부산대학교 도서관

The thermal load in the piston head is becoming heavy with the application of supercharging technology. This makes the piston cooling become more challenging to ensure the reliability of the piston. In this study, an oil-injection cooling process in a medium-speed Vtype diesel engine is numerically investigated. The simulations are performed for the direct coupling of the piston head structure and the two-phase flow in the cooling gallery. The effect of the flow pattern on heat transfer characteristics during the whole process is discussed. The results reveal a series of the flow characteristics including thrown flow, interrupted flow, wall impingement, oil oscillating and sedimentation during the reciprocating movement of the piston and the flow characteristics become more obvious with the increase of the engine speed, but the cooling oil is more widely distributed in the oil gallery due to more intense oscillation. After multi-cycle calculations, the flow characteristics of the cooling oil and the heat transfer characteristics of the piston both have a certain periodicity.