Separated Flow in a Low Speed Two-Dimensional Cascade: Part I — Flow Visualization and Time-Mean Velocity Measurements

Abstract

This study was conducted for the purpose of providing a more fundamental understanding of separated flow in cascades and to provide performance data for fully-stalled blade rows. Cascades of a single blade geometry and a solidity of unity were studied for three stagger angles and the full range of angle of attack, extending well into the stalled flow regime. Results are presented from flow visualization and time-mean velocity measurements of stalled flow in the cascade. Surface and smoke flow visualization revealed that the blade stagger angle is a key parameter in determining the location of the separation line and the occurrence of propagating stall. Time-mean velocity measurements obtained with a dual hot split-film probe also showed that the separated velocity profiles within the blade passages and the profiles in the wake have distinctly different characteristics depending on the stagger angle.

Large-eddy simulation of 3-D corner separation in a linear compressor cascade

“…However, the compressor blade loading is extremely limited by many 3-D flow losses in compressors, such as boundary layers, flow separations, leakages, and shocks. 1,2 During the last decades, the impact of corner separation in reducing the blade loading has been emphasized by many researchers, such as Dong et al, 3 Schulz et al, 4 Yocum and O'Brien, 5 Hah and Loellbach, 6 Gbadebo et al, 7 Lei, 8 Choi et al, 9 and Lewin et al 10 A corner separation forms at the junction between an end-wall (hub or casing) and a blade suction surface. It is closed off by limiting streamlines on walls, and a separation vortex is formed on the end-wall near the trailing edge, as sketched in Fig.…”

Turbulence modelling analysis in a corner separation flow

“…Extensive efforts has been devoted to compressor corner separation through experiment [2,3,4,5,6,7] and numerical simulations [8], but its physics is neither entirely understood nor mastered.…”