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Seegmiller, H. L.

Publications and source records attributed to Seegmiller, H. L..

33 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

Application of laser velocimetry to an unsteady transonic flow

Measurements of mean velocity, turbulent kinetic energy, and turbulent shear stress have been obtained in an unsteady but periodic flow. Polystyrene spheres, 0.35-0.55 microns in diameter, were injected into the tunnel settling chamber to seed the flow for a laser velocimeter. Synchronized counters together with an encoding interface and digital-to-analog converters were used to record the data on an analog tape recorder. Profiles of velocity and turbulence quantities are presented for several times during the periodic flow.

Seegmiller, H. L.↗
NASA NTRS1978

Torquing preload in a lubricated bolt

The tension preload obtained by torquing a 7/8 in. diam UNC high strength bolt was determined for lubricated and dry conditions. Consistent preload with a variation of + or - 3% was obtained when the bolt head area was lubricated prior to each torque application. Preload tensions nearly 70% greater than the value predicted with the commonly used formula occurred with the lubricated bolt. A reduction to 39% of the initial preload was observed during 50 torque applications without relubrication. Little evidence of wear was noted after 203 cycles of tightening.

Seegmiller, H. L.↗
NASA NTRS1978

Steady and unsteady transonic flow

An investigation of the transonic flow over a circular arc airfoil was conducted to obtain basic information for turbulence modeling of shock-induced separated flows and to verify numerical computer codes which are being developed to simulate such flows. The investigation included the employment of a laser velocimeter to obtain data concerning the mean velocity, the shear stress, and the turbulent kinetic energy profiles in the flowfield downstream of the airfoil midchord where the flow features are more complex. Depending on the free-stream Mach number, the flowfield developed was either steady with shock-wave-induced separation extending from the foot of the shock wave to beyond the trailing edge or unsteady with a periodic motion also undergoing shock-induced separation. The experimental data were compared with the results of numerical simulations in which a computer code was employed that solved the time-dependent Reynolds' averaged compressible Navier-Stokes equations.

Seegmiller, H. L.↗
NASA NTRS1976

Evaluation of mean and turbulent velocity measurements in subsonic accelerated boundary layers

Exploratory measurements of the mean and turbulent flow in the wall boundary layer of a 15.2- by 10.2-cm channel were obtained as part of an instrumentation development program for measurements in compressible flow. Mean surface and flow field surveys were obtained at channel Mach numbers ranging from 0.2 to 0.9. The mean velocity distributions were obtained with total pressure probes and a laser velocimeter. At a channel Mach number of 0.2, several types of hot-wire probes were used to obtain both velocity fluctuations and Reynolds shear-stress results.

Sandborn, V. A.↗
NASA NTRS1976

An experimental and computational investigation of the flow field about a transonic airfoil in supercritical flow with turbulent boundary-layer separation

A combined experimental and computational research program for testing and guiding turbulence modeling within regions of separation induced by shock waves incident on turbulent boundary layers is described. Specifically, studies are made of the separated flow over the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include high-frequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.

Rubesin, M. W.↗
NASA NTRS1976

An experimental and computational investigation of the flow field about a transonic airfoil in supercritical flow with turbulent boundary-layer separation

A combined experimental and computational research program is described for testing and guiding turbulence modeling within regions of separation induced by shock waves incident in turbulent boundary layers. Specifically, studies are made of the separated flow the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include highfrequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling.

Rubesin, M. W.↗
NASA NTRS1976

Evaluation of mean and turbulent velocity measurements in subsonic accelerated boundary layers

Exploratory measurements of the mean and turbulent flow in the wall boundary layer of a 15.5- by 10.2-cm channel were obtained as part of an instrumentation development program for measurements in compressible flow. Mean surface and flow-field surveys were obtained at channel Mach numbers ranging from 0.2 to 0.9. The mean velocity distributions were obtained with total pressure probes and a laser velocimeter. At a channel Mach number of 0.2, several types of hot-wire probes were used to obtain both velocity fluctuations and Reynolds shear-stress results.

Sandborn, V. A.↗
NASA NTRS1972

Effects of roughness on heating and boundary-layer transition. Part 1: Effects of simulated panel joints on boundary-layer transition

The effects of distributed roughness, arising from space shuttle orbiter panel joints, on boundary layer transition are investigated. The North American Rockwell 134B delta wing shuttle configuration was used for the study. Results show: (1) Premature boundary layer transition occurred in models having simulated heat shield panels with rased joints. (2) Laminar flow was maintained with slot type panel joint models to a Reynolds number twice that at which transition occurred in raised joints. (3) Significant increases in peak surface temperature and the time during which turbulent flow occurs may result from distributed roughness of heat shield panel joints. (4) Laminar and turbulent heating levels were predicted within available theories. (5) A complex interference between the wing and fuselage flow was observed in the delta wing model.

Seegmiller, H. L.↗