Load Analysis Of Variable Geometry Turbine Guide Blade Adjusting Mechanism

With the development and advancement of science and technology,the types and performance of aeroengines are becoming more and more diversified.The traditional fixed geometry turbine engine can no longer meet.the needs of practical applications today.The variable geometry turbine can change the turbine by adjusting the angle of the adjustable guide vane.The flow area of the gas,which in turn changes the airflow matching between the turbine moving blades and stator blades,and the overall working performance of the turbine.The angle of the guide vane is changed by a set of mechanical adjustment mechanism driven by a power source installed on the outside of the engine’s outer culvert casing.The load of the adjustment mechanism mainly acts on the adjustable guide vane of the main flow channel.The adjustable guide vane is located in a high temperature and high pressure environment and bears a large temperature load and aerodynamic pressure load.The equivalent stress produced by temperature load and aerodynamic pressure load is the most important factor affecting the strength and life of turbine guide blades.During the movement of the adjusting mechanism,the working torque of the actuator changes.This working torque is a key parameter for the design of the adjusting mechanism.The accuracy is directly related to the design result of the adjustment mechanism.This thesis takes a certain type of aero-engine variable geometry turbine guide vane as the research object.Through the establishment of a CFD simulation calculation model,the load analysis is carried out.The main research contents of the paper are as follows:(1)The guide vane of the adjustment mechanism is designed as an air-cooled blade,and the leading edge and the blade body are equipped with air film holes.In order to accurately predict the temperature load and pressure load on the adjustable guide vane,a fluid-solid based FLUENT is established.Coupled with a numerical calculation model to simulate the flow field of the adjustable guide vane in the entire rotation range.The calculated exit Mach number is compared with the experimentally measured value to verify the correctness of the simulation results.(2)Design the stress analysis model of the guide vane,combined with the specific working state of the adjustment mechanism,and carry out the stress distribution and deformation of the adjustable guide vane under different deflection angles,different turbulence degrees,different flow ratios and different air film hole diameters.After analyzing and summarizing the law of change.(3)The working torque of the adjusting mechanism under different working conditions is calculated.The aerodynamic torque of the guide vane body and the fricti on torque at the rotating shaft are calculated.The UDF function is written to achieve the solution calculation,and the calculation is accurately calculated within the adjustment angle range.The aerodynamic torque of the guide vane body and the friction torque at the rotating shaft can be adjusted,and the working torque after the two superimposed can be obtained.Change the boundary conditions and blade model,calculate the different deflection angles,mainstream turbulence,relative flow ratio of hot and cold gas,air film hole position and diameter of the air film hole on the surface pressure load of the guide vane,explore its distribution and cause of formation,and summarize The general law of the working torque changes when the working conditions are changed,and it provides accurate working torque for the design of the variable geometry turbine guide vane adjusting mechanism.