Abstract:

One topic of current interest in thermoacoustic research is an annular prime mover [Lin et al., J. Acoust. Soc. Am. 100, 2846(A) (1996)]. The starting point for this research is an investigation of a constricted annular resonator. A literature search of the field resulted in surprisingly few references. The results of analytic, numerical, and experimental investigations are presented. It was found that introducing a constriction to an annular resonator split each longitudinal duct mode into two modes, one of a higher frequency with a pressure antinode at the constriction, and one at a lower frequency with a velocity antinode near the constriction. While changing the size of the constriction appreciably modified the lower resonance frequency and the position of the velocity antinode, the upper resonance frequency was only moderately modified and the position of the pressure antinode was virtually fixed. [Work supported by the Office of Naval Research and the American Society for Engineering Education.]