Mechanical Engineering ETDs

Publication Date



An experimental investigation was conducted to determine the effect of high static pressure on a closed thermoacoustic sound generator.

The theory for thermoacoustic oscillations is reviewed and analyzed for the case of elevated static pressure. Design equations for high internal pressure oscillators are developed from the principles of dimensional analysis, and a general de­sign equation is proposed.

A closed double-end thermoacoustic oscillator was designed to withstand high temperatures and pressures and was used in the experimental investi9ation. Both air and helium were used as the working gases.

The results of both the theoretical and experimental investigations show that acoustic sound-pressure level increases with static pressure as long as sufficient thermal power is supplied. The thermoacoustic and mechanical efficiencies were studied as functions of internal pressure. Thermoacoustic efficiency abruptly increases and then gradually decreases with increasing static pressure. Mechanical efficiency mono­tonically increases with increasing static pressure.

Criteria for the inception of thermoacoustic oscillations are developed. It is shown that the power required to initiate an oscillation is an exponential function of pressure. In addition, it is determined that at pressures above a certain minimum, the static mechanical efficiency becomes constant for the inception of oscillations. A criterion for the maintenance of a thermoacoustic oscillation, once it has been initiated, is also developed. It shown that the power required to sustain an oscillation is a linear function of pressure. A table of design data for thermoacoustic oscillations at ele­vated static pressures is presented.

Degree Name

Mechanical Engineering

Level of Degree


Department Name

Mechanical Engineering

First Committee Member (Chair)

Karl Thomas Feldman

Second Committee Member

Maurice Wilbert Wildin

Third Committee Member

Maurice Wilbert Wildin

Fourth Committee Member

William Ernest Baker

Document Type