| As one of the core components of the aero-engine,the aerodynamic behaviour of the compressor is the key factor of the aero-engine performance.The complex flow phenomenon has been embodied inside the compressor,which is always the technical difficulties for the compressor development.Researches showed that,the highly-loaded design will face the conflict of the efficiency and the stability margin of the compressor.One of the main reasons of the instability is the separation flow on the blade surface of a highly-loaded compressor.In order to delay the onset of separation within the boundary layer,slotted blade has been proposed as a flow control method.The principal is that the slot is penetrated from the concave to the convex of the blade,and a jet flow is formed by the pressure difference between the pressure side and the suction side.The flow separation can be delayed by injection of the high momentum jet flow towards the boundary layer of the suction side.Slotted blade has attracted many researchers’ attention because of its simple geometric configuration,easy engineering achievement and remarkable flow control effect.In this paper,a convergence slot structure has been designed.The effect of the various slots with parallel or convergent shape on the performance of the cascade has been predicted by CFD.Detailed numerical investigation has been undertaken for the condition of the inlet Mach number being 0.3 to 0.6 and incidence angle being-5°to +15°.Results show that the velocity of the jet flow is lower than the mainstream when the incidence angle is small due to the low level of the loss of the flow.The total pressure loss has been increased because of the mix of the jet low and the mainstream.When the incidence angle is large,the total pressure loss has been decreased obviously by the jet flow.The convergent slot has achieved better flow control effect than the parallel slot.In addition,the effect of the relative position of the slot at the tip of the rotor blade has been investigated.Three cases for the relative location of the slot,i.e.before the shock wave（20%of chord length）,before the separation point（50%of chord length）and inside the separation region（80%of chord length）,has been designed.The investigated results show that the flow control scheme of the separation region slot has gained better flow control effect with the total pressure ratio increase of 2.78%and the stability margin improvement of 1.38%.Finally,the flow control method of coupled rotor/stator slotted-blade,i.e.,the rotor with a full-span slotted blade and the stator with a half-span slotted blade,has been proposed.Results indicate that the jet slot can suck the low momentum flow on the concave and blow it on the convex.Meanwhile,the undercurrent along the spanwise direction can be blocked.The total pressure ratio has been increased 1%along with the improvement of the stability margin of 2.59%by the scheme of the coupled rotor/stator slotted-blade. |
