Water leak diagnosis of tiled roofs under vibration and scattering by wind tunnel experiment
This paper describes a water leak test of roof tiles. The 100 roof tiles were set up on 10 lines and 10 rows on the pitched roof in the downstream of the flow from the wind tunnel. The flow velocity was increased gradually from the low velocity to the high velocity, and the effects of the wind on the roof tiles were investigated by the water leak test. The situation of the water leak test was filmed by video camera. Two accelerometers were simultaneously used. The roof tiles which showed significant vibration at any velocity were found in a series of experiments and the accelerometers were attached to the two neighboring roof tiles on the model roof. The water leak phenomena in the experiment by using the artificial rainfall apparatus are discussed in this paper. Some mechanisms with relatively large amplitudes at low-frequency vibrations, which caused water leak phenomena were made clear.
Researches on Vibration and Scattering of Roof Tiles by Wind Tunnel Test (3rd Report, Water Leak Tests of Tiled Roof by Rainfall Apparatus)
In previous investigations, a series of wind tunnel tests was conducted on the vibration and scattering behavior of full-sized model of roof tiles, which were used widely for roofings of Japanese wooden dwellings. As a result, the mechanism of vibration and scattering of roof tiles could be understood. This paper describes a water leak test of roof tiles. The 100 roof tiles were set up on 10 lines and 10 rows on the pitched roof in the downstream of the flow from the wind tunnel. The flow velocity was increased gradually from the low velocity to the high velocity, and the effects of the wind on the roof tiles were investigated by the water leak test. The experimental apparatus for the purpose of reproducing the wind and the rain was used. The situation of the water leak test was filmed by video camera. Two accelerometers were simultaneously used. The roof tiles which showed significant vibration at any velocity were found in a series of experiments and the accelerometers were attached to the two neighboring roof tiles on the model roof. The water leak phenomena in the experiment by using the artificial rainfall apparatus are discussed in this paper. Some mechanisms with relatively large amplitudes at low-frequency vibrations, which caused water leak phenomena were made clear.
Characteristics of fluctuating suction and conical vortices on a flat roof in oblique flow
Abstract The characteristics of suction fluctuation on a flat roof in smooth and turbulent flows are investigated by a wind tunnel test. The large suction fluctuation is induced near the windward corner by conical vortices when flow attacks oblique to a roof. This suction fluctuation is induced by two different causes in the low and high frequency ranges. The low frequency part of the fluctuation is owing to the slow in-phase sway of a pair of conical vortices separated from the edges of the roof. The high frequency part of the fluctuation is brought by the rotation of spiral axes of the conical counter-rotating vortices. The lateral component of approaching turbulence amplifies the sway of the vortices and then induce much larger suction fluctuation.