Study On The Design Method Of Super Low Rotating Speed And Super High Loaded Fan Rotor

The technical reserve for the future development of the high bypass ratio turbofan engine was provided with the study of the aerodynamic design method of super low rotating speed and super high loaded fan. By means of optimization and numerical analysis, the blade aerodynamic design and the influence factors of the aerodynamic performance of super low rotating speed and super high loaded fan were explored. The characteristics of the aerodynamic and geometrical of the rotor were analyzed. And the design concept of blade which load was negative was proposed.Firstly, the aerodynamic design flow of the super low rotating speed and super high loaded fan rotor was established. The design indexes were based on the aerodynamic performance of existing high bypass ratio fan rotor, through S2 through flow calculation, the study on the effect of load coefficient and flow coefficient of the rotor dynamic performance was carried out. And the super low rotating speed and super high loaded fan rotor was obtained by the S1 flow profile design, the S1 flow profile optimization and the radial product stacking. NUMECA software calculation results showed that on the premise of the same flow rate and pressure ratio distribution, the rotor rotating speed dropped from the original 3750 RPM to 2240 RPM, the load of rotor in the top of the blade was 0.82, total pressure ratio was 1.78, isentropic efficiency was 0.964, and stall margin was 24.78%. And the main aerodynamic design features which included the low rim speed, the high twisting velocity and the high flow turning angle and the geometry characteristics which included the big blade camber, the thin blade and the light overall quality of the super low rotating speed and super high loaded fan rotor were realized.Secondly, by adjusting the low meridian surface slope, expanding the root blade proportionally and sweeping the stacking line of blade, the optimized improvement of the rotor was studied, and the impact of these changes were analyzed. The results showed that the slope of meridional surface change had little influence to the isentropic efficiency and the total pressure ratio of the rotor, but flow ability had improved; The root blade proportional expansion improved the work capacity of the rotor, the isentropic efficiency only near the stall was improved obviously, but the flow capacity was reduced slightly; The modified stacking line unchanged total pressure ratio, the isentropic efficiency and stall margin had improved significantly.Again, utilizing mature blade design and optimization platform, the aerodynamic design of stator whose inlet conditions was the rotor outlet dynamic parameters was researched. It mainly included the S2 through-flow calculation and S1 stream surface of blade design, S1 stream surface of blade optimization and stacking into fan stator radially. The aerodynamic performance calculation of fan stator was carried out under fan stage environment with software NUMECA. The calculation results show that the aerodynamic performance of the stator was expected to achieve the design goals basically.Finally, the impact factors of the aerodynamic performance of fan stage were studied, which contained the rotor root blade proportional expansion, stator root blade profile optimization and the improvement of rotor stacking line. The results show that the rotor root blade proportional expansion improved total pressure ratio of fan stage and rotor, other aerodynamic performance was basically unchanged; Stator root blade profile optimization had little impact on the rotor dynamic performance, but aerodynamic performance of stator and fan stage had greatly improved; The improvement of rotor stacking line made the operating range of the fan stage increased significantly, so isentropic efficiency and stall margin of fan stage significantly improved.