Acoustic anemometer for simultaneous measurement of three fluid flow vector components

An apparatus for measuring a velocity vector of a fluid flow comprising:

• a signal generator for generating an oscillating electrical signal;
• an acoustic transmitter for receiving the oscillating electrical signal and generating an acoustic signal proportional to said oscillating electrical signal;
• at least three acoustic receivers for receiving the acoustic signal and generating electrical signals in response thereto which are phase shifted by the influence from the fluid flow;
• a support structure for supporting the acoustic transmitter and the at least three acoustic receivers in a noncoplanar array;
• a signal processor for receiving and processing the oscillating electrical signal generated by the signal generator and the electrical signals generated by the at least three acoustic receivers to determine a time delay for each acoustic receiver caused by the influence of the fluid flow;
• and
• wherein the signal processor determines fluid flow velocity vector components u, v, w, in accordance with the formula
• u2+v2+w2−Ai(Ciu+Div+Eiw)−Bi=0
• where Ai and Bi are coefficients dependent on the time delays and Ci, Di, and Ei are coefficients dependent on the relative positions of the acoustic receivers to the acoustic transmitter.