Thermo-Elastohydrodynamic Connecting Rod Simulation of a Four Stroke Medium Speed Engine

To analyze thermal effects in hydrodynamic plain bearings, beside the structural dynamics of the elastic bodies, friction-related energy inputs into the lubricating film and the running surfaces must be taken into account when calculating the hydrodynamic bearing pressure distribution.For a thermo-elastohydrodynamic (TEHD) simulation of a connecting rod bearing, in addition to Reynolds equation, the transient energy equation in the lubricating film and the heat conduction equation of the adjoined bodies have to be solved. The particular challenge to the simulation strategy consists of the different time scales on which structural dynamics and pressure build-up take place in comparison to the temperature distribution and distortion of connecting rod and crank pin. Using the connecting rod bearing of a four stroke medium speed motor as an example, this paper shows the influence of the temperature distribution in the bearing on oil viscosity and lubrication gap and thus on the load capacity of the bearing.