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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Diffusive-convective vapor transport across horizontal and inclined rectangular enclosures

The enhancement of vapor transport across horizontal and inclined rectangular (two-dimensional) enclosures by expansive convection is studied numerically for a range in Grashof number that extends up to boundary layer flow. Comparison is made with predictions of the simplifying model and resulting analytical treatment of Klosse and Ullersma (1973) for various aspect ratios of the enclosure. The influence of varying Schmidt and Prandtl numbers is investigated. Solutions for interfacial (growth) flux and temperature distributions are given, showing practically important nonuniformities.

Markham, B. L.↗
NASA NTRS1988

Large inclination change using lunar-swingby techniques

The use of lunar-swingby maneuvers to transfer a spacecraft from an equatorial orbit to a polar orbit has been investigated in order to verify the technical feasibility of the NASA/ESA equatorial science phase (ESP)/Cluster mission. The solar aspect angle constraints of the spacecraft spin-axis and the dependence of the total Delta-V cost of the transfer on the initial ESP orbital parameters (particularly perigee radius and inclination) have been studied. The results indicate that a satisfactory ESP-to-Cluster orbit transfer can be achieved using a double lunar-swingby sequence.

Lee, T.↗
NASA NTRS1989

Numerical studies of convective heat transfer in an inclined semiannular enclosure

Natural convection heat transfer in a two-dimensional differentially heated semiannular enclosure is studied. The enclosure is isothermally heated and cooled at the inner and outer walls, respectively. A commercial software based on the SIMPLER algorithm was used to simulate the velocity and temperature profiles. Various parameters that affect the momentum and heat transfer processes were examined. These parameters include the Rayleigh number, Prandtl number, radius ratio, and the angle of inclination. A flow regime extending from conduction-dominated to convection-dominated flow was examined. The computed results of heat transfer are presented as a function of flow parameter and geometric factors. It is found that the heat transfer rate attains a minimum when the enclosure is tilted about +50 deg with respect to the gravitational direction.

Wang, Lin-Wen↗
NASA NTRS1989

Tidal evolution of the Uranian satellites. II - An explanation of the anomalously high orbital inclination of Miranda

It is proposed that the current, anomalously high orbital inclination of the Uranian satellite, Miranda, can be accounted for by temporary capture into the 3:1 resonance with Umbriel. This would imply that the orbits of the satellites have tidally evolved sufficiently to have permitted passage through this resonance. Escape from resonance is suggested to have occurred by way of a novel dynamical mechanism, in which the trajectory encounters low-order commensurabilities between the libration frequency of the resonant argument and other fundamental system frequencies.

Tittemore, William C.↗
NASA NTRS1989

Numerical studies of convective heat transfer in an inclined semi-annular enclosure

Natural convection heat transfer in a two-dimensional differentially heated semiannular enclosure is studied. The enclosure is isothermally heated and cooled at the inner and outer walls, respectively. A commercial software based on the SIMPLER algorithm was used to simulate the velocity and temperature profiles. Various parameters that affect the momentum and heat transfer processes were examined. These parameters include the Rayleigh number, Prandtl number, radius ratio, and the angle of inclination. A flow regime extending from conduction-dominated to convection-dominated flow was examined. The computed results of heat transfer are presented as a function of flow parameter and geometric factors. It is found that the heat transfer rate attains a minimum when the enclosure is tilted about +50 deg with respect to the gravitational direction.

Wang, L.-W.↗
NASA NTRS1991

Bending waves and orbital inclinations

Disk tides may play an important role in the formation of a planetary system. Modification of protoplanet semi-major axes and eccentricities through density waves was suggested and calculations of linear and non-linear protoplanet-nebula interactions were carried out by a number of researchers. The possible significance of radial drift to the accretion process was discussed, while the evolution of orbital eccentricities was studied for a perturber orbiting external to a ring and for a perturber embedded in the ring. The possible importance of bending waves to the early evolution of protoplanet inclinations is described.

Ward, William R.↗
NASA NTRS1991

Effect of solidity and inclination on propeller-nacelle force coefficients

A series of wind tunnel experiments were conducted to study the effect of propeller solidity and thrust axis inclination on the propeller normal force coefficient. Experiments were conducted in the Langley 14 by 22 foot Subsonic Tunnel with a sting mounted, counterrotation, scale model propeller and nacelle. Configurations had two rows of blades with combinations of 4 and 8 blades per hub. The solidity was varied by changing the number of blades on both rows. Tests were conducted for blade pitch setting of 31.34 deg, 36.34 deg, and 41.34 deg over a range of angle of attack from -10 deg to 90 deg and range of advance ratio from 0.8 to 1.4. The increase in propeller normal force with angle of attack is greater for propellers with higher solidity.

Gentry, Garl L., Jr.↗
NASA NTRS1992

A reanalysis of the orbital inclination of Cygnus XR-1 determined polarimetrically

The orbital inclination of the Cyg XR-1/HDE 226868 system was determined by Dolan and Tapia (1989) to be 62 deg (+5 deg, -37 deg) from polarimetric observations. Together with the spectroscopic mass function of the binary, this corresponds to a mass of 6.3 solar masses for the X-ray source. Numerical simulations show that there is no straightforward way to removing tidal deformation polarization (TDP) from polarimetric observations of close binaries. A reanalysis of the data shows that the existence of TDP in the Stokes parameter light curves observed from Cyg XR-1 does not significantly bias the mass derived to larger values. The mass of Cyg XR-1 must be significantly larger than 5 solar masses. This fact alone does not require Cyg XR-1 to be a black hole, however. Recent theoretical investigations of possible equations of state of matter at nuclear density show that the maximum mass of a compact object which is not a black hole may be much greater than 5 solar masses.

Dolan, Joseph F.↗
NASA NTRS1991

Inclination distributions and size measurements of hemlock and red spruce needles

Needle inclination angle distributions were plotted for 5 and 10 deg intervals for two hemlock trees and one red spruce. The distributions for the hemlock and spruce were similar, with the peak normal angle occurring between 10 and 20 deg. These distributions are between two theoretical (planophile and spherical) leaf angle distributions. The results can be used as an input to radiative transfer models that require a distribution of the orientation of the scattering elements of the canopy.

Kimes, Daniel S.↗
NASA NTRS1992

On the distribution of minor planet inclinations

The distribution of minor planet orbits with inclination to the ecliptic plane and with respect to the Jupiter orbit is studied. Position of the plane considered as the mean plane of the asteroid belt is determined.

Shor, Viktor A.↗
NASA NTRS1993

A three-dimensional algebraic grid generation scheme for gas turbine combustors with inclined slots

A 3D algebraic grid generation scheme is presented for generating the grid points inside gas turbine combustors with inclined slots. The scheme is based on the 2D transfinite interpolation method. Since the scheme is a 2D approach, it is very efficient and can easily be extended to gas turbine combustors with either dilution hole or slot configurations. To demonstrate the feasibility and the usefulness of the technique, a numerical study of the quick-quench/lean-combustion (QQ/LC) zones of a staged turbine combustor is given. Preliminary results illustrate some of the major features of the flow and temperature fields in the QQ/LC zones. Formation of co- and counter-rotating bulk flow and shape temperature fields can be observed clearly, and the resulting patterns are consistent with experimental observations typical of the confined slanted jet-in-cross flow. Numerical solutions show the method to be an efficient and reliable tool for generating computational grids for analyzing gas turbine combustors with slanted slots.

Yang, S. L.↗
NASA NTRS1993

Effects of inclination angle on the spectra of X-ray binaries

Iron emission and absorption features from nine X-ray binaries are compared with a model that predicts characteristics of iron K-shell features corresponding to different viewing angles for the accretion disk. In this model, emission and absorption features arise from an accretion disk corona whose structure is computed under the assumptions of ionization, thermal, and hydrostatic balance of gas illuminated by the central continuum source. Hence the equivalent widths of the emission and absorption features are predicted without the introduction of any free parameters to control the physical conditions in the disk corona. Our data/model comparison suggests an explanation for the equivalent widths of the iron K-alpha emission and the depth of the absorption edge in terms of (1) the angle of inclination between the observer's line of sight and the plane of the accretion disk and (2) the shape of the incident source spectrum.

Vrtilek, S. D.↗
NASA NTRS1993

Reliability of magnetic inclination angle determinations for pulsars

We compare the recent estimates of the inclination angle alpha between the rotation and magnetic axes of 56 pulsars made by both Lyne and Manchester (1988) and Rankin (1990). Their results agree reasonably well when alpha is less than about 40 deg; however, there is no correlation between the two estimates of alpha if either estimate exceeds 40 deg. The correlation is better for pulsars with beams having more complicated core structure. Nevertheless, the differences between the two sets of estimates are large enough that use of these estimates to investigate pulsar physics is questionable. We discuss the method for determining alpha based on the Radhakrishnan and Cooke (1969) single-vector model, emphasizing its sensitivity to measurement errors. This method complements the approaches of Rankin and Lyne and Manchester and is preferable when accurate polarization data are available.

Miller, M. C.↗
NASA NTRS1955

Application of the Generalized Shock-expansion Method to Inclined Bodies of Revolution Traveling at High Supersonic Airspeeds

The generalized shock-expansion method is applied to obtain solutions to the flow field about pointed bodies of revolution at high supersonic airspeeds and small angles of attack. Simple explicit expressions are obtained for the surface Mach numbers and surface pressures in the special case of slender bodies. In the case of inclined cones, algebraic solutions are obtained defining the entire flow field. Experimental pressure-distribution data for cones and ogives at Mach numbers from 3 to 5 are included. (author)

Savin, Raymond C↗
NASA NTRS1953

Comparison of the Experimental and Theoretical Distribution of Lift on a Slender Inclined Body of Revolution at M = 2

Pressure distributions and force characteristics have been determined for a body of revolution consisting of a fineness ratio 5.75, circular-arc, ogival nose tangent to a cylindrical afterbody for an angle-of-attack range of 0 degrees to 35.5 degrees. The free-stream Mach number was 1.98 and the free-stream Reynolds number was approximately 0.5 x 10 sup 6, based on body diameter. Comparison of the theoretical and experimental pressure distributions shows that for zero lift, either slender-body theory or higher-order theories yield results which are in good agreement with experiment. For the lifting case, good agreement with theory is found only for low angles of attack and for the region in which the body cross-sectional area is increasing in the downstream direction. Because of the effects of cross-flow separation and the effects of compressibility due to the high cross-flow Mach numbers at large angles of attack, the experimental pressure distributions differ from those predicted by potential theory. Although the flow about the inclined body was, in general, similar to that assumed as the basis for Allen's method of estimating the forces resulting from viscous effects (NACA RM A91I26), the distribution of the forces was significantly different from that assumed. Nevertheless, the lift and pitching-moment characteristics were in fair agreement with the estimated value.

Perkins, Edward W↗
NASA NTRS1951

A Study of Effects of Viscosity on Flow over Slender Inclined Bodies of Revolution

The observed flow field about slender inclined bodies of revolution is compared with the calculated characteristics based upon potential theory. The comparison is instructive in indicating the manner in which the effects of viscosity are manifest. Based on this and other studies, a method is developed to allow for viscous effects on the force and moment characteristics of bodies. The calculated force and moment characteristics of two bodies of high fineness ratio are shown to be in good agreement, for most engineering purposes, with experiment. (author)

Allen, H Julian↗
NASA NTRS1927

The effect of flight path inclination on airplane velocity

This report was prepared at the request of the National Advisory Committee for Aeronautics in order to supply a systematic study of the relations between the flight velocity V and its horizontal component V subscript H, in power glides. Curves of V and V subscript H plotted against the inclination of the flight path 0 are given, together with curves which show the maximum values of V subscript H and the corresponding values of 0. Curves are also given showing the effect of small departures from the horizontal in high speed performance testing.

Diehl, Walter S↗
NASA NTRS1954

A Wind-Tunnel Investigation of the Effects of Thrust-Axis Inclination on Propeller First-Order Vibration

Data on the aerodynamic excitation of first-order vibration occurring in a representative three-blade propeller having its thrust axis inclined to the airstream at angles of 0 degree, 4.55 degrees, and 9.80 degrees are included in this report. For several representative conditions the aerodynamic excitation has been computed and compared with the measured values. Blade stresses also were measured to permit the evaluation of the blade stress resulting from a given blade aerodynamic excitation. It was concluded that the section aerodynamic exciting force of a pitched propeller may be computed accurately at low rotational speeds. As section velocities approach the speed of sound, the accuracy of computation of section aerodynamic exciting force is not always so satisfactory.

Gray, W H↗