The Studies On Design Methods For Exterior Noise Reduce Of Rotary Machines

With the development of industry,the kinds and numbers of rotary machine continuously increase.Lots of rotary machines bring strong noise when they rotate.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.Many equipment designers and manufacturers broken new fields of noise research,developed numerous low noise mechanical products and impelled this field developing and perfecting continually.The frame radiated noise is one of the major noise resources of rotary machines,especially for air compressor structure,the frame radiated noise energy account for more than 60%of total sound energy.So if we could not successfully resolve the problem,the noise of rotary machines would never be effectively controlled.This article take Rotary machine exterior pipeline structure noise as the main object, compared with systematically to the structure acoustic radiation nature,the structure acoustic radiation major effect factor as well as the Rotary machinery exterior pipeline structure noise control universal method has conducted the research.First aims at when the sound wave incidence pan when some specific frequency or specific incident angle can cause the acoustic radiation ability greatly to increase and to have sound energy massive transmission this phenomenon,discussed in detail has had the coincidence effect condition;And aimed at each kind of size,the material quality board which the project actual applied infers it to tally separately the frequency and the critical frequency formula,has obtained the thick plate and the material aeolotropy can cause the conclusion which the structure the critical frequency dropped.Then discusses the noise muffling of several kinds of plates.It gives the modifying formula of the mass law and verifies its accuracy with an example.At last,this paper explains the effect of stiffeners and damping on the plates' muffling characteristics.Finally extends to from the board structure question to the pipeline question,and discussed the pipeline to use one method to calculate the column shell the vibration acoustic radiation theoretical value,extended the board structure for the column shell(i.e.single pipeline model),and has correspondingly made the corresponding value simulation by VA-One.Using the finite element analysis method,a boundary element analysis method have carried on the quite systematic analysis to the pipeline coupled oscillation noise,has provided the theory basis for the vibration noise control.