山区地形条件下塔式仿古建筑风压与风场绕流分析

利用计算流体动力学方法并引入RNG (Renormalization Group)k-ε湍流模型,以山区复杂地形条件下的高层塔式仿古建筑为研究对象,分析了高层塔式仿古建筑表面的风压分布和风场绕流特性,以及建筑高度、建筑与山脚之间距离、山地地形等因素对风压和风场绕流的影响.结果表明:在不同的地形条件下,建筑表面的风压分布具有差异性;建筑表面风压绝对值随着建筑高度的增长而增大,随着建筑与山脚之间距离的缩短而减小;山地地形及其参数对建筑表面上部风压的影响明显大于对建筑表面下部风压的影响.

重檐歇山顶中国古建筑风压与风场数值模拟分析

运用ANSYS Fluent软件并引入Renormalization-group k-ε湍流模型,以北京天安门城楼复杂形体为对象,数值计算分析重檐歇山顶式古建筑的风压与风场特性,揭示了不同风向角下建筑风压与风场的变化规律,开展了城楼城台封闭和城台开敞、曲面斜坡屋面和直线斜坡屋面等对建筑风压和风场的影响.研究表明,风向角对建筑屋面和重檐风压分布影响显著;城台开敞可降低建筑周围整体气流流速,减小屋面和重檐的负风压;直线斜坡可降低屋面与重檐处气流速度,但将增大重檐间区域的气流速度.给出了无周边遮挡建筑物情况下重檐歇山顶古建筑的风荷载体型系数,可为此类古建筑的抗风设计提供技术参考.

The Mechanism of Flow Field around a Rotating Cylinder with Fins for High Performance Magnus Wind Turbine

Spiral Magnus is a unique wind turbine system that rotates with cylinders which have spiral-shaped fins coiled around them （instead of using the more common propeller-type blades）. In the present study, three models （cylinder with no fins, cylinder with straight fins and cylinder with spiral fins） were installed, and fluid force measurements were performed by a strain gauge force balance. A PIV （particle image velocimetry） system was used to better understand the flow fields around the cylinder. Considering the results of the experiment, it was confirmed that, the aerodynamic performance of the rotating cylinder can be improved by the fin. However, the straight fin makes the flow close to the cylinder surface ineffective. The rotary cylinder with the spiral fins was able to generate the greatest lift among three models, because the spiral fin effectively influences the vicinity of the cylinder surface.