Thermo-elastohydrodynamic Analysis of Piston Connecting-rod Big End Journal Bearing Lubrication System
Keywords:
Thermo-elastohydrodynamic, 2-D Reynolds Equation, 2-D Energy Equation, Contact Pressure, Film Profile.Abstract
The existence of friction could be both detrimental and beneficial. On the one hand, friction prevents slipping on a moving vehicle but on the other hand, friction induces by the engine tends to reduce the power. Hence, the aim of the present study is to derive a thermo-elastohydrodynamic mathematical model to predict frictional losses along the piston connecting-rod big end journal bearing lubrication system. A thermo-elastohydrodynamic mathematical model is implemented by integrating 2-D Energy equation with 2-D Reynolds equation to solve the fluid film formation along the piston connecting-rod big end journal bearing. It is used to deduce the tribological properties of the lubricant, namely contact pressure and film profile. Under isothermal condition with increasing lubricant viscosity, both pressure hydrodynamic and film thickness increase. Similar results are demonstrated when there is an increase in the velocity or applied normal load. Under thermal condition, the viscous heating generated during the engine operation tends to increase the temperature, leading to the reduction of lubricant viscosity and film thickness. The mathematical model is simulated and validated with the literature data obtained. However, the simulated results do not correlate well with the extracted literature data although the mathematical model is capable in predicting film thickness in the similar range. This could due to the underestimation on the effect of squeeze film in this study.
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