Effects of water jacket cross section types design improvement of cylinder head bridge zone on boiling heat transfer

With respect to the serious heat load issue of cylinder head bridge zone for the highly intensified diesel engine, three typical water jacket structure of cylinder head bridge zone was simplified as T-type, rectangle plus V-type and rectangle plus O-type with established corresponding models. The gas-liquid two-phase flow boiling heat transfer model was used to simulate the fluid-solid coupling heat transfer system which consists of the simplified bridge zone structure and cooling water jacket. Simulation results agree well with the cylinder head temperature field test results. On the basis of this, the experimental design method was used to study the effects of cooling water inlet velocity and temperature on the highest temperature of the bridge zone. The results showed that cooling water inlet velocity and temperature has large influence on the highest temperature of the bridge zone. In the case of minimum cooling water inlet velocity or maximum inlet temperature, the improved three cross section types are more beneficial to the decrease of the highest temperature of the exhaust port bridge zone. The highest temperature of flow path bridge zone of the improved T-type cross section is lower than that without improvement under the same inlet velocity or inlet temperature conditions.