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在雷诺数为(1.1~6.8)×105的范围内测量了5种截面宽厚比(B/D分别为2.0、2.5、3.0、3.5和4.0)的二维矩形截面柱体模型的表面风压时程,研究了各模型的平均风压分布以及脉动风压分布随雷诺数的变化规律,并分析了雷诺数对5个模型的背风面中点风压系数的影响,进而从模型周围气流绕流的角度解释了矩形截面柱体模型雷诺数效应的机理。试验结果表明,5个模型的表面风压分布都受雷诺数的影响,且雷诺数不仅影响模型侧面气流再附区的风压分布,也影响模型侧面前缘气流分离区的风压分布。不同截面宽厚比的模型受雷诺数的影响程度也不同,其中B/D=4.0模型的表面风压分布对雷诺数最敏感,当雷诺数达到6.8×105时,其分离剪切层更易再附于模型侧面,其气流再附位置明显向前缘移动。此外,B/D=4.0模型的背风面负压绝对值随雷诺数的增大呈现先增大后急剧减小的变化规律。
Five kinds of cross-sectional aspect ratio (B / D 2.0, 2.5, 3.0, 3.5 and 4.0, respectively) were measured in the range of Reynolds number of (1.1 ~ 6.8) The influence of Reynolds number on the mid-point wind pressure coefficient of the leeward surface of five models was analyzed, and then the flow around the model The mechanism of the Reynolds number effect of a rectangular section cylinder model is explained. The experimental results show that the surface pressure distributions of the five models are all influenced by the Reynolds number, and the Reynolds number not only affects the wind pressure distribution in the re-attachment zone of the model side but also affects the wind pressure distribution in the airflow front separation zone. The model with different cross-section aspect ratio is affected by Reynolds number. The surface pressure distribution of B / D = 4.0 model is most sensitive to Reynolds number. When the Reynolds number reaches 6.8 × 105, the separated shear layer is easier to re-attach On the side of the model, the air flow attached to the front significantly moved to the front. In addition, the absolute value of the leeward negative pressure of B / D = 4.0 model shows a sharp decrease with the increase of Reynolds number.