UNCALIBRATED ROTATING HOT-WIRE PROBE FOR THE MEASUREMENT OF SMALL VELOCITY VECTORS

The working principle of a rotating hot-wire probe is described. Its electrical signal contains a definite minimum which permits, as a zero indicator, the circumferential velocity of the hot wire to be equalized to the flow velocity. Related to this minimum an additional single pulse per revolution gives information on the direction of the velocity in order to yield the complete flow velocity vector. By means of experiences obtained by use of a prototype measuring device the possibilities are discussed to develop the method to a feasible instrument for low velocity application as well in the fields of climatic, environmental and energy techniques as in meteorology.