Optimization design of cooling water jacket in diesel engines

The cooling uniformity of each cylinder is one of the basic requirements in designing highly intensified diesel engines. In this paper, commercial CFD software STAR-CCM+ is used as a tool to conduct simulation and optimization design of cooling water jacket for a six-cylinder diesel engine. It is found that when the inlet and outlet of cooling water are located on the same end of engine, it is likely to cause uneven water flux distribution, leading to significant difference in the flow velocity of cooling water in cylinder head. According to the relationship between flux and pressure drop, a concept of flow resistance chart is introduced with flow resistance analysis performed. By changing the size of water holes between cylinder block and cylinder head and hence the corresponding flow resistance, the distribution of water flux in each cylinder can be flexibly adjusted. The results show that after modification with the scheme proposed, the water flux distribution is basically uniform with the maximum unevenness of water flux reducing from 50% to 4.6%. Finally by changing the overall inlet mass flow, the effectiveness of the scheme is further verified.