To reveal the impact mechanism of water droplet diameter distribution in the rain zone on the cooling capacity and water-splashing noise for natural draft wet cooling towers (NDWCTs), a 3 D numerical model of thermal performance and a theoretical calculation model of water-splashing noise were established and validated, respectively. Using these two models, the influences of different diameter distributions on the ventilation, thermal performance, and the sound pressure level (SPL) of water-splashing noise were analyzed to an NDWCT used for 1000 MW unit. The diameter distribution is described by the number ratios, which is the ratio of the number of water droplets with the same diameter to the total number of all the water droplets in the rain zone. The results revealed that, as the number ratio of the water droplet with a diameter of 1 mm or 2 mm increases, the SPL decreases and the cooling capacity worsens. Conversely, when the number ratio of the water droplet with the diameter of 4 mm increases, the SPL also increases, and the cooling capacity is enhanced. In addition, an increase in the number ratio of the water droplet with a diameter of 3 mm acts to improve the ventilation and thermal performance, while the SPL demonstrates a slight reduction. Therefore, when considering the simultaneous optimization of cooling capacity and water-splashing noise, it is recommended that the number ratio of the water droplet with a diameter of 3 mm is increased. When the number ratio of the water droplet with the diameter of 3 mm reaches 45%, compared with the working condition of the actual measured water droplet diameter distribution, the outlet water temperature reduces by 0.22 °C, the ventilation rate increases by 4.72%, while there is no significant change in the SPL.

为了揭示雨区水滴直径分布对自然通风湿式冷却塔（NDWCT）的冷却能力和水溅噪声的影响机理，建立了一个3D热力数值模型和一个水溅理论计算模型分别建立和验证了噪声。使用这两个模型，分析了用于1000 MW机组的NDWCT的不同直径分布对通风，热性能和水声噪声的声压级（SPL）的影响。直径分布由数量比描述，数量比是相同直径的水滴数与雨区内所有水滴总数的比值。结果表明，随着直径为1毫米或2毫米的水滴的数量比增加，SPL降低，冷却能力恶化。相反，当直径为4mm的水滴的数量比增加时，SPL也增加，并且冷却能力增强。另外，直径3mm的水滴的数量比的增加起到改善通风和热性能的作用，而SPL显示出轻微的降低。因此，在考虑同时优化冷却能力和溅水噪声时，建议增加直径为3 mm的水滴的数量比。当直径为3 mm的水滴的数量比达到45％时，