Investigation of Reynolds Number Effect on Dimensionless Coefficients of Three-Hole Yawmeter Probe Using Experimental and SPM Analytical Methods

Using proper dimensionless coefficients that are insensitive to various operating conditions is a crucial issue during the utilization of a yawmeter probe. These dimensionless coefficients produce the deviation angle of flow, stagnation and static pressures. In the current study, these coefficients are analyzed using SPM analytical and experimental methods. A comparison of experimental and analytical results shows that SPM analytical method predicts the flow deviation coefficients satisfactorily at the operational angle range of three-hole probe. This method also calculates the stagnation pressure coefficient precisely at the deviation angle range of ±10 degrees. The experimental results show that due to the assumption of constant speed on the probe, the analytical method cannot calculate the static pressure accurately. Experimental observations also demonstrate that velocity is increased and pressure is decreased over the probe. This is due to the suction region at the downstream of probe. Unlike analytical results, experimental observations depict that at zero degrees, the flow static pressure is equal to the average of pressure at the left and the right side of probe. Due to sensitivity of dimensionless coefficients of flow static pressure to variation of Reynolds number, various values are reported at different kinds of literature for these coefficients. These coefficients change with Reynolds number variations and their accuracies are decreased. In the current study, a new proper dimensionless coefficient is introduced which represents minimum sensitivity to Reynolds number.