Effects of Tip Cavity Depth, Width, and Location on the Leakage Flow in an Axial Turbine Cascade

概要

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In this study, effects of the tip cavity with various depths, widths, and locations on the leakage flow and performance of an axial turbine cascade have been investigated numerically. The blade was a linear model of the tip section of the GE-E3 high-pressure turbine first-stage rotor blade. The Delayed Detached Eddy Simulation (DDES) model was used in the simulations. The computational results showed that the leakage mass flow rate and mass-averaged total pressure loss decreased as the depth and width of the tip cavity increased. And, it was shown that the cavity near the pressure side is more effective than that near the suction side. These effects depend on a vortex generated behind the pressure side in the cavity, which is changed with the depth, width, and location. The vortex entrains the leakage flow through the clearance toward the bottom of the cavity and in the chord wise direction, which reduces the flow leaking out.