典型覆冰导线脉动气动力特性及风偏响应

Fluctuating aerodynamic characteristics and wind-induced swing response of typical iced conductors

为了研究冰风工况下导线的风偏响应特性,通过刚性模型高频天平测力风洞试验,测定D形和新月形覆冰导线气动力的平均值和脉动值,获得两类覆冰导线的气动力系数随风攻角的变化规律,验证了覆冰导线顺风向脉动风荷载的准定常假定.利用频域计算方法,研究两类覆冰导线的风偏特性.从覆冰导线气动力和风偏特性两方面对我国规范相关规定的合理性进行研究.结果表明,覆冰导线气动力受覆冰形状和风攻角的影响很大;D形覆冰导线在某些风攻角工况下的风偏响应接近大风工况下的裸导线;我国现行输电线路设计规范忽略覆冰形状和风攻角等因素对导线气动力的影响,对导线的阻力系数取单一值,这种规定不尽合理;采用规范风荷载计算得到的覆冰导线风偏响应在大多数工况下偏小.

The mean and fluctuating aerodynamic forces of D-shaped and crescent iced conductors were measured through rigid model high frequency force balance wind tunnel tests in order to analyze the windinduced swing response characteristics of conductors in ice-wind cases.The change law of iced conductors＇ aerodynamic coefficients with wind attack angle was obtained,and the quasi-steady assumption of alongwind fluctuating wind loads of iced conductors was verified.Wind-induced swing response characteristics of iced conductors were analyzed by frequency-domain calculation method.The rationality of Chinese codes was investigated from the aspects of aerodynamic and wind-induced swing characteristics.Results show that both ice shapes and wind attack angle greatly influence the aerodynamic forces of iced conductors.The wind-induced responses of D-shape iced conductors in certain cases may be close to those of bare conductors under strong wind conditions.Current codes ignore the influences of ice shape and wind attack angle on aerodynamic characteristics of conductors and give single value for the drag coefficient of iced conductors,which is not completely reasonable.The wind-induced responses of iced conductors may be underestimated in most cases with method in codes.