Calibration and use of non-orthogonal cross-wire probes

A calibration method utilizing the modified cosine law (Hinze, 1959) has been developed for cross-wires with unknown wire angles. The unknown wire angles with respect to the probe axis and the yaw factor (k) of each wire were determined from calibration data using the method of Least Squares Calibration data consisting of measurements of the ratio of effective normal velocity to actual flow velocity versus probe angle were represented to within 4.7% by the optimum curve fits. The solution to the calibration equations for the velocity components has been presented in detail along with calculations of the acceptance angles for the cross-wires in terms of the calibration parameters. The method of calibration presented in this paper was demonstrated using data from a custom-made probe for which the principle measurement direction was approximately 70 degrees from the probe axis.