Tip Vortex and Crenulation Effects in a Compressor Cascade with Moving Endwall

摘要

The effects of changing Reynolds number and flow coefficients on the velocity and pressure flow fields within a linear cascade with moving endwall were investigated in this experimental thesis. All flow field measurements were taken at a constant compressor blade tip gap clearance of 1.0 % chord and endwall speed of 318.6 ft/s (97.1 m/s), with flow coefficients of 0.40, 0.52, 0. 62 and 0.72. All data acquisition occurred in a plane 23 % chord downstream of the trailing edge plane of the linear cascade. Hotwire probes determined the complete passage, three-dimensional fowled behind both crenulated and regular blade geometries. Vector plots showed that the mid-span crenulations aligned the flow axially, increasing the wake mixing and reducing the spanwise flow evident in the regular blade's wake region. A total pressure rake measured the pressure fowled behind the blades, showing that the crenulated blade geometry produced larger, less intense areas of total pressure loss than for the regular blades. Overall, the crenulated blade tested showed equal passage total pressure losses, increased wake mixing, reduced wake deficit and a reduced flow turning angle compared to a regular blade of similar overall dimensions.