Wind Tunnel Experiments on the Shelter-hedge

概要

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It seems that a role of turbulence which affects the wind break effect has been very little known. But it can be considered that decrease of turbulence is effective for the wind break as well as decrease of mean wind velocity. The present experiments have been done from this point of view and mainly dealt with the turbulence. The results obtained are summarized as follows:(1) Friction velocity v* beyond which sands uniformly scattered over a constant area of aflat-plate begin to move is maximum in the case where the turbulence was not given and minimum is the case where the the turbulence was given (a value in the former case is more than three times as large as that of the latter case) and it takes an intermediate value when the turbulence with large scale generated by an obstacle of the leading-edge of the flat-plate is eliminated by setting a shelter behind the obstacle. Then, it should be noticed that removed quantities of sands can not be uniquely determined from v*, even if other conditions have been kept constant.(2) Both the rate of decrease of mean wind velocity and. that of energy of turbulence due to a net are larger than those due to rod-belt and screen. Especially, the turbulence increases down stream from the distance of 7h-8h for the case of the screen (h denotes height of screen), a shelterhedge with large closed area such as a screen is not suitable. Each effective area of the wind break of screen, rod-belt and net is within 3h, 4h and 5h respectively (in this case, wind velocity:U∝≅4m/sec, height from the flat-plate: z=3mm).(3) Increase of the row of the rod-belt (corresponding to increase of thickness of shelter-belt) is not effective for the wind break, this rather results in increase of turbulence.(4) The lattice is more effective than the the rod-belt, and the effective area covers the distance of 6h in this experiment.
日本農業気象学会の論文

Wind Tunnel Experiments on the Shelter-hedge

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概要

日本農業気象学会 | 論文

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