The Coupling Heat Transfer Research On Piston Group-Liner-Coolant Of Engine

Nowadays, more and more engine are developing in the direction of high power and low fuel consumption, which requires the various parts of the overall performance is increasingly high. Therefore, in order to allow the engine can be in a good working environment when in operation, and to ensure the temperature of various parts and so on within the specified range, the engine heat transfer process research has a vital role. However, the engine heat transfer is a complex process, not only related to the structure of the engine(piston group, cylinder, cooling water) coupling, but also related to the physical field(fluid field and solid field) coupling. By the piston group, cylinder, cooling water as a whole, the overall heat transfer on the engine coupling can be achieved.Firstly, in this paper, transfer oscillating of the piston oil chamber is simulated using multiphase flow model、dynamic mesh technology, and obtain the distribution of oil chamber wall heat transfer coefficient and oil at different crank angle. The results shows that:, the oil mostly distributes on the top wall at TDC;, the majority of oil is located to the below wall at BDC. In the vicinity of 1200, the volume fraction of oil is the maximum; in the vicinity of 3300, the volume fraction of oil is minimum. The trends of the average heat transfer coefficient and is roughly the same as the oil volume fraction, but slightly lagging, the maximum heat transfer coefficient substantially after the BDC.Then, the heat transfer coefficient of the oil chamber is average processed, t he results applied to the coupling model of piston group- cylinder- cooling water using sequential coupling, and then the heat transfer of piston、cylinder、cooling water is studied through direct coupling. Among them, the flow and coupled heat transfer on lubricant film is ignored, the lubricant oil is treated as a one-dimensional thermal resistance. Other outer boundary conditions on coupled model can be defined according to the empirical formula, the third boundary condition or reference to literature and so on.Through the above analysis, the use of sequential coupling and direct coupling combination of approaches, can better study the engine heat, and it provides a new way to solve the temperature field of the piston.