Influence of Ellipsoidal Dimple Column Number on Performance of Highly-loaded Compressor Cascade

The impact of the column number of ellipsoidal dimples on a highly-loaded compressor cascade (NACA65-K48) under design conditions was investigated by using a numerical simulation method. Ellipsoidal dimples with a thickness of 0.2 mm were located at the position of chord length ranging from 10% to 36%. The span-wise interval was 5.0 mm. The performance and flow field structures of cascades with 1 to 5 ellipsoidal dimpled columns were compared, and the results showed that the turbulent kinetic energy intensity near the wall was enhanced and the fluid separation resistance was consequently improved. The total pressure loss was reduced by all modified ellipsoidal dimples. In addition, the separation bubble of the suction side was broken or weakened, the corner separation was improved, and the influence range of the passage vortex was reduced. Moreover, the improvement effect of cascade performance parameters initially increased with the increase in the number of dimple columns and then reduced as the number of columns was further increased. The reductions in the total pressure loss of the cascade were 0.59%, 1.47%, 1.69%, 1.91%, and 1.73% for column numbers 1 to 5, respectively.