The Aerodynamic/Structure Design Of Subsonic Aspirated Compressor Cascade

In order to restrain or eliminate the boundary separation of a rotor with large turning angle and keep it working in high efficiency, the rotor's inlet should be pre whirled so that its reaction was reduced. As a result, the stator has an extra-large turning angle. The application of aspiration on compressor stator should be carried out in order to control its intensive 3D separation flow.In this dissertation, the evaluating method and standard of pressure loss and efficiency is firstly discussed, when the boundary layer suction is applied. When the total pressure loss of the whole vane is evaluated, the pressure loss of the gas which is sucked should be considered.In this dissertation, the large turning cascade with 70 degree turning angle is researched. By numerically simulation and topological analysis, it indicates that the flow flied in the large turning cascade has several characteristics. There is large separated flow on the cascade suction surface. The strength of secondary flow on the endwalls is high because of the high lateral pressure gradient. The interaction of separated flow and secondary flow makes the flow flied more complicated.This dissertation numerically investigates the compressor cascade using boundary layer suction and analyses the impact of flow field within cascade occurred by different suction slot widths on condition of same suction location and same bleed mass, different slot locations on condition of same bleed mass, different bleed masses on condition of same slot location and compound boundary layer suction slots. The investigation presents, compared to original cascade, the boundary layer suction can improve the condition of flow, reduce the loss. The suction slot width on condition of same suction slot location and same bleed mass has little difference in the effect on the flow field. But different slot locations and different bleed masses have different effects on the flow field. There is the optimal suction slot location and the optimal bleed mass. Compound boundary layer suction can limitedly improve the flow field. But considering the endwalls suction can complicate the actual suction structure, the suction is only applied on the cascade suction surface in this dissertation. Before the design of the actual suction structure, this dissertation numerically investigates and analyses the impact of flow field by different suction slot shapes. The investigation presents, when the suction slot is downstream, it can reduce the pressure loss at the outlet of the suction slot. Based on the investigation, two kinds of actual suction structure are designed. One has two outlets with one cavity; the other has one outlet with three cavities. The numerical result of the former one approaches the optimal result and the latter one is not so good. But the latter one can also reduce the separation flow and loss to an acceptable level.