Coupled oil film lubricated contact simulation for ICEs

Abstract

The authors have developed a coupled simulation methodology to target strong interactions between component dynamics, lubricated contacts and connecting oil supply lines in internal combustion engines. The dynamics of engine components, called bodies, is represented by a flexible multi-body approach. The mixed lubricated contacts between the component surfaces are represented by an averaged Reynolds equation considering an asperity contact model according to Greenwood and Tripp. The connections between oil bores are modelled by an oil supply line network. Within the network straight cylindrical lines are considered. The oil is assumed to be incompressible with isothermal viscosity. The flow in each line is described by a steady-state one-dimensional Euler equation, i.e. Bernoulli equation. Fictitious force effects, which result from the motion of the enclosing component, and cavitation effects are considered. The article discusses in particular the theory and the implementation of the oil supply line network as well as its coupling to the multi-body system and the hydrodynamic equations. Furthermore, the validation of the oil line model is presented. This is done via comparison with an equivalent three-dimensional computational fluid dynamics simulation. Finally, an application is shown for a single-cylinder internal combustion engine. All bodies of the model are represented to be flexible. Oil supply lines connect the big end bearing with one main bearing and with the small end bearing.