Investigations on the Effects of Inflow Condition and Tip Clearance Size to the Performance of a Compressor Rotor

Abstract

To clearly clarify the effects of different upstream boundary layer thickness and tip clearance size to the detailed tip flow field and flow mechanism, numerical simulations are performed on a subsonic compressor rotor, which is used for lowspeed model testing of a rear stage embedded in a modern highpressure compressor. First, available experimental data are adopted to validate the numerical method. Second, comparisons are made for tip leakage vortex (TLV) structure, the interface of leakage flow/mainflow, endwall loss, isentropic efficiency and pressurerise among different operating conditions. Then, effects of different clearance sizes and inflow boundary layer thicknesses are investigated. Finally, the selfinduced unsteadiness at one nearstall (NS) operating condition is studied for different cases. Results show that the increment of tip clearance size has a deleterious effect on rotor efficiency and pressurerise performance over the whole operating range, while thickening the inflow boundary layer is almost the same except that its pressurerise performance will be increased at mass flow rate larger than design operating condition. Selfinduced unsteadiness occurs at NS operating conditions, and its appearance largely depends on tip clearance size, while the effect of upstream boundary layer thickness is little.