雷诺数效应对斜拉索风致振动的影响

为了从雷诺数效应的角度分析斜拉索发生大幅振动的机理,利用不同粗糙度表面无人工水线的斜拉索模型和光滑表面贴有人工水线的斜拉索模型,进行了测力和测振风洞试验,得到了斜拉索模型气动力系数、驰振表达式的数值和气动稳定性的结果。通过分析相关的关系表明：在临界雷诺数区域,力系数及流场的变化特性可能导致斜拉索发生大幅振动,这可能是干索驰振的机理;斜拉索表面粗糙度能改变雷诺数效应的强弱和临界雷诺数的区域;水线的存在能改变雷诺数效应,一些水线位置在特定的雷诺数范围内,由于力系数的特殊变化规律导致dCF/dα为负,斜拉索发生符合驰振判据的振动;在高雷诺数区域,振动还可能与力系数急剧下降和流场的不稳定有关。

Reynolds Number Effect on Wind-induced Vibration of Stay-cables

In order to analyze the large amplitude vibration mechanism of cables based on Reynolds number effect,wind forces measurement and free vibration tests were carried out on cable models with/without artificial water rivulet.In the tests,the cable models without artificial water rivulet were in different surface roughness and those with artificial water rivulet attached were in smooth surface,and artificial water rivulet was attached in different positions respectively.Wind force coefficients,Den Hartog galloping coefficients and free vibration amplitudes were obtained.It is shown that in critical Reynolds number range,there is the possibility that the special wind force coefficient characteristics and flow pattern induce vibration,and this is the possible mechanism for dry cable galloping.The roughness of cable surface can change the intensity of critical Reynolds number effect and the range of critical Reynolds number.The existence of water rivulet can change the critical Reynolds number effect.For some water rivulet positions,in certain Reynolds number range,dCF/dα0,vibration happens,which agrees with the Den Hartog galloping criterion.In high Reynolds number range,besides Den Hartog galloping,vibrations are relevant to significant decrease of wind force coefficients and unstable flow pattern.