Research On Engine Flowpath Design Based On S1/S2 Flowsurface Coupling Theory

In the early stage of aeroengine design,the flow-path design determines the flow-path size of each component in the engine,which is applied to the overall structural design and the internal components design.On the stage of the program feasibility calculation of flow-path can grasp of the size of the machine to determine that whether the overall program can meet the requirements of machine size.Throughout the design process,the design of the flow path and the components need to be repeated and coordinated many times.Precise and reasonable engine 2D flow path preliminary design method can accurately estimate the performance and size of the internal components of the engine,thus effectively reducing the iterative design time.Simultaneously,the research of 2D overall performance based on the flow-path design and CFD is also the development trend of the research on engine overall performance.This paper mainly studies S1/S2 flow surface coupling theory of aeroengine flow channel design technology,and determines the Mach number of characteristic section serves as a core parameter throughout the flow-path design process.In this paper,a design method of engine flow-path based on the Mach number of characteristic cross section is developed.In order to ensure the smoothness of the flow-path,the third-order Bessel spline structure is adopted.Based on the overall performance parameters of aeroengine gas turbine,this paper designs the gas turbine flow-path,compressor and turbine blades by using the design method of the impeller based on S1 flow surface.Subsequently,this paper verifies the averaging model,which is based on the circumferential averaging,in three cases of NASA Rotor67,a 3.5-stages fan and the PW E3 high-pressure turbine,and then verifies the designed flow-path performance by using the through-flow model calculation method.The calculation results show that the flow-path can better meet the design requirements,which proves that the flow-path design procedure in this paper possesses the ability to generate the flow-path of the whole engine quickly and reliably.Finally,a turbofan engine fan,low pressure turbine,internal and external culverts,mixing section and tail nozzle and other components were coupled through-flow calculated,in order to study the influence of the geometric parameters of each part matching and transition section on the overall performance of the engine.The results show that the maximum error between the calculated characteristic parameters and the experimental values of each section along the engine under the design state does not exceed 5.0%.The comparative analysis shows that the fan outlet manifold controls the bypass ratio and has some influence on the fan performance and turbine export mixing segment rectifiers have a greater impact on fan and LP turbine performance.By adjusting the geometric parameters of the transition section,the performance of each component can be matched to meet the overall performance requirements of the engine.