Simulation And Analysis Of Guide Vane Adjustment Mechanism Of Variable Geometry Turbine

The variable geometry turbine of the aero engine completes the process of “Turbine changing the geometry” through the guide vane adjustment mechanism.The accuracy and efficiency of the mechanism have a great influence on the performance of the engine.Its structure contains complex transmission mechanisms and actuators,so there are inevitably a large number of kinematic pair and gaps.The existence of the kinematic pair gap will affect the movement law and dynamic characteristics of the mechanism.In addition,the working area of the guide vane adjustment mechanism is large,and the temperature difference between the areas is relatively large.Under the influence of the temperature field,component s of mechanism will produce an uneven temperature field distribution.Therefore,the amount of clearance of the kinematic pairs will change accordingly.This article will study the influence of the two factors of gap and temperature on the guide vane adjustment mechanism and give structural optimization suggestions based on the simulation results.This article mainly includes the following:The kinematics model of the guide vane adjustment mechanism under ideal conditions was established;the change law of the input and output angles affected by the elastic deformation of the rocker arm was analyzed;the dynamic simulation model of the guide vane adjustment mechanism with clearance at normal temperature was established;The influence of the motion pair clearance on the mechanism movement and dynamic characteristics and the transmission error of the mechanism are analyzed;the simulation model of the heat transfer analysis of the regulating mechanism is established;Through simulation analysis,the temperature distribution cloud diagram of the mechanism,the change in the gap of each joint and the elastic modulus of the material at high temperature are obtained;according to this condition,the dynamic model is modified;then the simulation analysis is performed again.The results show that the presence of gaps at normal temperature causes collisions and impacts between the movement joints,and therefore it produces empty strokes.Neither the displacement of the limit groove nor the rotation angle of each guide vane can reach the designed target value.And the transmissi on error will accumulate as the rotation angle of the linkage ring increases.When the working load is applied to the model,the collision of the kinematic joint with clearance will become more intense,and the phenomenon of empty travel will become more s erious.Under the action of the temperature field,the clearance of the moving pair in the mechanism decreases and the contact stiffness decreases.This change improves the transmission accuracy and dynamic characteristics of the mechanism and alleviates t he impact of the mechanism when it comes into contact with the collision.