Fundamental Studies of the Thermoacoustic Effect: Interactions of Acoustic Waves with Viscous Fluids

Drexel University, Philadelphia PA

Investigators

Abstract

Farouk 0853959 This is an experimental and numerical study of acoustically-driven viscous flows in resonators embedded with either a layer of closely-spaced thin plates (a stack) or with close-packed plain-weave metal screens (a regenerator). Accurate and high-fidelity computational models will be developed for nonlinear and time-dependent behavior of acoustically-excited flows in compressible, viscous and conductive fluids in such devices. The models will be validated with experiments to be carried out in our laboratories. Optimization studies of the effects of acoustic power input to the systems shall be conducted. Specially designed experiments will be conducted for measuring the time-dependent pressure, temperature and velocity fields in the resonators (with and without embedded stacks), driven by compression drivers with acoustic waves of varying intensities and frequencies. The measurements will provide fundamental data on the pressure, and velocity fields. Flow visualization studies will determine the possible formation of steady streaming flows and their behavior as a function of acoustic power input. The effects of the resonator shapes on the pressure amplitude in the resonators will be determined as functions of the operating parameters of the compression driver. The Navier-Stokes equations for a compressible flowfield will be solved numerically to obtain the velocity, pressure and temperature fields in these representative problems. This research will enhance the current level of sophistication in analyzing a wide variety of acoustically-driven problems of technological importance, specifically related to the design improvement of thermoacoustic refrigerators. The interdisciplinary nature of the problems addressed in the proposal will interest a broad section of scientists and engineers. The PI has significant past experience in the areas of computational acoustics and experimental methods. The PI and his students will collaborate with leading scientists from government laboratories (NRL, Washington, DC and NIST, Boulder, CO) and industry (CFIC Inc., Troy, NY). The training of both graduate and undergraduate students is integrated into the program and efforts will be made to recruit graduate students from the underrepresented groups. The software developed can be used as a tool for designing commercial scale devices and optimizing the operating conditions to desired goals.