由润滑油密度求黏度的新黏压关系式探讨

A New Viscosity-Pressure Formula for Calculating Viscosity from Density of Lubricating Oils

研究了润滑油密度与黏度的关系,并提出了一个由密度求黏度的新黏压关系式.以Dowson-Higginson密度公式为媒介,新公式只改变一个常数可退化为Barus黏压关系,而改变两个常数可退化为Doolittle自由体积黏压关系.用Dowson-Higginson密压关系消去密度,新公式具有与Roelands黏压关系相同的结构,但对应常数各不相同.以squalane油为例,给出了由实验数据确定新公式中两个待定常数的简单方法,而如此确定下来的新公式可以与全部实验数据吻合良好.应用新公式计算黏度并以squalane油品为润滑剂,可顺利求得等温椭圆接触弹性流体动力润滑的数值解,说明新公式具有良好的适应性.

The relation between the density and viscosity of lubricating oils was studied, and a new formula for calculating the oil viscosity from the density under a certain pressure was proposed. With the Dowson-Higginson＇s density-pressure relation as bridge, the new formula can regress into the Barus＇ s viscosity-pressure formula or the Doolittle＇s free-volume viscosity formula by simply changing one or two constants. Furthermore, the new formula can become the same form as the Roelands＇ viscosity-pressure formula but with different constants. Taking squalane as example, a simple way for the determination of the values of constants in the new formula was presented. It is shown that the viscosity predicted by the formula agrees well with experimental data. The isothermal elastohydrodynamic lubrication problem of elliptic contacts was solved with a multi–grid solver by using the new formula and with squalane as lubricant, and the applicability of the new formula proved to be very good.