【作者】 张宇；

【导师】 陈长征；

【作者基本信息】 沈阳工业大学 ， 固体力学， 2006， 硕士

【摘要】 大型动力机械的发展有着悠久的历史,随着工业的发展,其种类和数量都不断增多。大量的大型动力机械在运转时产生强烈的噪声,因而给人们的日常工作和生活带来许多烦恼。为了降低噪声,许多研究人员经过几十年的研究和实践,总结出许多降低机械设备噪声的理论和成功的经验,取得了不少有益的研究成果。 本文以大型动力机械为主要对象,比较系统地对结构声辐射、吸声隔声材料特性、噪声控制进行了研究,具体研究成果如下: (1)结构噪声是大型动力机械的主要噪声源之一,结构振动辐射声能占总声能的比例甚至可以达到90～95%,结构噪声的产生是由于零件加工精度不够,即设计存在某些问题,大型动力机械噪声就不能得到有效的控制。建立了动力机械结构噪声分析的简化模型,研究了各参数对噪声声辐射功率的影响。 (2)提出双层次噪声控制理念,即主动噪声控制与被动噪声控制相结合。机械故障产生的振动噪声也是大型动力机械的重要噪声来源,对机械设备进行诊断去除故障降低声源能量辐射,对声源进行主动控制,再利用吸声结构降低噪声辐射,有效地进行噪声控制。 (3)宽频带阻抗复合吸声结构。大型动力机械噪声具有宽频带特征,现有复合吸声结构仅采用单一吸声材料,只能对某一个频带有较高的吸声系数,因此,不能获得理想的降噪效果。本文提出宽频带阻抗复合吸声结构,对原有复合吸声结构的吸声部分进行了改进,有效的加宽了结构的吸声频带,提高了降噪效果。 (4)使用ANSYS和SYSNOISE两种有限元软件,建立宽频带阻抗复合吸声结构和一般吸声结构在点声源声场中的有限元模型,比较两种吸声结构对声场的影响。宽频带阻抗复合吸声结构的降噪效果较一般吸声结构有明显的提高,同时,吸声结构内层的宽频带组合式吸声板有效的削弱了内部混响。 (5)宽频带阻抗复合吸声结构应用——氨制冷螺杆压缩机组噪声控制。采集了两台氨制冷压缩机组的噪声信号,并进行频谱分析。根据信号特征确定吸声材料和吸声结更多还原

【Abstract】 With the development of industry, the kinds and numbers of rotary machine continuously increase. Lots of power machines bring strong noise. As the result of the noises, the people feel very annoyance in their daily life. Many researchers have taken much efforts to reduce the noise. With decades years research and experience, we have summarized many theories of reducing equipment noise and successful experience, acquired lots of useful achievements.In view of this case, the paper mainly studied sound radiation properties of structure, acoustics material characteristic and the way to control the noise radiated by large power machines. The detail research shows as fellows:(1) The frame radiated noise is one of the major noise resources of power machines, the frame radiated noise energy account for more than 90% of total sound energy. So if we could not successfully resolve the problem, the noise of power machines would never be effectively controlled. Although there are much research in the field, most research only deal with special machine, special part in some way. It is short of systematicness and popularity.(2) Two grades noise control method is put award. Active noise control and passive noise control should be considered together in noise control project. Active noise control in this paper is different from others, it is made up of fault diagnosis and vibration reduction. The energy eradiated from noise source is reduced after active noise reduction. Then noise energy in room can be reduced by sound-absorbing structure. The effect of noise reduction should be enhanced in this way.(3) The noise eradiated from large power machine have large channel characteristic. There is only one sound-absorbing material in compounding sound-absorbing structure which is existed. It’s not applicable to large channel noise. Compounding sound-absorbing structure for large channel noise is put forward in this paper. The sound-absorbing channel can be increased, absorbing coefficient can be obtained by using this structure.(4) The compounding large channel sound-absorbing structure and normal sound-absorbing structure finite element model is built using ANSYS and SYSNOISE. The variation of sound field is much different after compounding large channel sound-absorbing structure or normal sound-absorbing structure is place into the field of point sound source. The effect of noise reduction with compounding large channel sound-absorbing structure is much better than with normal sound-absorbing structure. The reverberation can be faded by using compounding large channel sound-absorbing structure.(5) Noise control on refrigerator of screw compressor with ammonia by using compounding large channel sound-absorbing structure. Signal of noise eradiated from refrigerator of screw compressor had been collected, and transform the signal into spectrum. Reverberation had disappeared and sound pressure level had declined in the room after noise reduction. A practicality value can be gotten in noise control project with compounding large channel sound-absorbing structure.更多还原