Numerical Study of an I4 Engine Oil Ejection During an Accidental Cap-off Running Condition for Two Baffle Designs

Three-dimensional transient numerical simulations are conducted to study the oil flow in a four-cylinder internal-combustion engine while it operates without its oil filler cap on. The emphasis of the study is on analyzing the consequential oil ejection through the oil-cap open boundary. Navier-Stokes equations are solved together with the multiphase Volume of Fluid (VOF) model and the k-ϵ turbulence model. The engine crank shaft is mechanically connected to two cam shafts through a chain, which operates below the oil-filler duct. A baffle is located between the chain and the duct, shielding the latter to minimize oil ejection and potential spills. The chain geometry and dynamics are captured accurately through volume remesh and conformal mapping techniques. The motion of the four pistons, crank shaft, and two cam shafts is also considered. Retaining all these mechanical and geometrical details in the simulations is essential to obtain accurate oil ejection results. The crank shaft rotates at 1200 RPM, and the study is conducted for two different baffle designs. Quick turn-around-time rolling-average results from numerical simulations are compared with experimental data for baffle designs 1 and 2. Findings demonstrate good agreement both in trend and in magnitude for an application previously considered impractical in Computational Fluid Dynamics (CFD) while using the Volume of Fluid (VOF) method.