The moving thermoacoustic array: A theoretical study

A theoretical study of the moving thermoacoustic array as an underwater sound projector is presented. The movement imparts to the acoustic signal a Doppler shift which is direction dependent. Extremely high Doppler shifts are achievable because it is a noncontact source. While the moving thermoacoustic array has certain interesting features compared to conventional acoustic projectors, notably the noncontact property and the direction-dependent Doppler shift, its thermoacoustic energy conversion efficiency is found to be no better than that of the stationary thermoacoustic array. It was found that the thermoacoustic conversion was most efficient when the laser energy was delivered as an impulse train. The efficiency is fundamentally limited by the physical properties of the medium, particularly the coefficient of thermal expansion and the specific heat.