A blended CFD/multi-body analysis method for elastohydrodynamics of plastic oil pan.

The noise, vibration and harshness(NVH) feature is attracting more and more attentions due to its effects on durability, comfort and compliance with noise regulations. The thin-walled components play an important role in NVH of an engine. In this paper, a computational fluid dynamics (CFD) and finite element multi-body analysis blending method is proposed to analyze the dynamic characteristics of oil pan and the hydrodynamic/structural factors affecting camshaft speed fluctuations. With CFD approach, the oil-air two-phase flows in plastic oil pan on different time scales are simulated, and the evolution processes of oil in an oil-air two-phase system with gravitational load are depicted. By coupling the fluid viscosity effect and multi-body interactions of solid contacting surfaces, the NVH performance is well demonstrated. Numerical results show that plastic oil pan has 31.20% ~ 42.04% increase in modal frequency and 2.9 ~ 7.2 dB reduction in sound power level compared to metal oil pan. Comparison results validate present method in simulations of elastohydrodynamics in automotive engineering and provide the key factors of NVH performance for modern diesel engine design.