ASA 124th Meeting New Orleans 1992 October

2pPA9. A ray theory model of sonic boom propagation through a turbulent ground layer.

Leick Robinson

Appl. Res. Labs., Univ. of Texas at Austin, Austin, TX 78712-8029

The ZEPHYRUS computer model has been developed to calculate sonic boom propagation through a realistic, nonturbulent atmosphere [L. Robinson, Ph. D. thesis, Univ. of Texas at Austin (December 1991)]. A technique is presented to extend this model to include the effects of a turbulent atmospheric ground layer on the shape of sonic boom waveforms. Ray theory is used to model the effects of refraction and subsequent folding of the wave front by an instantaneous realization of the turbulence. The problem of maintaining wave-front coherence and efficient eigenray identification algorithms are discussed. A Monte Carlo method is used to form a statistical ensemble of predicted sonic boom waveforms. These results are compared with characteristics observed in sonic boom measurements. [Work supported by NASA---Langley.]