RINGPAK simulates the motion of each separate ring on the piston assembly, based upon an axis-symmetric assumption. The ring motion is decomposed into twist, axial and radial motions. The effects of the surrounding gas pressure, boundary lubrication, hydrodynamic lubrication, system friction and inertia are taken into account in force and momentum balances.
Sealing calculations can be performed based upon detailed gas-flow analysis through the ring pack. From these studies, blow-by and blow-back values can be predicted. Using this methodology, RINGPAK forms an interconnected system of gas volumes. The gas flow between these volumes is controlled by either the ring motion or by the conformability of the rings to the liner body during deformation.
RINGPAK includes two flow models, one based upon isentropic conditions and the other based upon compressible isothermal flow. Each flow model can either be selected explicitly, or RINGPAK can be left to decide the best solution method based upon flow parameters.