Calibration of a Three-Hole Probe Employed in Measuring the Performance of a Wind Tunnel Compressor Cascade

Calibrating three-hole probes before using them to obtain measurement data from turbomachines has become imperative. Calibration of the three-hole probe prior to its use in any turbomachinery measurement is crucial due to manufacturing inaccuracies during production. This study presents the calibration of a three hole probe used to measure the performance of a suction wind tunnel compressor cascade. A transonic wind tunnel with a diameter of 203 mm was used to calibrate the three-hole probe. Other equipment employed during the calibration included a pitot-static tube, five micromanometer transducers, a barometer, and a thermometer. Micromanometers 1 and 2 were used to obtain the values of the wall static and total pressures from the pitot tube, while micromanometers 3, 4, and 5 measured the total, static 1, and static 2 pressures from the three-hole probe. The results show that the total pressure coefficient at the stagnation point around zero yaw angle decreases at lower and higher yaw angles. For the plot of static pressure coefficient, it was observed that it is nearly independent of the flow angle. However, at higher flow angles, some points in the static pressure coefficient plot fluctuated significantly across different Mach numbers investigated. The study demonstrates that the relationship between the flow angle and the directional coefficient is linear for small angles, but at higher negative and positive flow angles, the probe’s sensitivity in the flow direction becomes greater