Temperature compensation for thermal anemometers using temperature sensors independent of flow sensors

In this paper, a new temperature compensation technique for thermal anemometers is presented. The compensation is realized by using a temperature sensor independent of the flow sensor into a single Wheatstone-bridge circuit of the anemometer and adopting a novel design approach to the resistors of the bridge for balancing out the temperature drift. The temperature sensor does not have to possess an equal temperature coefficient of resistance to that of the flow sensor. The temperature compensation in a dynamic measurement does not affect the measurement of velocity fluctuations when the temperature fluctuations are of lower frequencies than the bandwidth of the temperature sensor. The compensation method was theoretically proved and experimentally tested in different temperature and flow conditions. Results showed that the error of the anemometer induced by the temperature variation could be effectively eliminated from 30% to 2% over a range of ambient temperatures (30-60 degrees C) using the proposed compensation method.