風洞実験によるかわらの振動と飛散現象の研究(流体工学,流体機械)

概要

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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. This study has investigated the nature and source of the vibrating and scattering behavior of roof tiles with the aim of providing a better insight to the mechanism. The roof tiles were set up on the pitched roof in the downstream of the flow from the wind tunnel. The vibration of the roof tiles was measured by the Laser Doppler Vibrometry and the accelerometer, and the practical natural frequency of the roof tiles was analyzed by the method of impulse force hammer test. The motions of the vibration and scattering were observed by the high-speed video camera. Based on the consideration on the results of the measurements, there is a basic mechanism which can lead to flow-induced vibrations of the roof tiles. This mechanism is that of the so-called fluttering instability, which appears as the self-excited oscillation in the natural mode of the structure at the certain critical flow speed. It is concluded that the values of frequencies of the forced vibration for the fluttering coincide nearly with the values of natural frequencies.
社団法人日本機械学会の論文
2005-10-25