Numerical simulation of the shock-tip leakage vortex interaction in a HPC front stage

For a single-stage transonic compressor rig at the TU Darmstadt, three-dime nsional viscous simulations are compared to L2F measurements and data from the EGV leading edge instrumentation to demonstrate the predictive capabili ty of the Navier-Stokes code TRACE_S. In a second step the separated region s at the blade tip are investigated in detail to gain insight into the mech anisms of tip leakage vortex-shock interaction at operating paints close to stall, peak efficiency, and choke. At the casing the simulations reveal a region with axially reversed flow, leading to a rotationally asymmetric dis placement of the outermost stream surface and a localized additional pitch- averaged blockage of approximately 2 percent. Loss mechanisms and streamlin e patterns deduced from the simulation are also discussed. Although the flo w is essentially three-dimensional, a simple model for local blockage from rip leakage is demonstrated to significantly improve two-dimensional simula tions on S1-surfaces.