FLUCTUATIONS OF SPECTRAL DENSITY OF WIND VELOCITY AND RESONANCE WIND LOAD

V. N. Ivanov and Yu. S. Rusakov

Measurements at a 300-m mast in different weather conditions are used to estimate small-scale characteristics of wind velocity fluctuations that determine dynamic wind loads on structures and flying vehicles. It is shown that in the inertial interval and in the adjacent low-frequency region the fluctuations of the turbulent energy dissipation rate ε and related fluctuations of the spectral density of wind velocity are governed by the lognormal distribution, the dispersion and the average of distribution being determined by an averaging scale of ε and described by relationships proposed earlier by Kolmogorov and Obukhov. Numerical values in these relationships turned out to be invariable in different weather conditions. Engineering formulas are obtained for estimating the mean time between outliers of ε as a function of the threshold εth and a response time constant of an object.