D形断面柱体驰振耦合气动力特性试验研究

Characterisitcs of coupled aerodynamic forces of a galloping cylinder with D-section

覆冰导线驰振耦合气动力特性的研究是解释驰振机理的主要手段,也是开发气动抑振措施的主要依据。以常被作为模拟导线覆冰形状的D形断面为研究对象,采用静态气动力、驰振响应及耦合气动力测试风洞试验,研究分析了D形断面柱体的静态气动力特性,基于准定常假设的单自由度横风向驰振理论预测了驰振发生的风向角及临界风速,通过驰振响应及动态气动力分析,揭示D形断面驰振的气动力变化过程。结果表明:D形断面在来流与其直线侧夹角为40°左右时易发生横风向大幅振动;振动是由气流的分离状态随风向角变化引起的,其响应的主要气动力贡献也来自分离点后的尾流区域。这种对分离点的敏感表明,通过控制气流的分离点可以提供有效的抑制驰振措施。

The coupled aerodynamic forces on a galloping cylinder can reveal the generation mechanism of galloping and provide a measure of developing galloping suppression. A cylinder with D-section, which has been used to simulate the shape of the iced conductor, is tested in wind tunnel to obtain the static aerodynamic forces, galloping response and coupled aerodynamic forces. The characteristics of the aerodynamic forces are illustrated. The across-wind single-degree-of-freedom galloping insta-bility and critical wind speed are estimated based on the quasi-steady assumption. By analyzing the galloping responses and cou-pled aerodynamic forces, a coupled aerodynamic force variation process is revealed. The result shows that the galloping more likely occurs when the angle between the wind direction and the line side of the D-section is around 40°. This vibration is in-duced by the variation of the separation state with the angle of attack. The responses are mainly contributed by the wind pres-sure on the region behind the separation points. This reveals that galloping is a wake flow induced vibration and the sensitivity of the vibration on separation points make a possibility on suppressing the galloping response by controlling the separation points.