Dynamic Response Analysis Of Elastic Damping Leaf Damper Based On Fluid-structure Coupling

The torsional vibration of the diesel shaft system inevitably exists when the diesel engine is running.If this harmful vibration is not suppressed,the machinery equipment will not work properly,even the torsional vibration will lead to the fatigue failure of the diesel engine shaft.Elastic damping leaf damper plays an important role in reducing the torsional vibration of ship propulsion shafting.It can reduce torsional vibration of the shaft by changing the natural frequency of the shaft.Due to the damping produced by lubricating oil,elastic damping leaf damper can effectively reduce the resonance amplitude and protect the engine crankshaft,camshafts,intermediate shafts and propeller shaft.Therefore,carrying the dynamic response analysis of elastic damping leaf damper based on fluid-structure coupling,has important theoretical and practical value to improve the reliability of damper operational safety.This paper is based on multi-body dynamic simulation theory and hydrodynamic theory,combining with finite element numerical simulation technology,the torsional vibration characteristic of elastic damping leaf damper is calculated,in addition,the fluid-structure coupling simulation of the leaf damper is analyzed.The research work in this thesis can be summarized as follows:(1)A dynamic lumped parameter model for the diesel engine crankshaft system equipped with elastic damping leaf damper is established.The dynamic equation is solved by the system matrix method,and the torsional vibration characteristic of main parts of crankshaft system is obtained,and then the influence of moment of inertia,torsional stiffness and relative damping of the damper on the torsional vibration of diesel engine crankshaft system is analyzed.The diesel engine can be safely operated within the scope of normal rotate speed;when one cylinder of diesel engine misfires,the diesel engine can be safely operated within the scope of 20~100r/min without restriction.(2)With the help of ANSYS Workbench,combining with the angular velocity,the dynamic contact finite element model of elastic damping leaf damper is established.Through the dynamic contact finite elements simulation,the stress contour of elastic damping leaf damper under the rated conditions,the dynamic contact force curve and the torsional vibration characteristic of the external components of the damper can be obtained.(3)Based on the hydrodynamic theory,Fluid analytical model of internal flow channel of elastic damping leaf damper which contains oil supply system is built,and the flow field dynamic simulation of elastic damping leaf damper is conducted by dynamic mesh technology.Then the regularities of distribution of pressure,velocity,on internal flow channel and the curve of outlet flow rate are obtained at different rotation angle by CFD simulation.(4)Based on principle of fluid-structure coupling,the solid finite element model and the fluid analytical model of internal flow channel are built.Then the simulation considering coupling between flow field of elastic damping leaf damper and reed pieces are conducted.The torsional vibration characteristic of the external components of the damper under the action of fluid is obtained.Then,the law influence of the rotational speed,moment of inertia and width of internal flow channel on the torsional vibration characteristic of the external components.