The flow and heat transfer characteristics of engine oil inside the piston cooling gallery

The current study employed the Eulerian multiphase model and the geometry reconstruction scheme to describe the periodic flow and heat transfer processes of engine oil inside the piston cooling gallery. The effects of engine speed and oil jet velocity on the heat transfer were explored. The heat transfer coefficients increase with an increase in the engine speed and tend to present a similar distribution. The optimal jet velocities of cooling oil under different engine speeds were also suggested. Compared with the CLSVOF model, the numerical results from the Eulerian multiphase model are more close to the actual state. The traditional empirical formula can only predict the average heat transfer coefficient over one period. By contrast, the numerical results in the present study are able to provide precise thermal boundary conditions for finite element analysis on the piston temperature and further analysis for the heat flux distribution during the combustion process, so as to achieve the optimized design of the piston.