Holographic interferometry: An approach to study the unsteady temperature fields in the stack region and its neighborhood

Abstract

Holographic interferometry combined with high-speed cinematography is a measurement technique, which allows the investigation of unsteady temperature distributions without affecting the physical process. Therefore it is the most suitable measurement technique for the investigation of the oscillating temperature field in the stack region and its neighborhood. In order to apply holographic interferometry, vibrations of the experimental setup have to be kept below a fraction of the wavelength of the used laser light, 514 nm. The first research efforts were focused in the design and verification of a feasible experimental setup which satisfies the requirement of low vibrations. Currently, temperature measurements, applying holographic interferometry to our thermoacoustic refrigerator model, are carried out. From the obtained interferometric fringe patterns the temperature distribution can be reconstructed quantitatively applying digital image processing. Results of these measurements will yield valuable information about the heat transfer mechanism occurring in the stack region and its neighborhood, which can be used to improve the heat exchanger design. [Work supported by the Office of Naval Research; Martin Wetzel is also supported by a scholarship from DAAD.]