The Effect of Thermal Barriers on Sound Wave Propagation

Abstract

Sound propagation through regions of non-uniform temperature distribution in a gas is studied numerically. The main objective of this study is to determine the impact of temperature gradients on the sound wave parameters and to evaluate the effectiveness of using regions of hot gas as sound barrier. Such regions of hot gas (low acoustic impedance) can be generated by remotely depositing energy into a selected volume of gas, for example, by means of electrical discharge. Sound attenuation through the hot gas region is studied systematically for a range of sound wave and thermal field parameters by solving the two-dimensional unsteady compressible Euler's equations along with the ideal gas state equation using a finite volume scheme. Particular attention is given to the practical case when sound wavelength is comparable to the thickness of the thermal barrier. The present two-dimensional model indicates that considerable sound attenuation can be achieved at large incidence angles and a critical angle for total internal reflection is possible.