Research On Vibration Reduction Characteristics Of Turbine Twisted Shrouded Blade With Impact And Friction

Aero-engine is regarded as the heart of the airplane,which can provide the main power for the airplane during its working.The blades are the key parts of the aero-engine,which can significantly affect the performance of the engine.The blades always work in high temperature and high-pressure environment,and they are easy to get high cycle fatigue.Consequently,the research on the vibration reduction characteristics of blades is very valuable.Taking the demand of vibration reduction of turbine shrouded blade as background,and considering the effects of blade stagger angles and twist angles,the analytical model of turbine rotating shrouded blade is established using Hamilton’s principle and Galerkin method.In this model,the rotating shrouded blade is simplified by a cantilever beam with mass on its free end.Moreover,on the basis of the analytical model and taking the impacts,friction and the combination effects between impact and friction among adjacent shroud interfaces into consideration,the analytical model of twisted shrouded blade with impact and friction is developed,and the influences of some parameters like shroud gaps,contact stiffness,shroud inclination angles on the dynamic responses and vibration reduction characteristics are investigated.The main contributions are listed as follows:(1)Considering the rotating effects of shrouded blade,such as the centrifugal stiffening,spin softening and Coriolis force,the analytical model of rotating twisted shrouded blade is established,and its effectiveness is validated by finite element model using ANSYS software.In addition,the effects of stagger angles and twist angles on the natural characteristics of twisted shrouded blade are discussed.(2)Taking the effects of impacts among adjacent shrouds into the analytical model of twisted shrouded blade,the analytical model of shrouded blade with impacts is developed,and the vibro-impact dynamic characteristics are analyzed using two different impact models.In addition,the influence of shroud gaps,contact stiffness,stagger angle and twist angle on the dynamic responses of shrouded blade are discussed and the impact mechanisms of the two impact models are revealed.(3)Analytical model of rotating twisted shrouded blade with dry friction is proposed in this part,and in this model,shroud friction is modeled by using macro-slip model with hysteresis spring.This analytical model is verified by the results from references and finite element model.Moreover,the effects of some parameters like normal contact loads,coefficient of friction,contact stiffness,shroud inclination angles,stagger angles and twist angles on the dynamic and vibration reduction characteristics of turbine shrouded blade are analyzed.(4)Considering the combination effects between impact in normal direction and friction in tangential direction on the shroud interface,the dynamic model of turbine shrouded blade with impact and friction is developed,whose validity is verified by finite element model in ANSYS software.Based on the developed model,the dynamic responses and vibration reduction characteristics of shroud structure of shrouded blade under different normal load,shroud gaps,coefficient of friction are investigated.