侧风对湿式冷却塔空气动力场影响的数值分析

Numerical Analysis of Crosswind Effect on Wet Cooling Tower Ae rodynamic Field

基于CFD软件Fluent,对侧风影响下的自然通风逆流湿式冷却塔进行了三维数值模拟,对风速廓线指数和雨滴当量直径进行了敏感性分析,研究了侧风风速对冷却塔内外空气动力场和塔内传热传质区冷却性能的影响。结果表明,侧风造成进风口进风相对偏离度增大,并形成横向通风量;横向通风量虽强化了雨区冷却性能,但使塔纵向通风量降低;纵向通风量的降低对填料区传热传质强度形成不利影响,降低了填料区冷却水温降,使出塔水温升高。进风相对偏离度的分析表明,通过改善进风口空气动力场,可以降低环境侧风对进风口径向风速周向分布的影响,提高侧风影响下的冷却塔总体冷却性能。

Based on CFD code FLUENT, three-dimensional numerical analyses were carried out for natural draft wet cooling tower under crosswind conditions. Sensitivity analyses to parameters such as ambient crosswind velocity profile and water droplet equivalent diameter validated the adopted numerical model. The effect of crosswind on wet cooling tower inner and outer aerodynamic field and tower internal heat and mass transfer performance were investigated numerically. The results show that crosswind causes the increase of air inflow relative departure degree and induces horizontal air mass flow rate which improves rain zone heat and mass transfer but reduces tower vertical air mass flow rate, and then produces an unfavorable effect on fill zone and increases outflow water temperature. The analyses about air inflow relative departure degree show that improving the air inflow aerodynamic field can reduce the unfavorable effect of crosswind on the circumference distribution of air inlet air radial velocity and then improve the total cooling performance of wet cooling tower under crosswind conditons.