上海近海海域低层风特性分析

基于南汇和奉贤两个海上测风塔观测资料,采用数值统计分析方法,研究了上海近海海域低层风特征,包括风切变指数特征、风的阵性特征和湍流强度特征。结果表明,上海近海10~70 m高度风切变指数在0.09左右,阵风系数在1.20左右,均小于《建筑结构荷载规范》的推荐值。随着风速的增大,风切变指数和阵风系数均呈减小的变化。当风力等级在4级及以上时,切变指数可靠性较好,阵风系数变化较小,湍流强度基本相等。上海近海阵风系数和湍流强度均随着高度的增加而减小,在40 m以上时都趋于稳定。研究结果可为上海近海风资源评价、重大工程规划设计和施工建设以及区域防灾减灾实践提供科学依据和参考。

CHARACTERISTICS OF LOW-LEVEL WIND IN SHANGHAI OFFSHORE

The development and utilization of wind energy resources is one of the important measures of energy development strategy and power structure adjustment in China. Compared with onshore wind, offshore wind farm has many advantages, such as saving land resources, higher wind speed, higher utilization rate of wind power, and no more complex terrain to affect air flow, which makes it become the forefront of wind power technology development and industry competition in China. However, many scholars have focused on the analysis of onshore wind energy resources, and there is few studies regarding to the offshore wind resources due to a relative lack of observation data. Based on the observation data from two anemometer towers in the coastal waters of Nanhui and Fengxian, the characteristics of low-level wind, including wind shear exponent, gustiness factor and turbulence intensity in Shanghai offshore, were analyzed with numerical statistical methods. The results indicate that wind shear exponent from 10 m to 70 m is about 0.09, and gustiness factor from 10 m to 70 m is about 1.20 in Shanghai offshore. Both wind shear exponent and gustiness factor are less than the recommended values of Load Code for the Design of Building Structures. With the increase of wind speed, both wind shear exponent and gustiness factor have decreasing trends. When the wind scale is in grade 4 or above, the wind shear exponent has a good reliability, the gustiness factor changes small and the turbulence intensity remains basically unchanged. Offshore gustiness factor and turbulence intensity decrease with the increase of height, and they are stable in the heights from 40 m to 70 m. The findings from this paper can provide scientific basis and reference for wind resource assessment, major engineering design and construction over Shanghai offshore as well as the regional disaster prevention and mitigation practice.