The motion of a ring pack an oil film covering the cylinder liner has been considered. In the paper, equations, a numerical method, algorithm of solution and results of numerical simulations of this phenomena have been presented. The model presented takes into account hydrodynamic, spring and gas forces acting on each ring. The cases of motion with full and partial wetting of ring land have been considered. The influence of engine rotational speed, ring land curvature, oil viscosity on individual rings radial motion and oil film thickness have been analysed. The results of the calculations have been presented in graphical form.

The motion of a ring pack on a thin oil film covering a cylinder liner has been analysed. In contrast to the previous paper [8], which considered only hydrodynamic phenomena, in the present paper a mixed lubrication case is also taken into account. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works of Patir, Cheng [5], [6] and Greenwood, Trip [2] have been combined and used in this paper. Results of numerical simulations of this phenomenon have been presented. The model of ring motion considered takes the following phenomena into account: hydrodynamic and contact forces, spring and gas forces and the local motion of each ring in piston grooves. Differences between the motion of the ring on a thick and thin oil film are analysed and discussed.

The motion of a ring pack on a thin film covering a cylinder liner has been analysed. In contrast to the previous papers [30], [31], which considered a primary hydrodynamic phenomena (including mixed lubrication), in the present paper an additional degree of freedom of a ring i.e. a twist motion is also taken into account. Equations describing the twist of rings are presented and used in simulation. The twist phenomena of a single ring have been analysed in the past [25]. In this paper, the twist effects of separate rings forming a ring pack are considered. In the pack configuration, the twist of the upstream ring strongly influences the operation of the downstream ring. The phenomenon commonly treated as secondary effect seems to be influencing the ring motion strongly. Differences between results obtained applying and neglecting ring twist motion are analysed and discussed.