森林环境近地表自然风的动态特性

森林环境近地表自然风动态特性是森林环境风场、森林防火理论和室内空调设备送风模式等相关研究的基础.该文通过对北京林业大学鹫峰试验林场森林环境中的近地表自然风采样分析,研究了近地表自然风在二维方向的动态特性.研究结果表明主风向风速的速度均值和方差较大,但平均湍流强度却小于侧向风的平均湍流强度;自然风的风向变化非常显著,当风速均值较小时,风向角度的标准差较大,当风速均值较大时,风向角度的标准差较小;主风向与侧风向的二维风速分布呈正偏态分布,二维风速分布的偏度系数γ3>0,峰度系数γ4>3.其中,侧风向速度分布的偏度系数和峰度系数均明显大于主风向的对应值;近地表自然风在主风向与侧风向的二维风速信号均表现出很高的随机性.此外,主风向与侧风向的二维风速信号间的相关性很低.

Analysis on dynamic characteristics of natural wind near earth surface in forest environment

The dynamic characteristics of natural wind near the earth surface in forest environment is the foundation of several relevant researches such as forest environmental wind field, forest fire prevention theory and room conditioning's blow mode. In this paper, the dynamic characteristics of natural wind near the earth surface were studied by means of signal sample analysis of two dimensional wind speed in the Experimental Forestry Center of Beijing Forestry University. The results show that: the average speed and speed variance in X direction (main direction) are quite large, but average turbulence intensity of wind speed in X direction is lower than that in Y direction (side direction); the direction variation of natural wind is obvious, when average speed is lower, the standard deviation of wind direction angle is large, nevertheless, as average speed increases, the standard deviation of wind direction angle decreases; the speed distribution of wind speed in X and Y directions deviates from normal distribution in right, and the skewness index and kurtosis index of speed distribution in Y direction are larger than those in X direction; there is highly randomicity in two dimensional wind speed signal. Furthermore, wind speed signal in X direction is less correlated with that in Y direction.