Optimized Design And Performance Analysis Of A Certain Type Of Aircraft Air Inlet Airflow Adjustment Device

Inlet is an important part of jet engine,whether it can work efficiently or not is related to the performance of the whole aircraft thrust system.For the wide Mach fighter,the variable geometry inlet can adjust the size parameters and aerodynamic characteristics of the inlet according to the external environment and the flight speed of the aircraft,so that the current intake and the engine airflow demand can reach the flow balance.The purpose of this paper is to design an inclined plate air flow control device for a certain type of variable geometry inlet,which not only overcomes the weakness of the original mechanism,but also can work normally under various adverse conditions.At the same time,the air flow regulating device also has a good regulating effect on the supersonic air flow.In this paper,the two-dimensional model of the air flow control device is designed,and then the kinematic model is established according to the motion relationship and kinematic characteristics of the mechanism,and the program is written.In order to adapt the designed mechanism to a specific type of inlet,it is necessary to find out the specific size of the mechanism.Therefore,the established kinematic model is used,and a set of complete size parameters of the mechanism is derived through some known size parameters.Because this group of dimensional parameters are derived from the kinematic relationship of the mechanism,without considering the force of the actuator,transmission ratio and other factors,it needs to be optimized and adjusted.The parameter adjustment of the mechanism is a multi-objective optimization problem,and a single parameter adjustment can not meet all the objective requirements.Therefore,particle swarm optimization algorithm is used to adjust the multi parameter and multiobjective of the mechanism,and a group of optimal size parameters are obtained.In order to ensure the feasibility of the mechanism,the operation range of the mechanism is within its travel limit,and the mechanism will not appear dead point in the process of movement.According to the obtained parameters,a three-dimensional model is established,and the strength check and vibration analysis of the mechanism under various working conditions are carried out by using workbench.Through the simulation results,it can be concluded that the air flow control device can work normally in a variety of conditions,and there is no strength failure problem.The subsequent modal analysis and harmonious response analysis of the mechanism have determined the vibration frequency band where the maximum vibration displacement of the weak part of the mechanism is located.Finally,in order to test the regulating effect of the air flow regulating device on supersonic air flow,the device is installed in a specific type of inlet,and supersonic air flow with different velocity is introduced into the inlet.The flow field of the inlet is analyzed by fluent,and the total pressure coefficient of recovery,distortion index and stamping ratio at the outlet of the inlet are calculated.It is concluded that the air flow regulating device is well matched with the inlet,and the regulating effect on the supersonic flow meets the expected requirements.