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为了比较得到水下管道安全悬跨长度的判别条件并验证其合理性。使用弹性力-重力相似理论设计模型实验,管道两端均采用固定约束,管道与水流之间的角度分别为90°、75°、60°、45°和30°,悬跨管长分别为1.00 m、0.81 m、0.73 m、0.70 m。通过实验比较fn≥10 fs、fn≥(0.7)-1 fs、fn=5 fs(fn为悬跨管道固有频率;fs为水流激振频率)3种条件对悬跨管道振动的判别情况。研究表明,根据fn=5 fs,即约化速度Vr=1的条件,计算得到的临界长度较安全、合理,并由fn=5 fs条件给出了不同管径、壁厚和流速条件下管道临界长度的规律图,研究结果可为水下悬跨管道的安全评价提供借鉴。(图3,表2,参13)
In order to get the determination conditions of safety span of underwater pipelines and verify its rationality. The model experiment was designed using elastic force-gravity similarity theory. Fixed constraints were adopted on both ends of the pipeline. The angles between the pipeline and the flow were 90 °, 75 °, 60 °, 45 ° and 30 °, respectively. m, 0.81 m, 0.73 m, 0.70 m. The experimental results show that fn≥10 fs, fn≥ (0.7) -1 fs, fn = 5 fs (fn is the natural frequency of suspended pipeline; fs is the frequency of excitation of water flow). The results show that the calculated critical length is safer and more reasonable under the condition of fn = 5 fs, that is, the reduction speed Vr = 1, and the pipe with different diameters, wall thicknesses and flow rates is given by fn = 5 fs Critical length of the law, the results of the study can provide a reference for the safety evaluation of underwater suspended pipelines. (Figure 3, Table 2, Reference 13)