THE EFFECT OF SENSOR SIZE ON THE PERFORMANCE OF FLUSH-MOUNTED HOT-FILM SENSORS

A parametric study was performed to determine the effect of sensor siz e on the performance of flush-mounted hot-film sensors, operated using constant-temperature anemometry. Three nickel sensors with surfaces o f 12.5 x 125 microns, 25 x 250 microns, and 50 x 500 microns were depo sited on glass flat-plate substrates. The frequency response and sensi tivity of the sensors were measured using both electrical and flow tes ting. Electrical testing was performed using both sine and square wave s. Flow testing was performed in a shock tube by subjecting the flush- mounted sensors to a shock-induced boundary layer. As the sensor size was decreased, frequency response increased and sensitivity decreased. These trends were observed for both electronic and flow testing condi tions.