Hot-wire, hot-film and surface hot-film applications in strongly temperature loaded flows

Hot-wire, hot-film, and surface hot-film measurements in heated or cooled flow are presented. On the basis of an integral heat balance, the ratio of conductive to convective heat loss of a hot-wire, hot-film, or surface hot-film can be formulated in relation to an appropriate Reynolds number. This heat balance is extended to near-wall measurements by a wall-induced heat-loss term. To check the accuracy of the procedure, measurements in undisturbed external flows as well as in turbulent and transitional boundary layers at flow velocities of 3-25 m/s and temperatures of -55-160°C are given. It is shown that the single-point calibration procedure overcomes the restrictions imposed by other calibration methods and therefore can be used for probes even of small aspect ratios in order to compensate for changing fluid temperature