3-D Flow Field Characterization and Blockage Effects in an Open Jet Probe Calibration Wind Tunnel

Abstract This paper presents a detailed investigation into the 3-D flow field characterization and blockage effects in an open-jet probe calibration wind tunnel, utilizing a wide array of advanced measurement techniques. The design of the calibration wind tunnel, along with the sensor setup and associated uncertainties, is thoroughly described. An analysis of Mach number calculation errors highlights the unexpectedly high significance of humidity measurement in achieving accurate results. This study employs Hot-Wire Anemometry, Five-Hole Probes, Kiel Probes, and Stereo Particle Image Velocimetry to characterize the flow in the measurement section of the probe calibration wind tunnel. These techniques are used to evaluate both the Mach number and the Turbulence Intensity distribution, revealing a high-quality flow field. Furthermore, Stereo Particle Image Velocimetry and Computational Fluid Dynamics analyses are integrated to explore the interaction between the core jet of the calibration wind tunnel and the probe. An experimental investigation examines the occurrence of blockage effects, such as upstream flow disturbances caused by probe-nozzle interactions, across varying Mach numbers and probe diameters. From this analysis, an empirical equation is proposed to predict the onset of blockage, providing a valuable tool to avoid suboptimal calibration conditions.