Investigation Of Dimples On The Aerodynamic Performance For A Highly Loaded Compressor Cascade

Using highly loaded compressor cascade is an effective method to achieve the goal of lower weight and higher-pressure ratio for a compressor.Based on a typical high turning compressor stator cascade NACA65-K48,a flow separation control method that arranging dimples on blade suction side is proposed.The results show that dimples have effects in suppressing the separation bubble and three-dimensional corner separation on the suction side.This paper is mainly about the following work:Firstly,the modeling and mesh generation processes for the dimpled rectangular compressor cascade have been completed.The numerical validation and grid independence study are conducted based on the Reynolds averaged N-S method(RANS).Under the flow condition of minimum flow loss,three kinds of parameters,such as the amount,depth,and location of dimple are studied.The results have been shown that within the allowable range of processing,a certain number of dimples with smaller depth can achieve a lower flow loss(10%-20%);The dimple array located upstream from the separation line which is also near the leading edge of the blade can effectively restrain the three-dimensional corner separation and reduce the associated flow loss.Based on above calculations,the mechanism of restraining separation by dimples is analyzed and summarized:the vortex structures inside the dimples can promote the mixing process between the boundary layer and mainstream,improving the kinetic energy level of the fluid within the boundary layer,which can delay flow separation.Meanwhile,some dimple schemes are selected to study their effects in loss reduction under different inlet Mach number and different flow incidence.It is found that the designed dimple configurations have potential in loss reduction under a wide flow condition.At last,some dimple configurations are selected to conduct experiments in a cascade wind tunnel.It is found that the dimples can reduce the flow loss under the negative flow angle,while under the positive incidence angle the flow loss increased.