A large span roof is one of the common designs for modern structures, such as sport stadiums,coal/oil storage, museums, or certain symbolic structures standing for religious or national
meanings. The most concerned of such design is its curved geometry and its sensitivity to wind
loads. For the past three decades, many works have been published to investigate the aerodynamic
characteristics on hemispherical domes. However, only limited description was given on discussing
spectrum characteristics. Systematic wind tunnel tests were carried out to investigate the spectrum
characteristics of fluctuating wind pressures on the surface of hemispherical domes due to Reynolds
number effects in both smooth and turbulent wind flows. Reynolds number in this study varies from
6.6×104 to 1.9×106 to have a wider range for discussion. Instantaneous fluctuating wind pressures
were measured and processed FFT for spectrum calculation. Power spectra and cross spectra
between two pressures along the meridian were selected for examination. It was observed that not
only the location but also the distance difference between two pressures can significantly affect the
spectrum distribution. From upstream to downstream, power spectra vary gradually as separation
occurs and forms a wake region. With the increase of Reynolds number, coherence varies
significantly in the lower reduced frequency range. Oncoming turbulence intensities somehow
enhance the wave form distribution over all frequency ranges. However, it is also mentioned that a
quantitative description may help more in defining how spectrum characteristics affect the wind
loadings on the surfaces.
關聯:
Proceedings of The 2nd Cross-Strait Symposium on Dynamical Systems and Vibration (SDSV 2012)
