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A pneumatic launcher is theoretically investigated to study its natural transverse vibration in water. Considering the mass effect of the sealing cover, the launcher is simplified as a uniform cantilever beam with a top point mass. By introducing the boundary and continuity conditions into the motion equation, the natural frequency equation and the mode shape function are derived. An iterative calculation method for added mass is also presented using the velocity potential function to account for the mass effect of the fluid on the launcher. The first 2 order natural frequencies and mode shapes are discussed in external flow fields and both external and internal flow fields. The results show good agreement with both natural frequencies and mode shapes between the theoretical analysis and the FEM studies. Also, the added mass is found to decrease with the increase of the mode shape orders of the launcher.And because of the larger added mass in both the external and internal flow fields than that in only the external flow field, the corresponding natural frequencies of the former are relatively smaller. 相似文献
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介绍了外加电流阴极保护技术在河口咸淡水交接处的工程应用实例,介绍了用于工程的广州中港圣维可防腐工程有限公司先进的远程监控系统技术,包括技术的选用、设备系统、辅助阳极的选用、施工措施、系统的调试和测试等。希望把外加电流阴极保护技术在我国进行推广和提高。 相似文献
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对不同静水压力下圆柱壳的频散特性进行研究,初步揭示无限长圆柱壳振动受到水深影响的变化规律。采用Flagge壳体运动方程和Helmhohz声学方程建立静水压力作用下耦合系统的频散方程,利用muller三点迭代法对该超越方程进行求解,得到传播波的频散曲线。结果表明:静水压力会对水下圆柱壳结构的频散特性产生一定的影响,其影响效果随水深的增加逐渐增大。与参考文献[4]的结果作比较发现,其对各支传播波起始频率的作用并不大,而对处于声速线上方的亚声速波影响明显,随水深增加,相应的波数呈下降趋势,等间距加大水深,其浸深绝对值越大影响也越大,图示曲线间距增加。 相似文献
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