Abstract
With a usual hot wire anemometer, air velocity is determined by utilizing the relation between the electric current, the temperature of a single heated resistance thermometer wire and air velocity. And the effect of the temperature of air to be measured is considerably large. Therefore it is necessary to heat the resistance thermometer wire to a tolerably high temperature.
The double hot wire type anemometer, here reported, utilizes the relation between the electric current, the temperature rises of the double wires and air velocity in order to determine the air velocity. That is, instead of a single wire, double resistance thermometer wires are placed in air flow and the difference of the temperature rises between the two wires is utilized.
Experimental results show that the effect of the air temperature is extremely small, and it is known that the air velocity can be measured with small temperature rises.
