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Accession Number:
ADA278989
Title:
Expansion Effects on Supersonic Turbulent Boundary Layers
Corporate Author:
OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING
Report Date:
1994-02-01
Abstract:
The effects of various expansion regions on the large scale structure of a Mach 3 fully-developed-turbulent boundary layer are investigated. Five cases are studied 7 deg and 14 deg centered expansions, 7 deg and 14 deg gradual expansions, and the flat plate. Multi-point surface pressure measurements, filtered Rayleigh scattering visualizations, and double-pulse visualizations were employed. Plan view images of the flat plate boundary layer reveal the presence of structures of a very large streamwise, and limited spanwise, extent. These structures were found well above the inner layer, nominally at ndelta 0.5-1.0. The structures were also found in the expanded boundary layers. Across the expansion, the large scale structures of the outer layer undergo an increase in scale and structure angle. The small scale turbulent motions of the incoming boundary layer are quenched by the expansion, while the large scale structures respond more gradually. Convection velocities from the pressure correlations are reasonable in the incoming boundary layer, but unreasonably high in the expanded boundary layers. Convection velocities from correlations of double-pulse images appear reasonable. The discrepancy between the two results suggests the relationship between the large scale structures and the convecting pressure field is severely altered by the expansions.
Descriptive Note:
Final rept. 1 Sep 1991-31 Dec 1993
Pages:
0191
Distribution Statement:
Approved for public release; distribution is unlimited.
Contract Number:
AFOSR-91-0412
File Size:
7.70MB
