【作者】 周尧；

【导师】 董大伟；

【作者基本信息】 西南交通大学 ， 车辆工程， 2006， 硕士

【摘要】 近十几年来,有源消声技术(ANC)成为噪声控制领域的研究热点。它以体积小、重量轻、低频消声效果好等优点获得普遍关注。但是针对往复式机械进排气噪声主动控制却少有研究。本文结合往复式机械进排气噪声的特点,进行了管道噪声有源控制中降噪量影响因素及改进措施的研究。 本文在综合分析管道声场理论和自适应算法理论的基础上,针对往复式机械进排气噪声的特性,以LabView为软件开发平台,编制了仿真和实验程序。仿真程序中的算法主要采用自适应控制中两种经典算法:最小均方算法(LMS)和最小二乘算法(RLS)。利用这两种算法进行了大量的仿真研究,分析了采样频率等因素对降噪量的影响,得出了一些有益于工程应用的结论。结合往复式机械进排气噪声主要由基频和倍频成分组成的特点,分析了基频与倍频混合信号在这两种算法下的消声效果。 本文设计了管道噪声有源控制实验系统,分析了系统主要参数的选择依据,完成了系统的安装调试工作。实验研究主要应用LMS算法进行,直接采用LMS算法时,初级声源和次级声源间较大的相位差会严重影响消声量。针对这一问题,本文提出了一种延迟LMS改进方法。实验结果表明,延迟LMS方法较之直接LMS算法,消声量有明显提高。 实验过程中,观察到误差传感器和次级声源在不同位置时对实验结果有一定影响,因此本文还进行了误差传感器和次级声源多种不同位置的消声效果对比研究,并得出如下结论:次级声源和初级声源反向较同向消声效果好,误差传感器在管道中心线较在中心线外消声效果好。 上述结合往复式机械进排气噪声的特点的仿真研究和实验研究,较全面地分析了管道噪声有源控制消声量的影响因素及其变化规律,并提出了改进的控制算法,这些研究对往复式机械进排气噪声的有源控制有一定参考价值。更多还原

【Abstract】 In recent decades, active noise control (ANC) has become a hot research subject in noise control field. With the advantages of small volume, light mass and effectiveness in low frequency, it attracts much attention. But the researchers have less focused on ANC for inlet and exhaust pipe of reciprocating machines. The critical factors influencing noise attenuation and improving measurements have been studied through the noise property in inlet and exhaust ducts of reciprocating machines.On the basis of the principles of acoustic field in a duct and ANC algorithms, simulated and experimental programmes were carried out aimed at the main frequencies of the noise from the inlet and exhaust pipe of reciprocating machines. The programmes for simulation and experimental study were developed by LabView.The simulation algorithms come from the classic control algorithms , which are the least mean square (LMS) and the recursive least mean square (RLS). A great deal of simulation study was accomplished with both algorithms and some factors such as sampling rate were analyzed on the level of noise attenuation. Then some useful conclusions were presented for the applications in engineering. Considering that the fundamental frequency and multiple frequencies make up the main frequencies in the noise of reciprocating machines, the signals mixed with the fundamental frequency and multiple frequecies were calculated by two algorithms.An experimental system for ANC in a duct was designed and the reasons for deciding major parameters of the system were analyzed. Installation and debugging of the system was completed. The experimental study is based on LMS and the experimental data showed that major phase difference existing between the two acoustic sources would affect noise reduction seriously. A new delayed LMS was brought forward to further improve the noise attenuation. The amount of noise attenuation was obviously increased.During the process of experiments, it found that different positions of error sensor and secondary acourstic source were compared in terms of noise attenuation result. The paper concluded that the best positon for the system is thatthe error sensor lay in the center of the duct and secondary acourstic source was opposite to primary acoustic source.The above simulation and experimental researches analyzed the influencing factors and changing tendency of noise reduction, and an improved algorithm was put forward. The research work has some referential value to the industrial application.更多还原