Investigation Of The Separation Flow Control Of Boundary Layer Suction In High Load Compressor Cascade

Development of aviation engine determines the level of Chinese aviation industry. When aviation engine reaches the advanced level, the aviation industry can continue to develop and advance. As an important part of the aeroengine, the aerodynamic performance of Compressor is a key factor for aeroengine. With the increase of the load of the compressor, the three-dimensional flow separation in the cascade is gradually increased, so that the design of the high-load compressor becomes more difficult. MIT has given the concept called low-reaction compressor. Then Professor Songtao Wang of HIT put forward another kind of low-reaction compressor and there is the boundary layer suction only in static cascades. Because of the low-reaction of the rotor, the load of the stator is higher and the boundary layer suction is adopted to control the flow separation to improve the aerodynamic performance. A low-reaction subsonic compressor and a low-reaction supersonic compressor are chosen to study the boundary layer suction in static cascade and the influence of the boundary layer suction on the aerodynamic performance. In order to improve the engineering practicability of the results, a blade cavity, suction holes, suction slots and air entrainment chambers are added.Firstly, Stage 35 data is chosen to prove the numerical method right. The grid number is about million. The k-ε turbulence model is adopted. Numerical result and experimental result are compared to prove that the k-ε turbulence model is appropriate and the numerical result in this paper is right.After proving the numerical method is right, a low rotating speed compressor is chose to study the boundary layer suction first. Blade cavities, suction holes and covers near the end walls are added in the static cascades. Depending on the original type of the three-dimensional flow separation, the program which suction the boundary layer from the suction surface and lower end wall. A special condition is chose to study the boundary layer suction. The results shows that there exists a separation flow near the upper end wall. But the effect of the boundary layer suction becomes better when the mass flow rises. Adjusting the local mass flow and location can make the suction flow distributed again and can also get a better effect. It proves that the strategy adjusting local mass flow to improve the result of boundary layer suction is feasible.A new program is carried out to make up the shortcoming in the previous program. The boundary layer is suctioned from the suction surface and both end walls. And other structures are held. The influence of the boundary layer suction on controlling the flow separation and the aerodynamic performance of compressor are studied in the entire range of operating conditions. The result shows that the boundary layer suction can control the flow separation well in the entire range of operating conditions. The total pressure ratio and the efficiency are both raised. The aerodynamic performance is improved better. Properly increasing the suction mass flow can also promote the aerodynamic performance of the compressor. The efficiency can reach 0.91 and the total pressure ratio can reach1.055 at the top.At the same time, the program which only suction boundary layer from the lower end wall is studied too in the entire range of operating conditions. The result shows that the boundary layer suction on single side can also control the flow separation near the choke point. There is a folded point on the characteristic lines. When the pressure of the outlet is raised to a certain degree, there is a flow separation near the upper end wall and the aerodynamic performance of the compressor drops suddenly. Before and after the folded point, the suction mass flow changes automatically. By means of comparing the results of suction on both sides and single side, it concludes that the effect of boundary layer suction from both sides is better.Finally a high rotating speed compressor is chose to study the influence of the boundary layer suction. After comparing the results of two slots and single slot on suction surfaces, it proves that the effect of the program with two slot is better. The program with two slots is chose to study the effect of the boundary layer suction in the entire range of operating conditions. The result shows that the program with two slots can control the flow separation well in the entire range of operating conditions. After observing the change of the suction mass flow, it proves that only if the suction mass flow is high enough, the effect of the boundary layer suction will be good.