Calibration of 5-Hole and 13-Hole Pitot Tubes Before and After a Full-Scale Wake Survey on the R/V Athena.

摘要

This report presents the results of the calibrations of spherical 5-and 13-hole pitot tubes before and after they were used in a full-scale wake survey. Brief descriptions of standard and specifically developed calibration instrumentation and of claibration procedures are included. The purpose of the calibrations was to determine differential pressure ratios which, during a full-scale wake survey, could be used to compute velocity component ratios. Differential pressure ratios obtained during th calibrations are depicted graphically in terms of angle of inclination for the pitot tubes at 20 fps (6.10 m/s). In addition, one 5-hole pitot tube was run at four velocities ranging from 6 to 25 fps (1.83 to 7.62 m/s). The calibrations were shown to have a small speed dependence at higher speeds but a significant speed dependence at the lower speeds. Finally, the composite test results for the 5-hole pitot tubes were analyzed statistically to obtain the means, spreads and tolerance intervals. Due to the observed spread of the data among different tubes, the application of individual calibrations, as opposed to one average calibration, was recommended. (Author)