Flow velocity measurement method and apparatus, including applications thereof for measuring heat flow, and wind velocity and/or direction generation

Apparatus for measuring the flow velocity of a flowing fluid, comprising:

• an electrical resistor having a resistance varying with temperature to be immersed in the flowing fluid;
• a power supply for supplying said electrical resistor with electrical current to heat it to a predetermined temperature above that of the flowing fluid;
• and
• a processor for measuring the change in resistance of said electrical resistor to produce a measurement of the rate of thermal heat dissipation caused by the flowing fluid in which the electrical resistor is immersed, and thereby a measurement of the flow velocity of the flowing fluid;
• characterized in that said electrical resistor is a positive temperature coefficient thermistor driven by a constant voltage from said power supply and having a resistance which increases sharply at said predetermined temperature at which it is maintained by said constant voltage, 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.