小尺度浮管结构水动力特性研究

发布时间：2018-10-23 18:51

【摘要】：小尺度浮管结构为海洋工程中的基本组成单元,广泛存在于各种海洋工程设施中,但其在波浪下的水动力特性一直存在较大的争议。为此,本文对固定杆件的水动力系数选取和双浮管结构筏式养殖系统的运动特性和受力特性做了研究。对于固定杆件,本文主要利用了垂直杠杆原理,设计新型的试验装置,提取了浮管在水流及波浪下的受力曲线,基于Morison方程,分析计算了不同波浪要素下的水动力系数CD和CM取值以及系数随波浪相角的变化规律。定义分析了新的波高参数KH,周期参数KT,对小尺度浮管结构在波浪下的水动力系数进行了全面的分析。结果表明,当认为水动力系数与波浪相角无关时,波高参数KH、周期参数KT、雷诺数Re均对水动力系数的取值有较显著影响:CD、CM整体随波高KH呈幂指数衰减;CD、CM整体随着波周期KT的增大亦呈衰减趋势;相同波高条件下,CM随Re数增大而增大,而CD值相对稳定。研究表明,水动力系数与波浪相角有密切联系:CD基本呈“U”字形变化;CM呈现周期性三角函数的变化规律,可由波浪的一倍频和二倍频三角函数与常数项叠加而成。最后本文给出了波浪条件下水动力系数CD和CM的经验计算公式。对于双浮管结构的筏式养殖系统,本文通过模型试验,利用CCD图像采集系统和受力采集系统获得了不同波要素及布设角度下的运动和动力学响应。研究了波浪参数、负重等对运动和动力响应的影响。结果表明,波高的增加使得管筏受力、垂直幅值线性增大,且迎波面增大速率较背波面迅速;周期的增大使得管筏倾角略有减小,大周期的波浪使迎波面和背波面锚定点的受力分布更均匀;负重重量的增加会导致系统的受力和水平幅值在整体上降低,但在个别周期下会导致受力和倾角的剧烈变化;管筏与波向呈60°、30°角时管筏锚定点拉力较大,0°角时刻拉力最小,在60°角时,拉力出现最大值。
[Abstract]:Small-scale floating pipe structure is a basic element in ocean engineering, which widely exists in various marine engineering facilities, but its hydrodynamic characteristics under waves have always been controversial. Therefore, the selection of hydrodynamic coefficients of fixed members and the kinematic and mechanical characteristics of raft culture system with double floating pipe structure are studied in this paper. For fixed members, this paper mainly uses the principle of vertical lever, designs a new type of test device, extracts the force curve of floating pipe under current and wave, and based on Morison equation, The values of hydrodynamic coefficients CD and CM under different wave elements and the variation law of coefficients with wave phase angle are analyzed and calculated. The new wave height parameter KH, periodic parameter KT, is defined and analyzed. The hydrodynamic coefficients of small scale floating pipe structures under waves are analyzed comprehensively. The results show that when the hydrodynamic coefficient is not related to the wave phase angle, The wave height parameter KH, period parameter KT, Reynolds number Re has significant influence on the value of hydrodynamic coefficient: the whole CD,CM decreases exponentially with the wave height KH, and the whole CD,CM decreases with the increase of wave period KT. Under the same wave height, the CM increases with the increase of Re number, but the CD value is relatively stable. The results show that the hydrodynamic coefficient is closely related to the wave phase angle: the CD is basically "U" shaped, and the CM presents the law of periodic trigonometric function, which can be superposed by the trigonometric function of the double frequency and the second frequency of the wave and the constant term. Finally, the empirical formulas for the hydrodynamic coefficients CD and CM of wave conditions are given. For the raft culture system with double floating pipe structure, the motion and dynamics responses of different wave elements and setting angles are obtained by using CCD image acquisition system and force acquisition system through model tests. The effects of wave parameters and load loading on motion and dynamic response are studied. The results show that with the increase of wave height, the vertical amplitude increases linearly, and the increasing rate of the front wave surface is faster than that of the back wave surface, and the inclined angle of the tube raft decreases slightly with the increase of the period. The large period wave makes the stress distribution of the anchoring point on the front and back wave surface more uniform, and the increase of the weight will lead to the decrease of the system force and the horizontal amplitude, but it will lead to the violent change of the force and the inclination angle under the individual period, and the increase of the load weight will lead to the decrease of the force and the horizontal amplitude of the system as a whole. When the angle of the tube raft and the wave is 60 掳, when the angle of 30 掳is 30 掳, the tension of the anchor point of the tube raft is larger, the tension at 0 掳angle is the smallest, and when the angle is 60 掳, the maximum tensile force appears.
【学位授予单位】：浙江海洋学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P751;P731.2

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