Simultaneous measurements of temperature and heat flux using ultrasound

Noninvasive and quantitative method for measuring both temperature distribution near heating surface of a material and heat flux through the heating surface is presented. In the method, temperature distribution of a heated material is determined by a combined technique consisting of an ultrasonic pulse-echo measurement and an inverse analysis coupled with a one-dimensional finite difference calculation, and heat flux is then estimated from the determined temperature distribution near the heating surface. To demonstrate the feasibility of this method, an experiment with a single-side heated steel plate is carried out. Ultrasonic pulse-echo measurements are performed with the heated steel plate, and measured ultrasonic signals are used for the analysis to determine internal temperature distributions of the plate and then heat fluxes through the heating surface are determined. The temperature distributions estimated by the ultrasonic method agree well with those measured by thermocouples installed in the plate, and the validity of the heat flux estimated by the present method is also investigated. It has been observed in the experiment that heat flux through the heating surface increases rapidly just after heating starts and then decreases gradually with elapsed time.