Numerical investigation on impact of blowing control in flush-mounted S-shaped inlet to rear fan-stage performance

Abstract

In this paper, numerical simulation of the whole structure of a half flush-mounted S-shaped air-intake and the rear fan stage was conducted for investigating the impact of air-intake exit distortion on the fan-stage performance. Considering substantial boundary layer ingesting, a scheme of blowing control imposed near the first bend of the inlet where the flow separation occurs was also carried out. The results show that the air intake internal separation is eliminated, and the distorted air region at its exit decreases significantly after blowing, simultaneously, the aerodynamic performance of the rear fan stage improves dramatically. The choked mass flow increases about 1.45%, and the maximum isentropic efficiency as well as the corresponding total pressure ratio at this point increases about 1.83% and 1%, respectively. In addition, the distorted fluid always covers several blade passages no matter with blowing control or not when it goes through the fan stage. Both relative total pressure and velocity of air in these distorted blade passages are lower than that in other uniform passages and have slightly increased with blowing. Under effect of the inlet flow angle increase caused by the non-uniform air admission and the adverse pressure gradient in the rear part of the flow passage, serious flow separation occurs at the stator blade suction side but mainly exists at 50% span and below and weakens after blowing control.