Research On Transient Response Of Blade Tip Clearance Of High Pressure Turbine Based On Temperature And Revolution

The high-pressure turbine clearance of an aero-engine has an important impact on engine efficiency and safety.It is necessary to research tip clearance of the high-pressure turbine whether the aero-engine works in stable or transient state.In this paper,three-dimensional models of turbine blade,turbine disk and casing are established by Solidworks software based on structure characteristics of high pressure turbine tip clearance,and the models are introduced into ANSYS Workbench for numerical analysis.The thermal-solid coupling finite element analysis method is used to analyze the steadystate performance while maintaining the maximum take-off power.The results show that when the blades and turbine disks are maintained at the maximum take-off power,the radial extension of the turbine blades and turbine disks is affected more observably by temperature than centrifugal load.The impact of heat on the casing is mainly concentrated in the middle of the casing and it is significantly necessary to reduce the thermal stress and deformation by impinging heat transfer with the cooling system.Under temperature load,the maximum radial extension of the casing is located at the rear mounting edge and the radial extension at the hook of the casing and the liner ring can be effectively reduced by using the reinforcing rib.Based on the steady-state analysis and the data collected by the Quick Access Recorder(QAR)of an aero-engine,the high-pressure turbine clearance is calculated under transient state and the deformations of the blade,the disk and the casing are analyzed respectively,then the transient variation rule of high pressure turbine clearance is obtained.Complex temperature boundary conditions and the nonlinear of material deformation,temperature and centrifugal load are considered in the calculation.The results show that deformation caused by centrifugation during the idling phase of the aircraft is the main factor.The reason is that the turbine disk has a large heat capacity and requires a certain temperature response time.The blade deformation rate is faster than that of the wheel disk.The reason is that the blade mass is small and the sufficient heat transfer and the response rate is faster than the roulette wheel.The radial thermal deformation of the casing gradually stabilizes during the late climbing period because the high-temperature gas temperature gradually increases during the accelerated climbing process.The minimum clearance value occurs between the end of the take-off phase and the beginning of the climb phase.During the time,the speed will change quickly,which leads to a large amount of centrifugal rotor elongation.Although the temperature inside the turbine also increases rapidly,the rotor centrifugation is faster than the thermal deformation rate of the casing.The clearance rules with and without HPTACC are compared,which shows that ACC can effectively prevent scraping between the blade and casing when the engine idling and during takeoff.In this paper,the transient change rule of high-pressure turbine clearance is obtained,which lays a foundation for the reliability optimization design of the high-pressure turbine active clearance control.