Deformed Aeroengine Rotor Caused By Thermal Environment Dynamics Research

The aero-engine is praised as the "heart" of the aircraft.It is the most maintenance system and has highest failure rate in the aircraft.Because of the improvement of the efficiency,the clearance between blade and casing are very small.Therefore,the small deformation of the aero-engine rotor may cause friction between the rotor and the case,Which seriously affect the normal operation of the aircraft engine.The main content of this thesis is the influence of deformation of aero-engine rotor due to the internal heat environment in the aero-engine.The deformation mainly includes the thermal bending deformation caused by the engine shutdown and the thermal sliding phenomenon of the aero-engine during start and stop process.The effect of thermal deformation on the dynamic characteristics of an aero-engine rotor is also studyed in this thesis.The thermal bending and thermal creep phenomena are studied separately in this paper.Firstly,the mechanism of thermal bending is studied.A finite element model of aero-engine rotor is established,and The law of rotor temperature change after aircraft engine shutdown is obtained using computational fluid dynamics(CFD)simulation.The variation law of the bending amount of an aero-engine rotor is also obtained.A thermal bending rotor test-bed is designed to verify the correctness of the theoretical calculation.Then The influence factors(ambient temperature,Cold blowing)were also studied.Secondly,the mechanism of thermal creep is studied.First of all,the finite element model of typical bolted connection structure is established.The mechanism of thermal creep is studied by using the finite element method.the influence factors(bolt pretension and uneven temperature distribution)were studied as wall.Secondly,the finite element model of Aero-engine Turbine components is established,by calculating fluid mechanics method,the temperature environment of turbine component during start and stop period is obtained.Then,the variation law of thermal creep and slip of turbine components is calculated.Finally,a dynamic analysis model of aero-engine high pressure rotor is established by using finite element method.The thermal bending and thermal creep are converted to the unbalance of the rotor.The dynamic characteristics of the aero-engine rotor are analyzed.The influence of thermal deformation on the critical speed and unbalance response of the rotor is also obtained..