Experimental Demonstration of a Thermoacoustic Diode

Abstract

To control one-way propagation of pressure waves in air or water, acoustic diodes typically employ a nonlinear medium to double frequency, or specially designed diffraction structures with which power loss is unavoidable. The authors present a three-stage device that instead takes advantage of the thermal interaction between gas particles and the walls of a porous material with a temperature gradient along the wave path. This thermoacoustic diode $a\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}p\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}f\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}s$ the transmitted sound waves, while blocking backward propagation.