Pressure characteristics of square flat roofs induced by conical vortices

Abstract:

To reveal wind pressure spectra and establishes the energy spectrum, vortex movement or the evolution of the relationship between turbulence scales, the wind tunnel experiments were performed which focused on the vortex axis direction and cross wind direction measuring points. Wind pressure distribution and the vortex axis motion characteristics of square flat roof surface were investigated when the flow was not perpendicular to the windward wall with different flow condition (uniform, grid-generated turbulence and the terrain B) and different wind direction (15°, 30° and 45°) through the rigid model wind tunnel pressure tests. Results show that the maximum wind suction appears near the windward point of lower triangular area with three different flow conditions. The peak mean and rms pressure coefficient reach the maximum at 30° wind direction. For the same incoming flow condition, the angle between the vortex axis and the leading edge of the windward direction and the range of reattachment are gradually decreasing as the wind angle increases. The peak value of the wind pressure spectrum near the windward point with the vortex axis direction is proportional to the corresponding roof wind suction. In the high frequency range, the measured wind pressure spectrum response frequency is corresponding to the peak spectral energy, also with the greater the average wind suction. In the low frequency range, the corresponding frequency is corresponding to the spectral energy peak, also with the greater the pulsating wind suction. The correlation between the measuring points in vortex axis direction with uniform flow condition is poor, and cross spectrum is the exponential decay mode with grid-generated turbulence and terrain B flow condition.