三维扇形覆冰单索及串列双索风致振动及尾流驰振分析
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摘要
斜拉索偏心覆冰后,气动外形不再稳定,在风荷载作用下,可能诱发驰振。主要对三维扇形覆冰斜拉索以及串列双索尾流驰振进行研究。首先应用FLUENT中的SST k-ω模型对三维扇形覆冰斜拉索及串列双索的绕流场进行数值模拟,得到全向角下的阻力系数、升力系数及驰振力系数,然后依此判定覆冰斜拉索是否发生驰振,并得到某大跨斜拉桥部分斜拉索的驰振临界风速。数值分析结果表明,经过三维模拟计算的扇形覆冰直索及斜索的驰振力系数均大于零,表明在模拟的工况下,扇形覆冰单索在风荷载作用下不会发生驰振;而串列双索会在40°左右存在驰振力系数小于零的区域,会发生尾流驰振,但驰振临界风速很小。
After eccentric iced accretion, the aerodynamic shape of the stay cable is no longer stable, which may induce galloping vibration under wind load. Wake galloping analyses of 3 D fan-shaped single stay cable with iced accretion and tandem double cables with iced accretion were conducted. Firstly, the SST k-ω model in FLUENT was used to simulate the flow field around the 3 D fan-shaped single stay cable with iced accretion and tandem double cables with iced accretion, to obtain the drag coefficient, lift coefficient and galloping force coefficient under the omnidirectional angle. Then, it was determined whether the fan-shaped stay cable with iced accretion occured galloping, and the critical wind speed of the partial cable stay of a large-span cable-stayed bridge was obtained. The results of numerical analysis show that the galloping force coefficient of the fan-shaped stay cable and straight cable with iced accretion calculated by 3 D simulation are greater than zero. This indicates that under the simulated working condition, the fan-shaped single cable with iced accretion would not gallop under the wind load. However, the tandem double cables would have a region where the galloping force coefficient is less than zero at around 40°, and wake galloping would occur, but the critical wind speed of the galloping is small.
After eccentric iced accretion, the aerodynamic shape of the stay cable is no longer stable, which may induce galloping vibration under wind load. Wake galloping analyses of 3 D fan-shaped single stay cable with iced accretion and tandem double cables with iced accretion were conducted. Firstly, the SST k-ω model in FLUENT was used to simulate the flow field around the 3 D fan-shaped single stay cable with iced accretion and tandem double cables with iced accretion, to obtain the drag coefficient, lift coefficient and galloping force coefficient under the omnidirectional angle. Then, it was determined whether the fan-shaped stay cable with iced accretion occured galloping, and the critical wind speed of the partial cable stay of a large-span cable-stayed bridge was obtained. The results of numerical analysis show that the galloping force coefficient of the fan-shaped stay cable and straight cable with iced accretion calculated by 3 D simulation are greater than zero. This indicates that under the simulated working condition, the fan-shaped single cable with iced accretion would not gallop under the wind load. However, the tandem double cables would have a region where the galloping force coefficient is less than zero at around 40°, and wake galloping would occur, but the critical wind speed of the galloping is small.
引文
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[2] DEN HARTOG J P.Transmission line vibration due to sleet[J].Transactions of the American Institute of Electrical Engineers,1932,51(4):1074-1077.
[3] NIGOL O,BUCHAN P G.Conductor galloping-part Ⅱ:torsional mechanism[J].IEEE Transactions on Power Apparatus and Systems,1981,100(2):708-720.
[4] YU P A,SHAH H.POPPLEWELL N.Inertially coupled galloping of iced conductors[J].Journal of Applied Mechanics,1992,1(59):140-145.
[5] 温晓光.斜拉索干索驰振的机理研究[D].长沙:湖南大学,2013.
[6] 李寿英,黄韬,叶继红.覆冰斜拉索驰振稳定性的理论研究[J].振动与冲击,2013,32(1):122-127.
[7] 李寿英,黄韬,叶继红.覆冰斜拉索气动力的试验与数值研究[J].湖南大学学报,2012,39(8):1-6.
[8] 马文勇,顾明.扇形覆冰导线气动力特性及驰振不稳定性研究[J].振动与冲击,2012,31(11):83-85.
[9] SOCKEL H,WATZINGER J.Vibrations of two circular cylinders due to wing-excited interference effects[J].Journal of Wind Engineering & Industrial Aerodynamics,1998,74(1):1029-1036.
[10] 胡建华,陈政清.串列双索气弹模型的风洞试验研究[J].动力学与控制学报,2006,4(2):180-185.
[11] TANAKA H.Aerodynamics of cables[C]// Fifth International Symposium on Cable Dynamics.Santa Margherita Ligure,2003:11-21.
[12] 李永乐,王涛,廖海黎.斜拉桥并列拉索尾流驰振风洞试验研究[J].工程力学,2010,27(S1):216-221.
[13] 马如进,倪美娟.中间索面斜拉桥并列拉索尾流驰振数值研究[J].振动与冲击,2013,32(10):92-94.
[14] 唐浩俊,李永乐.基于能量方法的塔周长吊索尾流驰振性能研究[J].中国公路学报,2014,27(8):42-52.
[15] 腾二甫,段忠东,张秀华.新月形覆冰导线气动力特性的数值模拟[J].低温建筑技术,2008(1):86-88.
[16] 陈政清.桥梁风工程[M].北京:人民交通出版社,2005.
[17] 王福俊.斜拉桥拉索参数振动及斜拉桥动力分析[D].成都:西南交通大学,2007.