<p>This paper presents the impact of an axially tilted variable stator vane platform on penny cavity flow and passage flow, exploiting both optical and pneumatic measurements in an annular cascade wind tunnel as well as steady numerical analyses. Variable stator vanes (VSVs) in axial compressors require adjustability. Therefore, in a shrouded vane design, penny cavities are inevitable around the vane platform in the hub. Production and assembly deviations can result in a vane platform that is tilted about the circumferential axis in such a way that a backward facing step occurs on the platform’s upstream part as well as on the downstream part. Penny cavity and main flow in geometries with and without platform tilting have been compared in an annular cascade wind tunnel which comprises a single row of 30 VSVs. Operating conditions lead to a Mach number of 0.34 at the VSV inlet and a Reynolds number of 382,000 based on axial chord length. For evaluation of unsteady velocity data, detailed particle image velocimetry measurements have been conducted inside the penny cavity and in the vane passage. Steady pressure and velocity data is obtained by two-dimensional multi-hole pressure probe traverses in the inflow and the outflow covering 2.5 passages. Furthermore, pneumatic measurements have been carried out using pressure taps on the vane and inside the penny cavity. Additionally, oil flow visualization has been conducted on the airfoil, hub, and penny cavity surfaces. Steady CFD simulations with boundary conditions according to the measurements are benchmarked against experimental data. Results show that tilting the VSV platform reduces the mass flow into and out of the penny cavity. By decreasing the penny cavity leakage, platform tilting also affects the passage flow where it leads to a reduced turbulence level and total pressure loss in the leakage flow region. In summary, the paper demonstrates the influence of penny platform deformation on cavity flow and passage flow and provides new insights into the mechanisms of penny cavity associated losses.</p>

Effect of an Axially Tilted Variable Stator Vane Platform on Penny Cavity and Main Flow

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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