基于次级声源布局优化的风洞背景噪声主动控制研究

发布时间：2018-02-28 02:33

本文关键词： 风洞主动降噪声学仿真蒙特卡罗布局优化　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：当今时代,各种军民用机械和设备对环境的噪声污染得到越来越多的关注。因此诸如汽车、飞机、列车等的风洞声学试验显得越来越重要。在这些空气动力声学试验中,较大的风洞背景噪声会将目标的有用声信号淹没,频带内的背景噪声难以去除且严重降低有用声信号的信噪比。如何降低风洞试验背景噪声已经成为空气动力声学试验中的重要问题。常规声学风洞的建造,大多采用吸声材料、隔音处理、削弱反射等被动降噪方法,对高频噪声效果显著,但对低频噪声收效甚微。本文采用对低频噪声抑制作用明显的主动降噪技术,将其针对风洞环境工程化改进后,应用于空气动力声学试验中,配合传统噪声抑制方法,进一步降低整个频带内的风洞背景噪声,提高声学试验的试验精度。本文基于主动降噪技术的声学分析,提出一种基于蒙特卡罗法声学仿真的次级声源布局优化方法,从次级声源布局的角度提高多次级声源主动噪声抑制系统的抑噪性能。通过推导多通道主动降噪控制算法,提出了易于工程实现的基于一维自适应滤波的变步长多通道主动抑噪控制算法,以高性能的噪声控制算法提高主动噪声抑制系统的稳定性和噪声削弱效率。并搭建了双通道主动降噪试验系统,以本文方法为支撑对实验室声学环境进行降噪试验。试验结果表明本文提出的优化方法和控制算法对单频噪声和混频噪声均能起到扩大抑噪区域增强抑噪效果的作用。最后将本文方法应用于实际风洞试验环境,并进行降噪试验,取得了目标频率-7dB,综合声压级-1.4dB的降噪效果。该试验结果验证了本文提出的次级声源布局优化方法以及噪声控制算法的正确性,表明了本文改进后的主动降噪技术应用于风洞背景噪声抑制的可性能。
[Abstract]:Nowadays, more and more attention has been paid to noise pollution caused by various kinds of military and civilian machinery and equipment. Therefore, wind tunnel acoustic tests such as cars, aircraft, trains and so on are becoming more and more important. In these aerodynamic acoustics tests, The larger wind tunnel background noise will drown the useful sound signal of the target. The background noise in the frequency band is difficult to remove and the signal to noise ratio of useful acoustic signals is seriously reduced. How to reduce the background noise in wind tunnel tests has become an important problem in aerodynamic acoustic tests. Passive noise reduction methods, such as sound insulation, weakening reflection and so on, have remarkable effect on high frequency noise, but little effect on low frequency noise. In this paper, the active noise reduction technique, which has obvious effect on low frequency noise suppression, is adopted to improve the environment of wind tunnel. In the aerodynamic acoustic test, with the traditional noise suppression method, the background noise of the wind tunnel in the whole frequency band is further reduced, and the test accuracy of the acoustic test is improved. In this paper, the acoustic analysis based on the active noise reduction technique is presented. A method of optimizing secondary sound source layout based on Monte Carlo acoustic simulation is proposed to improve the noise suppression performance of multi-stage active noise suppression system from the point of view of secondary sound source layout. The multi-channel active noise reduction control algorithm is derived. A variable step size multi-channel active noise suppression control algorithm based on one-dimensional adaptive filtering is proposed, which is easy to realize in engineering. The high performance noise control algorithm is used to improve the stability and the noise weakening efficiency of the active noise suppression system. The experimental results show that the proposed optimization method and control algorithm can expand the noise suppression area and enhance the noise suppression effect for both single-frequency noise and mixed-frequency noise. Finally, the method is applied to the actual wind tunnel test environment. The noise reduction experiment is carried out, and the noise reduction effect of target frequency -7dBand sound pressure level of 1.4dB is obtained. The experimental results verify the correctness of the proposed secondary sound source layout optimization method and the noise control algorithm. It is shown that the improved active noise reduction technique can be used to suppress the background noise of wind tunnel.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB535

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