Turbulence characteristics in corner separation in a highly loaded linear compressor cascade

The corner separation flow in a highly loaded prescribed velocity distribution (PVD) cascade has been studied by using DDES method based on SST k-ω model (DDES-SST). The numerical simulation results of DDES and RANS have been compared with experiment. The DDES-SST method could provide accurate predictions on corner separation region and RANS-SST method overestimate the corner separation flow in the cascade. The development and structure of vortices in the corner separation flow have been carefully studied. The velocity histogram of the monitor points in mainstream and corner region are collected and the velocity “bimodal” distribution in corner separation region, which was once found in the experiment, has been approved with numerical result by DDES method. Turbulence anisotropy has been discussed with Lumley anisotropy invariant map (AIM) theory and the high anisotropy region is found corresponding to high shear stress region. Other turbulence characteristics, like turbulence energy spectra, turbulence helicity density and velocity skewness have also been discussed and analyzed carefully to help understand the different aspects of turbulence behaviors of the three-dimensional (3D) corner separation flow in the cascade.