Shock Expansion Tube as a Potentially Useful Tool for Sonic Boom Simulation

Abstract

Considering the emphasis being placed on studies of community reaction to sonic-boom phenomena, the simulation of these pressure transients has increased in economic and scientific importance. The expansion of shock waves produced by burst diaphragm techniques similar to those used in the shock tube provides waveforms that approximates the subjective pressure experienced during the onset of a sonic boom. Conventional shock-tube analysis, combined with Whitham's theory concerning the gas dynamics of a nonuniform channel, provides the basis for predicting the pressure time history of the waves generated in the expansion tube. Two shock tubes in a unique arrangement are attached to one acoustic horn. When the two burst diaphragms are subsequently punctured by an electrodynamically driven plunger, a pressure signature is generated which closely resembles the waveform subjectively experienced by an observer of a sonic boom. Experimental data are presented indicating the wide range of pressure amplitudes and pulse durations achievable utilizing this tool. [Work supported by the National Aeronautics and Space Administration, Langley Research Center.]