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首页> 外文期刊>Energies >Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades
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Forces and Moments on Flat Plates of Small Aspect Ratio with Application to PV Wind Loads and Small Wind Turbine Blades

机译：小纵横比平板上的力和力矩及其在光伏风载荷和小型风力涡轮机叶片上的应用

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摘要

To improve knowledge of the wind loads on photovoltaic structures mounted on flat roofs at the high angles required in high latitudes, and to study starting flow on low aspect ratio wind turbine blades, a series of wind tunnel tests were undertaken. Thin flat plates of aspect ratios between 0.4 and 9.0 were mounted on a sensitive three-component instantaneous force and moment sensor. The Reynolds numbers varied from 6 × 104 to 2 × 105. Measurements were made for angles of attack between 0° and 90° both in the free stream and in wall proximity with increased turbulence and mean shear. The ratio of drag to lift closely follows the inverse tangent of the angle of incidence for virtually all measurements. This implies that the forces of interest are due largely to the instantaneous pressure distribution around the plate and are not significantly influenced by shear stresses. The instantaneous forces appear most complex for the smaller aspect ratios but the intensity of the normal force fluctuations is between 10% and 20% in the free-steam but can exceed 30% near the wall. As the wind tunnel floor is approached, the lift and drag reduce with increasing aspect ratio, and there is a reduction in the high frequency components of the forces. It is shown that the centre of pressure is closer to the centre of the plates than the quarter-chord position for nearly all cases.
机译：为了提高对在高纬度所需的高角度下安装在平屋顶上的光伏结构上的风荷载的了解，并研究低纵横比的风力涡轮机叶片上的启动流，进行了一系列风洞测试。将长宽比在0.4到9.0之间的薄平板安装在灵敏的三分量瞬时力和力矩传感器上。雷诺数从6×10 4 到2×10 5 不等。测量了在自由流中和在壁附近，湍流和平均剪切力增加时，迎角在0°和90°之间。对于几乎所有测量，阻力与升力的比率都严格遵循入射角的反正切。这意味着感兴趣的力主要是由于板周围的瞬时压力分布引起的，并且不受剪切应力的影响很大。对于较小的纵横比，瞬时力似乎最为复杂，但在自由蒸汽中，法向力波动的强度在10％至20％之间，但在壁附近可能超过30％。随着接近风洞底板，升力和阻力随着纵横比的增加而减小，并且力的高频分量减小。结果表明，几乎在所有情况下，压力中心都比四分之一和弦位置更靠近板的中心。

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