In the paper, the author analyses a model of a ring pack motion on an oil film. The local thickness of the oil film can be compared to the height of the combined surface roughness of a cylinder liner and piston rings. Equations describing the mixed lubrication problem based on the empirical mathematical model formulated in works by Patir, Cheng [6, 7] and Greenwood, Tripp [3] have been combined [13] and used in this paper. A model of a gas flow through the labyrinth seal of piston rings has been developed [14,16]. In addition, models of ring twist effects and axial ring motion in piston grooves have been applied [15,16].
In contrast to the previous papers of the author, an experimental verification of the main parts of developed mathematical model and software has been presented. A relatively good compatibility between the experimental measurements and calculated results has been achieved.
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.