超大型冷却塔风荷载特性风洞试验研究

对某超大型冷却塔进行同步测压风洞试验获得内、外表面的脉动风压分布。在外压测试中,改变外表面粗糙度和调整风速等措施,较好地实现了冷却塔大缩尺比模型对表面绕流高雷诺数效应的模拟;采用热线风速仪对冷却塔尾流进行测试,验证了由冷却塔整体气动力时程频谱函数确定涡脱频率方法的合理性;分析了环向断面阻力系数沿塔高的分布规律,在考虑相关性的基础上建议了冷却塔环向外表面的风压极值分布拟合曲线。在内压测试中,比较多种填料层透风率对于内压影响的基础上,采用相关性分析方法确定了内压极值分布规律。

WIND TUNNEL INVESTIGATION ON WIND LOAD CHARACTERISTICS FOR SUPER LARGE COOLING TOWERS

The simultaneous pressure-measured tests of the rigid model for a super large cooling tower were conducted in TJ-3 wind tunnel of Tongji University. In the process of external wind pressure measurement, by adjusting surface roughness and wind velocity, the actual aerodynamic characteristics of archetype cooling towers were successfully illustrated in the scale-reduced model with lower Reynolds number. By measuring tail flow velocity history of the cooling tower model using a hot-wire anemometer, the primary vortex-shedding frequency is proved to be reasonable. The distribution rule about sectional drag force coefficients along the tower height is analyzed based on probability correlation technique, and the fitting curves of wind pressure extreme value distributions along the circumferential direction are proposed. Through measurement of internal pressure distribution for the cooling tower model under various ventilation ratios of stuffing layers located at the bottom of the tower, the internal wind pressure extreme value distributions for commonly-used ventilation ratio are suggested by considering the correlation of aerodynamic pressures.