低含沙水流水平轴潮流能水轮机水动力特性研究

发布时间：2018-03-23 01:28

本文选题：低含沙水流　切入点：水动力特性　出处：《浙江海洋学院》2015年硕士论文　论文类型：学位论文

【摘要】：我国潮流能储量约占全球的14%,浙江舟山群岛海域受水道的束流作用,潮流平均流速达到2~3 m/s。并且该海域水道利用岛屿的保护,海况平稳,易于开发。开发利用潮流能的关键技术是潮流动能的获取,最常用的设备是水轮机。水文资料表明,舟山海域平均含沙量约0.187~0.551g/L。流经水轮机的来流携带泥沙时,泥沙颗粒受水轮机旋转的影响,必然反作用于紊流脉动。尤其在流速和转速较高的情况下,水轮机盘面附近及近尾流区处于湍流状态,颗粒的旋转将会加剧流场的脉动,形成许多漩涡,是消耗压能的根源,能量的损失导致水轮机输出功率下降,水力效率也下降。本文首先研究了亚临界雷诺数下的圆柱绕流和方柱绕流,探究低含沙水流对水中结构物的水动力特性的影响。低含沙水流的主体是悬移质,通过研究圆柱和方柱的受力探索悬移质对水流粘性系数的作用机制,通过分析柱体尾流区漩涡脱落规律和流场分析探求悬移质对水流紊动扩散的影响。并且,通过模型试验验证CFD方法的可靠性。继而查阅水轮机设计的方法,计算水轮机叶片参数,通过翼型设计软件Profili,分析翼型动力特性,选用高升阻比的NA63A614,确定各叶素的攻角,MATLAB编程计算叶片参数,对安装角和弦长重新优化。经MATLAB计算的三维坐标导入三维建模软件Solid Works,得到叶片的三维实体。基于低含沙水流对圆柱和方柱绕流的作用机理的初步认识,对水平轴潮流能水轮机在低含沙水流中的表现展开探索。在二维绕流研究的基础上,利用CFD对潮流能水轮机在清水和浑水的表现进行对比分析。着重分析水轮机清水和含沙流场的静压、流线、叶尖涡、涡量强度等水动力参数,初步揭示了水轮机在低含沙水流下的特性。沙粒自进入流场即影响流场静压,尤其是叶片表面和近尾流区。沙粒的旋转影响涡量强度,破坏叶尖涡的形状。颗粒对水轮机水动力参数有显著的影响,含沙浓度高,流体粘性增强,轴向推力增大;含沙浓度高,颗粒的旋转和碰撞也更加剧烈,消耗压能,水轮机的输出功率低,某含沙量8%海况的水轮机功率比无沙海况降幅可达20%。低含沙水流对流速的影响体现在远尾流区,含沙浓度高流速在远尾流区的稳定值也略大。
[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.
【学位授予单位】：浙江海洋学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV136.1

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