/tilt); (2) respiratory (Grodin's model); (3) thermoregulatory (Stolwijk's model); and (4) long-term circulatory fluid and electrolyte (Guyton's model). The whole-body algorithm must be capable of simulating response to stresses from CO2 inhalation, hypoxia, thermal environmental exercise (sitting and supine), LBNP, and tilt (changing body angles in gravity).

Fitzjerrell, D. G.↗
NASA NTRS1973

The development of a whole-body algorithm

The whole-body algorithm is envisioned as a mathematical model that utilizes human physiology to simulate the behavior of vital body systems. The objective of this model is to determine the response of selected body parameters within these systems to various input perturbations, or stresses. Perturbations of interest are exercise, chemical unbalances, gravitational changes and other abnormal environmental conditions. This model provides for a study of man's physiological response in various space applications, underwater applications, normal and abnormal workloads and environments, and the functioning of the system with physical impairments or decay of functioning components. Many methods or approaches to the development of a whole-body algorithm are considered. Of foremost concern is the determination of the subsystems to be included, the detail of the subsystems and the interaction between the subsystems.

Kay, F. J.↗
NASA NTRS1979

Application of a numerical orthogonal coordinate generator to axisymmetric blunt bodies

An application of a simple numerical technique which allows for the rapid construction of orthogonal coordinate systems about axisymmetric blunt bodies is presented. This technique can generate orthogonal meshes which have unequally spaced points in two directions. Relations are given for the numerical generation of the metric coefficients. Body shapes ranging from simple analytical bodies to complex reverse curvature bodies are presented together with their orthogonal coordinate systems. The relatively good accuracy of the technique is shown in tabular data describing coordinate line slopes and metric coefficients. The predictor-corrector numerical method used to generate these results is both simple in concept and easy to program, so that the application of the technique should be broader than the results presented.

Graves, R. A., Jr.↗
NASA NTRS1979

On the effects of higher convection modes on the thermal evolution of small planetary bodies

The effects of higher modes of convection on the thermal evolution of a small planetary body is investigated. Three sets of models are designed to specify an initially cold and differentiated, an initially hot and differentiated, and an initially cold and undifferentiated Moon-type body. The strong temperature dependence of viscosity enhances the thickening of lithosphere so that a lithosphere of about 400 km thickness is developed within the first billion years of the evolution of a Moon-type body. The thermally isolating effect of such a lithosphere hampers the heat flux out of the body and increases the temperature of the interior, causing the solid-state convection to occur with high velocity so that even the lower modes of convection can maintain an adiabatic temperature gradient there. It is demonstrated that the effect of solid-state convection on the thermal evolution of the models may be adequately determined by a combination of convection modes up to the third or the fourth order harmonic. The inclusion of higher modes does not affect the results significantly.

Arkani-Hamed, J.↗
NASA NTRS1979

Application of the pseudostate theory to the three-body Lambert problem

The pseudostate theory, which approximates three-body trajectories by overlapping the conic effects of both massive bodies on the third body, has been used to solve boundary value problems. Frequently, the approach to the secondary is quite close, as in interplanetary gravity assist trajectories or satellite tour trajectories. In this case the orbit with respect to the primary is radically changed so that perturbation techniques are time consuming, yet higher accuracy than point-to-point conics (V-infinity matching) is necessary. This method reduces the solution of the three-body Lambert problem to solving two conic Lambert problems and inverting a 7 x 7 matrix, the components of which are all found analytically. Typically 90-95% of the point-to-point conic error with respect to an integrated trajectory is eliminated.

Byrnes, D. V.↗
NASA NTRS1979

Effects of precursor heating on radiative and chemically reacting viscous flow around a Jovian entry body

The influence of change in the precursor region flow properties on the entire shock layer flow phenomena around a Jovian entry body was investigated. The flow in the shock layer was assumed to be steady, axisymmetric, and viscous. Both the chemical equilibrium and the nonequilibrium composition of the shock layer gas were considered. The effects of transitional range behavior were included in the analysis of high altitude entry conditions. Realistic thermophysical and radiation models were used, and results were obtained by employing the implicit finite difference technique in the shock layer and an iterative procedure for the entire shock layer precursor zone. Results obtained for a 45 degree angle hyperboloid blunt body entering Jupiter's atmosphere at zero angle of attack indicates that preheating the gas significantly increases the static pressure and temperature ahead of the shock for entry velocities exceeding 36 km/sec. The nonequilibrium radiative heating rate to the body is found to be significantly higher than the corresponding equilibrium heating. The precursor heating generally increases the radiative and convective heating of a body. That increase is slightly higher for the nonequilibrium conditions.

Tiwari, S. N.↗
NASA NTRS1980

Application of a numerically generated orthogonal coordinate system to the solution of inviscid axisymmetric supersonic flow over blunt bodies

A numerically generated orthogonal coordinate system (with the body surface and shock wave as opposite boundaries) was applied with a time asymptotic method to obtain steady flow solutions for axisymmetric inviscid flow over several blunt bodies including spheres, paraboloids, ellipsoids, hyperboloids, hemisphere cylinders, spherically blunted cones, and a body with a concavity in the stagnation region. Comparisons with experimental data and with the results of other computational methods are discussed. The numerically generated orthogonal coordinate system is described and applications of the method to complex body shapes, particularly those with concave regions, are discussed.

Hamilton, H. H., II↗
NASA NTRS1980

Investigations regarding the drag characteristics of flow-disturbing bodies which are arranged in line and attached to the wall

The flow characteristics of rectangular bodies mounted on the base area of a rectangular closed wind tunnel are investigated. As many as four bodies are mounted in line with equal distances between successive bodies. The Mach number of the flowing air is in the range from 0.1 to 0.5. Total and individual drag values could be charged within a wide range by a suitable selection of the distance between successive bodies.

Balkowski, M.↗
NASA NTRS1980

Calculation of Water Drop Trajectories to and About Arbitrary Three-Dimensional Bodies in Potential Airflow

Calculations can be performed for any atmospheric conditions and for all water drop sizes, from the smallest cloud droplet to large raindrops. Any subsonic, external, non-lifting flow can be accommodated; flow into, but not through, inlets also can be simulated. Experimental water drop drag relations are used in the water drop equations of motion and effects of gravity settling are included. Seven codes are described: (1) a code used to debug and plot body surface description data; (2) a code that processes the body surface data to yield the potential flow field; (3) a code that computes flow velocities at arrays of points in space; (4) a code that computes water drop trajectories from an array of points in space; (5) a code that computes water drop trajectories and fluxes to arbitrary target points; (6) a code that computes water drop trajectories tangent to the body; and (7) a code that produces stereo pair plots which include both the body and trajectories. Code descriptions include operating instructions, card inputs and printouts for example problems, and listing of the FORTRAN codes. Accuracy of the calculations is discussed, and trajectory calculation results are compared with prior calculations and with experimental data.

Norment, H. G.↗
NASA NTRS1979

Gravitational waves from rotating and precessing rigid bodies - Simple models and applications to pulsars

An axially symmetric, torque-free rigid body, rotating and precessing, emits gravitational quadrupole radiation at two frequencies, omega and 2 omega, corresponding to the l = 2, m = 1,2 spherical harmonics. The paper presents explicitly the waveforms of the two polarizations at both frequencies. From observations of gravitational waves, one can derive information about the body's orientation and its precession amplitude. Electromagnetic radiation emitted by a spot fixed on the surface of the body arrives in pulses at a mean frequency Omega which is typically different from omega. If the body is not axially symmetric but the amplitude of the precession is small, the gravitational radiation at the lower frequency omega is split into two frequencies on either side of the electromagnetic pulse frequency. Explicit waveforms for the two polarizations in this case are also presented.

Zimmermann, M.↗
NASA NTRS1980

The restricted three-body problem including radiation pressure

The force of radiation pressure is included in the restricted three-body problem by considering the major radial components of the pressure force for the case of a particle in the vicinity of two luminous massive bodies, as well as by introducing the Poynting-Robertson effect for the case of one luminous body. The positions of the Lagrangian points L4 and L5 are found as functions of the ratio of radiation to gravitational forces. The Poynting-Robertson effect renders the L4 and L5 points unstable on a time scale that is long compared to the period of rotation of the two massive bodies. Implications for space colonization and a mechanism for producing azimuthal asymmetries in the interplanetary dust complex are discussed.

Schuerman, D. W.↗
NASA NTRS1980

Solution of Euler's Equations of Motion and Eulerian Angles for near symmetric rigid bodies subject to constant moments

Analytic expressions are found for Euler's Equations of Motion and for the Eulerian Angles for both symmetric and near symmetric rigid bodies under the influence of arbitrary constant body-fixed torques. These solutions provide the body-fixed angular velocities and the attitude of the body, respectively, as functions of time. They are of special interest in applications to spinning spacecraft (such as the Galileo Spacecraft to be launched in 1984) because they include the effect of time-varying spin rate. Thus they can be applied to spin-up and spin-down maneuvers as well as to error analysis for thruster misalignments. The solutions are given for arbitrary initial conditions in terms of Fresnel, Sine and Cosine Integrals. Numerical integration of the governing differential equations has verified that the approximate analytic solutions are very accurate in many physical situations of interest.

Longuski, J. M.↗
NASA NTRS1980

Effect of three-body interactions on the structure of small clusters

Minimum energy configurations of microclusters (up to six atoms) have been calculated using two- and three-body interactions. Structural changes were parametrically analyzed as a function of the intensity of three-body forces. The results are qualitative in nature; they indicate, however, that three-body interactions play an important role in the equilibrium structure of microclusters. The effect of the intensity of the three-body interactions on the structure of small clusters is not manifested in a continuous manner. Rather, changes in the energetically most stable structure occur abruptly. The results are in qualitative agreement with experimental observations as well as other calculations.

Halicioglu, T.↗
NASA NTRS1981

Unsteady Newton-Busemann flow theory. Part 2: Bodies of revolution

Newtonian flow theory for unsteady flow past oscillating bodies of revolution at very high Mach numbers is completed by adding a centrifugal force correction to the impact pressures. Exact formulas for the unsteady pressure and the stability derivatives are obtained in closed form and are applicable to bodies of revolution that have arbitrary shapes, arbitrary thicknesses, and either sharp or blunt noses. The centrifugal force correction arising from the curved trajectories followed by the fluid particles in unsteady flow cannot be neglected even for the case of a circular cone. With this correction, the present theory is in excellent agreement with experimental results for sharp cones and for cones with small nose bluntness; gives poor agreement with the results of experiments in air for bodies with moderate or large nose bluntness. The pitching motions of slender power-law bodies of revulution are shown to be always dynamically stable according to Newton-Busemann theory.

Hui, W. H.↗
NASA NTRS1980

Scaling of metabolic rate on body mass in small laboratory mammals

The scaling of metabolic heat production rate on body mass is investigated for five species of small laboratory mammal in order to define selection of animals of metabolic rates and size range appropriate for the measurement of changes in the scaling relationship upon exposure to weightlessness in Shuttle/Spacelab experiment. Metabolic rates were measured according to oxygen consumption and carbon dioxide production for individual male and female Swiss-Webster mice, Syrian hamsters, Simonsen albino rats, Hartley guinea pigs and New Zealand white rabbits, which range in mass from 0.05 to 5 kg mature body size, at ages of 1, 2, 3, 5, 8, 12, 18 and 24 months. The metabolic intensity, defined as the heat produced per hour per kg body mass, is found to decrease dramatically with age until the animals are 6 to 8 months old, with little or no sex difference. When plotted on a logarithmic graph, the relation of metabolic rate to total body mass is found to obey a power law of index 0.676, which differs significantly from the classical value of 0.75. When the values for the mice are removed, however, an index of 0.749 is obtained. It is thus proposed that six male animals, 8 months of age, of each of the four remaining species be used to study the effects of gravitational loading on the metabolic energy requirements of terrestrial animals.

Pace, N.↗