The directional response of a constant temperature hotwire anemometer to variations in pitch and yaw is reviewed, and a new data reduction technique for obtaining velocity vector data in a steady flow is described. Sequential sampling of the signal as the probe shaft is rotated through 360 ~ provides data to yield a threedimensional velocity vector. Jorgensen's expression was found to be suitable for the data reduction using independently measured pitch and yaw coefficients. Within the range of velocity and flow direction investigated, the velocity magnitude and direction can be determined to within 2% and 2 ~ respectively if the yaw coefficient is neglected. This measurement method is currently being used to determine velocity distributions on the intake-valve/cylinder boundary for different induction system designs.
List of symbols
diameter of hot wire yaw coefficient pitch coefficient length of hot wire output voltage of hot-wire anemometer valve lift free stream velocity effective measured velocity variance of the mean axial distance parallel to valve stem square root of the residual velocity cone angle probe shaft rotation angle velocity phase angle