船舶可倾瓦推力轴承润滑油膜的轴向动特性计算方法

Calculation method for axial dynamic characteristics of lubricant oil film in marine tilting pad thrust bearing

推力环和推力瓦之间的楔形润滑油膜是实现螺旋桨推力传递的重要环节,其轴向动特性直接关乎船舶轴系转子的纵向振动特性。文章分别论述了船舶可倾瓦推力轴承楔形润滑油膜轴向动特性的一维流近似解析方法和二维流数值方法,在已求得油膜静特性基础上,分别结合偏导数法和小摄动法获解了油膜动特性,推导了两种方法计算油膜动特性的求解式,并给出了详细计算过程。以某船舶可倾瓦推力轴承为算例,对两种方法的计算结果作了比较分析,得到了最小油膜厚度、油膜承载力和油膜轴向刚度三者间的一般变化规律,讨论了油膜动特性随轴转速的变化关系。计算结果为基于转子动态模型研究轴系纵向振动的传递机理提供了油膜动特性数据。

The oil film between thrust collar and tilting pads is one of significant transmitters for propeller thrust transmission. The axial dynamic characteristics of oil film make great influence on longitudinal vibra-tion of propulsion shafting. In this paper, two methods are presented to evaluate the longitudinal stiffness and damping of oil film, namely one-dimension approximate analytical method and two-dimension numerical method. For the first method, the pad is interpreted as rectangle slider. While for the second method, the actual sector pad is directly used as objective. As the premise of dynamic analysis, the static characteris-tics of oil film with action of propeller steady thrust are firstly carried out based on dynamic lubrication principles. And then the calculations of oil film dynamic characteristics are derived in great detail by the partial derivative method and the small perturbation method. Taking the example of a marine thrust bearing, the comparison of results with two proposed methods is conducted. Further, the relationship among minimum film thickness, film carrying capacity and film stiffness is analyzed, and so also is for the rule between oil film dynamic characteristics and shafting rotating speed. The values of oil film dynamic characteristics can be applied for transmission research of propulsion shafting longitudinal vibration.