Working Process Numerical Modeling And Experimental Study On Cooling System Of Diesel Engine

As the output per liter of engine is improving continuously, correspondingly the heat flux density in the engine increases a lot and the problem that the coolant temperature is exorbitant becomes prevalent. Therefore, it is the key technology that must be broke through, that the cooling system of engine is optimized and improved as a whole and the cooling and thermal balance problems of engine with high power density are resolved well.Through integrating the experimental researches and simulation calculations, the cooling performance and thermal balance state for a vehicle diesel engine cooling system were studied deeply.Firstly, in order to learn the water stream and heat flux distributions among all the cylinder blocks, the water stream distribution experiment and heat flux distribution experiment were carried out on the heavy duty diesel engine, which would provide some warranties for the validating of the simulation calculations and analyses.Secondly, according to the detailed arrangements, the one-dimensional simulation model was established and was validated that the model was authentic by the experimental data. Some parameters of the cooling system were changed, such as radiator efficiency , flow rate of pump and so on. And then the factors influencing the cooling performance were analyzed in detail and some improving schemes were proposed through contrasting the results of simulation calculations.Thirdly, the three-dimensional model for the cooling water jacket of the engine was set up and the CFD calculations were processed on the single cylinder water jacket. The CFD calculation results were certificated in accordance with the experiment results and some important flow fields in the water jacket were analyzed, such as nose bridges, cylinder body and so on.The research shows that the distributions of the water stream and heat flux in the prototype engine were uneven. The flowing condition is good in cylinder head while it is not so good in the back of the cylinder body and some improvement ought to be obtained. The cooling parts of the engine can meet the requirements of cooling performance by and large when the vehicle runs at medium speed and high speed. However, in order to fulfil the requirements that the vehicle runs under the conditions of low speed and high atmosphere temperature in summer, there should be some rematches on the cooling parts.