我国不同下垫面的近地层风切变指数研究

利用国家气候中心2009-2011年在内蒙古锡林浩特市、河北黄骅市、江西湖口县和星子县开展的100 m铁塔大气湍流观测试验数据,分析不同下垫面、不同稳定度条件下地面到100 m的风切变指数变化情况,得到了一些有意义的结论:(1)内陆简单地形整体风切变指数α0.3的情况出现在稳定和非常稳定层结状态下,分层风切变指数α0.4的频率为2.95%;(2)沿海平坦地形大气层结越稳定,整体风切变指数α的高值出现频率越高,分层风切变指数α0.4的频率略高,为4.2%;(3)对于内陆湖复杂地形,星子地形更为复杂,大于0.3的整体风切变指数出现频率高,分层风切变指数α0.4的频率高达10%,而湖口大于0.3的整体风切变指数值出现频率略低,分层风切变指数α0.4的频率为3.37%。(4)按照风力发电机组设计要求中假设风切变指数α为0.2,一般会过高的估计轮毂高度的风速。

Study of Near Surface Wind Shear Exponents of Different Regions in China

Using the 100 m tower atmospheric turbulence observation data offered by National Climate Centre, wind shear exponents in different underlying surfaces and different atmospheric stabilities are analyzed. The experiments were carried out in Xilinhot City in Inner Mongolia, Huanghua City in Hebei, Hukou County and Xingzi County in Jiangxi during 2009-2011. The results show that (1) in inland simple terrain, the overall wind shear exponent >0.3 appears only in stable and very stable stratification, and the frequency of stratified shear exponent >0.4 is 2.95%. (2) In the coastal flat terrain, atmospheric stratification is more stable, the overall wind shear exponent has higher value, and the frequency of stratified shear exponent >0.4 is 4.2%. (3) Although Xingzi and Hukou both belong to the inland lake complex terrain, the terrain of Xingzi is more complex. The overall wind shear exponent >0.3 has high frequency, and stratified wind shear exponent >0.4 has the frequency up to 10%. However, in Hukou, the local lake land air circulation has a bigger effect. The overall wind shear exponent value >0.3 has lower frequency, and the frequency of stratified wind shear exponent >0.4 is 3.37%. (4) According to the design requirements for wind turbine generator systems, wind shear exponent is 0.2, which may overestimate the wind speed of hub height.