Accession Number : ADA322309

Title :   Laminar-Turbulent Transition in High-Speed Compressible Boundary Layers with Curvature: Controlled Receptivity and Extent-of-Transition Measurements.

Descriptive Note : Final rept. 15 Nov 93-14 Nov 96,

Corporate Author : PURDUE UNIV LAFAYETTE IN

Personal Author(s) : Schneider, Steven P. ; Collicott, Steven H.

PDF Url : ADA322309

Report Date : 16 JAN 1997

Pagination or Media Count : 12

Abstract : This grant supported experimental research into two aspects of the transition mechanisms on an elliptic cross section cone, at zero angle of attack. The Purdue Mach-4 Quiet Flow Ludwieg Tube was completed, allowing measurements under low noise conditions comparable to flight. The boundary layer on the elliptic cone was laminar to the maximum quiet flow length Reynolds number of 400,000, despite preliminary e**N transition estimates suggesting transition at 100,000. Apparatus was developed for generating repeatable perturbations, so that unambiguous and repeatable results can be obtained; this development continues. Repeatable localized perturbations were successfully generated abead of the cone, using a pulsed laser. The receptivity and instabilities of a hemispherical nose and a forward facing cavity were studied by measuring the development of the perturbations as they convected through the shock wave into the body. Measurements of the laser spot convecting into the elliptic cone boundary layer are continuing, although preliminary measurements indicate that the growth of the disturbance is small. Controlled localized perturbations are also being generated at the surface of the cone, using a glow discharge perturber. Finally, progress was made toward the design and fabrication of a larger Ludwieg tube with a higher quiet flow Reynolds number.

Descriptors :   *BOUNDARY LAYER TRANSITION, *WIND TUNNELS, SHOCK WAVES, TURBULENT FLOW, PERTURBATIONS, GLOW DISCHARGES, SUPERSONIC FLOW, INSTABILITY, REYNOLDS NUMBER, HOT WIRE ANEMOMETERS, LOW NOISE, HYPERSONIC FLOW, LASER SPOTS, OPTICAL INSTRUMENTS.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE