Abstract
In this study, a multi-stage transonic axial compressor has been investigated using a large-scale detached eddy simulation (DES) with approximately 4.5 hundred million computational cells. The flow field was analyzed by data mining techniques including vortex identification based on the critical point theory and topological data analysis of the limiting streamline pattern visualized by the line integral convolution (LIC) method. The loss production was evaluated by entropy production rate. It is found that the hub-corner separation occurs on the suction side of the first stator. Although only one hub-corner separation vortex is formed in the time-averaged flow field, hub-corner separation vortex is generated in multiple pieces and those pieces interfere with each other in an instantaneous flow field. The hub-corner separation produces loss over a wide range. However, loss generation around the hub-corner separation vortex is small, and the main loss factor of loss production is the shear layer between the mainstream region and the separation region. In the rear part of the stator, huge loss is generated in the shearing layer between leakage vortex and leakage flow and between leakage vortex and secondary flow.
