Numerical Calibration and Investigation of the Influence of Reynolds Number on Measurements With Five-Hole Probes in Compressible Flows

This paper presents an investigation into the numerical and experimental calibration of a five-hole probe and effects of Reynolds number variations on the characteristics of the probe. The test object is a cone-type drilled elbow probe with a head diameter of 1.59 mm and a cone angle of 60 deg. The experimental calibration maps of four different probes of the same type and nominal geometry are compared. A significant variation of the curves can be observed especially at high yaw angles. This led to a visual inspection of the probes with a 3D measurement system. The actual geometry of the three used probes and the surface and radii in particular varied significantly from that of the unused spare probe. Furthermore, a numerical calibration map of the ideal probe was generated for a Mach number of Ma = 0.3. A comparison between the experimental and numerical calibration coefficients revealed that total pressure, yaw and pitch angle were reproduced reasonably well. The dynamic pressure coefficient, however, has a considerable offset. Finally, a parameter study of the effect of varying the Reynolds number over different yaw angles was conducted. The calibration Reynolds number is of the order of Re = 1 · 104 and was varied between 0.5 · 104 < Re < 6 · 104. While the results suggest that only minor measurement errors occur for yaw angle, total pressure and static pressure, a relatively large error was observed for pitch angle measurements.