下击暴流非平稳脉动风速数值模拟

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振动与冲击 ›› 2014, Vol. 33 ›› Issue (14) : 54-60.

论文

下击暴流非平稳脉动风速数值模拟

李锦华，吴春鹏，陈水生

作者信息 +

Simulation of non-stationary fluctuating wind velocity in downburst

LI Jin-hua，WU Chun-peng，CHEN Shui-sheng

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文章历史 +

摘要

针对大气边界层近地风不同、下击暴流平均风速具有明显时变性及脉动风速具有较强非平稳特征，通过Kaimal非均匀调制函数的建立方法，获得Davenport调制函数、Simiu调制函数、Harris调制函数，为有效实现非平稳脉动风速模拟提供首要条件；考虑自回归AR模型时变性，建立非平稳随机过程TAR时变模型，为实现非平稳脉动风速模拟提供有效方法；考虑下击暴流平均风速时变特征，对下击暴流非平稳脉动风速进行模拟。结果表明，模拟的下击暴流非平稳脉动风速相关性随不同位置间距增大而减弱，振幅随时变平均风速增大而增大，与实际风场特性吻合，表明非均匀调制函数有效；功率谱时变特征明显，与目标时变谱时变特征吻合，且样本统计平均功率谱、相关函数与目标均吻合，表明下击暴流非平稳脉动风速模拟方法有效。

Abstract

Distinct from the atmospheric boundary layer wind, average wind speed of downburst has observable time-varying characteristics, and its fluctuating wind possesses strongly non-stationary characteristics. According to the evolutionary spectrum theory, to realize the effective simulation of non-stationary fluctuating wind needs to establish a non-uniform modulation function of the power spectrum, and an efficient simulation method of non-stationary wind speed. To do this, firstly in this paper the method to create Kaimal non-uniform modulation function is used to obtain other modulation functions of power spectra, such as Davenport, Simiu and Harris, which provide the precondition for simulating non-stationary fluctuating wind. Then, founded on the autoregressive (AR) model to further consider the time variability, a time-varying autoregressive (TAR) model is established, which provides an effectual method for non-stationary wind speed simulation. Finally, based on the precondition and method of the above, the non-stationary fluctuating wind speed in downburst is simulated with considering the time-varying features of average wind speed. The simulation results show: for the non-stationary fluctuating wind velocity of downburst, the cross-correlation weakens along with the distance increases between the different positions, and the amplitude increases with time-dependent average wind speed increases, which coincide with the actual wind field characteristics and indicate the effectiveness of non-uniform modulation function; the power spectrum has obvious time-varying characteristics which match well with the target time-varying spectrum, and the temporal average power spectrum and correlation function are also in agreement with the targets, which involve the efficiency of the method generating non-stationary fluctuating wind of downburst.

导出引用

李锦华;吴春鹏;陈水生. 下击暴流非平稳脉动风速数值模拟[J]. 振动与冲击, 2014, 33(14): 54-60

LI Jin-hua;WU Chun-peng;CHEN Shui-sheng. Simulation of non-stationary fluctuating wind velocity in downburst[J]. Journal of Vibration and Shock, 2014, 33(14): 54-60