A Comparison of the Transient and Heated-Coating Methods for the Measurement of Local Heat Transfer Coefficients on a Pin Fin

[+] Author and Article Information
J. W. Baughn, N. Saniei

Department of Mechanical Engineering, University of California, Davis, CA 95616

P. T. Ireland

St. Anne’s College and Department of Engineering Science, Oxford University, Oxford, United Kingdom OX26HS

T. V. Jones

St. Catherine’s College and Department of Engineering Science, Oxford University, Oxford, United Kingdom OX26HS

J. Heat Transfer 111(4), 877-881 (Nov 01, 1989) (5 pages) doi:10.1115/1.3250800 History: Received March 31, 1988; Revised January 23, 1989; Online October 20, 2009


Measurements of the local heat transfer coefficients on a pin fin (i.e., a short cylinder in crossflow) in a duct have been made using two methods, both of which employ liquid crystals to map an isotherm on the surface. The transient method uses the liquid crystal to determine the transient response of the surface temperature to a change in the fluid temperature. The local heat transfer coefficient is determined from the surface response time and the thermal properties of the substrate. The heated-coating method uses an electrically heated coating (vacuum-deposited gold in this case) to provide a uniform heat flux, while the liquid crystal is used to locate an isotherm on the surface. The two methods compare well, especially the value obtained near the center stagnation point of the pin fin where the difference in the thermal boundary condition of the two methods has little effect. They are close but differ somewhat in other regions.

Copyright © 1989 by ASME
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