Thermal-fluid Coupling Dynamic Simulation And Drag Torque Prediction Of Wet Multi-plate Friction Clutch

A pair of wet multi-plate friction clutch are generally installed in reversing clutchlarge marine gearbox. When one is in engaging, another is in disengaged. It can befound that the clutch overheating failures may appear not only in engaging process, butalso for high temperature caused by clutch friction plates slipping or lubricant shear, andproduce larger drag torque and energy loss in disengaged operation. Therefore, it is ofgreat theoretical significance and engineering importance to research the separatedprocess of the clutch simulation and drag torques prediction in the state of disengagedoperation to solve the problem of overheating of the clutch and improve the efficiency.The research of this thesis is supported by the Fundamental Research Funds for theState Key Laboratory of Mechanical Transmission, Chongqing University. Focusing onwet multi-plate friction clutch at the state of disengaged and idling operation, thedynamic simulation of flow field and drag torque prediction are conducted. The mainwork in this thesis can be summarized as follows:1) The parameterized finite element model of oil flow field is built in theANSYS/CFX software, and flow field simulation of the clutch is conducted by dynamicmesh technology based on the clutch plates transient equations of motion. After that theseparating process dynamic characteristics of flow field, the influence of spring onclutch plates location are explored and proposed. It is concluded that spring is beneficialto uniform distribution of oil layer thickness.2) According to the theory of oil layer shear heating, the clutch oil temperaturefield is calculated by thermal-fluid analysis method with the real oil way model gainedfrom fluid simulation as the research object. It is concluded that the oil temperature willincrease with the idling rotational speed increases, and decreased with the increases ofinlet flow.3) Fluid dynamics model is established between clutch plates of oil layer withradial grooves, the simulation analysis of the clutch drag torque is conducted based onthe principle of Newton internal friction. Results show that the radial grooves of frictionplate made drag torque reduced, and increases with increase of idling rotational speedand decreases with the increase of temperature.4) Focusing on clutch plates and oil layer between the clutch plates. the flow field,temperature field, stress field and displacement field are calculated by thermal-fluid-structure coupling method when the clutch in disengaged and idledoperation employing computational fluid dynamics, heat transfer and thermal elasticdeformation theory. It is concluded that oil pressure with the increase of oil layerthickness first and then decrease, temperature, stress and displacement increase with thedecrease of the decrease with the increase of reservoir thickness, along increases withthe rotational speed increases.