The impact of numerical schemes on flow separation capturing of a linear compressor cascade using DES method

摘要

Detached Eddy Simulation (DES) has been considered as a promising simulation method to calculate the massive flow separation, while the impact of numerical schemes on flow separation capturing using DES method in internal flow field is still unresolved. The investigation is conducted using DES method based on Spalart-Allmaras model. Three different numerical schemes for convection term have been tested, which are upwind schemes, including 1st order and 2nd order scheme based on Roe scheme, and 2nd central scheme with low artificial viscosity. Three-dimensional corner separation flow field of a linear compressor cascade is diagnosed under high incidence condition. Besides, the pressure-sensitive paint experimental result is used as a standard for numerical simulation accuracy evaluation. We detailly discussed the time-averaged and instantaneous flow filed, and the results show that: 1) the DES method using the central scheme is more accurate than the results of the upwind scheme in term of corner separation prediction; 2) The complex vortex structures in the corner region are mainly from three parts, i.e. corner separation, end-wall separation and suction surface separation. Although the results of two schemes capture the same vortex structures, the causes of the generation and the positions of the vortices are totally different; 3) The vortex fluctuation frequencies and intensities predicted by 2nd upwind scheme and 2nd central scheme are different, but they all shows the same relationship.