The current work experimentally investigates the flow characteristics of an air jet impinging on an open rotor-stator system with a low non-dimensional spacing, G = 0.02, and with a very low aspect ratio, e/D = 0.25. The rotational Reynolds numbers varied from 0.33×1050.33times10^5 to 5.32×1055.32times10^5, while the jet Reynolds numbers ranged from 17.2 × 103 to 43 × 103. Particle image velocimetry (PIV) measurements were taken along the entire disk diameter in three axial planes. From the obtained PIV velocity fields, the flow statistics were computed. A recirculation flow region, which was centered at the impingement point and possessed high turbulence intensities, was observed. Local peaks in root-mean-square fluctuating velocity distributions appeared in the recirculation region and near the periphery, respectively. Proper orthogonal decomposition analysis was applied to the cases of the jet impinging on the rotor with and without rotation to reveal the coherent structures in the jet region.
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