A lumped parameter approach for the filling analysis of V6 engine lubrication systems

The present work describes a lumped parameter approach for the filling analysis of engine lubrication systems. Filling analyses are typically carried out by means of multi-phase 3-D CFD models but, despite allowing detailed and reliable results, they require very demanding computational capabilities. Based on these premises, the authors present a modelling procedure to address the topic by means of a lumped parameter approach. By introducing a detailed modelling technique, the proposed method offers the possibility to reproduce not only the common and simple elements such as pipes and bends, but also permits the discretization of complex three-dimensional fluid domains. The proposed approach has been applied to the lubrication system of a heavy-duty V6 engine: since long stop intervals are planned during the engine lifetime, the filling time of the system plays a fundamental role. The analysis has been run with the obtained 0-D model, simulating at different lubricant temperature. The predictive capabilities of the numerical model are presented in terms of flow pattern and filling time of the circuit branches. The simulation has also been performed by means of a 3-D CFD model, providing the possibility of a result comparison: since this methodology is nowadays considered the state of the art for this kind of analyses, the results are taken as reference to evaluate the capabilities of the proposed 0-D approach. The comparative analysis concerns both the overall distribution of the lubricant over time, and the local phenomena. The differences in terms of computational effort are considered as well, to assess the approximation of the lumped parameter approach with respect to the complex but more accurate three-dimensional models. The results highlight the accuracy of the methodology on the estimation of the filling time. Moreover, the proposed procedure reveals great advantages in terms of computational effort.