Single pressure transducer probe for 3D flow measurements

ETH, Turbomachinery Laboratory, Sonneggstrasse 3, Zurich, Switzerland

^* Joel Schlienger: joel.schlienger@swissonline.ch
^† Axel Pfau: Axel.Pfau@flowtec.endress.com
^‡ Anestis I. Kalfas: akalfas@auth.gr
^§ Reza S. Abhari: abhari@lec.mavt.ethz.ch

Abstract

A new method of measuring 3D flow with a single pressure transducer mounted inside the head of a single probe is presented in this paper. The 3D flow field around the hemispherical or ellipsoidal probe head is used to derive the 3D flow vector in virtual 5-sensor mode. A pressure tap located in the vicinity of the probe head connects the instantaneous pressure of the measurement volume to the pressure transducer. By turning the probe to five different positions around the axis of the stem, a set of five pressures is formed. The relevant flow parameters such as total and static pressure, yaw and pitch angle as well as Mach number are derived from these five pressures using the proposed calibration model. A selection of six different probe head geometries with different pressure tap positions have been manufactured and calibrated in a free jet facility in order to find the ideal probe geometry. The results of the steady probe calibration showed that the probe captures 3D flow at a slightly higher error band compared to other probe techniques such as pneumatic multiple hole probes. A summary of the achieved model accuracy for each probe is given. Finally, the calibration model can be extended to any single sensor cylindrical probe, provided that the pressure coefficient shows a measurable variation with pitch angle.