THERMOACOUSTIC HEAT TRANSPORTATION AND ENERGY TRANSFORMATION .2. ISOTHERMAL WALL THERMOACOUSTIC EFFECTS

This paper discusses the acoustic wave motion and thermoacoustic effec ts in sound channels with isothermal walls. In this case, the main par ameter governing the propagation of sound waves is the relative width. The key thermoacoustic effect is the mutual transformation of the lon gitudinal and the transverse heat fluxes. The main parameter governing the transformation is the acoustic admittance. A critical acoustic ad mittance exists for longitudinal heat flux. When the local acoustic ad mittance is greater than the critical value, the longitudinal heat flu x increases; otherwise it decreases. A critical acoustic admittance fo r transverse heat flux also exists. When the local acoustic admittance is smaller than the critical value, heat is rejected to the environme nt; otherwise it is absorbed, if the Prandtl number of the gaseous med ium is smaller than the critical Prandtl number. When the Prandtl numb er is larger than the critical Prandtl number, heat produced by dissip ation dominates other effects, and heat absorption is replaced by the heat rejection effect.