| Fluid noise in water pipeline system can seriously affect stability of pipeline system itself and components related to the system,and deteriorate comfort of external environment.The measure commonly used to control this noise is to install water pipeline silencer.However,traditional silencers show some disadvantages on their both acoustic performance and hydrodynamic performance:(1)The transmission loss of silencers is proportional to the cross-sectional area of expansion chamber;(2)The existence of passbands in single-chamber silencer,and the range of noise elimination is too narrow;(3)The fluid resistance of expansion chamber is too large.In the case that significant column can not be allowed and multi-stage silencers are not used,anti-type silencers are obviously difficult to reach actual requirements.Based on the principle and theory of accumulator and elastic hydraulic filters absorbing hydraulic pulsation,this paper install resilient rubber membrane structure in expansion chamber silencers.When pressure pulsation is transmitted to the elastic membrane,it cause deformation and vibration of membrane.Then the elastic membrane and sticky rubber dissipate acoustic energy,which help achieve noise elimination in water pipeline.By using numerical simulation,the transmission loss of silencer in different sizes and structures can be predicted.Then creating a silencer prototype,testing its actual performance through experiments.The results of numerical calculation are verified by experiments.Firstly,building the model and create finite element mesh of internal fluid field,cylindrical membrane and air field in the membrane.Simulating the muffling process of elastic member by vibro-sound module in Virtual.Lab.Then the transmission loss of silencers can be predicted and change rule of transmission loss with the size and material of membrane can be analysized.Some other silencer proposals are presented and analysized.Establishing a circulating water pipeline to analog actual working environment of silencers,the noise reduction and transmission loss of silencer in different working conditions are tested.Then a thick-wall tube test bench is built to test the transmission loss of silencer.Results show that the curve of transmission loss measured in experiment is basically consistent with results of simulation.And silencer provide 10 to 20 d B muffling volume in every conditions. |
