Simulation Of Fluid-solid Coupling Heat Transfer In Multi-cylinder Diesel Engine Cooling System

Cooling system is an important part of diesel engine,and provides a powerful guarantee for the diesel engines under all operating conditions.In V6 diesel engine,the mass flow and heat transfer rate are uneven on one side,as well as on both sides,whitch leads the six cylinders are in different operating conditions and reduces practical effect of the cooling system.The three dimensional fluid-solid coupling heat transfer models of different cooling water jacket are built by Solidworks.The models include original model,Model 1,Model 2,Model 3,and ultimate improved V6 engine model.The grid models are built by ICEM software.Using FLUENT software to simulate the fluid-solid coupling heat transfer models of 1-3 cylinders and 4-6 cylinders of the original model,and analysis the all 6 cylinders.The results are as follows: the maximum temperature difference of cooling water at the inlet of six cylinder heads is 4.61K;the maximum temperature difference of cooling water at the outlet of six cylinder heads is 5.77K;the heat transfer rate non-uniformity of 1-6 cylinders is2.5%;the cooling water mass flow non-uniformity of 1-6 cylinders is 35.09%.With the increase of the total cooling water mass flow,the pressure difference between inlet and outlet incresses,and the maximum temperature differences at inlet and outlet of six sylinder heads decrease,but the non-uniformity of heat transfer rate and cooling water mass flow does not change much.Using FLUENT software to simulate the 1-3 cylinders of Model 1,Model 2,and Model3 with different cooling water flow directions.The result shows that,when the cooling water flow direction is down-top,comparing Model 1,Model 2,Model 3 with original model,the non-uniformity of cooling water mass flow,the maximum temperature differences at inlet and outlet of six cylinder heads all decrease,but the non-uniformity of heat transfer rate increases.When the cooling water flow direction is top-down,comparing Model 2,Model 3with original model,the non-uniformity of cooling water mass flow and heat transfer rate,the maximum temperature differences at inlet and outlet of six cylinder heads all decrease.When the cooling water flow direction is top-down,comparing Model 1 with original model,the non-uniformity of cooling water mass flow,the maximum temperature differences at inlet and outlet of six cylinder heads all decrease,but the non-uniformity of heat transfer rate increases.Comparing all models with original model,the pressure differences between inlet and outlet decrease.After consideration of all factors,the ultimate improved V6 engine model selects Model1 when the cooling water flow direction is top-down.After optimizing the model,the simulation model of fluid-solid coupling heat transfer of the final V6-cylinder is established.Simulate the final model by FLUENT software.The result shows that,the non-uniformity of cooling water mass flow of 1-6 cylinders is 4.53%.The maximum temperature differences at inlet and outlet of 1-6 cylinder heads are respectively 0.05 K and 0.38 K.The non-uniformity of heat transfer rate of 1-6 cylinders is 2.23%.