축류 압축기에서의 선회실속에 관한 3 차원 수치해석

It is known that a tip leakage flow has an important role on a stall inception. However, almost of researchers have taken no interest in a role of the hub-corner-stall on the rotating stall even though it is a common feature of the flow in an axial compressor operating near stall. Using a time-accurate unsteady simulation, it is found that the hub-corner-stall may be a trigger to collapse the axisymmetric flow. An asymmetric disturbance is initially originated in the hub-corner-stall because separations are intrinsically unstable. Then this disturbance is transferred to the tip leakage flows from the hub-corner-stall and grows to be stationary stall cells, which adhere to blade passage and rotate at the same speed as rotor. When stationary stall cells reach a critical size, these cells then move along the blade row and become a rotating stall. The rotating speed of stall cells comes down to 76 percent of rotor so they rotate in the opposite direction to the rotor in the rotating frame.