Session: 31-05 Experimental Methods

Paper Number: 151866

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

This paper presents a comprehensive study on the 3-D flow field characterization and blockage effects in an open jet probe calibration wind tunnel using a large variation of measurement techniques. Accurate calibration of aerodynamic probes in wind tunnels is essential for reliable measurements in fluid dynamics. Open jet wind tunnels, commonly used for this purpose, offer advantages such as a homogeneous and steady flow field as well as low turbulence. During calibration, interaction between probe and the wind tunnel can occur. One of this interaction is a local throttling of flow by probe being too large or mounted too close to the nozzle. This can cause an error on the total pressure measurement in the wind tunnel. 

The first section of the study focuses on detailed three-dimensional flow measurements in the test section of the wind tunnel, using techniques such as hot-wire anemometry, stereo particle image velocimetry (SPIV), five-hole probes and pitot probes. The resulting data is used to evaluate flow uniformity, velocity profiles, and turbulence intensity in the unblocked configuration, providing a baseline for comparison. Also, the results obtained by different measurement techniques are compared.

The second part of the study focuses on the influence of probes on the flow field of a probe calibration wind tunnel. Therefore, stereo PIV measurements are used as the probe is installed at the wind tunnel. The PIV setup contains a beam splitter that allows two laser sources to be controlled simultaneously. Thus, allowing the jet and the probe to be illuminated from two sides. The Stereo-PIV measurements with subpixel precision were corrected for disparity and yield a 3^rd component reconstruction residual much smaller than one across the entire jet core.

Furthermore, the influence of blockage is investigated by applying different sizes of probes (degrees of blockage) at different axial positions from the nozzle. This information is used to obtain a general guideline to prevent blockage effects on calibrations.

The paper concludes with recommendations for mitigating blockage effects, providing guidance for optimizing probe calibration procedures in open jet facilities.

Presenting Author: Konstantin Speck Technical University of Munich, Institute of Turbomachinery and Flight Propulsion

Presenting Author Biography: Konstantin Speck studied mechanical engineering at the Technical University Munich. He published his Master’s Thesis about numerical five-hole probe calibration together with his supervisor in the Journal of Turbomachinery. Following that, he joined the Institute of Turbomachinery and Flight Propulsion at Technical University Munich as a researcher. There, he is responsible for the high-speed compressor test rig and continues to work on the improvement of flow field measurements in compressors using experimental and numerical methods.

Authors:

Konstantin Speck Technical University of Munich, Institute of Turbomachinery and Flight Propulsion
Carlos Eduardo Ribeiro Santa Cruz Mendoza Technical University of Munich, Institute of Turbomachinery and Flight Propulsion
Patrick Steudel Technical University of Munich, Institute of Turbomachinery and Flight Propulsion
Rares Cotenescu Technical University of Munich, Institute of Turbomachinery and Flight Propulsion
Volker Gümmer Technical University of Munich, Institute of Turbomachinery and Flight Propulsion