风载作用下扇形覆冰斜拉索的疲劳损伤研究

Study on the Fatigue Damage of Sector Iced Cable Under Wind Load

在寒冷环境中,斜拉索易产生覆冰,覆冰将使得斜拉索的重心与轴线不重合,变成不稳定的气动外形。在大风的作用下,容易产生驰振失稳,驰振是一种低频大幅振动,会严重影响斜拉索的安全。因此,该文将选取一种典型的斜拉索覆冰冰型-扇形对斜拉索的覆冰驰振稳定性进行研究。该文主要根据Den Hartog驰振理论,采用FLUENT模拟软件监测斜拉索的升力及阻力时程曲线,计算得到平均升阻力系数及驰振力系数,根据驰振力是否小于0来判断斜拉索是否发生驰振失稳,并通过工程实例计算覆冰斜拉索的驰振临界风速。结果表明:扇形覆冰斜拉索存在小于0的风攻角区域且对应的驰振临界风速较小,说明斜拉索在此覆冰条件下易产生覆冰驰振。对比风洞试验和二维模拟数据,发现三维模拟得到的覆冰斜拉索气动力系数更接近于实验值。

In the cold environment,the cable was easy to produce ice,the ice would make the center of gravity of the cable and the axis did not coincide,became unstable aerodynamic shape.Under the action of strong wind,the cable was easy to generate galloping instability.Galloping vibration was a kind of low frequency vibration which would seriously affect the safety of the cable.Therefore,this paper would study the stability of a typical cable stayed type fan to the ice.In this paper,according to the Den Hartog galloping theory,the FLUENT simulation software was used to monitor the lift and resistance time history curve of the cable,and the average drag coefficient and the galloping force coefficient were calculated.According to whether the galloping force was less than 0,the vibration of the cable was calculated,and the galloping critical wind speed of the iced stay cable was calculated by engineering example.The results showed that there were less than 0wind attack angles and the corresponding galloping critical wind speed was low,which indicated that the iced cable was easy to generate ice galloping.Compared with the wind tunnel test and two-dimensional simulation data,it was found that the aerodynamic coefficient of the iced cable was more close to the experimental value.