Patent ID: 7036367
Filing Date: 2006-05-02
Classification: G01F,G01K,G01P

Abstract:
1. A method of measuring the flow velocity of a flowing fluid, comprising: immersing within the flowing fluid an electrical resistor having a resistance varying with temperature; applying electrical current through the electrical resistor to heat it to a predetermined temperature above that of said flowing fluid; and measuring the rate of change in resistance of said electrical resistor to produce a measurement of the rate of thermal heat dissipation caused by said flowing fluid in which the electrical resistor is immersed, and thereby a measurement of the flow velocity of said flowing fluid; characterized in that said electrical resistor is a positive temperature coefficient thermistor driven by a constant voltage source and having a resistance which increases sharply at said predetermined temperature, such that the thermistor is automatically self-controlled to substantially maintain said predetermined temperature, whereby the electrical current drawn by said thermistor is a measurement of the thermal load on the thermistor resulting from the thermal heat dissipation therefrom by the flowing fluid, and thereby a measurement of the flow velocity of the fluid.