Effect of friction force determination method on results obtained from model of gas flow from combustion chamber to the crankcase

The paper presents investigation of the influence of the friction force calculation method on the results of simulations run with the use of the model ofgas flow from the combustion chamber to the crankcase and piston rings motion in the grooves. The first series of simulations was run using the gas flow and ring motion model in which the friction force was calculated from the empirical equation. The second series was run with the use of the gas flow and ring motion model fully integrated with the ring lubrication model. In that case the friction force was derived from the hydrodynamic model of ring lubrication. Comparison of the results obtained in the first and second series of simulations indicated that despite the fact that the friction forces calculated with these two methods differed considerably, the method of friction force calculation had insignificant effect. This refers to the ąuantities determined in the simulations which are most important from practical point of view - i.e. displacements of the rings in the grooves, pressure courses in inter-ring regions and blowby rate. It is not necessary to integrate the gas flow and ring motion model with the model of ring lubrication, and doing so to complicate it very much, if the aim of the calculations is simulation of blowby and rings behaviour in the grooves.