Dynamic Characteristics Study Of Aero-engine Rotor System With Blade-casing Rubbing And Coupling Faults

The requirements of service efficiency and safety of civil aviation aircraft are increasingly more strict day by day with Chinese civil avation develop rapidly.Reducing the clearance between the blade tip and the casing is one of the most effective methods on improving the aero-engine efficiency.However,with the decreasing clearance,the rotor and the stator are at high risk of contacting and leading to rubbing faults.The rubbing has great effect on the vibration of the rotor system and has been recognized as one of the major causes of aero-engine safe operation.This paper establishes a rotor system dynamic model,which is based on a simplified civil aero-engine low pressure rotor system.The blade-casing rubbing with abradable coating,the coupling faults of blade-casing rubbing and other faults are considered in the model.The rotor system vibration characteristics are obtained by the numerical simulation and experimental.The main research contents are as follows:The rotor dynamics model is established on the basis of simplified civil aero-engine rotor.The rolling bearing force model which considered the Hertz contact and elastohydro-dynamic lubrication theory is established.The rubbing force model of blade-casing rubbing without abradable coating is developed on the basis of the law of energy conservation.A model of blade-coating rubbing force which considers the parameters of abradable coating is established on the basis of coating scraping process analysis.The two rub force models are introduced into the rotor system model,and the equations of motion of the rotor system are solved by the fourth order Runge-Kutta method.Dynamic characteristics of the rotor system with blade-casing rubbing fault are studied.The effects of the rotating speed,eccentricity and the initial clearance between rotor and stator are analyzed.The meshing stiffness model of single tooth of gear coupling is developed on the basis of analyzing the gear coupling working mechanisms.The meshing force model and misalignment force model are introduced into the rotor system under blade-casing rubbing with abradable coating.Dynamic characteristics of the rotor system with misalignment-rubbing fault are studied,the effect of misalignment on the rub force and vibration of rotor system is sought.The inner ring and roller fault mechanics model is set up by defining the pits and segment size of rolling bearing,dynamic characteristics of rotor system with rolling bearing fault is analyzed.In addition,dynamics characteristics of rotor system with bearing-rubbing faults is studied,and the effect of bearing pits on the rub force and vibration of rotor system is sought.A “0-2-1” supporting form test bench is set up based on the civil aero-engine rotor system.The blade-casing rubbing faults simulation device is designed.The vibration data is measured by the eddy current sensor and the pull and pressure sensor.Simulation experiment of blade-casing rubbing faults with/without abradable coating、simulation experiment of rubbing-misalignment coupling faults are respectively conducted.The dynamic characteristics of rotor system with these faults are studied.The simulation models are verified by the comparison between the simulation and experimental results.