Hot−wire anemometry in moderately heated flow

Abstract

Hot−wire probes have been calibrated in air flow at different velocities and air temperatures. The Reynolds number range was 0.5−2.5 at air temperatures of 20−100°C. The empirical heat loss equation was found to be significantly different from the often quoted one by Collis and Williams [J. Fluid. Mech. 6, 357 (1959)]. A two−wire probe followed by an electronic analog circuit was devised in order to provide simultaneous velocity and temperature signals in turbulent air flow. This circuit is appreciably simpler than the one reported by Chevray and Tutu [Rev. Sci. Instrum. 43, 1417 (1972)] and for a given probe configuration only minor circuit adjustments are needed before operation.