| During the development of jet engines,it is an important direction of development to increase the stage load for the purpose of reducing the stage number of the compressor and increasing the thrust ratio of the engine.With the increasing of relative Mach number near the blade tip of the high load compressor,supersonic compressors that use the complex shock wave system to achieve the pressure rising have gradually become a research hotspot for high performance compressors.Based on the existing design,the contraction section and the supersonic nozzle which connect the wind tunnel and the ram-rotor cascades are designed,and the effect of different design curves on the outlet flow quality of contraction section and supersonic nozzle is analyzed.The BP neural network system of genetics is applied to the design of the contraction section,and a supersonic nozzle which provides a stable exit Mach number in the range of 1.8 to 2.1 is designed to obtain supersonic flow conditions for ram-rotor cascade.According to the exit conditions of the designed supersonic nozzle,the numerical simulation of the ram-rotor cascade system is performed.The results of this paper show that the quality of the outlet flow in the contraction section designed by the BP neural network system is quite good.The thickness of the boundary layer,deflection angle,pitch angle,surface unevenness,dynamic pressure coefficient and static pressure coefficient are all improved.When designing a supersonic nozzle,attention should be paid to the wall curve of the expansion section.When using the characteristic line method to design the expansion section of the supersonic nozzle,different expansion angles should be designed according to different Mach number requirements for stable flow.Finally,the contraction section and the supersonic nozzle are simulated under different flow conditions,and different outlet conditions of the supersonic nozzle can be obtained,thus providing different stable incoming flow conditions for the ram-rotor cascade.After giving a specific supersonic inlet flow,the shock system is successfully produced in the flow path of ram-rotor cascade system. |
