非恒定流作用下丁壩水沙運動及水毀特征數(shù)值模擬
本文選題:非恒定流條件 切入點:丁壩沖刷模型 出處:《重慶交通大學》2014年碩士論文
【摘要】:丁壩是山區(qū)河流最常用的航道整治建筑物,由于山區(qū)河流坡陡流急,水位變化較大,水毀現(xiàn)象嚴重,開展非恒定流條件下丁壩水毀及水沙運動仿真模擬,對于提高山區(qū)河流航道整治工程規(guī)劃、設計和管理水平具有重大的理論意義和實用價值。論文重點研究了非恒定流條件下丁壩水沙運動及水毀特征的平面二維數(shù)值模擬方法,通過對比分析模擬計算結果,總結出非恒定流條件下丁壩特定的水沙運動規(guī)律,并與實際情況對比驗證,保證了數(shù)值模擬研究方法的科學有效合理性。 論文以泥沙運動力學、計算流體動力學等學科理論為根基,在對丁壩水毀特征進行實地考察和理論分析的基礎上,結合物理模型試驗成果,采用具有水、沙模擬計算功能的MIKE21軟件來對非恒定流作用下的丁壩水動力和動床模型進行平面二維數(shù)值模擬仿真,探索了非恒定流條件下丁壩水流結構、泥沙沖淤的模擬方法,并取得以下研究結論: 1、在有限體積法的基礎上,以三角形非結構網(wǎng)格為單元離散劃分的平面二維淺水方程與河床變形方程模型在計算非恒定流條件下的丁壩水沙運動時穩(wěn)定可靠,該研究方法能夠為相應物理模型實驗和理論分析提供支撐。 2、試驗證明與MIKE軟件傳統(tǒng)的剖分計算方法相比,用SMS軟件可以對模型網(wǎng)格進行優(yōu)化,使網(wǎng)格剖分質(zhì)量更好,模型計算更穩(wěn)定;以特定文件為接口使SMS與MIKE相結合的模擬方法可行有效,,比傳統(tǒng)MIKE模擬方法可以更好的模擬出水槽丁壩地形及其水沙運動特性。 3、非恒定流條件下的丁壩水流運動有其特殊規(guī)律:全流場范圍內(nèi)大流速主要集中在壩頂和丁壩下游主流區(qū)兩處位置;壩前流速沿壩軸方向從0開始逐漸增大,在壩長范圍內(nèi)近似線性分布;丁壩附近水流動力軸線上流速呈現(xiàn)先增大后減小的變化規(guī)律,最大值位于距離丁壩一定范圍內(nèi)的下游;壩后回流區(qū)的產(chǎn)生位置恰好與丁壩下游大流速范圍橫向?qū)?4、在非恒定流作用下,丁壩下游流場與水位呈現(xiàn)特殊關系,大流速的位置水位較高,回流區(qū)流速小反而水位較低,最低點在回流的漩渦中心。 5、非恒定來流對丁壩模型造成的沖刷主要包括:沖刷坑、淤積沙壟、壩頭沖刷、壩身塌陷和壩后沖刷5個特點。大洪峰流量造成的河床變形是發(fā)生丁壩水毀的重要成因。
[Abstract]:The spur dike is the most commonly used waterway regulation building in mountainous rivers. Due to the steep flow of mountain rivers, the change of water level is large and the phenomenon of water destruction is serious, the simulation simulation of the water damage and the movement of water and sediment under the condition of unsteady flow is carried out. It is of great theoretical significance and practical value to improve the planning, design and management level of river channel regulation engineering in mountainous areas. This paper focuses on the planar two-dimensional numerical simulation method for the characteristics of water and sediment movement and water destruction of spur dams under the condition of unsteady flow. By comparing and analyzing the simulation results, the specific water and sediment movement laws of groin under unsteady flow conditions are summarized, and compared with the actual conditions, the scientific and effective rationality of the numerical simulation research method is guaranteed. Based on the theories of sediment movement mechanics, computational fluid dynamics and so on, on the basis of field investigation and theoretical analysis of the characteristics of water destruction of spur dikes, combined with the results of physical model tests, the paper adopts water. The MIKE21 software of sand simulation function is used to simulate the hydrodynamic force and moving bed model of spur dike under unsteady flow, and the simulation method of water structure and sediment scour and deposition under unsteady flow is explored. The following conclusions are obtained:. 1. On the basis of the finite volume method, the plane two-dimensional shallow water equation and the riverbed deformation equation model, which are discretized by triangular unstructured meshes, are stable and reliable in the calculation of the hydro-sediment movement of the groin under the condition of unsteady flow. The research method can provide support for the corresponding physical model experiments and theoretical analysis. 2. Compared with the traditional method of MIKE software, the model mesh can be optimized by using SMS software, so that the mesh generation quality is better and the model calculation is more stable. It is feasible and effective to combine SMS and MIKE with special file interface. Compared with the traditional MIKE simulation method, it can better simulate the groin topography and the characteristics of water and sediment movement. 3. Under the condition of unsteady flow, the flow movement of spur dike has its special law: in the whole flow field, the large velocity is mainly concentrated at the top of the dam and the downstream of the dike, and the velocity in front of the dam increases gradually along the direction of the axis of the dam. The velocity in the hydrodynamic axis near the spur dike increases first and then decreases, and the maximum value is located downstream from the dike in a certain range. The location of the backflow zone is exactly corresponding to the large velocity range of the lower reaches of the spur dike. 4. Under the action of unsteady flow, the downstream flow field of the spur dike has a special relationship with the water level. The position of the large velocity of velocity is higher, but the water level of the backflow zone is lower, and the lowest point is in the center of the swirl of the return current. 5. The erosion caused by unsteady flow mainly includes: scour pit, silt ridge, dam head scour, dam body collapse and dam back scour. The river bed deformation caused by great Hong Feng discharge is the important cause of dike water destruction.
【學位授予單位】:重慶交通大學
【學位級別】:碩士
【學位授予年份】:2014
【分類號】:U617.91;U612.23
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