A semi-deterministic texture-roughness model of the piston ring–cylinder liner contact

Abstract

Many simulations already exist to model the piston ring–cylinder liner contact; however, very few models have been used to investigate the optimum surface texture. An axi-symmetric, time-dependent two-dimensional semi-deterministic texture-roughness model of the piston ring to cylinder liner contact with periodic boundary conditions and mass preserving global cavitation has been developed. The cylinder liner texture, generated by honing, was considered deterministically on the global scale, after an investigation comparing deterministic and homogenized solutions. The surface texture of a real cylinder liner was measured with white light interferometry and an algorithm developed to generate an artificial periodic texture representative of the real surface. The effect of cylinder liner plateau roughness has been incorporated on the local scale by homogenization of the Reynolds equation and calculation of flow factors from real surface topography. Using the homogenization technique to incorporate the effect of surface roughness leads to a more efficient solution than mesh refinement of the deterministic problem as the roughness does not need to be resolved on the global solution domain, allowing for significantly less degrees of freedom in the global problem. The lubricant boundary pressures have been calculated using results from a numerical ring-pack model and the lubricant viscosity has been adjusted based on the cylinder liner wall temperature. It was found from the result of a comparison between deterministic and homogenized solutions that surface texture should be modelled on the global and not on the averaged roughness scale as is the case with many previous investigations.