| This problem adopted the method of Computational Fluid dynamics, investigated the imitate experiment of windbreak control granule rised up. Research focused on airflow field distribution behind the windbreak of different configuration, and gain the purpose of control granule rised up by decrease velocity and turbulence intensity of airflow.Through the imitate experiment, we can get the result that the most important factors affected velocity and turbulence intensity of airflow is porosity. So this problem investigated the windbreak of different porosity, through calculated the variety rate of velocity and turbulence behind the windbreaks on different position, consequently get the result of the relationship between porosity and shelter effect of windbreaks.Minimum relative windspeeds behind the windbreaks of different porosity ranged from 5%-67.3% of open windspeeds, this minima were located 1-18 multiples of windbreaks height away from the windbreak. According the result of velocity contour and turbulence contour, consequently get the result of shelter height ranged from 0.6-0.8multiples of windbreaks-height, its position were located 1-10 multiples of windbreaks height away from the windbreak,at the same time get the distances what the windbreaks influence airflow.Through calculate the pressure of section setted on each side of windbreak, identify the coefficients for windbreaks, and get the result that linear relationship is existence between porosity and resistance coefficients. At the same time, we can identify what the resistance coefficients is related with decrease rate of flow velocity and increase rate of turbulence intensity. Therefore we can adopt resistance coefficients as a substitute parameter for porosity of windbreaks to investigate the relationship.At last, we can identify porosity of windbreaks is the most important parameter, and we can use it to predict minimum relative velocity, at the same time, a windbreak is showed in this paper, its porosity is 30%. |
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