Airborne shocks: Measurement methods and challenges.

Abstract

While most nonlinear phenomena are intriguing, the nature and behavior of acoustic shocks are particularly captivating. Rather ordinary sources can produce traveling wave fronts with pressure rises approaching 1% of atmospheric pressure on microsecond time scales. The resulting pressure signature can be challenging to record accurately; such measurements often require special sensors and always require an understanding of the influence of the sensor on the pressure field. Without careful design, such a measurement can become a characterization of the microphone itself with little information about the shock. There are a number of techniques for correcting the aberrations introduced by measurement microphones and a number of approaches to constructing special sensors. This presentation will summarize a subset of these techniques primarily in the context of measurement of weak shocks—shocks that travel at approximately the ordinary speed of sound but that have rise times from 10 μs down to a few tenths of a microsecond.