發(fā)布時間：2019-03-20 18:06

【摘要】：臺階溢洪道是集泄流和消能設施于一體的消能工，消能效果良好且工程造價低。隨著碾壓混凝土技術的發(fā)展，臺階溢洪道得到廣泛應用，因此，對臺階溢洪道水力特性的研究具有重要的實際意義。對臺階溢洪道水力特性的研究，通常借助物理模型試驗和數(shù)值模擬方法。近些年來，隨著計算機性能的不斷提升和計算流體力學的快速發(fā)展，使得數(shù)值模擬技術已成為研究臺階溢洪道水力特性的重要手段。本文主要通過數(shù)值模擬方法對臺階溢洪道的水力特性進行了研究，主要研究成果如下： 在CAD中建立三維模型，導入ICEM中劃分非結構網(wǎng)格，利用FLUENT軟件，選用k－ε兩方程紊流模型和VOF方法，對小灣河臺階溢洪道按定常流進行了三維數(shù)值模擬，將數(shù)值模擬結果與模型試驗結果對比發(fā)現(xiàn)，兩者吻合良好。 小灣河臺階溢洪道上的水流為滑行水流。臺階上產(chǎn)生順時針漩渦，水流速度由漩渦中心的零向四周逐漸增大。臺階上紊動耗散率和紊動能的分布規(guī)律基本一致，以臺階凹角處為中心，，向四周逐漸變大，但前者在凸角上達到最大，后者在臺階凸角兩側最大。臺階豎直面的上部均存在負壓區(qū)，隨著臺階的下移，負壓區(qū)的范圍越來越小。臺階底部壓力最大，沿著豎直面向上，壓力逐漸減小至負壓，然后又增大。臺階水平面上基本為正壓，但在臺階凸角處可能會出現(xiàn)較小的負壓。從臺階凹角處沿著水平面，壓力分布規(guī)律為：先減小，后增大，達到最大值后急劇減小，甚至出現(xiàn)負壓。并在首部臺階通過摻氣的方式來緩解臺階上負壓的產(chǎn)生。
[Abstract]:Step spillway is a kind of energy dissipator with discharge and energy dissipation facilities, which has good energy dissipation effect and low engineering cost. With the development of roller compacted concrete (RCC) technology, stepped spillway has been widely used. Therefore, the study on hydraulic characteristics of stepped spillway is of great practical significance. The hydraulic characteristics of step spillway are usually studied by physical model test and numerical simulation. In recent years, with the continuous improvement of computer performance and the rapid development of computational fluid dynamics, numerical simulation technology has become an important means to study the hydraulic characteristics of stepped spillway. In this paper, the hydraulic characteristics of step spillway are studied by numerical simulation method. The main results are as follows: three-dimensional model is built in CAD, unstructured grid is introduced into ICEM, and FLUENT software is used. The k-蔚 two-equation turbulence model and VOF method are used to simulate the steady flow in the stepped spillway of Xiaowanhe River. The comparison between the numerical simulation results and the model test results shows that the two models are in good agreement with each other. The stream on the stepped spillway of Xiaowan River is a sliding flow. A clockwise vortex is generated on the steps, and the velocity of the flow increases gradually from zero in the center of the vortex. The distribution law of turbulent dissipation rate and turbulent energy on the step is basically the same. At the center of the step concave angle, the turbulent dissipation rate increases gradually, but the former reaches the maximum on the convex angle, while the latter reaches the maximum on the two sides of the convex angle of the step. There is a negative pressure zone in the upper part of the vertical face of the steps, and the range of the negative pressure zone becomes smaller and smaller with the downward movement of the steps. The pressure at the bottom of the step decreases gradually to negative pressure and then increases. The horizontal level of the step is basically positive, but there may be a small negative pressure at the convex angle of the step. From the angle of the step along the horizontal plane, the pressure distribution law is as follows: first decrease, then increase, reach the maximum value, then sharply decrease, and even appear negative pressure. And in the first step through aeration to alleviate the negative pressure on the step.
【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TV651.1;TV135.2

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