Research On Dynamic Characteristics Of Rotating Blade-casing Rubbing Based On Plate Theory

Rotating machinery has been widely used in military and civilian equipment such as aviation,aerospace,power etc.In the study of engine field,on the one hand,in order to improve the engine power and compressor efficiency,do the clearance between blade and inner casing as small as possible;on the other hand,blade deformation occurs while the blade rotates under the impact of centrifugal force and aerodynamic loads.It can cause a rub-impact between blade-tip and casing,consequently engine failure generates.It is an extremely complicated process in blade-casing rub-impact;therefore study on the rubbing dynamic mechanism and dynamic characteristics are of great theoretical significance.In this paper,it mainly takes rotating blade as research project,based on energy method,Hamilton variation principle and Galerkin truncation method,the dynamic model of rotating blade under multi-load can be established and investigates the blade-casing vibration characteristic with different external excitation,furthermore analyzes the the blade vibration responses under centrifugal force,aerodynamic loads and different rub-impact casessuch as line rub-impact(along the entire width of blade tip),point rub-impact and local rub-impact.In this paper,the chief research contents are presented as follows:(1)On the basis of plate and shell vibration theory and the energy equation of plate,introducing Hamilton variation principle,then the mathematic model of cantilever plate under the action of multi-load is established and the characteristic of centrifugal stiffening,spin softening and Coriolis force are took into consideration.Meanwhile,modal testing experiment of the blade is carried out,by comparing with the measure results and finite element results;the validity of developed cantilever plate blade model is well verified in this paper.(2)A cantilever plate-casing coupling dynamic model considering rub-impact is established,the blade vibration responses of uniform thickness blade under the function of rub-impact force,centrifugal force and aerodynamic load are analyzed and the influences of responses for blade-casing with different rotational speed,minimum clearance and casing stiffness are deeply discussed.(3)Variable thickness model which is closer to the real blade is also established.System vibration responses of variable thickness blade under the function of rub-impact force,centrifugal force and aerodynamic load are analyzed and the influences of responses for blade-casing with different rotating speeds,minimum clearance and casing stiffness are discussed.Finally,the vibration responses of variable thickness blade shape are fully analyzed.(4)When disk-bladed and rotating shaft installation angle misalignment appears,it will make the distance from different places of blade-tip to inner casing not equidistant and point rub-impact and local rub-impact between blade-tip and casing may happen under the action of centrifugal force and aerodynamic force.In this paper,rub-impact style is judged after the given misalign angle,moreover,the vibration responses of the blade in the conditions of point rub-impact,local rub-impact and lifting process are investigated.(5)Through the blade local rub-impact experiment,the effect of rotating speeds,intrusion and materials of casing on blade vibration responses are investigated.