Transportation and Transformation of Air Bubbles in Aerated Oil through an Engine Lubrication System

The amount of free air in an engine oil can affect the performance of some engine components. Part of the air in an aerated oil can be dissolved into the oil, while some may remain as free air when the oil reaches these components. A methodology of analyzing how much air dissolves into the oil and how much remains as free air in a lubrication system is presented. A V6 gasoline engine is used as an example to calculate the changes of air bubble sizes due to compression and dissolution into the oil. The amount of air dissolved and the amount of free air in the oil when it reaches various locations along the lubrication passageways are estimated. It is concluded in the case studied that small air bubbles will be dissolved entirely before the oil reaches oil galleries in the heads, while most air in large air bubbles will stay as free air.