Numberical Analysis Of Axial Compressor Flow Stability Optimization By Applying Self-Circulation Air Bleeding And Injection

The continuous development of aero engine required higher performance of compressor, this makes pressure ratio in a single-stage compressor continues increasing. The internal flow state of compressor developed into transonic from subsonic. Interaction between shock wave and boundary layer and vortex caused more complex flow states in compressor passage, improving flow instability, so there exist the need for studies about optimization of flow stability in compressors. Currently, air bleeding and injection has been widely used in the flow optimization in compressor, but when air bleeding or injection are introduced alone will require additional energy input or cause losses of the working fluid, therefore this article will focus on the impacts of self-circulation air bleeding and injection on the stall margin.According to the flow characteristics in compressor, grid with different encryption level at different location was applied. By comparing the simulation results with experiment, verified the reliability of the numerical simulation. Finally used a grid with 1.1million cells, and turbulence model use standard k-ε, Stage35 in different working conditions’ numerical simulation was carried out.In this article, flow state within Stage35 was inspected and self-circulation air bleeding and injection successfully expanded the stalling margin of Stage35. By comparing the development and changes of main flow structures in Stage35 under different conditions, explored the reasons for the stalling process of Stage35 under different rotating speed. Research shows that stalling in Stage35 under the design speed are caused by flow blockage at the tip region of rotor blade which resulted by the interaction between tip vortexes and shock wave, and this reason change to the large scale separation of boundary layer on the suction side of rotor blade at mid span under the influence of shock wave when rotating speed decreased to 70% design speed, while Stage35 was working at 50% design speed the flow instability are the result of flow blockage in rotor tip region which caused by strong radial migration of air on suction side of rotor blade. The reasons for the different effects from self-circulation air bleeding and injection under different rotating speed are revealed.On this basis, studies about different injection position and different way to air bleeding was carried out using numerical method. The results shows that the front injection position and the suction position close to flow separations at the stationary blade suction side are more conducive to improving stability margin.