柴油机分流气体对冲排气消声器流场特性分析

ANALYSIS ON THE FLOW FIELD CHARACTERISTICS OF THE SPLIT-STREAM RUSHING EXHAUST MUFFLER FOR DIESEL ENGINE

传统柴油机排气消声器往往消声效果差、排气背压大,且二者相互矛盾。消声器内部气流速度是影响消声器综合性能的一个关键因素,以降低气流速度为出发点,课题组前期提出了分流气体对冲降速法,并针对某机型柴油机设计制作了实体消声器。为了分析分流对冲作用对消声器流场的影响,本文利用数值模拟方法对该消声器内部气流速度以及降速与内流场之间的关系进行了研究。得出如下结论:通过分流对冲作用后,气流流速可得到大幅下降,平均降幅为65%;气流对冲在降速的同时也产生了明显的压力损失,对冲压降占整个消声器压力损失的52.9%;湍动能主要集中在两处对冲区域周围,且湍动能最大值随着入口速度的增加而增加。

The traditional diesel engine exhaust mufflers often have poor noise elimination and high exhaust back pressure,and the two often contradict each other.The internal airflow velocity is a key factor affecting the comprehensive performance of the muffler.Starting from airflow velocity deceleration,in the early stage,the research group put forward the method of split-stream rushing deceleration,and designed and manufactured a solid muffler for a certain type of diesel engine.In order to analyze the influence of split-stream rushing on muffler flow field,in this paper,the numerical simulation method was used to study the internal airflow velocity of the muffler,and the relationship between the deceleration and the internal flow field.It could be concluded that after rushing,the airflow velocity slowed down greatly by an average decrease of 65%;The airflow rushing also caused a significant pressure loss while reducing the speed,which accounted for 52.9% of the muffler total pressure losses;The turbulent kinetic energy was mainly concentrated around the two rushing regions,and the maximum value increased with the inlet velocity increasing.