Experimental Study of the Fluctuating Wind Characteristics of Typhoon Jangmi Measured at the Top of a Building

Abstract

Based on wind field data measured during the landfall of Typhoon Jangmi in Wenzhou in 2008, this study analyzes wind field characteristics, including wind speed, wind direction, probability density, turbulence intensity, gust factor, peak factor, power spectrum, turbulence integral scale, coherence, and the autocorrelation coefficient of Typhoon Jangmi. Results showed that the wind field characteristics for the east and west measuring points were basically the same and followed an approximately similar pattern. The probability density of fluctuating wind tends to obey a Gaussian distribution. The turbulence intensity gradually decreases with increasing 10 min averaged wind speed, but the reduction rate gradually drops. The turbulence intensity is affected by the change in a time interval because turbulence intensity decreases as the time interval increases. With an increase in the 10 min average wind speed and time interval, the gust factor decreases. The peak factor decreases, though insignificantly, with increasing mean wind speed, and the distribution of peak factors is greatly scattered. The variation in the peak factor with time is in good agreement with the Durst curve. The gust factor increases as the turbulence intensity increases and is in line with the empirical curves of Ishizaki, Choi, and Cao. The power spectra of the fluctuating wind speed of Typhoon Jangmi in all directions agree well with Von Karman’s empirical spectrum. The turbulence integral scale increases slightly with increasing average wind speed, and the distribution is relatively scattered. The coherence of the fluctuating wind speed components matches the exponential function proposed by Davenport, and the autocorrelation coefficient decreases as τ increases.