Thermal response of a nanoscale hot-wire in subsonic and supersonic flows

A comprehensive characterization of the thermal response of nanoscale hot-wire probes is performed in both subsonic and supersonic flows. A constant current anemometer was designed for the measurement of the intrinsic thermal inertia of hot-wire probes. In particular, the nanoscale probe is considered with the effect of gold-plating on the supporting structure of the sensing element. Gold-plated nanoscale probes present a response time one order of magnitude smaller than conventional cylindrical hot-wire probes. Heat transfer simulations show that the temperature profile is considerably modified by the addition of a conductive metal layer, hence increasing the sensor’s frequency response in both subsonic and supersonic flows. The increase of frequency response is finally exemplified by the numerical computation of the power spectral density of a turbulent flow signal without any electric compensation of the hot-wire signal.