Analysis of Cooling and Warm-Up Performance of Oil-Cooled Engine with Fin-Shaped Oil Jacket

An oil-cooled engine has been developing to achieve better warm-up performance. The oil-cooled engine has an oil jacket that pass through around the exhaust port and the cylinder liner. Fins were installed inside the oil jacket to enhance cooling performance. The result of a bench test shows that the fins enhance the cooling performance with slight loss of warm-up performance. The aim of this study is to clarify effects of the fins. This study conducted two simulations. One is a cooling simulation that was conducted to clarify the reason why the fins enhanced the cooling performance. The other is a warm-up simulation that was conducted to clarify the reason why the fins almost maintained the warm-up performance. The cooling simulation was conducted by steady flow simulation. It simulated a full-load operation of the bench test. It compared converged temperature between the engines with/without the fins. The warm-up simulation was conducted by unsteady flow simulation. It simulated a warm-up operation of the bench test. It compared transitional temperature between the engines with/without the fins. The cooling simulation shows that the fins increase heat transfer coefficient of the oil jacket. Further, the fins mix the oil in the oil jacket. Therefore, the fins transfers large amount of heat from the engine to the oil and thus enhance the cooling performance. The warm-up simulation indicates that location of the fins and location of the oil jacket affect the warm-up performance.