The variations of drag force acting on the windbreak and the bulk drag coefficients for different windbreak widths were studied experimentally in the Eiffel-type non-circulating wind tunnel at the Hydraulic Engineerin...The variations of drag force acting on the windbreak and the bulk drag coefficients for different windbreak widths were studied experimentally in the Eiffel-type non-circulating wind tunnel at the Hydraulic Engineering Laboratory, Saitama University, Japan, to elucidate the effects of windbreak width in the wind direction on wind velocity reduction behind a windbreak. The variations of flow field for different windbreak widths were studied numerically by using the two-dimensional Reynolds-averaged Navier-Stokes （RANS） equation with a k-c turbulence closure model. Results show that the total drag force to wind increased with increasing windbreak width, but the bulk drag coefficient decreased slightly. The relationship between the bulk drag coefficient Cd and the windbreak width W and height H can be presented by the equation of Ca= kd （W/H）^-b （kd, b： constants）. The result of the numerical simulation shows that the windbreak width greatly affects the location and the value of the minimum wind velocity. The wind velocity decreased by 15%-22% as the windbreak width increased.展开更多
防风林带结构是影响防风效能的主要因素。建立不同宽度、不同株行距林带防风效能与林带后距离之间的统计模型,可以为防风林建设提供指导性意见。通过风洞实验,在11 m·s-1风速下,对4种宽度、5种株行距林带的背风面0~10H(H为林带高度...防风林带结构是影响防风效能的主要因素。建立不同宽度、不同株行距林带防风效能与林带后距离之间的统计模型,可以为防风林建设提供指导性意见。通过风洞实验,在11 m·s-1风速下,对4种宽度、5种株行距林带的背风面0~10H(H为林带高度)的风速进行测定,采用曲线参数估计法、傅立叶模型、SSF模型(Sum of Sin Functions),构建了不同结构林带防风效能与林带后距离间的统计模型。结果表明:傅立叶模型拟合不同宽度林带的防风效能与林带后距离的关系效果最优,可决系数(R2)均在98%以上;SSF模型拟合不同株行距林带的防风效能与林带后距离的关系效果最优(R2>0.98)。根据构建的统计模型,风速为11 m·s-1左右时,林带宽度8 m(两行一带)的防风林的防风效能存在明显优势;5种株行距的林带中,株行距为8 m×8 m的防风林带本试验条件下防风效果最好。展开更多
文摘The variations of drag force acting on the windbreak and the bulk drag coefficients for different windbreak widths were studied experimentally in the Eiffel-type non-circulating wind tunnel at the Hydraulic Engineering Laboratory, Saitama University, Japan, to elucidate the effects of windbreak width in the wind direction on wind velocity reduction behind a windbreak. The variations of flow field for different windbreak widths were studied numerically by using the two-dimensional Reynolds-averaged Navier-Stokes （RANS） equation with a k-c turbulence closure model. Results show that the total drag force to wind increased with increasing windbreak width, but the bulk drag coefficient decreased slightly. The relationship between the bulk drag coefficient Cd and the windbreak width W and height H can be presented by the equation of Ca= kd （W/H）^-b （kd, b： constants）. The result of the numerical simulation shows that the windbreak width greatly affects the location and the value of the minimum wind velocity. The wind velocity decreased by 15%-22% as the windbreak width increased.
文摘防风林带结构是影响防风效能的主要因素。建立不同宽度、不同株行距林带防风效能与林带后距离之间的统计模型,可以为防风林建设提供指导性意见。通过风洞实验,在11 m·s-1风速下,对4种宽度、5种株行距林带的背风面0~10H(H为林带高度)的风速进行测定,采用曲线参数估计法、傅立叶模型、SSF模型(Sum of Sin Functions),构建了不同结构林带防风效能与林带后距离间的统计模型。结果表明:傅立叶模型拟合不同宽度林带的防风效能与林带后距离的关系效果最优,可决系数(R2)均在98%以上;SSF模型拟合不同株行距林带的防风效能与林带后距离的关系效果最优(R2>0.98)。根据构建的统计模型,风速为11 m·s-1左右时,林带宽度8 m(两行一带)的防风林的防风效能存在明显优势;5种株行距的林带中,株行距为8 m×8 m的防风林带本试验条件下防风效果最好。
