Results of Volumetric PIV and High Resolution PIV on a Transonic Cascade

Tomographic PIV (tomo-PIV), conventional stereo PIV (SPIV) and astigmatism particle tracking (APTV) are utilized in order to characterize the complex transonic flow within a highly loaded compressor cascade at M1 = 0.60. The flow is dominated by a passage vortex which is driven by the pitchwise pressure gradient between pressure and suction side. The investigation presented herein demonstrates the applicability of volumetric PIV and high resolution PIV in a highly loaded compressor cascade at M1=0.60. With four simultaneous camera views it was possible to measure the complex corner flow of the cascade volume at three regions with respect to the side wall. The final vector resolution is 54×74×13 vectors at a spacing of 0.64 mm in x (chord-wise direction) and a spacing of 0.32 mm in y and z. Averaged results of the corner flow are presented to show conformance to the expected flow. The feasibility study on Astigmatism particle tracking (APTV) using a single camera concentrates on the evaluation of the calibration function through the tunnel window. Due to the relatively low laser pulse energy and laser light reflection the signal to noise ratio (SNR) was not sufficiently high. The measurements were complemented with stereo PIV (SPIV) measurements at distinct planes to provide a basis for comparison between the employed volumetric techniques