Simulation of the oil supply through the connecting rod to the piston cooling channels in medium speed engines

Abstract

The importance of the oil flow simulation in connecting rod oil channels during the engine development process is recently increasing. This can be observed either in medium speed engines, where, as one of the traditional solutions, the oil for piston cooling is supplied through the connecting rod, or in automotive engine VCR (variable compression ratio) connecting rods, where engine oil is used to change the compression ratio of the engine. In both cases, precise numerical results are necessary to shorten the prototyping period and to reduce the overall development cost. The multi-physics character of the simulation problem basically consists of the interaction between the dynamics of the crank train components and the oil flow. For the oil supply to the piston cooling channels through the connecting rod in medium speed engines, being the objective of this paper, a major influencing factor is the oil pressure behavior in the piston cooling gallery providing periodical interaction with its supply. At the same time, the connecting rod elastic deformation during engine operation can be regarded as negligible and the planar motion of the connecting rod can be reproduced by combination of translational and rotational acceleration fields in the CFD solver. The paper includes the description of the applied simulation approach, the results and a comparison with the state-of-the art calculation without consideration of the above-mentioned influencing factors.