三边形桅杆杆身风荷载特性风洞试验研究

Wind Tunnel Investigation on Wind Load Characteristics of Triangular Guyed Mast

应用高频测力天平技术,分别对有附属结构和无附属结构的三边形桅杆杆身进行了均匀流和两种紊流下的风洞试验,得到了桅杆的平均风力系数、均方根力系数和顺风向、横风向及扭转向风荷载谱.分析了雷诺数、紊流度、风向角、附属结构等对风荷载系数的影响,对比了试验体型系数和不同国家规范关于桅杆及其附属结构体型系数的规定.谱分析结果表明,顺风向风荷载谱和脉动风速谱的基本特征相同,横风向、扭转向风荷载谱主要由低频部分的紊流激励谱和高频部分的旋涡脱落激励谱组成,无附属结构模型旋涡脱落谱有一个峰,峰值折减频率在1.8左右,带附属结构模型在90°风向角下出现两个明显的旋涡脱落谱峰,峰值折减频率分别在0.9和2.2左右,探讨了格构式塔架旋涡脱落谱的特性以及附属结构对其的影响机理.

Two models of triangular guyed mast were tested by high frequency force balance （HFFB） technique under uniform and turbulent flow with different turbulent intensities, respectively. The mean and RMS force coefficients and the force spectra in along-wind, across-wind and torsion direction were ob- tained from wind＇tunnel test. Some existing codes and standards for the mean drag coefficients for guyed mast and ancillaries were employed and compared with＇test results, with emphasis on the influence of Reynolds number, turbulent intensity, wind incidence angle and ancillaries on wind force coefficients. The force spectra in along-wind direction are similar to the spectra of fluctuating wind velocity, while the force spectra in across-wind and torsion direction consist of the wind turbulence spectra in low frequency range and vortex shedding spectra in high frequency range. The vortex shedding spectra of the guyed mast without ancillaries have one peak, and the reduced frequency of the peak is close to 1.8. When the attack angle reaches 90°, the vortex shedding spectra of the guyed mast with ancillaries have two distinct peaks with the reduced peak frequencies closed to 0.9 and 2.2, respectively. The characteristics of the vortex shedding spectra for lattice mast and the influence mechanism of the ancillaries were discussed.