峡道潮流能提取远场水动力影响数值分析

Numerical simulation of far-field hydro-dynamic impact of tidal current energy extraction in a strait channel.

以群岛海域典型峡道——龟山水道为例,在验证良好的平面二维潮流数学模型的基础上,采用等效阻力法概化发电机组的近区影响,对不同潮流能提取功率系数条件下的区域远场潮流进行了模拟计算.从水位、流速时空变化及平均潮流能功率密度变化等方面分析了峡道潮流能提取对周围海域远场水动力的影响.模拟计算显示,发电机功率系数取0.5时影响比0.3时大,但影响基本局限在5km范围内;2种情况下,周围海域水位的变化都在5cm以内;潮周期内,急流时刻流速影响最大;机群内部及上下游流速都减小,而机群两侧及邻近水道流速会增大;平均功率密度的减小沿机群周围分布,且偏向于优势流方向,同时机群两侧和邻近水道平均功率密度会增大.

Based on a well-verified 2D mathematical model for tidal current, the tidal current fields with two different power extraction schemes are simulated, where the presence of tidal current turbines is included as an additional bed friction source term. Guishan Channel, which is in a sea with many islands, is taken as a typical area where tidal current energy is extracted. The changes of water level, current velocity and mean tidal current power density are analyzed to study the far-field hydro-dynamic impact of tidal current energy extraction. The simulated results illus- trate that the first scheme with a power coefficient 0.3 is found to have lower impact on original flow than the second scheme （the power coefficient equals 0.5）. In both schemes, the changes of water levels are less than 5cm. The ve- locities reduce inside the array, and both upstream and downstream of the array, but increase along the sides of the array and in the neighboring channels. The impacts of mean tidal current power density are distributed inside and a- round the arrays, especially tending to the direction of the preferential flow.