【作者】 陈林；

【导师】 孙江龙；

【作者基本信息】 华中科技大学 ， 船舶与海洋结构物设计制造， 2022， 硕士

【摘要】 近年来,随着海洋强国战略的实施,国家将越来越多的人力物力投入到了海洋资源的开发利用中。浮标、逃生舱、深潜器等结构物作为海洋资源开发的重要工具,有众多学者对它们各方面的性能开展研究,但却鲜少有人研究不同尺度结构物上浮性能之间的相关性。鉴于此,本文以圆球作为研究对象,对其上浮运动性能的尺度相关性开展了研究,并探究了上浮运动中存在的共同特性和重心位置及侧向来流对圆球上浮运动的影响。本文首先建立了一种对静水中圆球的上浮运动进行计算模拟的数值模拟方法,通过模型试验验证了该方法的有效性。然后对多个不同尺度圆球的上浮运动进行了模拟分析研究;研究发现圆球在稳定上浮阶段的阻力系数大致为常数1,不随雷诺数变化而产生较大变化;若两个圆球满足相似条件且尺度之比为λ,则它们的稳定速度之比和上浮总时间之比大致为√λ。通过分析不同属性圆球的上浮运动发现圆球的上浮运动可分为加速上浮阶段、减速上浮阶段和稳定上浮阶段,相比其它学者研究圆球上浮运动时的阶段划分多了减速上浮阶段,其产生原因主要是圆球上浮时出现侧向运动;圆球在加速上浮阶段是一个垂直上浮的过程;侧向运动会使圆球上浮时的阻力大于给定速度下的圆球阻力。最后研究了重心位置和侧向来流对圆球上浮运动的影响,得出了如下规律:重心位置主要影响圆球的上浮稳定速度,重心与浮心距离越大,圆球的上浮稳定速度也越大;侧向来流主要影响圆球的上浮最大速度,侧向来流会使得圆球的上浮最大速度减小。本文建立的圆球上浮运动数值模拟方法对于其它结构物的上浮运动研究具有一定的借鉴意义,分析总结出的与圆球上浮运动相关的研究结论对于海洋结构物的开发和设计具有一定参考价值。更多还原

【Abstract】 In recent years,with the development of the marine potestatem strategy,more and more intellectuals and material resources have been invested in the exploitation and utilization of marine resources.Marine equipment such as buoys,escape capsules,and submersibles,as important tools,has received more and more attention.Many scholars have studied their performance in various aspects,but few people have studied the correlation between the rising motion of structures with different size.In view of this,sphere has been take as target to analyze the scale effect in rising motion,and some common characteristics in the rising motion of sphere and some factors that affect the rising motion have been studied.Firstly,this paper establishes a numerical simulation method to simulate the rising motion of a sphere in still water.The validity of the numerical simulation method is verified by comparing the results of model experiment.Then,by means of numerical simulation method,the rising motions of several spheres with different diameters are studied.It has been found that the drag coefficient of the sphere in the stable rising stage roughly equal constant 1,which does not change greatly with the change of Reynolds number.If there are two similar spheres and the ratio of their diameters is λ,the ratio of their respective stable rising velocities may equal to the ratio of their respective total spending time in rising motion and the ratio roughly equals to √λ.By analyzing the rising motions of some spheres with different properties,it has been found that the rising motion of the sphere can be divided into three stages: the stage with velocity increase,the stage with velocity reduction and the stable rising stage.Comparing with the classification of other scholars in rising motion,there is an additional stage,in which the sphere is rising with velocity reduction.The main reason of rising velocity reduction is that the movement in other direction appears when the sphere rising.And the trajectory of rising sphere in the stage with velocity increase is a vertical line.What’s more,the appearance of the movement in other direction makes the resistance of the rising sphere higher than the sphere in uniform flow.Finally,the paper analyzed the influence of the center of gravity and the side flow on the rising motion of sphere.Some findings has been obtained.The center of gravity mainly affects the stable rising velocity of sphere,and the side flow mainly affects the maximum rising velocity.With the increase of the distance between the center of gravity and buoyancy,the stable rising velocity of sphere will increase.The side flow may reduce the maximum rising velocity of sphere.The numerical simulation method established in this paper provides a way for the research on the rising motion of other structures,and the research conclusions related to the rising motion of sphere can be used for reference in the development and design of marine structures.更多还原