台风“米雷”近地层脉动风特性实测研究

Field measurement of turbulence characteristics near ground during typhoon 'Meari'

基于10m、20m、30m和40m高度处台风"米雷"影响下的上海浦东地区近地风实测数据,对台风过程中平均风速与风向、湍流度、阵风因子、湍流积分尺度和脉动风速功率谱进行分析。结果表明:各高度处各向湍流强度和阵风因子均随平均风速的增大而减小;实测湍流度和阵风因子的相关性与Choi经验公式较为符合;各向湍流积分尺度均有随平均风速的增大而增大的趋势,10m、20m和40m高度处湍流积分尺度均值之间的比值Lxu∶Lxv∶Lxw分别为1∶0.69∶0.08、1∶0.61∶0.09和1∶0.65∶0.13;整个台风过程中,各向湍流分量功率谱的高频能量随时间推移而下降,而低频能量则增大;台风初期惯性子区各湍流分量功率谱的分布斜率小于-2/3,随后逐渐满足Kolmogorov-2/3律;纵向脉动风速功率谱与Von Karman经验谱吻合较好,而横向和竖向脉动风速功率谱与Von Karman经验谱在高频段却有所偏差。

In this paper, the wind characteristics of typhoon ＇ Meari＇ , such as wind speed, wind direction, turbulence intensity, gust factor, turbulence integral scale and power spectra are discussed on the basis of long-time measurement data, The data is recorded respectively at the height of 10m, 20m, 30m and 40m above the ground in Pudong District of Shanghai. It is shown that turbulence intensity and gust factor increase with mean wind speed. The obtained relation between turbulence intensity and gust factor agrees will with that by Choi Empirical Formula. Turbulence integral scale increases with mean wind speed, and the average ratios of turbulence integral scale among the turbulence components for all 10min data are 1 ： 0.69 ： 0.08,1 ： 0.61 ： 0.09 and 1 ： 0.65 ： 0. 13 respectively at 10m, 20m and 40m. Energy of observed power spectra of longitudinal, lateral and vertical wind components at high frequencies fall with the passage of time during ＇ Meari＇ , while increase at low frequencies. The slope rates of turbulence spectra are less than - 2/3 in the inertia range during ＇ Meari＇. It is shown that longitudinal fluctuating wind power spectrum roughly fit with Von Karman spectrum, but there is a slight deviation in high frequency band for lateral and vertical fluctuating wind power spectrum.