Analysis And Control On Structure-borne Noise Radiated By Large Power Machines

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.