Numerical Investigation of the Interaction between Probe, Flow and Blading in an Axial-Turbine

Kurzfassung

The measurement accuracy of pneumatic probes in turbomachinery is limited by their interaction with the flow and the blading especially in the small axial gaps between blades and vanes at high flow velocities. In the present paper, this issue is investigated by means of three-dimensional steady and unsteady RANS simulations of an axial turbine with a meshed pneumatic probe between stator 2 and rotor 2. The probe is “calibrated” numerically in a typical free-jet calibration duct. The numerical calibration data agrees very well with the experimental for moderate flow angles. By performing numerical “measurements” with the probe in the turbine rig and comparing the values with the flow field without probe, significant differences especially of the pitch angle values are shown. These can be traced back to displacement effects of the probe on the flow which are not compensated by the calibration procedure.