SIMULTANEOUS MEASUREMENT OF SURFACE TEMPERATURE AND HEAT FLUX USING A COMPOSITE SLAB

Abstract

A method capable of acquiring local convection heat transfer coefficients based on the simultaneous measurement of both local surface temperature and heat flux is explored. The method employs a composite slab consisting of a thin laminate layer of a low-conductivity material superposed upon a metal substrate of a highly conductive material. A thin coating of encapsulated liquid crystals is used on the outside surface of the laminate layer to give visual indications of the local surface temperatures. The substrate temperature is measured with a thermocouple and is assumed to be spatially uniform. From the resulting surface temperature contours, and assuming one-dimensional heat flux through the laminate layer, the local convection heat transfer coefficients are obtained. A numerical simulation was conducted to verify the assumptions made in this method. Detailed local heat transfer coefficients were measured for the case of an air jet impinging normal to a flat surface, and the results were compared with published data.