多点分布式导向台燃烧室结构优化模拟研究

Structural optimization simulation of multi-point distributed guide-table combustion chamber

为了改善柴油机燃烧室内燃油喷雾撞壁和混合气形成情况,提出一种直喷式柴油机多点分布式导向台燃烧室。将这种新燃烧室结构参数化,对7个设计变量进行多参数协同优化。以一台230 mm缸径的中速船用柴油机为基础模拟缸内工作过程,采用拉丁超立方取样的方法从设计空间得到600个样本点,根据模拟结果分析各设计参数对发动机性能的影响,根据不同的优化目标得到3种新燃烧室结构。仿真结果表明:在75%负荷工况下与原机ω型燃烧室相比,Ⅰ型燃烧室的指示油耗率(indicated specific fuel consumption,ISFC)降低1.83%,烟粒(soot)排放量降低86.83%;Ⅱ型燃烧室的ISFC降低0.97%,NO_(x)排放量降低7.44%,soot排放量降低68.26%;Ⅲ型燃烧室的INO_(x)和soot排放量分别降低10.52%和58.08%,ISFC基本不变。

In this study,a new direct-injection diesel engine with a multi-point distributed guide-table combustion chamber was proposed to improve the fuel spray impingement and mixture formation inside the combustion chamber of a diesel engine.This new combustion chamber structure was parameterized,and a multi-parameter collaborative optimization was performed on seven design variables.Based on a medium-speed marine diesel engine with 230 mm cylinder diameter,the cylinder working process was simulated,obtaining 600 sample points from the design space using latin hypercube sampling.The impact of each design parameter on engine performance was analyzed according to the simulation results,and three new kinds of combustion chamber structures were obtained based on different optimization objectives.The simulation results showed that under 75%load conditions,compared with the originalω-type combustion chamber,the ISFC of the Type I combustion chamber was reduced by 1.83%,and soot emission was reduced by 86.83%;ISFC of the Type II combustion chamber was reduced by 0.97%,NO_(x) emission was reduced by 7.44%,and soot emission was reduced by 68.26%;the NO_(x) emission and soot emission of the Type III combustion chamber were reduced by 10.52%and 58.08%,respectively,while ISFC remained unchanged basically.