C. Herman
C. Bartscher
M. Wetzel
M. Volejnik
Dept. of Mech. Eng., Johns Hopkins Univ., Baltimore, MD 21218-2686
Different visualization techniques are used to gain insight into the heat transfer and fluid flow processes in a thermoacoustic refrigerator model. For this purpose, an enlarged model of a thermoacoustic device, with transparent viewing windows in regions of interest, was built. The model operates with air at atmospheric pressure as the working fluid. The cross section of the resonant tube is rectangular to obtain essentially two-dimensional flow and temperature fields and to allow transillumination of the stack region with parallel laser light. On-line holographic interferometry combined with high-speed cinematography is used to analyze and measure the unsteady oscillating temperature fields in the stack region. The design also allows the visualization of the flow fields by smoke injection and the visualization of the temperature distribution on the stack plates using thermochromatic liquid crystals. The results of the visualization experiments provide new information on the stability and transition of the flow in the stack region and on the heat transfer processes. [Work supported by the Office of Naval Research.]