安装高度对水平轴潮流能水轮机尾流特性的影响

Influence of installation height on wake characteristics of horizontal axis tidal energy turbine

为探究水轮机的安装高度对水轮机尾流场的影响,本文以水平轴潮流能水轮机为研究对象,采用计算流体力学(Computational Fluid Dynamics,CFD)方法对水轮机尾流特性进行分析.分别设置水轮机的中心距离海底高度为1.5D、2.0D、2.5D(D为水轮机直径),对水轮机尾流场的轴向、径向上的速度亏损以及涡量结构图进行分析.研究结果表明:安装高度为1.5D时,约在下游轴向位置X/D=15(X为轴向距离)处,梢涡与海底碰撞导致涡结构发生破损,这也使得该工况在下游X/D=15后的速度亏损明显大于安装高度2.0D和2.5D,而安装高度为2.0D和2.5D工况的速度变化基本一致.同时从3种工况不同轴向位置速度亏损图可以看出,从下游X/D=10开始,最大亏损速度均出现在中心轴线的位置.因此在考虑到对下游流场的影响和安装的成本时,建议安装高度为2.0D.

In order to explore the influence of the installation height on the wake field of the turbine,this paper takes the horizontal axis tidal energy turbine as the research object,and employs the Computational Fluid Dynamics(CFD)method to analyze the wake characteristics of the turbine.The height of the center of the turbine from the seafloor was set as 1.5D,2.0D and 2.5D respectively,where D is the diameter of the water turbine;and the velocity deficit and vorticity structure chart of the turbine wake field in the axial and radial directions were analyzed.The research results show that when the installation height is 1.5D,the collision between the tip vortex and the seafloor leads to the damage of the vortex structure at the downstream axial position X/D=15,where X is the axial distance.It also makes the velocity loss after X/D=15 downstream being significantly larger than that of the installation height of 2.0D and 2.5D.The velocity changes of the installation height of 2.0D and 2.5D are basically the same as those of the installation height of 1.5D.It can be seen from the velocity deficit diagrams of different axial positions under the three working conditions that the maximum velocity deficit occurs at the central axis starting from the downstream X/D=10.Considering the impact on the downstream flow field and the cost of installation,the installation height is recommended to be 2.0D.