本文選題：低含沙水流　切入點：水動力特性　出處：《浙江海洋學院》2015年碩士論文　論文類型：學位論文

【摘要】：我國潮流能儲量約占全球的14%,浙江舟山群島海域受水道的束流作用,潮流平均流速達到2~3 m/s。并且該海域水道利用島嶼的保護,海況平穩(wěn),易于開發(fā)。開發(fā)利用潮流能的關鍵技術(shù)是潮流動能的獲取,最常用的設備是水輪機。水文資料表明,舟山海域平均含沙量約0.187~0.551g/L。流經(jīng)水輪機的來流攜帶泥沙時,泥沙顆粒受水輪機旋轉(zhuǎn)的影響,必然反作用于紊流脈動。尤其在流速和轉(zhuǎn)速較高的情況下,水輪機盤面附近及近尾流區(qū)處于湍流狀態(tài),顆粒的旋轉(zhuǎn)將會加劇流場的脈動,形成許多漩渦,是消耗壓能的根源,能量的損失導致水輪機輸出功率下降,水力效率也下降。本文首先研究了亞臨界雷諾數(shù)下的圓柱繞流和方柱繞流,探究低含沙水流對水中結(jié)構(gòu)物的水動力特性的影響。低含沙水流的主體是懸移質(zhì),通過研究圓柱和方柱的受力探索懸移質(zhì)對水流粘性系數(shù)的作用機制,通過分析柱體尾流區(qū)漩渦脫落規(guī)律和流場分析探求懸移質(zhì)對水流紊動擴散的影響。并且,通過模型試驗驗證CFD方法的可靠性。繼而查閱水輪機設計的方法,計算水輪機葉片參數(shù),通過翼型設計軟件Profili,分析翼型動力特性,選用高升阻比的NA63A614,確定各葉素的攻角,MATLAB編程計算葉片參數(shù),對安裝角和弦長重新優(yōu)化。經(jīng)MATLAB計算的三維坐標導入三維建模軟件Solid Works,得到葉片的三維實體。基于低含沙水流對圓柱和方柱繞流的作用機理的初步認識,對水平軸潮流能水輪機在低含沙水流中的表現(xiàn)展開探索。在二維繞流研究的基礎上,利用CFD對潮流能水輪機在清水和渾水的表現(xiàn)進行對比分析。著重分析水輪機清水和含沙流場的靜壓、流線、葉尖渦、渦量強度等水動力參數(shù),初步揭示了水輪機在低含沙水流下的特性。沙粒自進入流場即影響流場靜壓,尤其是葉片表面和近尾流區(qū)。沙粒的旋轉(zhuǎn)影響渦量強度,破壞葉尖渦的形狀。顆粒對水輪機水動力參數(shù)有顯著的影響,含沙濃度高,流體粘性增強,軸向推力增大;含沙濃度高,顆粒的旋轉(zhuǎn)和碰撞也更加劇烈,消耗壓能,水輪機的輸出功率低,某含沙量8%海況的水輪機功率比無沙海況降幅可達20%。低含沙水流對流速的影響體現(xiàn)在遠尾流區(qū),含沙濃度高流速在遠尾流區(qū)的穩(wěn)定值也略大。
[Abstract]:China's tidal energy reserves account for about 14 percent of the world's total. The Zhoushan Islands in Zhejiang Province are subjected to the beam action of the waterway, and the average tidal current velocity is up to 2m3 m / s. Moreover, the waterway uses the protection of the islands and the sea conditions are stable. The key technology for developing and utilizing tidal current energy is the acquisition of tidal current kinetic energy, and the most commonly used equipment is hydraulic turbine. Hydrological data show that the average sediment content in Zhoushan sea area is about 0.187 ~ 0.551g / L. Under the influence of turbine rotation, sediment particles are bound to react to turbulence pulsation, especially in the case of high velocity and rotating speed, the turbulence is near the disk surface and near wake area of the turbine, and the particle rotation will aggravate the pulsation of the flow field. The formation of many whirlpools is the root of pressure energy consumption. The loss of energy leads to the decrease of turbine output power and hydraulic efficiency. In this paper, the flow around a cylinder and a square cylinder at subcritical Reynolds number is studied firstly. The influence of low sediment flow on the hydrodynamic characteristics of water structure is studied. The main body of low sediment flow is suspended mass, and the mechanism of action of suspended mass on viscous coefficient of water flow is explored by studying the force of cylinder and square column. By analyzing the vortex shedding law in the wake region of cylinder and the flow field analysis, the influence of suspended mass on the turbulent diffusion of water flow is investigated. The reliability of CFD method is verified by model test, and then the design method of hydraulic turbine is consulted. The blade parameters of hydraulic turbine are calculated, and the dynamic characteristics of the airfoil are analyzed by the airfoil design software profili. the blade parameters are calculated by MATLAB with the help of NA63A614, which has a high lift-to-drag ratio, and the angle of attack of each blade element is determined by MATLAB. The installation angle and chord length are reoptimized. The 3D coordinates calculated by MATLAB are imported into the 3D modeling software Solid works, and the 3D entity of the blade is obtained. Based on the preliminary understanding of the mechanism of the low sediment flow acting on the flow around the cylinder and the square column, The performance of horizontal axis tidal current turbine in low sediment flow is explored. The performance of tidal current turbine in clear water and muddy water is analyzed by CFD. The hydrodynamic parameters such as hydrostatic pressure, streamline, tip vortex and vorticity intensity of turbine are analyzed, such as hydrostatic pressure, flow line, blade tip vortex and vorticity intensity. The characteristics of turbine in low sediment flow are preliminarily revealed. Sand particles from entering the flow field affect the static pressure of the flow field, especially the blade surface and near wake zone. The rotation of sand particles affects the vorticity intensity. The shape of blade tip vortex is destroyed. Particles have a significant effect on hydrodynamic parameters of hydraulic turbine, with high sediment concentration, enhanced fluid viscosity and increased axial thrust, higher sediment concentration, more violent particle rotation and collision, and higher pressure energy consumption. The output power of the turbine is low, and the power of the turbine with 8% sediment content can be reduced by 20. The influence of the low sediment flow on the velocity is reflected in the far wake zone, and the stable value of the high velocity of the sediment concentration in the far wake is also slightly larger.
【學位授予單位】：浙江海洋學院
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TV136.1

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