Analysis Of Steady State And Dynamic Performance Of Civil High Bypass Ratio Turbofan Engine Model

The aero-engine modeling and simulation have brought many advantages to the performance analysis,evaluation and the research of the engine control system.This paper is based on the performance analysis of the civil turbofan engine with double rotors,and the following research is carried out in accordance with a typical turbofan engine—CFM56-7B which is now at service.Firstly,the calculation method of the ground design point of CFM56-7B engine was performed by a simple constant specific heat method.The calculation result and reference data were reasonable and the relative error between them was 0.358%,and there is a certain error between the fuel consumption rate and reference value due to the fact that the specific heat calculation did not consider the change of the content of the air composition.Based on the relative parameters of the design point,both the steady-state and dynamic-state numerical model of the engine is established by using the modeling method at component-level.According to the flow balance power balance equations of arbitrary point working together to obtain compression ratio of five components and speed of high and low pressure rotor,then calculate performance of single points to get the working point corresponding parameters at the inlet and outlet of the parts,and the thrust and specific fuel consumption at the working point of the engine.Based on steady-state model of high bypass ratio turbofan engine,this paper uses Gasturb software to calculate the performance parameter by numerical simulation.In view of the change of five parts efficiency such as the fan efficiency,high and low pressure compressor efficiency,high and low pressure turbine efficiency influencing on engine performance,parameter sensitivity is analyzed in detail.The relationship between the performance parameters and the independent variables(NL,NH,T5,FF)is observed by simulating the gradual decline of the efficiency of each component in the 1% process when the engine performance deteriorated.In addition,the effect of 4 types of bleed air on the performance of the engine is also considered when 1% bleed air is gradually increased and the angle of the adjustable stator blade is closed to 2 degrees.Results were consistent with reference values.Based on the dynamic-state model of the high bypass ratio turbofan engine,In the dynamic process of the fuel flow increased with phase steps in the 9s time range,with t=0.5s,the dynamic characteristic curves of the engine under the ground standard condition and the air cruising condition are compared,and the application of the similarity theory to the dynamic performance of the engine is verified.The engine speed control based on similarity theory is studied.And based on the similarity theory the control of motor speed is studied.At different speeds,the transfer function of NL,NH,T4 and P3 on the fuel flow is obtained by MATLAB simulation,which can be used as the paving for the design of the controller.