Effect Of Combined Boundary Layer Suction On The Ram-rotor Performance

As an important symbol of the advanced level of national science and industry technology, the advanced gas turbine technology has been the focus of world attention all the time, as the core component of the gas turbine, the compressor is also the key point of the research. Nowadays, the world is facing a series of crisis, including shortage of resources, environmental pollution problems and so on, a variety of new technologies are used in compressor designing, Ram-Rotor is a new type of supersonic compressor based on shock compression technology, which is first proposed by United States, this kind of shock wave compressor has higher pressure ratio, higher efficiency, simpler structure and lighter weight than conventional compressor, it has attracted the attention of energy, power, transportation departments and research institutes.According to the ram-rotor which is designed by our research group, we establish the physical model of single passage of the ram-rotor with many suction slots on its hub and strake, hoping to achieve the improvement of the performance of the ram-rotor through this active control method.Firstly, the effects of hub boundary layer suction on the performance of the ram-rotor have been discussed, and four schemes of combined suction were presented, the influence of suction flow rate on performance of ram-rotor were also discussed. The results show that hub combined boundary layer suction can improve efficiency or pressure ratio of the ram-rotor; suction slotl make the separation bubble on throat ramp disappear, the flow near the left strake is significantly improved because of the suction slot2, the separation zone which gathered in the middle pitch near the hub is almost disappear due to the effects of suction slot3 and slot4, the mixing loss is decrease in the downstream, which cause the improvement of efficiency.Then, according to the distribution of limiting streamlines of strake wall without suction, five groups of suction slots are set on the left and right strake along the flow direction, numerical simulation of ram-rotor with different kinds of strake wall suctions have been carried out. The study found that every scheme of suction have the positive effect, the efficiency and pressure ratio of the ram-rotor are both improved effectively; when the suction slot is just located in spiral node at left strake, we get the greatest promotion of performance parameters, separated vortex along the trailing edge is weaken by the suction, which makes terminal shock wave at each pitch to be more clear, and the boosting capability is increased; the effect of suction slot on right strake is to control the corner separation near the diffuser ramp, when the suction position on the entrance of the diffuser ramp, flow structure becomes better; the suction slots can not only remove low energy fluid, but also produce the gap shock wave, these shocks waves could change the downstream pressure distribution and prevent the downstream disturbance at the same time.Finally, on the foundation of hub combined suction and strake suction, five schemes of hub-strake combined suction are designed, including the optimal schemes of hub and strake suction and others. The results indicate that the effects of hub and strake suction can’t be added together, so the further improvement couldn’t be realized; as the strake suction slot moving to the downstream position, the pressure ratio drops, the efficiency increases at first and then drops; the effects of each slot become bad when their positions are too close, the influenced area of each slot is so large that it can affect the flow field at most of pitch, therefor, in order to get better combined suction schemes, the effects of each suction slot and influences between the suction slots should be taken into good consideration.