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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 73 records · Page 4
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NASA NTRS1999

Turbulence Model Comparisons and Reynolds Number Effects Over a High-Speed Aircraft at Transonic Speeds

This paper gives the results of a grid study, a turbulence model study, and a Reynolds number effect study for transonic flows over a high-speed aircraft using the thin-layer, upwind, Navier-Stokes CFL3D code. The four turbulence models evaluated are the algebraic Baldwin-Lomax model with the Degani-Schiff modifications, the one-equation Baldwin-Barth model, the one-equation Spalart-Allmaras model, and Menter's two-equation Shear-Stress-Transport (SST) model. The flow conditions, which correspond to tests performed in the NASA Langley National Transonic Facility (NTF), are a Mach number of 0.90 and a Reynolds number of 30 million based on chord for a range of angle-of-attacks (1 degree to 10 degrees). For the Reynolds number effect study, Reynolds numbers of 10 and 80 million based on chord were also evaluated. Computed forces and surface pressures compare reasonably well with the experimental data for all four of the turbulence models. The Baldwin-Lomax model with the Degani-Schiff modifications and the one-equation Baldwin-Barth model show the best agreement with experiment overall. The Reynolds number effects are evaluated using the Baldwin-Lomax with the Degani-Schiff modifications and the Baldwin-Barth turbulence models. Five angles-of-attack were evaluated for the Reynolds number effect study at three different Reynolds numbers. More work is needed to determine the ability of CFL3D to accurately predict Reynolds number effects.

Rivers, Melissa B.↗
NASA NTRS1970

Space shuttle: MSFC booster (B-005) low speed static stability and landing investigation, high speed grit study

An experimental wind tunnel investigation on the Marshall Space Flight Center's (MSFC) booster configuration of the space shuttle system is discussed. Tests were conducted in the MSFC 14" x 14" trisonic wind tunnel. Parameters investigated include; (1) a landing study at Mach number of .3 with the booster at three discrete heights above a ground plane (maximum height above ground plane was six inches) and: (2) a static stability study at subsonic Mach numbers, which included eleven deflections of 0, 10, 20 and 30 degrees with canard deflections of 0, 5, 10 and 15 degrees. Both a trapezoidial and a delta shaped canard were investigated at the above conditions; a grit size study was made over the entire Mach range from .3 to 5.0.

Heim, D. E.↗
NASA NTRS1974

Aerodynamic investigations into various low speed L/D improvement devices on the 140A/B space shuttle orbiter configuration in the Rockwell International low speed wind tunnel (OA86)

Tests were conducted to investigate various base drag reduction techniques in an attempt to improve Orbiter lift-to-drag ratios and to calculate sting interference effects on the Orbiter aerodynamic characteristics. Test conditions and facilites, and model dimensional data are presented along with the data reduction guidelines and data set/run number collation used for the studies. Aerodynamic force and moment data and the results of stability and control tests are also given.

Mennell, R. C.↗
NASA NTRS1974

Balancing of high speed interconnect shafting for operation above multiple bending critical speeds

The present work first reviews the key elements of rotating system dynamics which are crucial to the control of lateral vibration levels for supercritical shafting of the type which is considered for use in advanced aircraft applications. Then the results of an analytical investigation of procedures for balancing flexible shafts designed for critical operation are discussed. Some of the conclusions made were: (1) even in undamped configuration, reasonably low vibration levels can be achieved through a sequential multiplane-multispeed balancing process; and (2) combination of analytical response and balancing prediction procedures yields a powerful tool for the dynamic analysis and design of advanced shaft-bearing systems.

Badgley, R. H.↗
NASA NTRS1976

Low-speed wind-tunnel investigation of the longitudinal stability characteristics of a model equipped with a variable-speed wing, 23 May 1949

The longitudinal stability characteristics of a complete model equipped with a variable sweep wings at angles of sweepback of 45 deg, 30 deg, 15 deg, and 0 deg investigated. Various wing modifications and an extern 1 flap arrangement designed to minimize the shift in neutral point accompanying the change in sweep angle were studied. The results indicate that stability at the stall was obtained at a sweep angle of 15 deg without recourse to stall control devices. The basic neutral point movement accompanying the change in sweep angle from 45 deg to 15 deg amounted to 56 percent of the mean aerodynamic chord (at zero sweep angle) and the most effective modification investigated only reduced this change to 47 percent of the chord. It appears, therefore, that for designs in which the fuselage is the major load carrying element some relative movement between the wing and center of gravity will be required to assure satisfactory stability at all sweep angles.

Donlan, C. J.↗