Hydrodynamics of tire hydroplaning.
Tire hydroplaning, noting lift force on planing surface and pressure distribution
LIFT COEFFICIENT↗
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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 model of the open magnetosphere
The Chapman-Ferraro image method is extended to construct an idealized model of the open magnetosphere that responds to a change of the interplanetary field direction as well as to a change of the field magnitude or of the solar wind momentum flux. The magnetopause of the present model is an infinite plane surface having a normal field component distribution that is consistent with the merging theory. An upper limit on the inward displacement of the magnetopause following a southward turning of the interplanetary field is obtained. The results are in fair agreement with a single event reported by Aubry et al. (1971). The model determines the field configuration and the total magnetic flux connecting the magnetosphere to interplanetary space.
Kan, J. R.↗
The oblique impingement of an axisymmetric jet
The mechanics of the oblique impingement of an axisymmetric jet on a plane surface are examined in detail. The stagnation point is discussed. A schematic drawing of the problem and coordinate system used to describe the flow field are given. The kinematic features of the flow above the plate are examined in the context of the conservation of mass, the vorticity of the jet, and the vorticity introduced by the jetplate interaction. The dynamic features of the flow are examined in terms of the surface pressure distribution and the cause-effect relationships which exist between the pressure and velocity/vorticity distributions. Flow calculations performed are given. The investigation is relevant to the flow resulting from the interaction of the propulsion jet with the main airfoil (STOL aircraft), and is appropriate to an over- or under- wing configuration.
Foss, J. F.↗
Space shuttle engineering and operations support. Isolation between the S-band quad antenna and the S-band payload antenna. Engineering systems analysis
The isolation between the upper S-band quad antenna and the S-band payload antenna on the shuttle orbiter is calculated using a combination of plane surface and curved surface theories along with worst case values. A minimum value of 60 db isolation is predicted based on recent antenna pattern data, antenna locations on the orbiter, curvature effects, dielectric covering effects and edge effects of the payload bay. The calculated value of 60 db is significantly greater than the baseline value of 40 db. Use of the new value will result in the design of smaller, lighter weight and less expensive filters for S-band transponder and the S-band payload interrogator.
Lindsey, J. F.↗
A correspondence principle for steady-state wave problems
A correspondence principle was developed for treating the steady state propagation of waves from sources moving along a plane surface or interface. This new principle allows one to obtain, in a unified manner, explicit solutions for any source velocity. To illustrate the correspondence principle in a particular case, the problem of a load moving at an arbitrary constant velocity along the surface of an elastic half-space is considered.
Schmerr, L. W.↗
Investigation of blown boundary layers with an improved wall jet system
The behavior of two dimensional incompressible turbulent wall jets submerged in a boundary layer when they are used to prevent boundary layer separation on plane surfaces is investigated. The experimental set-up and instrumentation are described. Experimental results of zero pressure gradient flow and adverse pressure gradient flow are presented. Conclusions are given and discussed.
Saripalli, K. R.↗
Development of basic theories and techniques for determining stresses in rotating turbine or compressor blades
A method for measuring in-plane displacement of a rotating structure by using two laser speckle photographs is described. From the displacement measurements one can calculate strains and stresses due to a centrifugal load. This technique involves making separate speckle photographs of a test model. One photograph is made with the model loaded (model is rotating); the second photograph is made with no load on the model (model is stationary). A sandwich is constructed from the two speckle photographs and data are recovered in a manner similar to that used with conventional speckle photography. The basic theory, experimental procedures of this method, and data analysis of a simple rotating specimen are described. In addition the measurement of in-plane surface displacement components of a deformed solid, and the application of the coupled laser speckle interferometry and boundary-integral solution technique to two dimensional elasticity problems are addressed.
Chien, C. H.↗
Numerical solutions of atmospheric flow over semielliptical simulated hills
Atmospheric motion over obstacles on plane surfaces to compute simulated wind fields over terrain features was studied. Semielliptical, two dimensional geometry and numerical simulation of flow over rectangular geometries is also discussed. The partial differential equations for the vorticity, stream function, turbulence kinetic energy, and turbulence length scale were solved by a finite difference technique. The mechanism of flow separation induced by a semiellipse is the same as flow over a gradually sloping surface for which the flow separation is caused by the interaction between the viscous force, the pressure force, and the turbulence level. For flow over bluff bodies, a downstream recirculation bubble is created which increases the aspect ratio and/or the turbulence level results in flow reattachment close behind the obstacle.
Shieh, C. F.↗
LPE growth of 1.3 micron InGaAsP CW lasers on /110/ InP substrates
A description is presented of the liquid-phase epitaxial (LPE) growth of high-quality InGaAsP/InP continuous-wave (CW) laser structures on (110) InP substrates using conventional LPE without the need for special growth procedures. Double heterojunction laser structures were grown using the LPE supercooling method with a horizontal sliding boat. Low broad-area current densities (970 A/sq cm) and CW operation achieved at room temperature indicate that results comparable to up-to-date devices may be achieved. The inherent tendency for surface planarity maintenance due to the perfect surface stoichiometry of the (110) surface is a feature that may lend itself to the generation of improved interface growth in quaternary III-V and related semiconductor alloy systems. The similar cross-sectional appearance of structures grown on (110) and (100) orientations show that conventional LPE can be used with (110) surface planes without introducing special growth procedures.
Hawrylo, F. Z.↗
Infrared-Responsive Monolithic MOS Circuit
Lead chalcogenide photoresistors integrated with FET amplifiers. Circuit combines voltage divider containing lead chalcogenide photoresistor with FET source follower. Source and drain of FET p-doped regions in underlying n-type silicon wafer. All other structures formed at or deposited above original surface plane of wafer.
Jhabvala, Muzban D.↗
Analysis of multispectral data using an unsupervised classification technique: Application to VAS
A statistical classification method based on clustering of multidimensional histograms was applied to several channels of the VAS multispectral imagery. The method automatically discriminates and classifies atmospheric ground features such as cloud types, atmospheric moisture patterns, ocean, or ground. Such a clustering method has the advantage of forming natural data groupings, without a priori classification. Clusters are not limited by straight lines or plane surfaces as is the case in threshold methods. The method was applied to simultaneous full resolution images from channels 8 (11.2 micron), 10 (6.7 micron), and 12 (3.9 micron). Twenty image segments of 64 by 64, 12 image segments of 128 by 128, and 4 image segments of 254 by 254 picture elements were analyzed. In addition, normal VISSR mode images at 1800, 1830, and 2000 GMT were used to identify the classes. The gray levels measured along a scan line and the result of the classification scheme (dashed curves) for the three channels investigated are shown. Each point of the image is affected to a class. Each class is identified by a center of gravity that is represented by a vector in the three dimensional space of gray levels.
Szejwach, G.↗
Analysis of coolant entrance boundary shape of porous region to control cooling along exit boundary
A cooled porous region has a plane surface exposed to a specified spatially varying heat flux. The coolant leaves the region through this surface, and it is desired to control the flow distribution to maintain a specified uniform surface temperature. This is accomplished by having the coolant entrance surface shaped to provide in the region the necessary variation of path length and, hence, flow resistance. The surface shape at the coolant entrance is found by solving a Cauchy boundary value problem. An exact solution is obtained that will deal with a wide variety of heating distributions for both two- and three-dimensional shapes.
Siegel, R.↗
X-ray spectrographs using radial groove gratings
A high efficiency spectrograph design for the EUV and soft X rays is presented. This grazing incidence system uses a plane surface reflection grating with rulings that are radial, like the spokes of a wheel. The grating is placed in a beam of light that is converging to a focus. The single reflection off the grating is in the conical diffraction mount ensuring maximum performance from the system. Aberrations and performance levels are discussed. The gratings can be manufactured with existing ruling engines. Sample applications to an X-ray monochromator and an EUV stellar spectrograph are discussed.
Cash, W. C., Jr.↗
Turbulent Boundary Layers in Oscillating Flows. Part 1: an Experimental and Computational Study
An experimental-computational study of the behavior of turbulent boundary layers for oscillating air flows over a plane surface with a small favorable mean pressure gradient is described. Experimental studies were conducted for boundary layers generated on the test section wall of a facility that produces a flow with a mean free stream velocity and a superposed nearly-pure sinusoidal component over a wide range of frequency. Flow at a nominal mean free stream velocity of 50 m/s were studied at atmospheric pressure and temperature at selected axial positions over a 2 m test length for frequencies ranging from 4 to 29 Hz. Quantitative experimental results are presented for unsteady velocity profiles and longitudinal turbulence levels obtained from hot wire anemometer measurements at three axial positions. Mean velocity profiles for oscillating flows were found to exhibit only small deviations from corresponding steady flow profiles, while amplitudes and phase relationships exhibited a strong dependence on axial position and frequency. Since sinusoidal flows could be generated over a wide range of frequency, studies at fixed values of reduced frequency at different axial positions were studied. Results show that there is some utility in the use of reduced frequency to correlate unsteady velocity results. The turbulence level u' sub rms was observed to vary essentially sinusoidally around values close to those measured in steady flow. However, the amplitude of oscillation and phase relations for turbulence level were found to be strongly frequency dependent. Numerical predictions were obtained using an unsteady boundary layer computational code and the Cebeci-Smith and Glushko turbulence models. Predicted quantities related to unsteady velocity profiles exhibit fair agreement with experiment when the Cebeci-Smith turbulence model is used.
Cook, W. J.↗
An experimental and computational study of turbulent boundary layers in oscillating flows
An experimental-computational study of the behavior of turbulent boundary layers for oscillating air flows over a plane surface with a small favorable mean pressure gradient is described. Experimental data were obtained for boundary layers generated on the test section wall of a new type of facility that produces a mean flow velocity with a superposed sinusoidal component over a wide frequency range. Experimental results for unsteady velocity profiles and turbulence intensity obtained from hot wire measurements at a fixed stream-wise position on the surface are presented for frequencies ranging from 5 to 21 Hz. Numerical predictions were obtained using an unsteady boundary layer computational code and the Cebeci-Smith and Glushko turbulence models. Predicted quantities related to unsteady velocity profiles exhibit fair agreement with experiment when the Cebeci-Smith model is used.
Cook, W. J.↗
On the viscoplastic response of a composite wafer
In the present treatment of a viscoplastic composite wafer formed from a viscoplastic matrix that is reinforced by elastic or viscoplastic fibers attached to its plane surfaces, one constitutive equation is established by considering the viscoplastic behavior of the matrix as determined by an integral-type constitutive law whose intrinsic time-measure is pertinent to endochronic viscoplasticity. Attention is given to asymptotic cases where fiber stiffnesses and the hydrostatic modulus of the wafer are much larger than the latter's shear modulus. An explicit calculation is used when the stress field is uniaxial.
Valanis, K. C.↗
Near-field acoustic environment of a supersonic plume adjacent to a wall
The interaction of a supersonic plume with an adjacent plane surface has been studied using phase-conditioned schlieren flow visualization and near-field microphone measurements. As a consequence of interaction with the wall, the round and 3:1 rectangular/divergent nozzle configurations generated the most intense screech at about one throat diameter from the wall. It is found that the low-aspect-ratio rectangular nozzle has a screech oscillation parallel to the wall which is enhanced by proximity to the wall.
Wlezien, R. W.↗
Measurement of the light flux density patterns from luminaires proposed as photon sources for photosynthesis during space travel
Two luminaires were evaluated to determine the light flux density pattern on a horizontal plane surface. NASA supplied both luminaires; one was made by NASA and the other is commercially available. Tests were made for three combinations of luminaire height and luminaire lens material using the NASA luminaire; only one configuration of the commercial luminaire was tested. Measurements were made using four sensors with different wavelength range capabilities. The data are presented in graphical and tabular formats.
Walker, Paul N.↗