Western Kentucky University
Department of Physics and Astronomy

Colloquium

Dr. Gordon Smith

Department of Physics and Astronomy
Western Kentucky University

"Thermoacoustics - Unveiling the Mystery of Dr. Smith"

September 23, 2002 @ 4:00 PM in TCCW 251

Coffee at 3:30 in TCCW 368

Abstract

You've all been wondering just who is this dashing new faculty member, Dr. Smith, and exactly what does he do? At last, the mystery behind the door to Room 255 can be revealed.

Thermoacoustics studies the interactions of heat and sound, and all the patentable devices you can create with such processes. The assumptions one makes when acoustics is covered in introductory physics courses are valid for 90% of the cases one typically encounters - namely that you doesn't have to worry about how well the gas conducts heat, and that the equations governing the fluid motion don't depend on the radial position. However, near the walls, interesting effects come into play from the thermoviscous nature of real acoustic fluids. Near a wall, one finds a small but measurable exchange of heat occurs between the gas and the wall. Applied properly, this effect can be utilized to drive a prime mover class of heat engine (converting thermal energy to acoustic work), to power a refrigerator class of heat engine (utilizing acoustic work to transport heat), or as both, to operate a heat-driven refrigerator.

Presently, this process is used in a wide variety of commercial devices, and much of the research done today is working to maximize the efficiency of these devices. In the course of his dissertation, Dr. Smith discovered an abnormally high streaming flow. This jetlike flow resulted in huge efficiency losses for the device. He additionally discovered a previously-unconsidered acoustic mode which may be responsible for the creation of such a flow.

A brief background in this line of research will be presented, along with practical demonstrations of thermoacoustic devices and cookies.