Turbofan Engine Combinations Change The Geometric Expansion Of The Stability And The Optimization Analysis

Modern low bypass ratio turbofan engine is the heart of the new fighter, whose performance and aerodynamic stability greatly affect the characteristics of the new fighter. Since the operating situation of the fighter is very complex, so the operating ranges of the turbofan engine are very wide. This brings forward more requests for the aerodynamic stability of the turbofan engine. To meet the needs for wider surge margin of the turbofan engine, a new model was developed to predict the characteristics of the fan/high pressure compressor and turbine in this thesis. Several ways, including, variable inlet guide vanes of the fan, variable guide vanes of the high pressure compressor, the variable inlet area ratio of the mixer and the nozzle areas, were presented to enlarge the surge margin of the turbofan engine. Meanwhile, a method of combined variable geometries for optimizing controls of inlet guide vanes of the fan, guide vanes and the first two stators of high pressure compressor, area ratio of mixer and nozzle areas was established. The results show that appropriate combined variable geometries can improve the engine aerodynamic stability greatly. Based on the visual technology, the graphical simulation interface of the turbofan engine was presented using multi-language program in this thesis.