本文選題：子母管線 + 沖姓坑�。� 參考：《大連理工大學(xué)》2014年碩士論文

【摘要】：本文采用數(shù)值模擬的方法研究了沖蝕固床上的子母管線在規(guī)則波作用下的水動(dòng)力特性,為工程設(shè)計(jì)人員進(jìn)行海底子母管線的設(shè)計(jì)和安全性評(píng)估工作提供了有價(jià)值的科研理論成果和指導(dǎo)。 本文采用三步有限元法離散雷諾方程,并通過標(biāo)準(zhǔn)k-co模型來模擬水波的湍流運(yùn)動(dòng),采用CLEAR-VOF法捕捉水體的自由表面,利用可吸收式無(wú)反射造波技術(shù)建立了數(shù)值波浪水槽。文中通過數(shù)值計(jì)算結(jié)果和物理模型試驗(yàn)數(shù)據(jù)的對(duì)比,從波面歷時(shí)曲線、管線水動(dòng)力荷載歷時(shí)曲線、管線周圍渦脫模式三個(gè)方面驗(yàn)證了數(shù)值計(jì)算結(jié)果的可靠性。本文的數(shù)值模型可以用來進(jìn)行子母管結(jié)構(gòu)的水動(dòng)力特性的研究。 本文基于所建立的數(shù)值水槽,數(shù)值研究了底床上沖蝕坑的存在對(duì)子母管線的水動(dòng)力荷載的影響,并考察了渦的運(yùn)動(dòng)和管線所承受的荷載的振蕩變化特征之間的關(guān)系,分析了沖蝕坑相對(duì)深度S/D、KC數(shù)對(duì)子管和母管的拖曳力系數(shù)、慣性力系數(shù)、升力系數(shù)以及升力振蕩頻率的影響。研究結(jié)果表明,沖蝕坑的存在使得子管和母管的水平力和升力幅值比平底地形時(shí)的有所減小,子管升力和母管升力的振蕩出現(xiàn)倍頻現(xiàn)象,且存在一定的相位差。在規(guī)則波浪作用下,子母管周圍的渦量場(chǎng)重復(fù)進(jìn)行著渦的脫落和反向粘附現(xiàn)象,而渦的脫落和反向粘附使得子管升力和母管升力達(dá)到極值。隨著沖蝕坑相對(duì)深度的增大,母管的拖曳力系數(shù)呈現(xiàn)先增大后減小的趨勢(shì),母管的慣性力系數(shù)和正向升力系數(shù)逐漸減小并趨向于平穩(wěn),負(fù)向升力系數(shù)則不斷增大,而沖蝕坑深度的變化對(duì)子管水動(dòng)力系數(shù)的影響很小。通過對(duì)沖蝕固床上單管結(jié)構(gòu)和子母管結(jié)構(gòu)的水動(dòng)力荷載進(jìn)行對(duì)比,得出子管的存在使得母管的水平力幅值減小約50%,而母管的升力幅值則有所增大,且升力的方向更多的表現(xiàn)為負(fù)向。隨著KC數(shù)的增大,子管和母管的拖曳力系數(shù)和升力系數(shù)逐漸減小并趨向于穩(wěn)定,而慣性力系數(shù)則逐漸增大；同時(shí),KC數(shù)的增大使得子母管周圍的湍流特征越來越明顯,子管和母管的升力頻譜曲線出現(xiàn)多個(gè)峰值,但是升力頻譜曲線的主峰對(duì)應(yīng)的頻率恒為2倍波浪振蕩頻率。
[Abstract]:In this paper, numerical simulation method is used to study the hydrodynamic characteristics of the parent pipeline on the erosion solid bed under the action of regular waves, which provides valuable scientific research results and guidance for the engineering designers to design and evaluate the safety of the subseabed pipeline.
In this paper, the three step finite element method is used to discrete the Reynolds equation, and the turbulence motion of water wave is simulated by the standard K-co model. The free surface of the water body is captured by CLEAR-VOF method. The numerical wave tank is established by the absorbable non reflective wave making technology. The time curve, the diachronic curve of the hydrodynamic load of the pipeline and the three aspects of the vortex removal mode around the pipeline verify the reliability of the numerical calculation results. The numerical model of this paper can be used to study the hydrodynamic characteristics of the tube structure.
Based on the numerical water trough established in this paper, the influence of the existence of the erosion pit on the bottom bed on the hydrodynamic load of the parent pipeline is numerically investigated, and the relationship between the vortex motion and the vibration characteristics of the load under the pipeline is investigated. The drag force coefficient and the inertial force system of the relative depth of the erosion pit S/D, the number of KC to the tube and the mother tube are analyzed. The results show that the existence of the erosion pits makes the horizontal force and lift amplitude of the tube and the mother tube decrease slightly than that in the flat bottom, and the oscillation of the lift force and the lift of the mother tube appears frequency doubling, and there is a certain phase difference. Under the action of regular waves, the vortex around the tube. The volume field repeats the phenomenon of vortex shedding and reverse adhesion, and the vortex shedding and reverse adhesion make the lift force and the lift force of the mother tube reach the extreme value. As the relative depth of the erosion pit increases, the drag coefficient of the mother tube increases first and then decreases, and the number of inertial force and the positive lift coefficient of the mother tube gradually decrease and tend to Yu Ping. The influence of the change of the negative lift coefficient on the hydrodynamic coefficient of the tube is very small. By comparing the single tube structure and the hydraulic load of the tube structure on the erosion solid bed, it is concluded that the existence of the sub tube reduces the horizontal force amplitude of the mother tube by about 50%, while the lift amplitude of the mother tube is increased. The direction of lifting force is more negative. With the increase of KC number, the drag force coefficient and lift coefficient of the tube and the mother tube gradually decrease and tend to be stable, while the inertia force coefficient increases gradually. At the same time, the increase of the KC number makes the turbulence characteristics around the tube more and more obvious, and the lift spectrum curve of the sub tube and the mother tube appears more than one. Peak value, but the frequency corresponding to the main peak of the lift spectrum curve is 2 times the wave oscillation frequency.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：P756.2

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