柴油机排气噪声有源控制的试验研究

尝试利用自适应有源噪声控制技术对４－８５柴油机低频噪声进行空间 消声，取得了一定的消声效果。首先对４－８５柴油机排气噪声频谱进行了分析，然后提出了针对此低频排气噪声应用有源噪声控制技术的可能性。其次讨论了妨碍应用有源噪声控制技术的三大困难，并找出了解决方法。引入次级声场的理论推导并完成了引入次级声场装置的设计、制造。通过对排气噪声信号与排气管上不同位置振动信号的相干性分析，选取参考输入信号，提出了采用自适应有源噪声控制技术，为试验提出了依据，对系统进行了建模并编程，对试验结果了记录并分析。

Experimental Study for Active Control of a Diesel Exhaust Noise

Adaptive active noise control technique has been used to attenuate the low-frequency exhaust noise of a diesel (4-85) and certain attenuation has been achieved in this thesis.Firstly,frequency characteristics of exhaust noise of diesel (4-85) are analyzed,thus,the possibility of using active noise control technique on such low-frequency exhaust noise is offered.Secondly,three main difficulties of hampering the usage of active noise control technique are discussed and the ways to solve are also found out.Then,the design and manufacture of a set of secondary source are finished.The coherence of exhaust noise signals and vibration signals of different points on exhaust duct are analyzed,so,the reference input signals is chosen.The adaptive active noise control technique which is put forward has been expounded,and it supplies the experimental basis on which a system model is built and computer program is programmed.Finally,the experiment result has been recorded and analyzed at last,a sum-up work has been done.