本文選題：導(dǎo)流隧洞　切入點(diǎn)：表孔挑流　出處：《西北農(nóng)林科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：馬嶺水利樞紐工程地形狹窄,下游消能空間有限,水力學(xué)問題較為復(fù)雜。施工導(dǎo)流期,導(dǎo)流洞的安全運(yùn)行影響工程度汛與建筑物施工,進(jìn)口體型對過流水流的流態(tài)有一定影響,流態(tài)變化又直接決定導(dǎo)流洞內(nèi)水力參數(shù)的變化,因此有必要對進(jìn)口體型進(jìn)行研究。樞紐運(yùn)行期,壩身泄水孔大流量泄洪時(shí)容易存在向心集中問題,而消能工體型不同,泄水孔水舌的能量分布與下游的沖刷深度就存在差異。為研究消能工體型對流場的影響,優(yōu)化導(dǎo)流與泄水建筑物布置形式,本文在模型試驗(yàn)的基礎(chǔ)上,利用數(shù)值模擬分別計(jì)算了導(dǎo)流洞與壩身泄水孔在不同體型下的流場分布。首先,利用FLUENT軟件對導(dǎo)流洞流場進(jìn)行數(shù)值模擬,計(jì)算得到的壓力等流場數(shù)據(jù)與模型試驗(yàn)結(jié)果基本吻合。通過其進(jìn)口體型的研究,發(fā)現(xiàn),如果進(jìn)口頂板曲線銜接順暢,就會對減小水流脫壁現(xiàn)象有利,因此,邊界連接處的設(shè)計(jì)應(yīng)盡量滿足相切的原則,以減小拐點(diǎn)的影響;進(jìn)口截面的形狀對水流流態(tài)的影響相對更加顯著,進(jìn)口截面采用矩型斷面后,相比城門洞型斷面,水流脫壁現(xiàn)象減弱,能量損失小,同時(shí)能夠降低門槽位置空化發(fā)生的可能性;綜合不同體型的研究,比較后認(rèn)為,導(dǎo)流洞采用矩型進(jìn)口更有利于導(dǎo)流泄洪。其次,利用FLOW-3D軟件對壩身泄水孔過流流場進(jìn)行數(shù)值模擬,數(shù)值計(jì)算結(jié)果基本能夠反映流場信息。研究發(fā)現(xiàn),溢流式泄水孔大單寬泄洪情況下,窄縫消能工水舌擴(kuò)散能力有限,下泄能量集中,而采用高差動坎消能工后,水舌能夠?qū)崿F(xiàn)縱向拉開和橫向擴(kuò)散,保證下泄水流能量的分散。進(jìn)一步分析高差動坎消能工的消能機(jī)理可得,這一消能工體型下,入水水舌形態(tài)多樣,下游動水墊的作用較強(qiáng),下泄水股能量耗散量大;河床受到的時(shí)均沖擊壓力較小而且分散,脈動(壓強(qiáng)波動)能量的分布也同樣比較分散,頻譜分析發(fā)現(xiàn),其能量大部分集中在低頻區(qū)域�？傊�,高差動坎消能工在大單寬泄洪條件下,消能效果較為顯著,而且聯(lián)合泄洪時(shí)其優(yōu)勢仍能得到較好地發(fā)揮。
[Abstract]:Maling water conservancy project has narrow topography, limited downstream energy dissipation space and complex hydraulic problems. During the construction diversion period, the safe operation of diversion tunnel affects the flood and building construction of the project, and the type of inlet has a certain influence on the flow pattern of the overflowing water flow. The change of flow state directly determines the change of hydraulic parameters in the diversion tunnel, so it is necessary to study the inlet shape. During the period of the hub operation, the problem of concentric concentration is easy to exist in the large discharge flood discharge of the discharge hole of the dam body, but the type of energy dissipator is different from that of the energy dissipator. In order to study the influence of energy dissipation on the flow field of energy dissipator and optimize the layout of diversion and drainage structures, this paper is based on the model test. Numerical simulation is used to calculate the flow field distribution of diversion tunnel and dam drainage hole in different shapes. Firstly, the flow field of diversion tunnel is numerically simulated by FLUENT software. The calculated data of pressure equal flow field are in good agreement with the results of the model test. Through the study of the inlet shape, it is found that if the inlet roof curve is connected smoothly, it will be beneficial to reduce the phenomenon of water flow dewalling. The design of boundary junction should satisfy the principle of tangent as far as possible to reduce the influence of inflexion, the shape of inlet section has more significant influence on the flow state of water. The phenomenon of water flow dewalling is weakened, the energy loss is small, and the possibility of cavitation in the gate groove position can be reduced at the same time. According to the study of different shapes, it is concluded that the rectangular inlet of the diversion tunnel is more favorable for the diversion and flood discharge. The numerical simulation of the flow field in the outlet of dam body is carried out by using FLOW-3D software, and the numerical results can basically reflect the information of the flow field. It is found that the diffusion capacity of the narrow gap energy dissipator is limited under the condition of large single width spillway of overflow discharge hole. When the energy is concentrated, the water tongue can be spread vertically and horizontally, and the energy dissipation mechanism can be obtained by further analyzing the energy dissipation mechanism of the energy dissipator of the high differential sill, and the energy dissipation mechanism can be obtained under this type of energy dissipator, and the mechanism of energy dissipation can be obtained by further analyzing the energy dissipation mechanism of the energy dissipator. The shape of the inlet water tongue is diverse, the action of the downstream dynamic water cushion is stronger, the energy dissipation of the outlet is large, the average impact pressure on the riverbed is small and dispersed, and the energy distribution of the pulsation (pressure fluctuation) is also dispersed. The spectrum analysis shows that, Most of its energy is concentrated in the low frequency region. In a word, under the condition of large single width flood discharge, the energy dissipation effect of high differential bar energy dissipator is more remarkable, and its advantages can still be well brought into play when combined flood discharge.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV551.1;TV65

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