Optimization Of Intake Port Of Diesel Engine Based On Structure Parameters

With the advantages of high heat efficiency, large power and long life, the diesel engines are used more and more wide. Good air motion in diesel engines could promote the mixing of unburned fuel and air, improve combustion rate, enhance engines’dynamic and economic resistance, and decrease combustion noise and harmful gas emission.As study object, the intake port of certain direct injection diesel engine is optimized, according to the low flow coefficient and high swirl ratio. Thus, on one hand, dynamic performance of engine is ensured by improving flow coefficient; on the other hand, distribution of fuel spray is more reasonable by reducing swirl ration of intake portThe comparative analysis of steady flow simulation and AVL steady flow test rig are carried out According to the pressure parameter variation of different cross sections and calculation formula of flow coefficient and swirl ratio, structure parameters of Vz component of fluid velocity, sectional area of vertical Z axis, effective inversion quantity of velocity is proposed as main influencing factors. According to the change law of structure parameters, the intake port is modified. By numerical simulation in the same condition, and comparison with original scheme, a new design is confirmed.For further evaluation of the new design,3d transient flow analysis is carried out for spray combustion and intake compression of the modification pre and post. The new designed plan is reasonable by verifying the variation of angle for turbulence strength center that is constructed and extracted, the influence of rich mixture with swirl ratio by using cross sections instead of space, and comparative analysis of other parameters related with combustion. The tests indicate that specific fuel consumption and NOx emission decrease for a certain content.Finally, this paper summarizes the content and makes some analysis and prospect.