Numerical Analysis Of Thermal Ehl Problems Considering Boundary Slippage Under Simple Sliding Condition

In this thesis,effect of boundary slippage on the elastichydrodynamic lubrication(EHL)problem under the simple sliding is studied.The main work is divided into three parts: the analysis of the effect of boundary slippage on the isothermal EHL of point contacts under the simple sliding,the derivation of the mathematical equations on the thermal EHL problem considering boundary slippage.and the numerical simulation of the thermal EHL problem under simple sliding considering the boundary slip.Firstly,based on the Navier-slip boundary condition,the mathematical model of isothermal EHL under the simple sliding considering with boundary slip is established.The multigrid method is used to numerically analyze the problem.It analyzes that the effect of the different boundary slippage condition to pressure and oil film thickness,and with different slip length,the variation of the numerical results of pressure and film thickness profiles are presented.Compared with the results of recent researchers,it is indirectly verified that the established mathematical model and the program being written are reliable.Secondly,the generalized Reynolds equation derived by Professor Peiran Yang is modified for considering the effect of boundary slippage,and the corresponding mathematical model of thermal EHL problem is established.The pressure is solved by the multigrid method while the temperature field is evaluated by a column-by-column scanning technique.The new modified generalized Reynolds equation can be used to solve roll-sliding,simple sliding,and reverse sliding conditions.Finally,under simple sliding conditions,the effects of slip length of moving surface on pressure,film thickness and temperature distribution are analyzed,and the increase of speed and load also are considered.The results show that the central pressure,central film thickness,the minimum film thickness and the temperature rises in the contact decrease with the increase of the slip length.The thermal rise is influenced more than the pressure and film thickness by the boundary slippage.Above a certain slip length,the thermal rise on the moving surface in the conjunction can drops to the ambient temperature,resulting in a temperature entrapment in the contact area.Moreover,the effect of the slip length on the "temperature-viscosity wedge" dimple is investigated by increasing the pressure-viscosity coefficient.