排气消声器压力损失仿真与试验研究硕士论文.pdf

重庆大学
硕士学位论文
排气消声器压力损失仿真与试验研究
姓名:赵世举
申请学位级别:硕士
专业:车辆工程
指导教师:罗虹
2010-05
中文摘要
摘要
压力损失是评价消声器性能的重要指标之一,直接关系到发动机的功率损耗。
为改善消声器的空气动力性能、降低消声器的压力损失,本文采用数值仿真与试
验相结合的方法,研究气流速度及消声单元尺寸特征参数对多种基本消声单元压
力损失的影响规律。
本文运用计算流体动力学(CFD)软件 CFX,重点研究了扩张比、腔体长度、
进口管直径对扩张腔消声单元压力损失的影响,插入方式对插入管消声单元压力
损失的影响,穿孔率、穿孔直径对穿孔管消声单元压力损失的影响以及穿孔率、
穿孔直径、穿孔板位置对穿孔板消声单元压力损失的影响。研究结果表明:消声
单元的压力损失随入口流速的提高显著增大。扩张腔消声单元存在一临界扩张比,
使其压力损失最大,临界扩张比随腔体长度的加长而增大;扩张腔腔体长度越大、
进出口管管径越小,扩张腔消声器的压力损失越大。对置式插入管消声单元的压
力损失随进出口管插入长度之和的增长而减小,偏置式插入管消声单元的压力损
失随出口管插入长度的增长而增加。直通穿孔管消声单元的压力损失随穿孔率的
增大而增加,小孔收缩、小孔扩张穿孔管消声单元及穿孔板消声单元的压力损失
随穿孔率的增大先急剧降低,后基本不变,穿孔直径对穿孔消声单元压力损失影
响较小。并结合流场分析结果,初步探讨了引起压力损失的原因。
通过对多种消声单元压力损失的测量,得到的试验结果与 CFD 仿真结果吻合
较好。说明 CFX 软件研究消声器流体动力性能和压力损失准确、有效,可用于消
声器的流体动力性能分析和压力损失预测。
运用 CFX 软件分析了某车用消声器内部流场,评价了其空气动力性能。根据
流场分析结果找到了其压力损失较大的原因,结合本文的研究结论,提出了具体
的改进措施,使改进后消声器的压力损失降低了 30%。
关键词:排气消声器,消声单元,压力损失,CFD,流场
I
英文摘要
ABSTRACT
Pressure loss is one of important factors in evaluating muffler performance, which
is related to power loss of engine directed. In order to improve fluid dynamics
performance, to decrease pressure loss of muffler, the influence of flow velocity and
dimension character parameters for pressure loss of several basic muffler elements was
studied with the way of simulation analysis and test.
Using putational fluid dynamics (CFD) software CFX, this paper
researched on pressure loss for expand muffler elements with expand ratio, expand
length, inlet diameter, insert muffler elements with insert pattern, perforated muffler
element with perforated ratio, perforated diameter, and perforated plate muffler
elements with perforated ratio, perforated diameter,the location of perforated plate. The
results show that: the pressure loss of muffler elements increased dramatically with the
inlet velocity increased. And the expand muffler elements have a critical expand ratio,
whose pressure loss is most. The critical expand ratio increases with the expand length
lengthening.