博斯腾湖东南侧近地层垂直风切变指数特征研究

Research on the Characteristics of Vertical Wind Shear Exponent in the Near Surface Layer of Southeastern Bosten Lake

摘要:

风切变指数对风机选型、轮毂高度选择等有显著影响，为探明巴州北部风切变指数特征，利用博斯腾湖东南侧2017年1月至2024年12月连续96个月的长序列、高时间分辨率测风塔观测资料，计算各层平均风速、风速离差系数、风切变指数，分析风切变指数时空特征及其与风速的关系。结果表明：（1）随高度增加，整层风切变指数以70 m高度为分割点呈分段式减小趋势。70～80 m高度风速差异最大，风速切变明显，稳定性较差。（2）春季至秋季风切变指数随高度增加分段降低，冬季10～70 m高度变化不明显，70～100 m高度差异较大。各层风切变指数日变化呈“双峰型”分布，风切变指数与风速日变化特征呈反位相关系。（3）35～70 m高度区间风速大于8 m·s-1时存在风速逆变区。70～100 m高度区间风切变指数以10 m·s-1风速为对称轴呈倒V型分布。（4）各风速段平均值和标准差基本表现为全风速段最大，≥3 m·s-1启动风速段次之，≥17.2 m·s-1大风风速段最小，随着风速增加，风场稳定性越高，风切变指数越小。

Abstract:

The wind shear exponent has a significant impact on the selection of wind turbines, hub height, and other factors. To investigate the characteristics of the wind shear exponent in northern Bazhou, according to 96 months of continuous, high time-resolution observational data from southeastern Bosten Lake wind measurement tower from January 2017 to December 2024, the average wind speed, wind speed deviation coefficient, and wind shear exponent at different heights were calculated, and the spatiotemporal distribution characteristics of the wind shear exponent, as well as the relationship between wind shear exponent and wind speed were analyzed. The study revealed that: (1) As the height increases, the overall wind shear exponent shows a segmented decreasing trend with a breakpoint at 70 m. The wind speed difference is greatest at heights of 70 to 80 m, with significant wind speed shear and relatively poor stability. (2) From spring to autumn, the wind shear exponent decreases in segments with increasing height. In winter, minimal variation is observed in the height range of 10 to 70 m, while significant differences emerge in the height range of 70 to 100 m. The diurnal variation of the wind shear exponent at all heights presents a 'bimodal' distribution characteristic, and the diurnal variation characteristic of the wind shear exponent shows a inverse correlation with the diurnal variation of wind speed. (3) There is a wind speed inversion zone in the height range of 35 to 70 m when the wind speed exceeds 8 m·s-1. In the height range of 70 to 100 m, the wind shear exponent shows an inverted V-shaped distribution with a wind speed of 10 m·s-1 as the axis of symmetry. (4) The averages and standard deviations of the wind speed bins generally show that the entire wind speed segment is the largest, followed by the ≥3 m·s-1 startup wind speed segment, and the ≥17.2 m·s-1 strong wind speed segment is the smallest. Wind field stability increases with rising wind speeds, concomitantly resulting in a reduction of the wind shear exponent.