燃烧室缩口位置对重型柴油机影响的数值模拟研究

Numerical Simulation of the Influence of Combustion Chamber Necking Position on Heavy Duty Diesel Engine

柴油机的燃烧过程主要受控于燃油空气混合速率,为了进一步改善重型柴油机的燃烧和排放,在合理提高压缩比的基础上,设计了5种新型燃烧室,并基于三维计算流体力学软件CONVERGE,通过数值模拟的方法,研究了燃烧室内缩口位置,包括缩口直径和深度对缸内混合、燃烧和排放过程的影响。研究结果表明:采用合理的缩口位置,可以明显提高缸内的涡流比,促进对燃油的利用,加快油气混合过程。与原机基础燃烧室相比,热效率可提高约2%。

Due to the fact that the combustion process of diesel engine is mainly controlled by the air/fuel mixing rate, five new types of combustion chambers are designed based on the reasonable increase of the compression ratio. The main difference lies in the necking position among these chambers. In this work, effect of the necking position in the combustion chamber, including the diameter and depth, on the mixing, combustion and discharge in the cylinder was studied by means of numerical simulation. The results show that the reasonable necking position can obviously increase the swirl ratio in the cylinder, promote the utilization of fuel kinetic energy and speed up the process of fuel/air mixing. Compared with the original machine, the thermal efficiency can be increased by about 2%.