ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1pEA16. Panel response to jet noise under near sonic conditions.

Charles C. Fenno, Jr.

NASA Langley Res. Ctr., Hampton, VA 23681

Alvin Bayliss

Northwestern Univ., Evanston, IL 60208

Lucio Maestrello

NASA Langley Res. Ctr., Hampton, VA 23681

The problem of the response of an array of flexible aircraft-type panels excited by noise from a jet under near sonic conditions from a converging nozzle is numerically studied. The problem is computed by solving the Euler equations for the unsteady field in the jet, fully coupled to equations describing the panel motion. Computations of the far-field sound, panel response, and panel radiation are presented. The effect of nozzle geometry on the radiated sound and jet instabilities is studied. In addition, the relationship between panel location, relative to the jet exit, and panel response is determined. The computation simulates the development of large amplitude, slowly propagating instability waves in the jet which act as additional sources of sound. Thus the computation allows for direct computation of the natural sources of jet noise, as well as the propagation of the resulting jet noise. The results demonstrate large disturbances in the vicinity of the converging nozzle which act as additional sources of sound. The panel response is concentrated in progressively lower frequencies as distance from the jet exit increases.