水消声器结构声耦合机理及性能试验研究

The water piping system of ship is attached directly to the outboard water, and is an important and efficient noise propagation path. In order to reduce the noise radiation of the sea pipe, the water muffler is often used. Accurate predicting the acoustic attenuation performance of the water muffler is the basis of the water muffler design and the piping system noise control. At present, the predicting method of the acoustic attenuation performance learns from the air muffler experience, and the effect of the interaction between the structure and the water on the water muffler’s acoustic attenuation performance is often ignored. The predicting result doesn’t agree with the experimental result. The structural and acoustic coupling mechanism of the water muffler needs to understand. Based on the continuum mechanics theory, this project is to study the structural and acoustic coupling theory of the water muffler and establish the finite volume method numerical analysis model to study the structural acoustic coupling of plate and shell structures. An improved time-domain impulse method is applied to predict the acoustic attenuation characteristics of the water muffler. The effect of the structure thickness, the material property and the boundary condition on the water muffler’s acoustic attenuation performance is investigated by this numerical analysis model. The influence mechanism of structural acoustic coupling on attenuation performance of the water muffler is summarized. The influences of the bench test are investigated to validate the predicted result. The present research would provide support for the design and predicting of the water muffler and the noise control of the water piping system.

船舶水管路系统与舷外水直接相连，是一条重要的噪声传递途径且效率极高，常采用消声器降低通海管口噪声辐射。消声器声学性能准确预测是水消声器的设计及水管路系统噪声控制的基础，目前水消声器声学性能预测简单类比空气消声器方法，很少考虑结构声耦合对水消声器声学性能的影响，理论结果与试验测试数据偏离严重，亟需揭示水消声器结构声耦合机理。本项目拟基于连续介质力学开展水消声器结构声学理论研究，并在此基础上建立板壳理论结构声耦合有限体积法数值分析模型，基于改进的时域脉冲法预测水消声器的声学性能，研究结构壁厚、材料属性及边界条件变化等对水消声器声学性能的影响，归纳总结结构声耦合对水消声器声学性能的影响机理，并在厚壁静止水管路系统上进行试验验证，为水消声器声学性能的设计预测及水管路系统噪声控制提供支撑。

流噪声可通过海水管路系统直接向外辐射噪声，工程上常采用消声器降低这部分噪声，但消声器声学性能的理论结果与试验测试数据偏离严重，为了准确的预报水消声器声学性能，揭示水消声器结构声耦合机理。本项目基于连续介质力学开展水消声器结构声学理论研究，建立了结构声耦合有限体积法数值仿真计算程序，提出改进的时域脉冲法预测水消声器的声学性能，并提出了基于双负载法的消声器传递损失预测方法，开展了充水膨胀腔消声器传递损失的试验测量。结果表明：本项目提出的方法通过空气消声器的传递损失仿真计算，该方法的仿真结果与传统方法的预测结果吻合良好；通过研究水消声的传递损失，发现该方法与传统方法的差别，传统的方法将水消声器台架的测试管段等其他部分认为是消声器的一部分，测量管段等部分会由于结构声耦合效应造成结果的偏差；随着水消声器腔壁厚度的减少，弹性结构与流体的耦合程度越强烈，结构声耦合效应对水消声器声学性能的影响程度越大，膨胀腔的通过频率向低频方向移动越多；周向腔壁的结构声耦合效应会造成膨胀腔消声器的传递损失曲线向低频方向移动，端部腔壁与水介质的耦合效应会使消声器传递损失曲线出现反共振峰、共振峰，这与充水消声器端板结构的(0，n)阶固有模态相关；膨胀腔壁的结构声耦合作用使传递损失曲线出现明显峰值，这是由于腔内声压出现了三维高次波；消声器管路结构声耦合效应对水消声器声学性能的影响不大；仿真结果与试验结果对比表明，在300Hz~600Hz频段内仿真结果比试验结果偏小，在1000Hz~2000Hz处基本一致，特别是在峰值频率1435Hz、2880Hz处吻合良好。