Experimental-Analytic Dynamic Techniques to Determine Acoustic Response to Sonic Boom Within Structures

摘要

An experimental and theoretical progam was undertaken to determine the time history of the airborne pressure and the corresponding acoustic and structural response within architectural structures due to sonic boom transients, and to determine those features of sonic boom signature which tend to shape the interior acoustic waveform. A simple sonic boom wave generator was built in which small scale models of architectural structures were tested. The phenomenon of 'spiking' occured and was found to depend on the rise time of the incident wave, the window dimensions and the distance of the microphone from the window. Increase of incident wave rise time was found to radically alter the high frequency content of the room response. Although a completely closed structure did not generate internal pressure spikes, it was found that the wall acceleration was dependent on the incident wave pressure. Then in response to fast rise sonic boom waves, a simple wall could excite small objects, with high resonant frequency that might be coupled to the wall. A general mathematical procedure was developed to calculate system transfer functions from measured data. (Author)