ASA 124th Meeting New Orleans 1992 October

1pEA3. Impingement tones of axisymmetric choked jets on small plates.

Brenda Henderson

Alan Powell

Dept. of Mech. Eng., Univ. of Houston, Houston, TX 77204-4792

As reported previously, the impingement of axisymmetric choked jets on small normal flat plates produces two classes of intense tones. These occur with large amplitude oscillations of the stand-off shock wave that interacts with the shock also present in a free jet, while the sound waves emanate from at least two definite flow regions. In one class, the sound waves are quite impulsive and appear to be emitted from the stand-off shock region of the flow, the diameter of that shock and the jet varying periodically. The other class occurs when at least two shocks of the free jet are present. The influence of an upstream reflector implies that acoustic feedback to the nozzle occurs, while the preferred upstream radiation appears attributable to a simple source array at the multiple shocks in the supersonic conical deflected jet flow. [Work supported by Texas Advanced Research Program and NASA Graduate Fellowship Program.]