Use of a thermocouple anemometer in shock-tube experiments

A method is described for measuring the mass flow in a shock tube with the aid of a thermocouple anemometer. An unsteady method is adopted to measure the convective thermal flux from the gas to the wire. The heat balance equations for the junction are analyzed by assuming that heat losses in unsteady regime can be ignored. A simple form for the convective heat flux is obtained along with an equation by which one can determine the hot wire constant from the constant of a control wire. The measuring circuit involves two bridges and a reference wire, and calibration is done with a pulsed current. Some calibrated couples were used to measure the Nusselt number as a function of Reynolds number in hypersonic flows.