Study On Vibration Characteristics And Reduction Technology Of Rotating Machinery With Bend Rotor

Vibration is the main index monitoring the safe and reliable operation of rotating machinery.Shaft bend and unbalance can cause unit vibration,it's of important practical significance to study the characteristics of bend rotor,which can help to distinguish the fault caused by shaft bend and unbalance and explore balancing method of bend rotor.Fristly,system dynamic equations to simulate vibration response under the coupled effect of shaft bend and unbalance were set up.The different vibration characteristics were analyzed on the unbalance case and bend rotor case.Changes of vibration response with rotating speed were calculated and analyzed when the angle between the unbalance plane and the bend plane is different.It shows that the vibration on shaft will superimpose on each other when the angle between the unbalance plane and the bend plane is in the same direction.The vibration on shaft will weaken each other when the unbalance plane and the bend plane are in a large angle,and the effect is the best when the angle is 180 degrees.Secondly,a finite element model for steam turbine HP-IP rotor was set up.To the flexible rotor,the phenomenon of the increase of vibration caused by the inconsistency between balancing and unbalance plane was calculated and analyzed in the paper.Results show that rotor bending deformation will be caused by inconsistency between balancing and unbalance plane at high rotating speed,and then,it may lead to the increase of vibration.The steam turbine HP-IP rotor is easy to have creep deformation due to its high temperature operation environment.The phenomenon is more obvious for high pressure rotor of large steam turbine.The shaft bend caused by the inconsistency between balancing and unbalance plane can not be neglected,since it may lead to the increase of vibration.The balance should be carried out in the unbalanced plane as far as possible.Finally,the measurement method of bend rotor was put forward.The relationship of the trigonometric function was calculated between the date of dial indicator and rotation angle of rotor.Rotor bending size and its circumferential angle can be determined by data of dial indicator under two rotating angles of rotor.The method is easy to operate and can improve the accuracy of the measurement of bend rotor.