本文關(guān)鍵詞： 管道沖刷 三維流場 漩渦 沖刷深度 模型試驗　出處：《沈陽農(nóng)業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著運輸行業(yè)的不斷發(fā)展,管道運輸在輸水、輸氣、輸油、供電等方面給人們生活帶來了極大的便利。然而,近年來水下管道破壞問題并沒有得到很好解決。管道一旦損壞不僅會給帶來經(jīng)濟損失,還會人們的生活帶來不便,甚至引起一系列環(huán)境污染問題。目前國內(nèi)外有關(guān)于管道沖刷方面的研究不是很多,而直接能應(yīng)用于實踐的研究成果更稀少,故亟需加快對穿河管道沖刷方面的研究。本研究的主要目的是通過物理模型試驗的方法了解管道周圍流場特性及沖刷特點,為管道穿越工程設(shè)計提供科學(xué)依據(jù)。同時,通過本次研究也可以豐富管道與河流的沖刷機理,促進(jìn)泥沙運動理論的進(jìn)一步發(fā)展。本次研究采用定床模型試驗和動床模型試驗相結(jié)合的方法,利用超聲多普勒流速儀測量管道周圍三維流速,研究管道模型周圍流場及沖刷規(guī)律。本次試驗共設(shè)置12組工況條件,其中動床模型試驗和定床模型試驗各6組。通過對定床模型試驗和動床模型試驗結(jié)果的對比分析,可以總結(jié)出以下規(guī)律:(1)橫管在不同工況下尾跡漩渦寬度基本保持在1.2～1.5倍直徑范圍內(nèi),并在大漩渦的產(chǎn)生過程中伴有小漩渦不斷形成、消失的現(xiàn)象;而立管尾跡漩渦隨傅汝德數(shù)增大而變窄,當(dāng)傅汝德數(shù)在0.104～0.393之間時,尾跡漩渦寬度在1.2～2.0倍直徑范圍內(nèi)。(2)水流在流經(jīng)管道模型前縱向流速減小而垂向流速增大,橫管最大流速在中層管后位置,而立管最大流速出現(xiàn)在管道兩側(cè)。管道模型周圍紊動強度和雷諾應(yīng)力都隨流速的增大而增大,立管在各工況下底層、中層、表層流速、紊動強度和雷諾應(yīng)力分布規(guī)律基本一致,而橫管中層紊動強度和雷諾應(yīng)力最大,流速變化最大。(3)從水平推力、動水浮力和凈水平推力隨流速變化規(guī)律的曲線圖可以看出凈水平推力增長的最快,而動水浮力增長的最慢。(4)當(dāng)管前水流流速小于模型沙起動流速時,管道基本不會產(chǎn)生局部沖刷。當(dāng)管前水流流速大于模型沙起動流速時,半埋狀態(tài)下最先發(fā)生沖刷的位置是橫管前約0.5倍直徑處,而立管兩側(cè)位置最先發(fā)生沖刷。(5)在同一來流條件下,橫管的局部沖刷深度要大于立管,這是由于橫管周圍紊動強度大于立管。橫管半埋在模型沙中時,流速越大,管道從半埋至完全裸露歷時越短。立管沖刷過程前期沖刷速度比較快,當(dāng)局部沖刷停止時達(dá)到最大沖刷深度。(6)從沖刷坑平面形態(tài)看,立管周圍沖刷坑的范圍隨流速的增大而增大;而橫管沖刷坑范圍基本不變,在順?biāo)鞣较蛏蠈挾燃s為三倍管徑大小。
[Abstract]:With the continuous development of transportation industry, pipeline transportation in water, gas, oil, power supply and other aspects of people's lives has brought great convenience. In recent years, the problem of underwater pipeline damage has not been solved very well. Once the pipeline is damaged, it will not only bring economic loss, but also bring inconvenience to people's life. Even cause a series of environmental pollution problems. At present, there are not a lot of research on pipeline erosion at home and abroad, and the research results that can be directly applied in practice are more rare. The main purpose of this study is to understand the characteristics of the flow field and scour around the pipeline by physical model test. It provides scientific basis for pipeline crossing engineering design. At the same time, through this study, it can enrich the erosion mechanism of pipeline and river. To promote the further development of the theory of sediment movement. In this study, the method of fixed bed model test and moving bed model test was used to measure the three-dimensional velocity around the pipeline by ultrasonic Doppler velocimeter. The flow field and scour law around the pipeline model were studied. Twelve working conditions were set up in this experiment. There were 6 groups of moving bed model test and fixed bed model test respectively. The results of fixed bed model test and moving bed model test were compared and analyzed. It can be concluded that the following rule: 1: 1) the wake vortex width of the transverse tube under different working conditions is basically kept in the range of 1.5 times the diameter of the wake, and in the process of the formation of the maelstrom, the small swirl is formed continuously. The phenomenon of disappearance; The wake vortex of the riser becomes narrow with the increase of the Fourier number, when the Fourier number is between 0.104 and 0.393. The wake vortex width is within the range of 1.2 ~ 2.0 times diameter.) the longitudinal velocity decreases while the vertical velocity increases before the flow through the pipe model, and the maximum velocity of the transverse tube is located behind the middle tube. The maximum flow velocity of the riser appears on both sides of the pipeline. The turbulence intensity and Reynolds stress around the pipe model increase with the increase of the velocity. The turbulent intensity and Reynolds stress distribution are basically the same, while the turbulent intensity and Reynolds stress in the middle layer of the transverse tube are the largest, and the velocity variation is the largest. The curve of dynamic water buoyancy and net horizontal thrust with the change of velocity can be seen that the net horizontal thrust increases fastest, but the slowest of dynamic water buoyancy increase. 4) when the flow velocity in front of the pipe is less than that of the model sand starting velocity. When the flow velocity in front of the pipe is larger than the starting velocity of the model sand, the first scour in the semi-buried state is about 0.5 times the diameter of the transverse pipe. Under the same flow condition, the local scour depth of the horizontal tube is greater than that of the riser, which is because the turbulence intensity around the horizontal tube is greater than that of the riser, and the transverse tube is half buried in the model sand. The higher the velocity of flow, the shorter the duration of pipeline from half-buried to completely exposed. The earlier scour speed of riser scour process is faster, when the local scour stops, the maximum scour depth is reached. 6) from the plane shape of scour pit. The range of the scour pit around the riser increases with the increase of velocity. However, the range of the horizontal pipe scour pit is almost unchanged, and the width is about three times the diameter of the pipe in the direction of the water flow.
【學(xué)位授予單位】：沈陽農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：U171

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