A DIRECTIONALLY SENSITIVE HOT-WIRE ANEMOMETER

A new directionally sensitive velocity measurement system based upon a single oscillating hot-wire probe has been developed. The vibration o f the hot-wire was effected by a piezoelectric oscillator that could b e driven at different amplitudes and frequencies. The sign of the loca l flow velocity was determined by the phase shift between the motion a nd the output from the hot-wire. The system was used to measure mean a nd fluctuating velocities profiles of the separated flow behind a back ward facing step.