Axial Compressor Transonic Rotor Shock Interaction With Upstream Stator Row

Abstract

Abstract Modern high-performance multistage axial compressors are designed for high aerodynamic loading and efficiency, wide range and operate front stages with rotor inlet relative Mach number above one over a large portion of span. Understanding unsteady flow phenomena and rotor-stator interactions is paramount in the design of front stages. With increased aerodynamic loading, rotor shock waves may propagate upstream and interact with stator vanes. Such interaction may affect both performance and aeromechanics as shock propagation and reflection may destabilize boundary layers leading to higher aerodynamic losses and unsteady pressure pulsations. Unsteady numerical simulations prove to be necessary to predict and minimize the impact of rotor to upstream stator shock interactions. This paper discusses rotor-stator shock interactions using unsteady numerical simulations. The computations are performed on three stage designs, under the constraint of same capacity and total pressure ratio but differ in axial gap and load distribution in stator and rotor. Speedlines from steady and unsteady computations compare the different designs, and the detailed flow fields are analyzed at design and close to stall conditions. The analysis reveals the importance of relative orientation of shocks generated in the rotor row with the upstream stator camber line, while steady simulations predict a different stator-rotor loss split. This orientation affects the intensity of the shock boundary layer interactions and the shock reflections as well as compressor performance. The comparison of the designs suggests possible ways to mitigate the growth of shock-driven losses.