多山地形风场流动数值模拟

Numerical simulation of wind farm flow on multi-hill terrain

随着风能的不断开发,风电场从平坦地形开始转向复杂地形。复杂地形下的风电场内部流动对风电机组的布机具有决定性的影响。本文针对多种典型复杂地形,包括不同高宽比的孤立山丘地形和带不同深度山谷的双山地形,采用三维数值模拟研究了复杂地形下的绕流场分布,分析了流动形成机理和合理的布机位置。模拟结果显示:山丘的高宽比对山丘顶部的加速比和山丘下游速度恢复有很大影响,山丘地形下的布机需要综合考虑山丘高度和山丘下游的速度恢复距离;连续山丘顶部的加速比减弱,且背风面易形成较大的分离流动;连续山丘之间的山谷有利于减弱连续山丘背风面的流动分离,距离较近的双山之间存在相互影响,山顶的加速效比均比孤立山丘的加速比小;双山之间的山谷较浅时,有利于山顶的加速效果的恢复,但山谷较深时,会增加后山下游的速度恢复距离。

With the continuous development of wind power,more and more wind farms are built in complex terrain.The internal flow in complex terrain wind farm has a decisive influence on layout of wind turbines.In this paper,three-dimensional numerical simulation is carried out to study the characters of flow field around a variety of typical complex terrains,including isolated single hill with different height to width ratios and double hills with valleys of different depths,and the flow mechanism and reasonable layout location are analyzed.The simulation results show that,the ratio of height to width has significant influence on the acceleration ratio at the top of the hill and the speed recovery at the downstream of the hill.The height of the hill and the speed recovery distance of the downstream of the hill should be considered simultaneously in the layout of the wind turbine under the hill terrain.The acceleration ratio at the top of the continuous hill is weakened,and large separated flow is easily formed on the suction side surface.The valley between the continuous hills is conducive to weakening the flow separation on the suction side of the continuous hills,and there is interaction between the two nearby hills.The acceleration ratio of the top is smaller than that of the isolated hill.When the valley between the two hills is shallow,it is conducive to the recovery of the acceleration effect of the top of hill.However,when the valley is deep,the speed recovery distance of the downstream of the hill will be increased.