Circuit Project Electronic

A sensitive and reliable way to measure airflow is to exploit the predictable relationship between airspeed and the heat dissipated by a sensor exposed to the flow while being held at a constant temperature differential above ambient. The power required to maintain the elevated sensor temperature is proportional to the square root of the airspeed (King’s law). The popular hot-wire anemometer uses this principle, but suffers from the disadvantage of using a relatively fragile airflow sensor, a thin metallic filament.

Read more original source:http://www.edn.com/archives/1996/031496/06di3.htm