Influence of Oil Film Inertia on Piston Skirt Lubrication in High Speed Engine

By an iteration method, the influence of oil film inertia on piston skirt lubrication in a high speed engine is investigated. By alternately solving the Navier-Stocks equations and the Reynolds equation, the new iteration method can trace the variations of velocity field and pressure field with time. Based on this, the mixed-lubrication model suitable for the piston skirt of high engines is proposed. By introducing the inertia coefficient, the new lubrication model includes the inertia term in oil film. The model can be also used to solve for the lubrication performances of a piston skirt in low or medium speed engines and for lubrication problem in general excluding the inertia term of oil film , when the inertia coefficient is put equal to zero. The calculation results show that the influence of oil film inertia on the friction force increases with the ratio of the piston skirt's length to its diameter, the inertia coefficient and the eccentricities of the lower and the upper piston skirt, with other conditions kept constant, while the influence of it on the load capacity of oil film is small.

Research on Effect of Oil Film Inertia on Piston Skirt by Iteration Method

The influence of oil film inertia on piston skirt lubrication in a high speedengine is investigated by an iteration method that alternately solves the Navier-Stocks equationsand the Reynolds equa-tion by finite element method and difference method. The Reynolds lubricationequation including oil film inertia is developed, in which the inertia coefficient is introduced toinvestigate the effect of oil film inertia. The iteration procedure and finite formulation ofsolving the new Reynolds lubrication equation are given to analyze the effect of oil film on pistonskirt in this kind of engine. The calculation results show that the oil film inertia has someeffects on the friction force, pressure force and load capacity of oil film and its effect isobvious for the last. The Reynolds lubrication equation proposed can be also used to analyze thelubrication performance of the piston skirt in low or medium speed engine and some other lubricationproblems generally excluding oil film inertia with the inertia coefficient being set at zero.