Numerical investigation of the effect of hub leakage flow on transonic compressor rotor

The effect of leakage flow due to the upstream hub axial gap on the rotor performance and the mechanism of interaction between the hub leakage flow and the rotor blade passage flow were studied based on the numerical simulations of the flow fields of a transonic compressor rotor with upstream hub leakage. The hub leakage flows were modeled and calculated in two different ways: the flow fields inside hub axial gap were calculated together with blade passage flow in an integrated manner, and the leakage flows due to the hub axial gap were modeled as inlet boundary conditions. It is found that the hub leakage flow leads to an increased flow blockage near the hub, resulting in drop of rotor performance. Additionally, the larger the circumferential velocity component of hub leakage flow, the greater the deleterious effect of hub leakage upon the rotor flow.