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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Does a 'two-stream' flow model apply to wakes of large bodies in space

Structural patterns of ion and electron currents observed on the wake axes of the Ariel I and the Gemini 10 space vehicles are reexamined, together with relevant theoretical and laboratory 'simulation' studies. Some insight into existing in situ data is provided. The possibility that 'converging-stream' models describe structural features of current enhancements in the wake region of large spacecraft is discussed.

Samir, U.↗
NASA NTRS1979

Evaluation of the discrete vortex wake cross flow model using vector computers. Part 1: Theory and application

The current program had the objective to modify a discrete vortex wake method to efficiently compute the aerodynamic forces and moments on high fineness ratio bodies (f approximately 10.0). The approach is to increase computational efficiency by structuring the program to take advantage of new computer vector software and by developing new algorithms when vector software can not efficiently be used. An efficient program was written and substantial savings achieved. Several test cases were run for fineness ratios up to f = 16.0 and angles of attack up to 50 degrees.

Source record↗
NASA NTRS1979

Two-dimensional zonal mean flow model

The interactions of dynamics, photochemistry and radiation in the stratosphere can be described by the continuity, momentum, and energy equations. A more comprehensive model for stratospheric transport theory was developed for the purpose of aiding predictions of changes in the stratospheric ozone content as a consequence of natural and anthropogenic processes. This model is time dependent and the dependent variables are zonal means of the relevant meteorological quantities which are functions of latitude and height. The detailed formulation of a numerical model both in physics and mathematics is given. A set of fundamental dynamical equations, and the numerical method used in the integration are described.

Chen, H. C.↗
NASA NTRS1978

Flap survey test of a combined surface blowing model: Flow measurements at static flow conditions

The Combined Surface Blowing (CSB) V/STOL lift/propulsion system consists of a blown flap system which deflects the exhaust from a turbojet engine over a system of flaps deployed at the trailing edge of the wing. Flow measurements consisting of velocity measurements using split film probes and total measure surveys using a miniature Kiel probe were made at control stations along the flap systems at two spanwise stations, the centerline of the nozzle and 60 percent of the nozzle span outboard of the centerline. Surface pressure measurements were made in the wing cove and the upper surface of the first flap element. The test showed a significant flow separation in the wing cove. The extent of the separation is so large that the flow into the first flap takes place only at the leading edge of the flap. The velocity profile measurements indicate that large spanwise (3 dimensional) flow may exist.

Fukushima, T.↗
NASA NTRS1984

A unified data flow model for fault tolerant computers

The Dataflow Simulation System (DFSS) at USL was used as the medium on which a functional simulaton of sIFT was produced. DFSS is written in PL/I and is supported by MULTICS. Within the simulation, all the interprocessor communication, fault simulation, system state data, and monitoring were implemented in dataflow and supported directly by DFSS. The actual processor level computation was carried out by the SIFT code in PASCAL. The interface between DFSS in PL/I and the SIFT code in PASCAL was supported under a mechanism in DFSS called a Node Realization Module (NRM).

Rao, T. R.↗
NASA NTRS1985

Computations and turbulent flow modeling in support of helicopter rotor technology

The angle of attack (AOA) tandem cavity wind tunnel experiment was prepared. Actual wind tunnel testing started shortly after the beginning of 1985. A multi-probe aerodynamic rake was designed and installed for use in surveying the shear layers present over the open cavity on the Kuiper Airborne Observatory (KAO). The nature of the behavior of the thermal environment within the KAO cavity at operational altitudes was determined. Assistance was given in the design of the cavity for the University of Denver radiometer. Attempts to distinguish between the optical terms of blur circle size (or image size) and the term due to jitter were discussed.

Rose, W. C.↗
NASA NTRS1985

A granular flow model for dense planetary rings

In the present study of the viscosity of a differentially rotating particle disk, in the limiting case where the particles are densely packed and their collective behavior resembles that of a liquid, the pressure tensor is derived from both the equations of hydrodynamics and a simple kinetic model of collisions due to Haff (1983). Density waves and narrow circular rings are unstable if the liquid approximation applies, and the consequent nonlinear perturbations may generate 'splashing' of the ring material in the vertical direction. These results are pertinent to the origin of the ellipticities of ringlets, the nonaxisymmetric features near the outer edge of the Saturn B ring, and unexplained residuals in kinematic models of the Saturn and Uranus rings.

Borderies, N.↗
NASA NTRS1988

Turbofan forced mixer lobe flow modeling. Part 3: Application to augment engines

Military engines frequently need large quantities of thrust for short periods of time. The addition of an augmentor can provide such thrust increases but with a penalty of increased duct length and engine weight. The addition of a forced mixer to the augmentor improves performance and reduces the penalty, as well as providing a method for siting the required flame holders. In this report two augmentor concepts are investigated: a swirl-mixer augmentor and a mixer-flameholder augmentor. Several designs for each concept are included and an experimental assessment of one of the swirl-mixer augmentors is presented.

Barber, T.↗
NASA NTRS1990

On near-wall turbulent flow modelling

The behavior of various terms in the Reynolds-stress transport equations is evaluated in view results of near-wall turbulence characterizations which show that all components of the velocity-pressure gradient correlation vanish at the wall. A methodology for deriving an asymptotically correct model of the velocity-pressure gradient correlation is proposed, and a model capable of approaching the high-Reynolds number model for pressure distribution far from the wall is derived. A parametric study of the model constants introduced by the near-wall closure reveals that one constant in the dissipation-rate equation is Reynolds number-dependent; with this modification, excellent agreement is obtained with measured and simulated near-wall turbulence statistics.

Lai, Y. G.↗