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

1pPA11. Application of model experiment data to test sonic-boom propagation models.

Bart Lipkens

MacroSonix, 1054 Technology Park Dr., Glen Allen, VA 23060

Model experiments are successful in simulating the propagation of sonic booms through the atmospheric turbulent boundary layer. In the model experiment spark-produced N waves propagate across the turbulent flow field of a plane jet. The N waves are measured by a wide band condenser microphone and the turbulence is measured by hot-wire anemometry. The results from the model experiment, pressure waveforms and turbulence characteristics, are used to test various sonic-boom models for propagation through turbulence. Both waveform distortion models and rise time prediction models are tested. Only Pierce's model [A. D. Pierce, 906--924 (1971)] based on the wavefront folding mechanism at a caustic yields a fairly accurate prediction for the rise time of the mean waveform after propagation through the turbulence. Results from other models are not confirmed by the model experiment data. [Work supported by NASA Langley.]