计入水污染和空穴的船舶艉轴承润滑特性数值分析

Numerical Analysis of Ship Stern Bearing Lubrication Characteristics Considering Water Contamination and Cavitation

为探究少量海水侵入对船舶艉轴承润滑特性的影响,通过实验测量并计算含水率在10%内滑油参数的变化,结合数值分析的方法统筹考虑工质含水率、黏温特性及空穴等因素对液膜润滑特性的影响。结果表明,通过多项式能够较好地拟合流体的黏温特性,且计算过程中液膜的空化和工质的黏温特性不可忽略;在选定工况下,含水率的增加会提高工质的运动黏度,进一步提高液膜压力、承载力、摩擦系数;水的加入明显提高乳液密度和比热容,增强工质携带热量的能力,降低了液膜的总体温度;较高的含水率更易生成空穴,空穴增强了液膜的动压特性,提高了液膜承载力,也降低了液膜的摩擦系数和液膜外侧的最高温度。

The impact of minor seawater intrusion on the lubrication properties of stern bearings in marine vessels was studied.Experimental measurements and subsequent calculations were conducted to evaluate the consequences of up to 10%water content on the lubricating oil’s parameters.Numerical analysis was utilized to holistically consider the impact of various factors,such as water content,viscosity-temperature characteristics and cavitation on the fluid film’s lubrication properties.It was shown that the fluid’s viscosity-temperature properties can be accurately represented using a polynomial equation,and in the calculation process,the formation of cavitation and the viscosity-temperature characteristics should not be overlooked.Under the chosen operating conditions,an elevation in water content boosts the fluid’s dynamic viscosity,thereby enhancing the film pressure,load-bearing capacity,and friction coefficient.The water’s addition also significantly increases the emulsion’s density and specific heat capacity,thus improving the fluid’s heat-carrying capacity and lowering the film’s overall temperature.Furthermore,a higher water content fosters cavitation formation,which simultaneously boosts the film’s dynamic pressure characteristics and load-bearing capacity,and decreases the friction coefficient and the maximum temperature on the film’s external side.