Spectral characteristics of wind-induced forces on rectangular column structures are analyzed for the frequency range higher than the spectral peak. The developed model is based on the assumptions that 1) ambient wind turbulence is fully developed and isotropic, and 2)dominant wind forces on the structure are caused by pressure fluctuations associated with the ambient turbulence. Using the Kolmogorov theory and length scales of effective pressure fluctuation, the power spectra of the transverse force on the column are found to be proportional to the frequency to the -10/3 power. The similar analysis leads to the result that the power spectra of the streamwise force are proportional to the frequency to the -4/3 power or -2/3 power, depending on the frequency range.

抄録全体を表示

In an Atmospheric Boundary Layer, turbulent shear stress or Reynolds stress is one of the most important factors to express the turbulent characteristics. In this study, the Reynolds Stress was simulated in an actively controlled turbulent wind tunnel, in which the turbulence was controllable. The Reynolds Stresses were reproduced in an uniform shear flow with grids (1), in a turbulent shear flow with grids (2), and in a turbulent flow by controlling both fans and airfoils (3). As the results showed, the Reynolds stress could be simulated with any one of these methods, however the obtained other turbulent parameters, such as integral scale and power spectrum were different for individual method. Moreover the transitions of the mean velocity, turbulent intensity, integral scale and power spectrum along the mean flow direction in the case of controlling the fans and airfoils were also examined.

抄録全体を表示