Oil Aging Influence on the Slide Journal Bearing Lubrication

In this study authors solve the fundamental set of equations of the hydrodynamic theory of lubrication, namely are: the continuity equation, conservation of momentum and conservation of energy for the case of stationary slide bearings lubrication with a thixotropic lubricant. Adoption of assumption of steady flow loads in the considered phenomenon to the changes absence of the flow parameters in a short time period i.e. in one hour. In the constitutive equation is assumed that the stress tensor is a function of strain tensor, dynamic viscosity of oil and hydrodynamic pressure. Dynamic viscosity decreases in a long period of time of work f. ex. after 10 000 by 20 000 kilometres. In a thin layer of oil film, density and thermal conductivity was assumed to be constant. Authors define the lubricant’s dynamic viscosity as a product of viscosity changes in temperature, pressure and time = (T)· (p)· (t). In the analysis of hydrodynamic lubrication, Authors consider a journal bearing of finite length, with the smooth sleeve with a full circumferential angle. Fundamental equations are written in dimensionless form and estimated according to the theory of a thin boundary layer. Prepared in this way equations of motion can be solved by various methods. Authors propose to solve the motion equations with a method of small parameter. The small parameter method we define the unknown functions in a form of uniformly convergent power series expanded in the neighbourhood of the small parameters. In most used cases, absolute value of the small parameter is less than unity. These functions are substituted into simultaneous fundamental equations, then the series are multiplied using Cauchy’s method. Comparing coefficients with the same exponents of small parameter, simultaneous set of differential equation is acquired, from which next approximations of unknown functions are appointed. With so obtained equations, the equation that allows assigning hydrodynamic pressure and hydrodynamic pressure corrections resulting from taking into account the impact of pressure, temperature and ageing in viscosity changes of the lubricant successively can be assigned.