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.
Key words
downburst /
non-stationary /
fluctuating wind velocity /
simulation /
time-varying mean wind speed
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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
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