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风洞试验气弹模型缩尺比常选为1/300~1/800以满足紊流积分尺度相似要求,但一些复杂结构气弹模型实际缩尺比为1/40~1/100以减少模型加工难度及提高模型精度。这类大几何缩尺比造成紊流积分尺度的相似性严重偏离,必须对紊流积分尺度不相似时的风洞试验结果偏差进行修正。基于随机振动理论,推导了考虑1阶基本振型的顺风向风振响应及风振系数计算表达式。通过对一格构式输电塔风振响应分析,研究了顺风向紊流积分尺度Lxu对该结构风振响应的影响。研究结果表明:紊流积分尺度对结构抖振响应有显著影响,对峰值响应及风振系数影响也较大。对于该塔1/40大缩尺气弹模型风洞试验,由紊流积分尺度不相似带来的风振系数试验值的最大偏差可达27%,风振系数平均偏差也接近14%,试验结果偏保守。为便于应用,建议了较为通用的、由紊流积分尺度不相似引起的修正系数,这一修正系数随着结构阻尼比、结构频率与风谱卓越频率的比值(频率比)的增加而减小。
The scale scale ratio of wind-tunnel test aeroelastic model is usually 1/300 ~ 1/800 to meet the similar requirements of turbulence integral scale. However, the actual scale ratio of aeroelastic model of some complicated structures is 1/40 ~ 1/100 to reduce the model Processing difficulty and improve model accuracy. Such large geometrical scale scale seriously deviates from the similarity of the turbulence integral scale, and the deviation of wind tunnel test results when the turbulence integral scale is not similar must be corrected. Based on the random vibration theory, the downwind wind-induced response and the wind-induced vibration coefficient calculation formula considering the first-order fundamental mode are deduced. Through the analysis of the wind-induced vibration response of a grid transmission tower, the influence of the downwind turbulence integral scale Lxu on the wind-induced vibration response of the structure is studied. The results show that the turbulence integral scale has a significant effect on the chattering response of the structure and the influence on the peak response and the wind-induced vibration coefficient. For the 1/40 large-scale aeroelastic model wind tunnel test, the maximum deviation of the wind-induced vibration coefficient test value caused by the dissimilarity of the turbulent integral scale can reach 27% and the average wind-vibration coefficient deviation approaches 14% The result is conservative. For ease of application, a more general correction factor due to dissimilar turbulence scale scales is proposed. This correction factor decreases as the ratio (frequency ratio) of structural damping ratio, structural frequency to excellent frequency of wind spectrum increases .