The flow in the hub end-wall region has a substantial influence on the aerodynamic performance of axial-flow compressors. A numerical investigation of this three-dimensional flow phenomenon, often referred to as boundary layer skew, that contributes to the interaction between the end-wall and blade suction surface flow, thus determining the losses in this area, is the topic of this report. A single-staged model compressor (flow coefficient: 0.5, work coefficient: 0.34) with a 7-blade rotor row and a highly loaded 11-blade stator row was designed for the simulation. To account for the complex time-dependent flow patterns in the end-wall area, a transient calculation with the rotor and stator rows fully modeled (360°) is carried out. The flow is assumed to be incompressible as the velocities of the low-speed axial compressor do not exceed a Mach-number value of 0.3. The calculations show that the boundary layer in the end-wall region is highly skewed and transient. There is a direct connection to local flow phenomena such as separation as well as to global pressure loss coefficient distributions in pitchwise and streamwise direction. Different levels of flow overturning in the end-wall area are observed, depending on the boundary layer skewness varying by simulating the compressor at different operational points.
A CFD-Based Investigation of Boundary Layer Skew in the Hub Region of a Low Speed Axial Compressor and its Influence on Performance and Losses
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Hilgert, M, & Bo¨hle, M. "A CFD-Based Investigation of Boundary Layer Skew in the Hub Region of a Low Speed Axial Compressor and its Influence on Performance and Losses." Proceedings of the ASME 2009 Fluids Engineering Division Summer Meeting. Volume 1: Symposia, Parts A, B and C. Vail, Colorado, USA. August 2–6, 2009. pp. 2125-2130. ASME. https://doi.org/10.1115/FEDSM2009-78181
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