C. Herman
M. Wetzel
M. Volejnik
Dept. of Mech. Eng., Johns Hopkins Univ., Baltimore, MD 21218-2686
In order to study the oscillating temperature and flow fields in the stack region, a model of a thermoacoustic refrigerator is built. The model allows the application of visualization techniques such as holographic interferometry, thermochromatic liquid crystals, and smoke injection. In the first experiments, the correct operation of the thermoacoustic refrigerator is verified. Using the Kundt's dust tube method, the propagation of longitudinal plane-wave fronts is analyzed. Furthermore, the distortion due to the presence of higher harmonics in the resonance tube is kept small. This is verified by applying the Fourier transform to a pressure signal at several positions within the resonance tube. The focus of current investigations is to apply the above visualization techniques in the stack region and its neighborhood. These measurements provide information which can be used to determine requirements for the design of heat exchangers. An improved design of the heat exchangers and a better understanding of heat transfer processes and flow phenomena are key issues to improve the efficiency of thermoacoustic refrigerators. [Work supported by the Office of Naval Research; Martin Wetzel is also supported by a scholarship from DAAD.]