不同浪向下超大型船舶载荷响应特征的模型试验研究

Experimental model analysis of load responses of ultra-large vessels under different direction waves

探寻超大型船振动响应随不同浪向的变化规律对预报真实海况和后期的结构评估具有重要意义。在拖曳水池对某超大型集装箱船进行了分段船模斜浪试验,详细介绍了船模设计原则和斜浪试验测试系统,并通过改变船模分段数量来探究船体弹性效应对振动响应的影响,结果表明船体自身的弹性效应对颤振影响很大,船体固有频率小,更容易出现颤振现象。研究了各浪向下的弯矩响应和砰击压力时历曲线,并对不同成分的弯矩响应和砰击压力随浪向和波长船长比的变化规律进行了分析,经分析发现,迎浪是发生高频颤振最严重的浪向,而斜浪时的最大弯矩多发生在λ/(L·cosβ)=1.0附近。相对于低频波浪弯矩,高频载荷响应对浪向的变化更加敏感。

It is of great importance to evaluate the vibrations response of ultra-large vessels under different wave directions. The segmented ship model test in oblique wave of an ultra-large container ship was carried out in a towing tank. The design principle of segmented ship model and oblique wave test system were introduced detailedly. The number of segments of model was changed to study the influence of hull elastic effect on vibration responses. Experimental results show that the elastic effect of hull has great influence on the whipping, and the lower the natural frequency of hull is, the earlier the whipping phenomenon occurs. Finally，time trace of bending moments and slamming pressure under different wave directions is discussed, and the variation of the different bending moment components and slamming pressure with wave directions and ratio of wave length to ship length was analyzed．It was shown that the most serious whipping is in head waves, and the maximum bending moment in oblique wave is near to λ/（L？cos β）=1.0. Compared with the low frequency wave moments, the high frequency load responses is more sensitive to the change of wave direction.