局部结构因素对抗性消声器性能影响的研究

发布时间：2018-03-09 19:55

本文选题：抗性消声器　切入点：局部结构　出处：《山东大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着工业产能的飞速提高,以机动车辐射噪声为主的环境噪声成为影响城乡居民工作和生活质量的突出问题,发动机排气噪声作为机动车辆整车噪声的主要组成部分无疑是噪声控制的重点。针对内燃机排气噪声的控制,目前切实可行而又简单有效的方法是在发动机排气口处安装消声器；消声器在发挥其消音降噪作用的同时,还会对发动机的功率特性产生影响,消声器的消声效果和其压力损失之间有很强的约束性,消声器的压力损失过大易造成发动机功率损失的增加；若能在减小或不改变消声器压力损失特性的前提下增加其消声量,或是调整其消声效果较好的频段与配套发动机排气噪声中噪声幅值较大的频段向吻合,对于消声器的优化改进设计具有重要意义。抗性消声器在工程机械领域应用广泛,从消声机理上来讲,它是利用其内部结构突变所造成的声阻抗失配来实现消声的,其结构参数的改变可以调节消声器的消声频率范围和消声量的大小；同时,气流的流动速度过大会产生一定的气动噪声,而气流的流动速度又受到气流通道形状和大小的影响；所以,调节抗性消声器的结构参数,是协调控制其综合性能,实现优化设计的核心。本文中以典型的抗性消声器为研究对象,分析讨论了局部结构参数因素对传递损失、压力损失和速度场分布的影响特征。本文首先以简单的抗性消声结构为例,对其进行局部结构的调整,研究传递损失、压力损失和速度场分布的变化规律,结果表明,通过局部结构的调整,可以在不改变消声器压力损失的情况下,调节传递损失特性：使消声频带发生移动,增大传递损失幅值,以及增大消声带宽；并且,还可以实现对流场分布和局部气流速度的调整。进而,在简单结构消声器局部调整研究的基础上,以典型的复杂结构抗性消声器为例展开了进一步的研究,结果表明内插管直径、横流穿孔直径和穿孔布局的调整,对简单结构和复杂结构抗性消声器的整体性能的影响具有一致性。综合利用本文研究的相关结论,并结合工程实践经验,对某型复杂结构抗性消声器进行改进设计,在通过数值仿真分析得到良好改进效果的基础上,进行消声器性能比较台架试验,结果表明,改进结构相对原消声器,在压力损失基本不变的条件下,消声量有明显增加。最后,搭建了消声器内部流场PIV测量系统,通过对简单结构抗性消声器内部流场的试验测量,观察到了消声器内部的气流运动状态,同时也发现了当前测试系统对烟雾粒子浓度和气流速度的控制有待改进,改进目标是实现二者的协调控制,得到不同流速下示踪粒子分布均匀的气流,用于流场测量试验,以期得到更好的PIV测量效果。
[Abstract]:With the rapid improvement of industrial production capacity, the environmental noise, which is dominated by the radiated noise of motor vehicles, has become a prominent problem affecting the quality of work and life of urban and rural residents. Engine exhaust noise, as the main component of vehicle noise, is undoubtedly the focus of noise control. At present, a feasible and simple and effective method is to install a muffler at the exhaust port of the engine. The muffler will have an impact on the power characteristics of the engine while playing its role of noise reduction. There is a strong constraint between the muffler's noise suppression effect and its pressure loss. The excessive pressure loss of the muffler can easily cause the increase of engine power loss. If the muffler's pressure loss characteristics can be reduced or unchanged, the muffler's noise loss can be increased. Or adjusting the frequency band with better noise suppression effect coincides with the frequency band with larger noise amplitude in the exhaust noise of the matching engine, which is of great significance for the optimization and improvement of the muffler design. The resistant muffler is widely used in the field of construction machinery. In terms of the mechanism of silencing, it uses the acoustic impedance mismatch caused by its internal structure mutation to realize the silencing. The change of the structure parameters can adjust the muffler's noise frequency range and noise quantity, at the same time, the flow velocity of the airflow is too large to produce certain aerodynamic noise, and the flow velocity of the airflow is affected by the shape and size of the airflow channel. Therefore, adjusting the structural parameters of the resistant muffler is the core of coordinated control of its comprehensive performance and optimal design. In this paper, the transmission loss caused by the local structural parameters is analyzed and discussed with the typical resistant muffler as the research object. The influence of pressure loss and velocity field distribution. In this paper, a simple anti-noise structure is first taken as an example to adjust the local structure, and to study the variation law of transmission loss, pressure loss and velocity field distribution. The results show that, by adjusting the local structure, The characteristics of transmission loss can be adjusted without changing the pressure loss of muffler: the frequency band of silencing is moved, the amplitude of transmission loss is increased, and the bandwidth of silencing is increased; and, The flow field distribution and local airflow velocity can also be adjusted. Furthermore, on the basis of the study of local adjustment of simple structure muffler, taking the typical complex structure resistant muffler as an example, the results show that the diameter of the intubation, the diameter of the perforation and the layout of the perforation are adjusted. It has the same effect on the whole performance of simple structure and complex structure resistant muffler. By synthetically using the relevant conclusions of this paper and combining with engineering practice, the design of a complex structure resistant muffler is improved. On the basis of numerical simulation analysis, the performance of muffler is compared with that of the original muffler. The results show that, compared with the original muffler, the silencing capacity of the improved structure is obviously increased under the condition of constant pressure loss. Finally, a PIV measurement system for the internal flow field of the muffler is set up. Through the experimental measurement of the internal flow field of the simple structure resistant muffler, the airflow state inside the muffler is observed. At the same time, it is also found that the control of smoke particle concentration and airflow velocity by the current testing system needs to be improved. The goal of the improvement is to realize the coordinated control between the two, and to obtain a uniform distribution of the tracer particles at different velocities, which can be used in the flow field measurement experiment. In order to obtain better PIV measurement results.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB535.2

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