Prediction of the Micro-pressure Waves Using an Unsteady Acoustic Analysis

Abstract

Micro-pressure waves (MPWs) radiated from a tunnel portal were numerically analyzed using unsteady acoustic analysis. First, the compression waveforms at the tunnel entrance were decided by linear acoustic analysis. Next, the nonlinear distortion of the compression waveform accompanying tunnel propagation was calculated using 1D theoretical propagation equation. Finally, the radiated MPWs were calculated by point source approximation. This research demonstrates that even if the difference in the waveform of the compression waves is slight at the tunnel entrance, it appears as considerable difference in MPW when the effects of the nonlinear distortion of the compression wave are taken into account.