Controlled Experiments on Instabilities and Transition to Turbulence on Elliptic Cones at Hypersonic Mach Numbers
Final rept. 1 Feb 1998-31 Oct 1999
NOTRE DAME UNIV IN DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
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This work involves the study of instabilities and transition to turbulence in boundary layers on cones at different angles of attacks at high supersonic and hypersonic Mach numbers. It utilizes facilities at NASA Langley Research Center which make use of quiet design nozzles to minimize the level of acoustic disturbances. The experiments include design Mach numbers of 3.5, and 8.0, and involve two models. The first is a 70 half-angle circular cross-section cone which has been previously used by us Cavalieri, 1995 Corke Cavalieri. 1997 Corke, Cavalieri Matlis, 1997 in experiments without angle of attack, at Mach 3.5. We used this model during the past year in order to investigate the effects of angles of attack and free-stream disturbances at Mach 3.5. The second model was designed and constructed during the past year. It consists of a 100 half-angle cone with a 41 elliptic cross section. The cone mounts on a sting which places it inside the worst-case estimate of the location of the quiet zone in the new Mach 8 tunnel at NASA LaRC. The model is annealed and hardened to withstand the 9000F free-stream temperature nd maintain a polished finish. A 3-D traversing mechanism capable or following the taperad elliptic surface, and operating at high temperatures in the hypersonic flow is presently being built. This will carry a miniature pitot probe or hot-wire sensor. Preliminary measurements with the elliptic cone at Mach 8 are planned for October.
- Fluid Mechanics