车辆排气系统消声器工作性能分析

发布时间：2018-07-06 12:47

本文选题：排气系统 + 消声器　；参考：《吉林大学》2014年硕士论文

【摘要】：排气系统的设计直接关系到整车的动力性、舒适性和经济性，随着国家对机动车噪声限制的日趋严格，使排气系统的优化设计成为车辆设计的重点之一，越来越受到人们的重视。现阶段我国排气系统的设计还处于被动降噪阶段，存在一定局限性。本文结合国家科技支撑计划课题“面向节能与安全的集成智能化工程机械装备研发”（课题编号：2013BAF07B04），以某车排气系统消声器为研究对象，通过计算机模拟技术，结合被动与主动控制设计方式，对该车排气系统消声器的传递损失、压力损失进行分析研究及优化设计。根据消声器结构参数，建立前、后消声器的数值模型，分别利用Virtual LabAcoustics软件进行了声学性能分析，利用Fluent软件进行了流体特性分析，得到了前、后消声器的传递损失和压力损失，详细评价了各消声器内的声压分布、流场的速度和压力分布等情况，指出了相关结构不足之处。对排气系统的消声效果进行试验测量，测量结果与仿真结果均显示在某些频率消声效果较差，从而验证了仿真方法的正确性。还就气体温度和气体流速等因素对消声器声学性能的影响进行了分析。在对消声器声学及气体动力性能分析的基础上，根据消声器的基本消声原理针对消声器结构存在的不足之处，对前消声器进行了四处改进设计，对后消声器进行了两处改进设计，将改进前后的传递损失进行仿真对比，结果表明改进后的消声器消声量增大、消声频带拓宽并且流体特性有所改善。另外还对安装有改进后的前、后消声器的排气系统进行了传递损失分析，分析表明该排气系统具有较好的消声效果，为实际工程设计提供了技术指导。为更好的对发动机排气噪声进行降噪处理，本文除了对消声器结构进行改进，还从有源消声器的主动控制方面对排气噪声进行降噪分析。在Matlab软件平台上建立了排气噪声主动控制模型，在发动机转速一定时，对收敛因子和滤波器长度对系统的影响进行了分析，，在此基础上设计了基于变收敛因子自适应算法的排气噪声主动控制模型，并对发动机不同转速下的排气噪声进行控制分析，计算结果表明设计的可变步长的自适应噪声主动控制系统设计合理，具有较好的鲁棒性，达到了控制要求，为工程中实现排气系统噪声的主动控制奠定了理论基础。
[Abstract]:The design of exhaust system is directly related to the power, comfort and economy of the whole vehicle. With the increasingly strict restrictions on vehicle noise in the country, the optimization design of the exhaust system becomes one of the key points of vehicle design. People are paying more and more attention to it. At present, the design of exhaust system in China is still in the stage of passive noise reduction, which has some limitations. In this paper, combining with the national science and technology support project "Integrated Intelligent Construction Machinery equipment Research and Development for Energy Saving and Safety" (subject No.: 2013BAF07B04), the muffler of a vehicle exhaust system is taken as the research object, and the computer simulation technology is adopted. Combined with the passive and active control design, the transmission loss and pressure loss of the muffler in the exhaust system of the vehicle are analyzed and optimized. According to the structural parameters of the muffler and the numerical model of the muffler before and after, the acoustic performance analysis is carried out by using Virtual LabAcoustics software, and the fluid characteristics are analyzed by fluent software. The transmission loss and pressure loss of the front and rear mufflers are obtained. The sound pressure distribution, the velocity and pressure distribution of the flow field in each muffler are evaluated in detail, and the shortcomings of the related structures are pointed out. The noise suppression effect of the exhaust system is measured experimentally. Both the measurement results and the simulation results show that the noise suppression effect of the exhaust system is poor at some frequencies, which verifies the correctness of the simulation method. The influence of gas temperature and gas velocity on acoustic performance of muffler is also analyzed. Based on the analysis of acoustics and aerodynamic performance of muffler, according to the principle of muffler, aiming at the deficiency of muffler structure, the design of front muffler is improved. Two improvements were made to the rear muffler, and the transmission loss before and after the improvement was simulated and compared. The results showed that the noise quantity of the improved muffler was increased, the frequency band of the muffler was widened, and the fluid characteristics were improved. In addition, the transmission loss analysis of the exhaust system with the improved front and rear silencers is carried out. The analysis shows that the exhaust system has a better silencing effect and provides technical guidance for the practical engineering design. In order to deal with the engine exhaust noise better, this paper not only improves the structure of the muffler, but also analyzes the exhaust noise from the active control of the active muffler. The active control model of exhaust noise is established on Matlab software platform. The influence of convergence factor and filter length on the system is analyzed when the engine speed is constant. On this basis, an active exhaust noise control model based on variable convergence factor adaptive algorithm is designed, and the exhaust noise at different engine speeds is analyzed. The calculation results show that the design of adaptive noise active control system with variable step size is reasonable and robust, which can meet the control requirements and lay a theoretical foundation for the active control of exhaust system noise in engineering.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U464.134.4;TB535.2

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