管路附件对管路系统声传递-辐射特性的影响

Effects of Pipe Fittings on the Acoustic Transfer-Radiation Characteristic through Pipelines

为控制海水冷却系统通海口产生的辐射噪声,考虑管路及管路附件的弹性影响,建立了简化的通海系统流噪声传递-辐射的仿真模型;从避免管路流噪声传递损失的角度,提出了基于总传递损失的管路系统声传递-辐射特性的评价方法;借助商业软件计算了不同管路附件影响下的管路声传递-辐射的总传递损失,给出了管路附件对管路声学总传递损失的影响规律。计算结果表明,与无管路附件的直管路相比,换热器可以使总传递损失提高94.9 dB,挠性接管可提高33 dB,截止止回阀可提高28.5 dB,相比之下,滤器、变径管、弯头对总传递损失的提升均小于10 dB,蝶阀仅可提高1.5 dB。通过研究发现,管路附件可以提高对通海系统辐射噪声的控制效果。实际的海水冷却系统的管路附件集中在系统出口管路,使得出口管路附件多于进口管路,导致进口管路辐射噪声控制不足。增加进口管路上的管路附件可提高系统辐射噪声的控制效果。

To control the radiation noise at the open end of pipe for a seawater cooling system,a simplified numerical model is established for the acoustic transfer-radiation of hydrodynamic noise throughout pipelines in the seawater cooling system in consideration of elasticity of pipe and pipe fittings.From the perspective of hydrodynamic noise transmission loss through pipes and pipe fittings,an evaluation methodology for the acoustic transfer-radiation characteristic through pipelines is proposed based on the total acoustic transmission loss.The total acoustic transmission loss of a pipe system with different pipe fittings is calculated using a commercial software of computational acoustics,and the effect of pipe fittings on acoustic transfer-radiation characteristic is revealed.Computation results show that the total transmission loss is increased by about 94.9 dB by the heat exchanger,33 dB by the flexible tube,and 28.5 dB by the stop check valve,compared with a straight pipe.However,the increment of total transmission loss is below 10 dB by colander,elbow and adapter bonnet,and is only 1.5 dB by butterfly valve.It can be concluded that pipe fittings tend to promote the total transmission loss.Outlet pipe of an actual cooling system usually contains a heat exchanger and more fittings than the inlet pipe,however,the radiation noise of the system in the inlet pipe is not properly controlled.So it is suggested that more pipe fittings be mounted into the inlet pipe to control the radiation noise.