Synchronization of small thermoacoustic oscillators

Abstract

Small high-frequency thermoacoustic oscillators can achieve high power densities in the conversion of heat to sound. In order to achieve high sound power output, it is advantageous to use arrays of such devices. Being a group of self-sustained oscillators, they switch on with a random phase at the threshold for oscillations. Moreover, small variations in the geometry of each device will affect the resonant frequency of each; the array will then not be in unison. This can be corrected by synchronizing them through global coupling; maximum power output will then be achieved. The strength of the coupling is assumed to be the ratio of mass of one thermoacoustic oscillator to the total mass of all devices and of the support to which they are mounted. By varying the strength of the coupling, the acoustic devices show synchronization, which for weak coupling is out-of-phase and at strong coupling is in-phase. Results are presented on the coupling of two prime movers operating near 2.5 kHz as well as for similar devices in an array consisting of five units. The synchronized behavior opens the field for large array systems and their applications.