Calculation of oil churning in crankcase of reciprocating pump (Calculation of free surface flow by Moving Particle Semi-implicit method)

Abstract

Mounted on high pressure washers, reciprocating pumps use oil for lubrication and cooling. If the lubricating performance is insufficient, problems such as a decrease in efficiency, seizure, and adhesion occur. Therefore, ensuring optimal lubrication performance is necessary. However, calculating the oil churning behavior due to the complex nature of dynamic oil flow within the crankcase is difficult. If the oil churning behavior can be calculated qualitatively and quantitatively via simulation, design study will be simplified and development costs could be significantly reduced. Considering these conditions, herein, we quantified the oil churning behavior within the crankcase using the MPS (Moving Particle Semi-implicit) method and thus improved the lubrication performance of the pumps. In the new design, the crankcase has an elliptical shape with ribs on the inside. We expect to have sufficient lubrication performance with less oil, because the churned-up oil is efficiently guided to the rotating part by the rib effect. The validation was evaluated by an operation test using a prototype. As a result, it was confirmed that the oil stayed clean in the new design.