Numerical Modeling of Plain Journal Bearings within a Heavy-Duty Engine Oil System using GT-SUITE

Abstract: Main and connecting rod bearings along the crankshaft in a heavy-duty engine oil system requires efficient feed of oil flow to ensure the performance of lubrication, cooling and cleaning. The bearings and builded bearing models considered in this work are based on a Volvo 13L engine. Two main models to predict the oil flow in main and connecting rod bearings have been investigated using the system analysis software GT-SUITE. These two models are based on two numerical methods called  the Mobility method and the Reynold's equation respectively. The main bearing and the connecting rod large end bearing loads calculated in the present work is similar to the reference bearing loads, especially for connecting rod large end bearing and at lower engine speeds. For higher engine speeds, the present load results are far off,  compared to the reference load results. This difference at the higher engine speeds showed also an increased difference in the oil volume flow rates. But more information regarding the calculations of the reference loads is needed to analyze the differences further. Considering the "split lines", where the upper and the lower bearing shell meet, in the bearing models increased the oil volume flow rate with 13.3\% on average for the main bearing. Main bearing stand for 86\% of the total flow whilst connecting rod large end and small end bearing stand for the rest 13\% and 1\% of the total flow. The feed of oil to main bearing and connecting rod large end bearing appears continuously whilst the feed of oil to connecting rod small end bearing appears in the form of a few pulsations. Comparing to the numerical reference flow results, the results in this work are similar at high oil temperatures and at low engine speeds, otherwise the results are far off. Considering the Reynold's equation when predicting the oil volume flow rates in plain journal bearings is a more accurate way than using the Mobility method since it takes more specific geometrical irregularities into account. The oil volume flow rate for main bearing differ with 2.7\% on average when solving the Reynold's equation compared to the Mobility method.