A Study of Heat Driven Pressure Oscillations in a Gas

Abstract

Large amplitude acoustical pressure oscillations can be generated in a gas by a steady heat addition. The thermoacoustical oscillation known as the Sondhauss oscillation occurs in a pipe having only one closed end. Experiments were performed to determine thermoacoustic oscillator characteristics for different system geometries and for different operating conditions. Based on these experimental studies, a physical explanation of the mechanism causing Sondhauss thermoacoustical oscillations is presented. The driving mechanism consists of two separate components, that of driving by simple thermal expansion, and that of expansion by the mixing of hot and cold gas in the pipe. The initiation of the oscillations is discussed. Thermoacoustic oscillation phenomena are shown to be analogous to the interaction occurring in a regenerative heat engine, where a steady heat input causes an oscillating mechanical energy output. A comparison of experiment and generalized theory is presented.