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.