桥梁风效应数值模拟研究

发布时间：2018-06-22 16:51

本文选题：桥梁结构 + 三分力系数　；参考：《湖南大学》2014年硕士论文

【摘要】：近年来，随着计算流体力学理论的完善和计算机技术的发展，基于计算流体动力学(CFD)的数值方法迅速成熟，虽然还不能代替风洞试验，但相比于传统的抗风研究方法有其独特的优势，由于该方法设计周期短、试验费用低、承担风险小，流动可视化易于实现等，已经成为研究桥梁风效应问题的一种有效手段。本文即借助计算流体动力学方法对桥梁风效应进行研究。 (1)以澧水大桥为工程背景，应用SST k-湍流模型，数值模拟不同攻角下主梁断面的三分力系数，提取计算结果与试验值进行对比，给出了主梁断面周围流场的压强与速度分布图并进行分析，进一步验证了CFD能够较为精确的数值模拟主梁断面的三分力系数及具有显示流体流动方面的优越性。 (2)采用计算流体力学软件FLUENT中的雷诺平均方法(RANS)的SST k-湍流模型求解不可压粘性流体纳维斯托克斯(N-S)方程。将二维矩形柱体简化为质量-弹簧-阻尼系统。网格建立过程中运用“刚性运动区域+动网格区域+静止网格区域”的方法首先对其进行分块，然后将Newmark-法代码编写入FLUENT的用户自定义函数(UDF)中对结构的振动响应进行求解，结合FLUENT软件中的动网格技术建立了结构涡振数值模拟方法。以宽高比为6的矩形断面为研究对象，对其在不同风速条件下进行绕流和涡振数值模拟，研究结果显示：涡激振动“锁定”区间和涡振响应振幅的数值模拟结果与风洞试验结果吻合良好；表明采用该方法进行具有分离、再附着现象的钝体断面涡激振动是可行的。 (3)采用欧拉—欧拉体系的两相流理论，将雨滴场作为连续介质场，在流体计算软件FLUENT基础上编写了相应的UDF计算程序，对矩形柱体周围的风雨运动进行三维数值模拟。采用雷诺平均方法得到了在不同雨相粒径、不同风速下的雨相流线图，模型表面的雨滴捕获率、冲击荷载等。采用大涡模拟方法得到顺风向、横风向和扭转向的荷载时程数据和力谱，并与无雨时作对比，发现风驱雨对模型静态荷载影响很小，对动态荷载的影响较大，但平均效应很小。与风洞试验相比，用CFD数值模拟方法研究桥梁风效应问题，不需要昂贵的风洞试验设备和测量仪器，也不需模型的制作，，并且该方法的可重复性很好，不具有风洞试验周期长、费用高等问题。数值模拟方法可以实现气动选型和对模型的参数识别。
[Abstract]:In recent years, with the improvement of computational fluid mechanics theory and the development of computer technology, the numerical method based on computational fluid dynamics (CFD) is rapidly mature. Although it can not replace the wind tunnel test, it has its unique advantages compared with the traditional wind resistance research method. Because the design period is short, the cost of the experiment is low, the risk is small, and the flow is small. The dynamic visualization has become an effective means to study the wind effect of bridge beams. In this paper, the wind effect of bridge is studied with the help of computational fluid dynamics.
(1) Taking Lishui bridge as the engineering background, the SST k- turbulence model is applied to simulate the three division coefficient of the main beam section under different angle of attack. The calculation results are compared with the experimental values, and the pressure and velocity distribution map of the flow field around the main beam is given and analyzed, and the more accurate numerical simulation of the main beam broken by CFD is verified. The three component coefficient of surface and its superiority in displaying fluid flow.
(2) the SST k- turbulence model of the Reynolds mean method (RANS) in the computational fluid dynamics software FLUENT is used to solve the incompressible viscous fluid nvius tox (N-S) equation. The two-dimensional rectangular column is simplified to a mass spring damping system. The method of "rigid moving area + dynamic grid region + static grid area" is used in the process of grid establishment. First, we block it, then write the Newmark- code into FLUENT's user custom function (UDF) to solve the vibration response of the structure, and establish a numerical simulation method of structure vortex vibration with the dynamic grid technology in the FLUENT software. The rectangular section with the width height ratio of 6 is studied under different wind speed conditions. The numerical simulation of flow around and vortex vibration shows that the numerical simulation results of the "locking" interval and the vibration response amplitude of the vortex excited vibration are in good agreement with the wind tunnel test results, which shows that it is feasible to use this method to carry out the vortex excited vibration of the blunt body section with separation and reattachment.
(3) using the theory of two phase flow in Euler Euler system, using the raindrop field as a continuous medium field, the corresponding UDF program is written on the basis of the fluid calculation software FLUENT. The three-dimensional numerical simulation of wind and rain movement around the rectangular column is carried out. The rain flow lines under the different rain phase particle size and different wind speed are obtained by the Reynolds mean method. Figure, the raindrop capture rate and impact load on the surface of the model. Using the large eddy simulation method, the load time data and force spectrum of the wind direction, the transverse wind direction and the torsional steering are obtained, and compared with the rain free time, it is found that the wind drive rain has little influence on the static load of the model, and the dynamic load has great influence on the dynamic load, but the average effect is small.
Compared with the wind tunnel test, using the CFD numerical simulation method to study the wind effect of the bridge beam does not require expensive wind tunnel test equipment and measuring instruments, and does not need the model, and the repeatability of the method is very good. It does not have long wind tunnel test period and high cost. The numerical simulation method can realize pneumatic selection and model reference. Number identification.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441

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