ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

1aPA8. Thermoacoustic sound source in the Helmholtz limit.

Richard Raspet

Jay A. Lightfoot

James R. Belcher

Henry E. Bass

Dept. of Phys. and Astron., Univ. of Mississippi, University, MS 38677

Thermoacoustic engines are placed in resonant cavities for Q amplification. Variations in the cross-sectional area of the resonator serve to reduce device volume and to minimize nonlinear distortion by detuning higher harmonics. In the case of a thermoacoustic sound source, these cross-sectional variations in the resonator area may be carried to an extreme such that the resonator approaches the Helmholtz limit. This limit produces a dimensionally compact, low-frequency thermoacoustic sound source. A thermoacoustic sound source in the Helmholtz limit has been constructed. The measured particle velocity and acoustic pressure in the device will be compared to Helmholtz idealization. [Work supported by ONR.]