地貌因素对垭口内风速影响的数值模拟

Numerical simulation of effects of topographic factors on wind speed in col

为了研究地貌因素对垭口内平均风速的影响,在轴对称山丘模型的基础上引入山脉长度这一重要因素.通过风洞试验手段验证数值模拟结果的有效性,选取最不利风向即正对垭口方向进行风场数值模拟.并研究了山顶距离和山脉坡度对加速效应的影响.结果表明,山脉长度对垭口内风加速比和加速区域大小均有显著的影响.当山脉长度介于1～3倍山高时,垭口内风加速效应明显且加速区域也较长;当山脉长度超过6倍山高时垭口内加速比和加速区域大小基本趋于定值;山顶间距越小风加速效应越大,但当间距小于2/3的山脉底部直径时,加速幅度降低;距山体表面50m空间内山脉坡度越大,垭口内风加速效应越明显;综合研究结果,给出最不利的垭口地貌因素组合.

The length of mountains that was considered as a significant factor was introduced in the axisymmetric hill models to investigate the effects of topographic factors on wind speed in col.Wind tunnel test was conducted to verify the validity of the numerical simulation results,then the most unfavorable incoming winds direction that was rightly against the col was selected to carry out the numerical simulation.The effects of distance between two peaks and gradient of the mountain slope were also investigated.Results indicate that the length of mountain range has a significant impact on speed-up ratio and acceleration region in the col.When the length of a mountain range is about 1to 3times the height of the mountain range,the wind acceleration effect is obvious and acceleration region in the col has its maximum range.The speed-up ratio and size of acceleration region gradually reach a constant value as the length of mountains enlarges to6 times the mountain height.The smaller the distance between the two peaks is,the higher the speed in col will be,but the wind acceleration amplitude decreases when the distance between two peaks is less than two thirds of the bottom diameter of a mountain.Wind acceleration tends to grow stronger with the increasing gradient of the mountain slope in the space up to 50 mabove the surface of the mountain range.To sum up,a combination of topographic factors which are the most unfavorable is provided based on the results of the research.