Numerical simulation is an important means to study the thermal and resistance characteristics of natural draft wet cooling towers. The treatment method of droplet diameter distribution in the rain zone directly affects the accuracy of the numerical model, which becomes a key problem in the numerical simulation at present. In this paper, to provide an appropriate treatment method of droplet diameter, three kinds of droplet diameter distribution treatment models for the numerical simulation are studied and compared, including equivalent diameter method (EDM), Gaussian distribution method (GDM), and diameter distribution method based on field test (FTDM), and the influences of each treatment method on the simulation results are presented respectively, which provide references for the subsequent numerical simulation. It is found that each method can reasonably simulate the thermal characteristics of the cooling tower by determining their key parameters, but the temperature drop calculated by FTDM is the most accurate with a relative error of 0.58%. Additionally, FTDM can most accurately simulate the pressure drop with a relative error of 4.18% and the motion trajectory of the water droplets, so the FTDM should be given priority under the premise of known the droplet diameter distribution data of the tower.

数值模拟是研究自然通风湿式冷却塔热阻特性的重要手段。雨区液滴直径分布的处理方法直接影响数值模型的准确性，这成为目前数值模拟中的关键问题。为了提供一种合适的液滴直径处理方法，研究并比较了三种用于数值模拟的液滴直径分布处理模型，包括等效直径法（EDM），高斯分布法（GDM）和直径分布法。基于现场试验（FTDM），分别介绍了每种处理方法对模拟结果的影响，为后续的数值模拟提供参考。发现每种方法都可以通过确定其关键参数来合理地模拟冷却塔的热特性，但是FTDM计算的温度降是最准确的，相对误差为0.58％。另外，FTDM可以最精确地模拟相对误差为4.18％的压降和水滴的运动轨迹，因此应在已知塔的水滴直径分布数据的前提下优先考虑FTDM。