液粘调速离合器油膜剪切空化及其动力传递失效机理研究

Hydro-viscous clutch (HVC) has a significant energy-saving effect in speed regulation and soft start of mechanical equipments. Our pre-research demonstrates that oil film cavitation directly causes the decrease of efficiency and reliability of the HVC. Therefore, this project intends to further investigate the shearing cavitation mechanism and dynamics of cavitation bubbles, and the effect of surface features of friction pair and cavitation-temperature coupling on transmission reliability of oil film. Firstly, based on a visual power test device for oil film, the critical condition and flow pattern of shearing cavitation are studied experimentally. Secondly, a dynamics model for cavitation bubbles of oil film is established to explore the formation, development and collapse of cavitation bubbles and its influence factors. Thirdly, an air-fluid two-phase model considering surface features is built to reveal the effect of surface features on oil film cavitation and transmission characteristics. Lastly, an oil film dynamics model considering cavitation-temperature coupling is built to explore the effect of cavitation-temperature coupling on pressure distribution, dynamic load, transmission torque of oil film. Based on the Tribology, Fluid Dynamics and Bubble Dynamics, and combining experimental study, theoretical derivation and numerical simulation methods, the shearing cavitation of oil film and its power transmission failure mechanism in HVC are finally revealed to enhance the efficiency and reliability of the hydro-viscous drive system.

液粘调速离合器在机械设备的调速和软启动方面具有显著的节能效果，前期预研表明油膜空化是降低其传动效率和可靠性的主要原因。本项目针对液粘调速离合器摩擦副间油膜剪切空化的形成机理和空泡群的动力学行为、摩擦副表面特征及空化-温度耦合作用对油膜动力传递可靠性的影响规律等科学技术问题开展深入系统的研究。通过油膜动力可视化试验，研究油膜剪切空化的临界条件和空化流型；建立油膜空泡群动力学理论模型，揭示空泡群的形成、发展和溃灭过程及其影响因素；建立考虑摩擦副表面多特征参数的气液两相流模型，揭示摩擦副表面多特征参数对油膜空化和传动特性的影响规律；建立基于空化-温度耦合的油膜动力学模型，探索空化-温度耦合作用对油膜的压力、动压承载力和传递扭矩的影响规律。通过摩擦学、流体动力学和空泡动力学，结合试验研究、理论推导和数值模拟，最终揭示液粘调速离合器油膜剪切空化及其动力传递失效机理，提高液粘传动系统的效率和可靠性。

节能调速技术一直是世界各国研究的热点之一，液粘调速离合器是通过改变旋转摩擦副间油膜厚度调节输出转速和扭矩、并兼有离合功能的节能调速装置，具有启动冲击小、无级调速、同步传动和高效节能等特点。本项目针对大功率液粘调速离合器中存在的迫切需要解决的技术问题，概括提取出科学问题，开展液粘调速离合器传动机理和可靠性等方面的理论和实验研究。.项目综合应用摩擦学、流体动力学和空泡动力学知识，结合试验研究、理论推导和数值模拟，揭示了油膜空化的临界条件和空化流型，掌握了不同工况下空泡的体积分数、分布规律和运动行为，为进一步深入研究提供了实验数据；建立了油膜空泡群动力学模型，揭示了油膜空泡群的形成、发展和溃灭过程及其影响因素，获取了避免油膜空化的方法；建立了考虑摩擦副表面多特征参数的气液两相流模型，揭示了表面特征参数对油膜空化和传动特性的影响规律，为设计更加合理高效的摩擦副表面结构提供了参考；构建了基于空化-温度耦合的油膜动力学模型，揭示了液粘调速离合器油膜动力传递失效机理，提高了系统传动效率和可靠性。.项目执行期间已发表学术论文16篇，其中SCI收录9篇、EI收录4篇；培养学生完成硕士论文6篇、博士论文1篇；授权发明专利11件，另外受理发明专利2件；参加国内外学术会议6次。研究成果获得中国机械工业科技进步二等奖1项、中国石油和化学工业科技进步二等奖1项。较为优秀地完成了项目预期目标。