Performance of a short parallel-plate thermoacoustic stack with arbitrary plate separation

Abstract

In 1983, Wheatley et al., using the analysis of N. Rott, showed that most of the heat transport in a thermoacoustic stack operating in the boundary layer regime (plate separations large compared to a thermal penetration depth) is due to standing wave phasing of the acoustic field (pressure and velocity in quadrature). With traveling wave phasing (pressure and velocity in phase), the heat transport is reduced by an order of magnitude. While the short stack approximation used in this calculation is reasonable (a longer stack can be considered to be a series of short stacks), the boundary layer approximation is more severe. Stirling cycle engines use regenerators with very small plate separations compared to a thermal penetration depth and a predominantly traveling wave phasing between pressure and velocity. The behavior of Stirling cycle engines as well as that of standing wave thermoacoustic engines should be contained in the complete thermoacoustic differential equations of N. Rott. Calculations of the performance of short thermoacoustic stacks with arbitrary plate separations and arbitrary acoustic phasing will be presented. [Work supported by ONR.]