Optimization Of Cylinder Head Cooling Structure With The Strengthening Of Diesel Engine

With the enhancement of the strengthening degree of the diesel engine,the heat load of the cylinder head becomes larger.In order to prevent the problem of thermal failure,it is necessary to optimize the corresponding cooling structure.The combination of a diesel engine products to enhance the power of strengthening design requirements,the fluid solid coupling numerical simulation method,the flow and heat transfer state of cylinder head cooling related structures are analyzed,in-depth study of the effect of the main structural parameters on the thermal load of cylinder,based on the proposed optimization scheme.The specific research contents are as follows:establish the flow calculation model of the water jacket of the diesel engine cylinder head,and build a visualization test bed for the cylinder head of the diesel engine.The reliability of the water jacket model is verified by comparing the simulation data and the experimental data.A one-dimensional simulation model of diesel engine was built and verified by experiments,and the boundary conditions of thermal calculation were obtained.The heat load calculation model of diesel engine cylinder head was built,and the influence of burst pressure lifting on the heat load of diesel engine was analyzed.According to the results of fatigue and flow calculation,the strengthening potential of diesel engine cylinder head is studied from the following four aspects.(1)the influence of the thickness of the bottom plate of the cylinder head fire surface.Thinning the thickness of the floor plate can effectively reduce the heat load of the cylinder head.(2)the influence of the outer wall of the water jacket on the wall surface of the water jacket.The safety coefficient of high cycle fatigue of the cylinder head and the minimum heat load of the cylinder head can be increased by moving the wall of the water jacket outside the wall 6mm.(3)the influence of the pore diameter on the intake side.Reducing the hole diameter on the intake side can effectively reduce the heat load of the cylinder head of the diesel engine.(4)the influence of the pore size and position of the upper water hole between the third,fourth cylinders.The expansion of the upper water hole near the intake side can effectively reduce the heat load.(5)strengthen the influence of the rib.The heat load of the floor of the fire surface can be reduced by the removal of the stiffeners.On the basis of the research on the potential factors for strengthening the water jacket of the diesel engine cylinder head,the final optimization scheme for the cylinder head water jacket of the diesel engine is put forward.By calculating and comparing the high and low cycle fatigue of the cylinder head before and after the optimization,it is found that the safety coefficient of the high cycle fatigue and the low cycle fatigue life are prolonged after the optimization of the structure of the water jacket.The test of second cylinder head temperature measurement before and after optimization is carried out,and it is found that the heat load of the cylinder head is obviously reduced after the water jacket structure is optimized.