Measurements of thermoacoustic functions for single uniform pores

Abstract

In previous work, a technique to measure the thermoacoustic properties of single pores was described [L. Wilen, J. Acoust. Soc. Am. 101, 1388–1397 (1997)]. By modulating the volume of a pore and measuring the resultant pressure response, the complex compressibility is measured as a function of frequency. Measurements of different lengths of a given pore allow the end effects to be subtracted out. By working down to very low frequencies, a wide range of values for the ratio of the thermal penetration depth to pore size are accessible. This technique will be briefly reviewed, and recent experimental results for pores of various geometries will be compared to the known theory. Experimental results will also be shown for pores not easily treated by analytic theory. Finally, possible applications to full tests of thermoacoustics in a single pore will be discussed. [Work supported by ONR and NSF.]