Research Of Turbofan Parameter Design Based On Fighter Flight Missions

The aero-engine plays a decisive role in the aircraft system and should be designed according to specific purpose and missions.However,according to the traditional design method,the aero-engine and the aircraft are designed seperately with the installation edge as the boundary.In the design stage,certain adjustment domains must be reserved so that the performance of the engine can not be fully utilized and the overall combat capability of the fighter is indirectly affected.In order to enhance the overall performance of the aircraft/engine system,to maximize engine performance,and to obtain the best matching design,it is necessary to design the engine based on the fighter flight missions.In this thesis,starting from the missions of fighter,the parameter design and performance analysis of two-spool small bypass ratio mixed exhaust turbofan engine are studied.The main contents of this paper are as follows:Constraint analysis model and mission analysis model of fighter are established respectively,and these models are implemented by C++ programming.Based on the constraint analysis of fighter aircraft,the constraint bounds and solution domain under different constraints of fighter are obtained.Then the initial design points of fighter are selected to obtain the relation of takeoff thrust-weight ratio and wing load.Combined with the results of constraint analysis,the mission analysis of fighter are implemented to obtain the fighter’s sea level takeoff thrust for engine design.The design point model and off-design point model of two-spool small bypass ratio mixed exhaust turbofan engine are established.The variable specific heat method is adopted in the modeling process,and the effects of bleed,cooling and power extraction are considered.Using object-oriented modeling method,the engine design point calculation program and off-design point calculation program are implemented by C++,and the fighter constraint analysis and mission analysis program are integrated to form the turbofan engine design software based on the fighter mission.Using database to store all the calculating data and results,the advantage of database is that large amounts of data can be called at any time and facilitate later data processing,and also the computer hardware requirements are low and the calculation time is short.The results obtained by the design point calculation program and the off-design point calculation program are compared with the calculation results of GasTurb11 software to verify the accuracy of the program.After that,the off-design point algorithm and component matching of the small bypass ratio turbofan engine was researched,and the characteristics of height,velocity and throttle of small turbofan engine were obtained.Finally,the software was used to verify all the fighter missions by off-design point algorithm,and the performance of the engine under different flight missions was obtained.And the results of the constraint analysis and mission analysis were used to design the engine scheme and determine the final size of the engine.