Effects of axial non-uniform tip clearances on aerodynamic performance of a transonic axial compressor

This paper presents a numerical investigation of effects of axial non-uniform tip clearances on the aerodynamic performance of a transonic axial compressor rotor (NASA Rotor 37). The three-dimensional steady flow field within the rotor passage was simulated with the datum tip clearance of 0.356 mm at the design wheel speed of 17188.7 rpm. The simulation results are well consistent with the measurement results, which verified the numerical method. Then the three-dimensional steady flow field within the rotor passage was simulated respectively with different axial non-uniform tip clearances. The calculation results showed that optimal axial non-uniform tip clearances could improve the compressor performance, while the efficiency and the pressure ratio of the compressor were increased. The flow mechanism is that the axial non-uniform tip clearance can weaken the tip leakage vortex, blow down low-energy fluids in boundary layers and reduce both flow blockage and tip loss.