Research Of Modeling Techniques For Small Civilian High Bypass Ratio Turbofan Engine

Engine Modeling technology can greatly reduce the cost of the development of engine and significantly improve the efficiency of research, the object of this thesis is to establish a model for a small civilian high bypass ratio turbofan engine, which is DGEN380 turbofan engine.First of all, according to the actual test data of DGEN380, a simplified real-time mathematical model with the interpolation method for DGEN380 was established without thinking of the internal structure, and the steady state simulation and brief performance analysis were done, including fuel flow and PLA, high pressure speed and fuel flow, low pressure speed and high pressure speed, turbine outlet temperature and low pressure speed.Then, a general steady state model and a dynamic simulation model were established. The general model based on the general mathematical model for engines, including the engine level, the engine component level, the aerodynamics model level, the numerical steady level, was built in MATLAB/SIMULINK environment. And real test for DGEN380 were used to verify and adjust this model.When solving the steady-state simulation model, the joint working equations were first established, and the Newton-Raphson Algorithm and the Genetic Algorithm were compared. As it is easy to call, has good convergence and ability to do global search, and could also get the approximate optimal solution, the Genetic Algorithm was chosen to solve the equations and to obtain the stable convergence resolutions, at the same time, the error analysis was done and according to the results,the model was improved. On the other side, for the dynamic simulation, after comparing the Volume Inertia Method and the Conventional Dynamic Simulation Method based on flow balance, the latter one was used, as the former requires the volume of every component of the engine, which was really difficult to obtain or estimate in our case.This paper used the SIMULINK block library and S-functions to establish a typical engine's component model library, focused on the steady-state and dynamic simulation based on four-level engine structure model. And the steady convergence solutions were obtained, by analyzing the solutions and test data, it proved that the model established was precise, and it had the steady-state and dynamic simulation capabilities.