An experimental and computational investigation on the effects of stator leakage flow on compressor performance
Abstract
Engineers are relying more on computational predictions to aid in the design of multistage compressors. As compressor designs advance to more sophisticated geometries with higher loadings, the predictive tools must be able to capture the effects on secondary flows, those flows not associated with the main compressor through flow. In the rear stages of a compressor where aspect ratios are low, secondary flows associated with endwall boundary layers and shrouded stator leakage flow must be understood. The objective of this research was to investigate the effects of stator leakage flow on compressor performance. All experimental research was conducted at the Purdue 3-Stage Axial Compressor Research Facility. The axial compressor is a scaled-up representation of the rear stages of a high pressure compressor with engine representative Mach numbers and Reynolds numbers. Computational research was conducted using a steady RANS CFD code with multiple meshes to investigate the sensitivity of computational modeling to stator leakage cavities. Facility specific boundary conditions were acquired experimentally and applied to the computational models. Detailed total pressure and total temperature measurements indicate that the inlet of the compressor is circumferentially uniform allowing for an axisymmetric boundary condition to be applied to both experimental and computational research. The shrouded stator cavity in the third stage of the compressor is open to ambient conditions. Mass flow rate through this cavity is measured using an orifice flow meter, and the cavity can be plugged to prevent any leakage flow. Static pressure measurements were acquired at the exit of the stator 3 cavity so that the leakage flow could be simulated and compared with experimental data. Radial total pressure profiles predicted by the different numerical models are compared with experimental profiles with the cavity open and plugged. The predicted compressor performance at high flow conditions was strongly dependent upon the particular leakage flow model employed. Physically meshing the stator cavities yielded the best comparison of overall performance predictions and radial profiles to experimental data near design loading. Since plugging the stator 3 cavity yielded only small changes in the radial total pressure profile, experimental and computational data suggest the leakage flow through the stator 3 cavity on the Purdue 3-Stage Axial Compressor has a relatively negligible impact on overall compressor and stage-by-stage performance.
Degree
M.S.A.A.
Advisors
Key, Purdue University.
Subject Area
Aerospace engineering|Mechanical engineering
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