Research On Component-Level Modeling Technology For High Bypass Ratio Civil Turbofan Engine

Modeling and simulation technology for high bypass ratio civil turbofan engine is one of the important tools to develop advanced commercial engines with lower cost, less risk and higher efficiency. Based on typical structures of high bypass ratio civil turbofan engine, A detailed nonlinear component-level model was developed, including the turbine active tip clearance estimate model and thrust reverser model.First, the basic characteristics of typical foreign high bypass ratio turbofan engines were analyzed from main structures, core machine-level, performance parameters and cycle parameters. A non-linear component-level model of PW4056 commercial engine was established. The hub and tip fan models were seperately built up considering the obvious influence of high bypass ratio on the fan component characteristics. A simplified core engine gas bleeding and discharging system model was developed, in order to estimate its influence on the civil engine total performance. This model could simulate the slow acceleration and deceleration process within the flight envelope and the entire flight process from land take-off to cruise.The advantages and disadvantages of pneumatic and mechanical active tip clearance control system for turbine were pointed out. From the internal structure of turbine components, how the three sub-components,such as shroud, blade and rotor, impacting the tip clearance of turbine due to thermal stress and mechanical stress were established in order to estimate the transient turbine tip clearance from land take-off to cruise flight, which provide an effective simulation tool to the design of turbine active tip clearance control system. Results show that the specific fuel consumption (SFC) could be reduced through the turbine active tip clearance control, and the model calculation accurancy would be better when considering the influence of tip clearance variation on turbine efficiency.Finally, by analyzing the inner structures of cascade thrust reverser and the impact on the engine, the corresponding simplified mathematical model of thrust reverser was established. Results show that the developed turbofan component-level model with cascade thrust reverser could simulate the transient process when cascade thrust reverser be switched on, which verifies the effectiveness of the thrust reverser model.