静态龙卷风下输电塔塔头风荷载特性试验研究

Wind Tunnel Test on Wind Load Characteristics of Transmission Tower Head Under Stationary Tornado

摘要:

利用龙卷风模拟器生成实验室尺度龙卷风，并验证模拟龙卷风的可靠性。在此基础上完成了两类涡流比龙卷风风场下典型输电塔塔头子结构模型的高频测力天平（HFFB）测力试验，研究了塔头模型在龙卷风作用下各向气动力系数的分布规律，并探究了龙卷风作用下塔头模型特有的扭转效应影响。结果表明：试验模拟的龙卷风风场与实测龙卷风吻合良好。塔头模型水平面合力系数最大值分别发生在1~1.5倍涡核半径位置附近。升力系数一般小于对应工况下阻力系数。而相较于风轴坐标系下气动力系数，体轴坐标系下气动力系数对风向角更为敏感。不同气动力系数最不利风向角差异性也较大。同时，受龙卷风较强旋转切向风速影响，具有长横担的输电塔塔头模型在位于龙卷风内部时会受到不可忽略的扭转作用，且扭转系数随涡流比的减小而增大。

关键词:输电塔;龙卷风荷载;龙卷风模拟器;塔头子结构;气动力系数;扭转系数

Abstract:

Laboratory scale tornado was generated with tornado vortex simulator， and the reliability of the simulated tornado was also verified. On this basis， wind-force measurement tests with high frequency force balance （HFFB） for typical transmission tower head model was completed under tornado wind fields with two kinds of swirl ratio. The distribution characteristics of the aerodynamic coefficients of tower head under tornado were studied. Moreover， the unique torsional effect of the tower head under tornado was also analyzed. The experimental results show that， the simulated tornado vortex matches well with the measured tornado. The maximum horizontal force coefficients of the tower head occur near the positions of 1 to 1.5 times the radius of the vortex core. The lift coefficient is generally smaller than the resistance coefficient under the corresponding conditions. Compared to the aerodynamic coefficient in the wind-axis coordinate system， the aerodynamic coefficient in the body-axis coordinate system is more sensitive to the wind angle. The difference in the most unfavorable wind angle among different aerodynamic coefficients is also significant. In addition， due to the strong tangential wind velocity of tornadoes， the tower head model with long cross-arm will experience an undeniable torsion effect when located inside the tornado， and the torsion coefficient increases with the decrease of swirl ratio.

Key words:transmission tower;tornado wind load;tornado vortex simulator;tower head;aerodynamic force coefficient;torsion coefficient