Engine crankcase, Oil pan and Lube system Multiphase CFD Analysis for predicting Oil Aeration

This paper explains transient, computationally rigorous, three-dimensional and one-dimensional multiphase CFD analysis of engine oil drainback system and lubrication system for predicting aeration. Aeration of engine oil is an important factor as it affects working of Hydraulic Lash Adjusters, bearings performance and it reduces lube system pressure itself which is detrimental for the entire engine. In this work specifically effect of engine tilting on lube oil aeration is presented. When engine is tilted, crankshaft and connecting rod/s are dipped in to oil, which creates air bubbles. These air bubbles travel to lube pump and then to the engine lube system. Therefore, it is essential to model aeration in Engine crankcase, Oil pan and Lube system for the purpose of predicting oil pressure reduction in lube system. The problem under consideration is spread over a bigger zone, involves rotating and translating components, passage’s dimensions are varying from microns to meters and involves multiphase physics. Therefore, it becomes a formidable task to accurately predict lube oil aeration using simulation. In current work, an approach is developed which involves use of multiple simulation tools for handling all the intricacies of geometries and complications of physics. Number of unique ideas have been developed in order to handle multiphase, moving boundaries, high fidelity CFD solution. The predicted lube system oil rifle pressure is compared with test data and the results are found to be within engineering accuracy. The developed procedure can be used to analyze effect of parts’ design change on aeration during engine design and development. The procedure can also be extended for modeling effect of vehicle dynamics on oil aeration.