本文選題：波浪 + 海底管道　； 參考：《大連理工大學(xué)》2016年博士論文

【摘要】：鋪設(shè)在海底的管道,在波浪和水流等復(fù)雜海洋水動(dòng)力條件作用下,極易發(fā)生局部泥沙沖刷,致使海底管道發(fā)生懸空。在交變流體作用力下,懸空的海底管道會(huì)發(fā)生渦激振動(dòng),誘發(fā)疲勞破壞。管道振動(dòng)響應(yīng)也會(huì)進(jìn)一步與泥沙沖刷發(fā)生相互作用。泥沙局部沖刷引起的管道懸空以及管道振動(dòng)都會(huì)危及管道的安全。一旦管道發(fā)生破壞,不但會(huì)造成巨大的經(jīng)濟(jì)損失,還會(huì)引起嚴(yán)重的環(huán)境污染。目前對(duì)于海底管道局部沖刷的數(shù)值研究多限于簡(jiǎn)單的單向水流作用下,固定管道的局部沖刷問(wèn)題。而對(duì)于波浪運(yùn)動(dòng)、管道振動(dòng)和泥沙運(yùn)動(dòng)耦合的數(shù)值分析尚未見(jiàn)開(kāi)展。針對(duì)波浪作用下,振動(dòng)管道的局部泥沙沖刷問(wèn)題建立數(shù)值模型,探索海底管道渦激振動(dòng)與局部泥沙沖刷之間的耦合動(dòng)力作用機(jī)理,具有清晰的工程背景和重要的科學(xué)價(jià)值。本文將建立綜合考慮波浪運(yùn)動(dòng)、管道振動(dòng)和泥沙輸運(yùn)的耦合動(dòng)力數(shù)值分析模型,并基于所建立的數(shù)值模型對(duì)波浪作用下振動(dòng)管道的局部泥沙沖刷耦合問(wèn)題進(jìn)行數(shù)值研究。第二章首先建立了基于Navier-Stokes方程的高階迎風(fēng)有限元數(shù)值模型,對(duì)低雷諾數(shù)下固定多圓柱繞流的基本理論問(wèn)題開(kāi)展了數(shù)值研究。在串聯(lián)雙圓柱繞流方面：首次發(fā)現(xiàn)在圓柱間距比為G／D=0.9的情況下,前、后圓柱的升力系數(shù)和渦脫落頻率也都存在突變的現(xiàn)象,這主要是由流動(dòng)不穩(wěn)定所導(dǎo)致的流態(tài)改變而引起的。進(jìn)一步的研究表明,在整個(gè)G／D的區(qū)間內(nèi),雙圓柱周?chē)鲌?chǎng)存在4種截然不同的流態(tài),這是對(duì)以往研究工作的重要補(bǔ)充；在附屬多圓柱群繞流問(wèn)題研究方面：通過(guò)數(shù)值模擬表明,在主圓柱周?chē)鶆虿贾枚鄠�(gè)附屬小圓柱后,能夠在較大的間距比(G／D)范圍內(nèi),有效的減小主圓柱所受的升力和拖曳力。進(jìn)一步的研究表明,主從圓柱的直徑比對(duì)主圓柱的受力影響較小。第三章在任意拉格朗日-歐拉方法的基礎(chǔ)上,建立了粘性流體與結(jié)構(gòu)相互作用的通用計(jì)算流體動(dòng)力學(xué)分析模型,并在前一章的基礎(chǔ)上,對(duì)圓柱群結(jié)構(gòu)的渦激振動(dòng)問(wèn)題進(jìn)行了數(shù)值模擬研究。研究工作表明,在主圓柱周?chē)鶆虿贾枚鄠�(gè)附屬小圓柱能夠有效減小圓柱群渦激振動(dòng)的響應(yīng)幅值及“鎖定”帶寬,并且圓柱群的”鎖定”區(qū)間隨著間距比G／D的增大向低約化速度方向移動(dòng)。第四章建立了波浪作用下,固定海底管道局部沖刷數(shù)值分析模型。該模型通過(guò)動(dòng)網(wǎng)格技術(shù)統(tǒng)一處理波浪自由表面和底床沖刷動(dòng)邊界問(wèn)題,不再將波浪作用簡(jiǎn)化為振蕩流。在水深較淺、波高較大的情況下,波浪自由表面的非線(xiàn)性效應(yīng)顯著,不能忽略。所以建立考慮自由表面效應(yīng)的管道沖刷模型具有更好的通用性。數(shù)值結(jié)果表明,入射波波高和周期均對(duì)管道的局部泥沙沖刷深度有較大的影響作用。進(jìn)一步對(duì)鋪設(shè)在斜坡上的管道局部沖刷問(wèn)題開(kāi)展的數(shù)值研究表明,由于斜坡的存在而導(dǎo)致的波浪自由表面變形,使得斜坡上的海底管道周?chē)木植繘_刷與平底情況下存在顯著不同,管道迎浪側(cè)和背浪側(cè)分別以淤積和沖刷作用為主。這是振蕩流模型不能考慮的。第五章建立了可綜合考慮波浪運(yùn)動(dòng)、管道振動(dòng)、泥沙輸運(yùn)過(guò)程以及底床變形的耦合動(dòng)力數(shù)值分析模型�；诮⒌臄�(shù)值模型重點(diǎn)研究了管道在波浪作用下的振動(dòng)與局部沖刷的耦合作用。數(shù)值模擬結(jié)果表明：當(dāng)約化速度Ur=2.73時(shí),振動(dòng)管道周?chē)淖畲鬀_刷深度是相同條件下固定管道沖刷深度的2倍。當(dāng)約化速度介于2.05Ur3.28的范圍內(nèi)時(shí),沖刷深度、管道受力以及振動(dòng)響應(yīng)相互作用顯著,體現(xiàn)了三者間的相互依賴(lài)關(guān)系。
[Abstract]:Under the action of complex marine hydrodynamic conditions such as wave and water flow, the pipeline is easily scoured under the action of wave and water flow, causing the submarine pipeline to be suspended. Under the alternating fluid force, the vortex shedding vibration will occur in the suspended submarine pipeline and induce fatigue damage. The vibration response of the pipeline will be further interacted with the sediment scour. The pipe suspension and pipe vibration caused by the local scour of sediment will endanger the safety of the pipeline. Once the pipeline is damaged, it will not only cause huge economic losses, but also cause serious environmental pollution. At present, the numerical study on the local scour of the submarine pipeline is mostly limited to the part of the fixed pipe under the action of simple and unidirectional flow. For the wave motion, the numerical analysis of the coupling between the pipeline vibration and the sediment movement has not yet been carried out. A numerical model is set up for the local sediment scour problem under the action of the wave, and the mechanism of the coupling dynamic action between the vortex induced vibration and the local scour is explored. In this paper, a numerical model of coupled dynamic analysis of wave motion, pipeline vibration and sediment transport will be established in this paper. The numerical model is used to study the local sediment scour coupling problem of a vibrating pipe under the action of waves. In the second chapter, the high order upwind based on the Navier-Stokes equation is established. The finite element numerical model is used to study the basic theoretical problem of the flow around a fixed multi cylinder under the low Reynolds number. In the series of double cylindrical flow, it is found for the first time that when the cylinder spacing ratio is G / D=0.9, the lift coefficient and the vortex shedding frequency of the rear cylinder are also mutated, which is mainly due to the flow instability. The further study shows that there are 4 completely different flow patterns in the flow field around a double cylinder in the whole G / D interval, which is an important supplement to the previous research work. After a small cylinder, it can effectively reduce the lift and drag force of the main cylinder at a larger distance than (G / D). Further research shows that the diameter of the main cylinder has less influence on the force of the main cylinder. In the third chapter, the interaction between the viscous fluid and the structure is established on the basis of any Lagrange Euler method. On the basis of the previous chapter, the numerical simulation of vortex induced vibration of cylindrical group structure is studied. It is shown that the response amplitude and "locking" bandwidth of the cylindrical vortex excited vibration can be effectively reduced and the "lock" of the cylinder group is locked. In the fourth chapter, the numerical analysis model of local scour for fixed submarine pipelines under the action of wave is established in the fourth chapter. The model is used to deal with the dynamic boundary problem of wave free surface and bottom bed by dynamic grid technology, and the wave action is no longer simplified as oscillating flow. In the case of shallow and high wave height, the nonlinear effect of the free surface of the wave is remarkable and can not be ignored. Therefore, the establishment of a pipe scour model considering the free surface effect is of better generality. The numerical study on the local scour on the slope shows that the free surface deformation of the waves caused by the existence of the slope makes the local scour around the submarine pipeline on the slope significantly different from that in the flat bottom, which is mainly deposited and scour on the wave side and the back wave side. This is the inability of the oscillating flow model. In the fifth chapter, a numerical model for coupled dynamic analysis of wave motion, pipe vibration, sediment transport and bottom bed deformation is established. Based on the numerical model, the coupling effect of vibration and local scour under the action of waves is studied. The numerical simulation results show that when the reduction rate is Ur=2.73, The maximum scour depth around a vibrating pipe is 2 times as high as the depth of a fixed pipe under the same condition. When the reduction speed is within the range of 2.05Ur3.28, the depth of the scour, the force of the pipe and the vibration response interact significantly, which reflects the interdependence of the three.

【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：P756.2

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