考虑导风装置大型冷却塔双塔风致干扰效应研究

Wind-induced interference effects of two large cooling towers with air-deflectors

为研究不同导风装置对双塔干扰下大型冷却塔表面平均和脉动风荷载分布特性的影响,基于风洞试验对比研究了三种有导风装置和无导风装置的大型冷却塔表面风压随机分布特性,其中包括平均风压、脉动风压、峰值因子、极值风压以及干扰因子等气动参数。研究结果表明:增设导风装置后塔筒背风面负压区气流紊乱,平均风压呈现明显波动;不同导风装置对塔筒下部断面测点峰值因子影响显著,数值主要分布在3.2~3.6之间;极值风压分布规律类似于冷却塔模态的正反对称特点,外部进水槽对喉部侧风面极值风压增大了近0.5;90°风向角为双塔布置的最不利工况,夹道效应导致塔筒侧风面平均风压、脉动风压与极值风压变化显著,此时带外部进水槽的冷却塔中上部断面层阻力系数的干扰因子达到最大值。

In order to study the effect of different air-deflectors on surface wind load of two cooling towers, investigations for large cooling towers are conducted by three wind tunnel tests with the air-deflectors and one without the air-deflector on wind pressure characteristics including the mean wind pressure, fluctuating wind pressure, peak factor, extreme wind pressures, and interference factors. Results show that, additional air-deflectors lead to negative pressure airflow disturbance in the leeward area of the towers, and significant fluctuations are observed in the mean wind pressure. Additional air-deflectors have significant influence on the peak factor of the lower sections, however, insignificant influence is observed on the measurement points in upper sections. The values of the peak factor are between 3.2 and 3.6. The extreme wind pressure distributions display a symmetric mode, which is similar to the mode of cooling tower. The extreme wind pressure increases by about 0.5 on the cooling tower at the throat sides with external sink. A 90-degree wind direction is the worst condition for the two towers, since the mean wind pressure, the fluctuating wind pressure, and the extreme wind pressures at tower sides significantly change due to the channel-effect. The interface factors reach its maximum values in the upper sections on the cooling tower with external sink.