A numerical study on the tip clearance in an axial transonic compressor rotor

The tip clearance flow in a transonic compressor rotor has been studied numerically. The three-dimensional Navier-Stokes equations with Spalart-Ammaras (SA) turbulence model are discretized in the physical space by using a discontinuous Galerkin method. The flow field is assumed to be periodic and a single-passage steady state model is used for the numerical simulation. An improved blockage indicator has been proposed to estimate the blockage in the transonic rotor. The results show that the tip clearance has a significant influence on the blockage in the rotor. The tip clearance flow and the main flow is interacted with each other, and the interface between them is becoming parallel to the blade leading edge plane as the mass flow rate is decreasing. The tip clearance flow in the transonic rotor can be divided into two parts, and the interface between them is in contact with the adjacent blade trailing edge in the near stall condition. A part of the tip clearance flow is ejected into the next blade passage when the mass flow rate is small enough. Besides, the shock and the tip clearance flow interaction can be seen clearly. Due to the tip clearance flow, the shock wave bends and its intensity is weakened. Meanwhile, the tip leakage vortex diffuses after the interaction with the shock.