Accession Number : ADA289475

Title :   Compressible Turbulence Measurements in a Supersonic Boundary Layer Including Favorable Pressure Gradient Effects.

Descriptive Note : Master's thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s) : Miller, Raymond S.

PDF Url : ADA289475

Report Date : 13 DEC 1994

Pagination or Media Count : 115

Abstract : The effect of a favorable pressure gradient on the turbulent flow structure in a Mach 2.9 boundary layer (Re/m approx. 1.5 x 10(exp 7)) is investigated experimentally. Conventional flow and hot film measurements of turbulent fluctuation properties have been made upstream of and along an expansion ramp. Upstream measurements were taken in a zero pressure gradient boundary layer 44 cm from the nozzle throat in a 6.35 cm square test section. Measurements are obtained in the boundary layer, above the expansion ramp, 71.5 cm from the nozzle throat. Mean flow and turbulent flow characteristics are measured in all three dimensions. Comparisons are made between data obtained using single and multiple-overheat cross-wire anemometry as well as conventional mean flow probes. Conventional flow measurements were taken using a Pitot probe and a 10 degree cone static probe. Flow visualization was conducted via imaging techniques (Schlieren and shadowgraph photographs). Results suggest that compressibility effects, as seen through the density fluctuations in the Reynolds shear stress are roughly 10% relative to the mean velocity and are large relative to the velocity fluctuations. This is also observed in the total Reynolds shear stress; compressibility accounts for 50 - 75% of the total shear. This is particularly true in the favorable pressure gradient region, where though the peak fluctuation intensities are diminished, the streamwise component of the mean flow is larger, hence the contribution of the compressibility term is significant in the Reynolds shear.

Descriptors :   *PRESSURE GRADIENTS, *BOUNDARY LAYER, *TURBULENT FLOW, *SUPERSONIC FLOW, SHEAR PROPERTIES, STRESSES, VELOCITY, DENSITY, PEAK VALUES, PROBES, HIGH TEMPERATURE, INTENSITY, FILMS, THESES, TURBULENCE, TEST EQUIPMENT, COMPUTATIONAL FLUID DYNAMICS, FLOW VISUALIZATION, PRESSURE MEASUREMENT, VARIATIONS, SHEAR STRESSES, IMAGES, DATA REDUCTION, SUPERSONIC FLIGHT, EXPANSION, MACH NUMBER, MEAN, NAVIER STOKES EQUATIONS, HYPERSONIC FLIGHT, PITOT TUBES, REYNOLDS NUMBER, NOZZLE THROATS, RAMPS, COMPRESSIVE PROPERTIES, SCHLIEREN PHOTOGRAPHY, MOMENTUM TRANSFER, SPARK SHADOWGRAPH PHOTOGRAPHY.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE