斜拉索风雨激振的数值模拟及基于滑移理论的机理研究
发布时间：2018-07-30 07:17
【摘要】：风雨激振是指在风雨条件下,斜拉索发生的低频率、大振幅的振动现象。该现象会直接破坏斜拉索防腐系统,导致斜拉索失效,严重威胁行人及车辆的安全。根据近三十年来诸多学者的研究表明,斜拉索表面水线形成和振荡与风雨激振现象有重要的关系。本文首先基于气液两相流理论及体积分数法VOF法,研究了不同风速对斜拉索表面水膜的影响,并将不同风速时的水膜运动与拉索振动进行单向耦合;然后基于滑移理论推导了二维两自由度斜拉索风雨激振理论模型,实现了水膜运动与两自由度斜拉索振动间的双向耦合;最后基于滑移理论与计算流体动力学CFD数值模拟技术,建立了三维斜拉索刚性节段水膜运动模型,并通过正则摄动法对方程进行化简,利用有限差分法求解,得到了不同工况下的水膜运动情况,从以上三个角度深入研究了风雨激振现象,主要研究内容如下:基于气液两相流理论及VOF法,计算了不同风速时二维斜拉索表面的水膜运动变化情况,得到不同时刻的上水线及下水线的形成与变化规律,并通过后处理得到各时刻的气动力时程及频谱分析,最后将得到气动力升力值施加到斜拉索单质点振动方程中,得到了不同风速时的斜拉索的振动规律,通过分析表明,上水线的周期性振荡是引起风雨激振的主要原因;基于滑移理论,建立了两自由度斜拉索风雨激振理论模型,首先考虑斜拉索振动在横风向及顺风向产生的加速度对水膜形态变化的影响建立了水膜运动方程,并利用CFD确定不同时刻的风压力系数pC和风摩擦力系数fC?和fzC,考虑了水膜形态变化导致斜拉索边界的变化及拉索振动引起的气流场变化,通过拟谱法求解,实现了水膜运动与两自由度斜拉索振动间的双向耦合,得到了不同时刻斜拉索顺风向及横风向的振动规律及上、下水线变化规律,通过与单自由度斜拉索风雨激振结果进行比较,发现两自由度斜拉索在横风向及顺风向均发生了大幅度的振动现象,其周围的气动力也发生了周期性的变化,而拉索表面上、下水线也出现了明显的周期性振荡,通过频谱分析发现拉索的振动频率与拉索周围的气动力变化频率、水线的振荡频率非常接近,且均接近于拉索的自振频率;考虑斜拉索气流及水流沿轴向的影响,基于滑移理论建立了三维斜拉索刚性节段水膜运动方程,利用正则摄动法对方程进行化简,忽略高阶项,并采用有限差分法中的交替方向隐式差分格式(ADI格式)进行数值求解;通过计算水平及竖直放置的斜拉索在仅受重力作用下斜拉索表面水膜的运动变化情况证明了该方法的准确性,然后计算了不同风速时,斜拉索表面水膜的分布及形态变化,通过研究发现该方法能很好的模拟水膜在三维斜拉索表面的运动变化规律,只有当风速增大到一定程度时,才会出现上水线,且上水线的位置变化受风速和重力的影响明显大于下水线。
[Abstract]:Wind and rain excitation is the phenomenon of low frequency and large amplitude vibration caused by cable in wind and rain conditions. This phenomenon will directly destroy the anticorrosion system of inclined cable, cause the failure of the cable cable and seriously threaten the safety of pedestrians and vehicles. According to the research of many scholars in recent thirty years, the formation and oscillation of the surface of the cable surface and the wind and rain induced vibration are shown. In this paper, based on the gas-liquid two-phase flow theory and the volume fraction VOF method, the influence of different wind speeds on the water film on the cable surface is studied, and the unidirectional coupling of the water film motion and the cable vibration at different wind speeds is carried out, and the theoretical model of the two dimension two degree of freedom cable wind and rain induced vibration is derived based on the slip theory. The bi-directional coupling between the motion of water film and the vibration of two degree of freedom cable-stayed cable is presented. Finally, based on the sliding theory and the computational fluid dynamics CFD numerical simulation technology, a three-dimensional water film motion model of the rigid segment of the cable is established, and the equation is simplified by the regular perturbation method, and the water film under different conditions is obtained by the finite difference method. The main research contents are as follows: Based on the theory of gas-liquid two phase flow and VOF method, the change of water film movement on the surface of two dimensional cable-stayed cable is calculated based on the gas liquid two-phase flow theory and VOF method, and the formation and change rules of the water line and the lower water line at different times are obtained. At the moment, the aerodynamic time history and spectrum analysis, the aerodynamic lift value is applied to the single point vibration equation of the cable-stayed cable, and the vibration law of the cable-stayed cable with different wind speeds is obtained. Through the analysis, the periodic oscillation of the water line is the main cause of the wind and rain excitation. Based on the slip theory, a two degree of freedom cable-stayed cable is established. In the theoretical model of wind and rain excitation, the equation of water film motion is established by considering the effect of the acceleration of the cable in the wind direction and the wind direction on the change of the shape of the water film. The wind pressure coefficient pC and the wind friction coefficient fC? And fzC are determined by CFD. The change of the flow field caused by the cable vibration is solved by the pseudospectral method. The two-way coupling between the water film movement and the two degree of freedom cable-stayed cable vibration is realized, and the vibration laws of the wind direction and the cross wind direction of the cable are obtained at different time, and the law of the change of the lower water line is obtained. By comparing the results of the wind and rain induced vibration with the single degree of freedom cable, it is found that two freedom is found. There is a large amplitude vibration phenomenon in the cross wind direction and the wind direction, and the aerodynamic force also changes periodically. On the surface of the cable, the lower water line also has obvious periodic oscillation. The frequency of the vibration of the cable and the frequency of the aerodynamic change of the cable circumference are found through the spectrum analysis. The oscillation frequency of the water line is not. It is close to and close to the vibration frequency of the cable. Considering the influence of the air flow and the flow along the axial direction of the cable, the motion equation of the three dimensional rigid segment of the cable is established based on the slip theory. The regular perturbation method is used to simplify the equation, ignore the high order, and use the alternating direction implicit difference scheme (ADI format) in the finite difference method. Numerical solution is carried out, and the accuracy of the method is proved by calculating the movement of the water film on the surface of the inclined cable surface under the action of gravity only. Then the distribution and morphological changes of the water film on the surface of the cable surface are calculated when different wind speeds have been calculated. It is found that the method can simulate the water film in three dimensions well. The change rule of the motion of the cable surface is only when the wind speed increases to a certain degree, and the change of the position of the water line is greatly influenced by the wind speed and the gravity.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U441.3;U448.27
[Abstract]:Wind and rain excitation is the phenomenon of low frequency and large amplitude vibration caused by cable in wind and rain conditions. This phenomenon will directly destroy the anticorrosion system of inclined cable, cause the failure of the cable cable and seriously threaten the safety of pedestrians and vehicles. According to the research of many scholars in recent thirty years, the formation and oscillation of the surface of the cable surface and the wind and rain induced vibration are shown. In this paper, based on the gas-liquid two-phase flow theory and the volume fraction VOF method, the influence of different wind speeds on the water film on the cable surface is studied, and the unidirectional coupling of the water film motion and the cable vibration at different wind speeds is carried out, and the theoretical model of the two dimension two degree of freedom cable wind and rain induced vibration is derived based on the slip theory. The bi-directional coupling between the motion of water film and the vibration of two degree of freedom cable-stayed cable is presented. Finally, based on the sliding theory and the computational fluid dynamics CFD numerical simulation technology, a three-dimensional water film motion model of the rigid segment of the cable is established, and the equation is simplified by the regular perturbation method, and the water film under different conditions is obtained by the finite difference method. The main research contents are as follows: Based on the theory of gas-liquid two phase flow and VOF method, the change of water film movement on the surface of two dimensional cable-stayed cable is calculated based on the gas liquid two-phase flow theory and VOF method, and the formation and change rules of the water line and the lower water line at different times are obtained. At the moment, the aerodynamic time history and spectrum analysis, the aerodynamic lift value is applied to the single point vibration equation of the cable-stayed cable, and the vibration law of the cable-stayed cable with different wind speeds is obtained. Through the analysis, the periodic oscillation of the water line is the main cause of the wind and rain excitation. Based on the slip theory, a two degree of freedom cable-stayed cable is established. In the theoretical model of wind and rain excitation, the equation of water film motion is established by considering the effect of the acceleration of the cable in the wind direction and the wind direction on the change of the shape of the water film. The wind pressure coefficient pC and the wind friction coefficient fC? And fzC are determined by CFD. The change of the flow field caused by the cable vibration is solved by the pseudospectral method. The two-way coupling between the water film movement and the two degree of freedom cable-stayed cable vibration is realized, and the vibration laws of the wind direction and the cross wind direction of the cable are obtained at different time, and the law of the change of the lower water line is obtained. By comparing the results of the wind and rain induced vibration with the single degree of freedom cable, it is found that two freedom is found. There is a large amplitude vibration phenomenon in the cross wind direction and the wind direction, and the aerodynamic force also changes periodically. On the surface of the cable, the lower water line also has obvious periodic oscillation. The frequency of the vibration of the cable and the frequency of the aerodynamic change of the cable circumference are found through the spectrum analysis. The oscillation frequency of the water line is not. It is close to and close to the vibration frequency of the cable. Considering the influence of the air flow and the flow along the axial direction of the cable, the motion equation of the three dimensional rigid segment of the cable is established based on the slip theory. The regular perturbation method is used to simplify the equation, ignore the high order, and use the alternating direction implicit difference scheme (ADI format) in the finite difference method. Numerical solution is carried out, and the accuracy of the method is proved by calculating the movement of the water film on the surface of the inclined cable surface under the action of gravity only. Then the distribution and morphological changes of the water film on the surface of the cable surface are calculated when different wind speeds have been calculated. It is found that the method can simulate the water film in three dimensions well. The change rule of the motion of the cable surface is only when the wind speed increases to a certain degree, and the change of the position of the water line is greatly influenced by the wind speed and the gravity.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U441.3;U448.27
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