实测风场风速风向耦合的三维非平稳特征研究

Three dimensional non-stationary analysis on field measured wind data with coupling wind speed and wind direction

为了获取考虑风速风向耦合效应的实测风场非平稳特征,在获取三维脉动风速时程的过程中,采用EMD方法建立了三维脉动非平稳风速模型,并推导出了脉动风速时程表达式,进一步发展了风速时变标准差、时变湍流强度的概念。以高层建筑实测台风数据作为算例,并与平稳风速模型进行对比分析,验证了非平稳风速模型的准确性和优越性:不需要选取基本时距;时变的物理量能反映微观特征,更能反映风速的非平稳性。通过平稳度指数检验了数据分析过程的平稳性特征,结果表明:风速在频域内的平稳性指数随着频率的增大而逐渐增大;不考虑风向时,风速的平稳性指数大小是与风速的变化速率相关的;非平稳风速模型所计算的脉动风速平稳性较平稳性模型方法所分析结果有所改善。

In order to investigate the three dimensional non-stationary characteristics of field measured wind data with the joint effect of wind speed and direction, a three-dimensional non-stationary wind speed model was proposed. The corresponding formula was established by utilizing the empirical modal decomposition（EMD） method to obtain the time history of the three dimensional fluctuating wind speed. Some continuous variables related to wind characteristics, such as the time-varying standard deviation and time-varying turbulence intensity, were furthermore proposed. In order to verify the accuracy of the proposed method, the field measured three dimensional wind data during the passage of typhoon over a high-rise building was adopted to investigate its non-stationary characteristics comprehensively by comparing with the traditional stationary wind data analysis model, The analyzed results show that the proposed method is not only accurate but also has good performance in the following aspects： no specific time interval is needed for the statistical analysis on the measured wind data; the local fluctuating characteristic and non-stationary characteristics could be described more clearly. Finally the analysis results on the stationary performance of the measured wind data are verified by the stationary index. The results show that the stationary index of the measured wind speed increases with the frequency and related to its varying rate. Furthermore the stationary performance of fluctuating wind speed obtained by the proposed non-stationary wind speed model is found to be more reasonable than that obtained by the traditional stationary wind model.