Numerical Study of the Three-Dimensional Oil Flow Inside a Wrist Pin Journal. Issue 3 (3rd May 2020)

• Record Type: Journal Article
• Authors: Schmidt, M.; Reinke, P.; Rabanizada, A.; Umbach, S.; Rienäcker, A.; Branciforti, D.; Philipp, U.; Bargende, M.; Preuß, A.-C.; Pryymak, K.; Matz, G.
• Is Part Of: Tribology transactions. Volume 63:Issue 3(2020)
• Page Start: 415
• Page End: 424
• Publication Date: 2020-05-03
• Subjects: Piston -- wrist pin journal -- 3D CFD -- oil transport; Tribology -- Periodicals; 621
• DOI: 10.1080/10402004.2019.1701163
• Languages: English
• ISSNs: 1040-2004

Abstract

Abstract: Lubrication of a wrist pin journal can become a limiting factor in the performance of internal combustion engines. A wrist pin journal is a hydrodynamic bearing with a radial clearance of only a few micrometers that is filled with a mixture of oil and air. Moreover, the radial clearance changes periodically with the piston motion and according to the working cycle of the internal combustion engine. Hence, a numerical study of the flow and oil transport inside a wrist pin journal requires an unsteady 3D two-phase model. Furthermore, the numerical model must include gravity and centrifugal forces, the unsteady rotation of the piston pin, and the oil feed on both sides of the piston pin boss. Presently, neither the oil feed surrounding the piston pin boss nor the mechanism transporting the oil into the gap between the piston and piston pin are fully understood. This study presents a numerical approach describing the lubrication inside the wrist pin journal. A particular aspect of the modeling is combining a structured mesh of hexahedron cells for the narrow gap and unstructured meshing in the surrounding geometry due to the difference in length scale of several orders of magnitude. The numerical model has been validated on test cases and experimental oil transport data obtained from a piston model experiment. The numerical results include images of complex 3D structures of oil and air fractions inside the oil film and in the regions surrounding the piston boss.