基于雨滴谱的人工降雨系统效能评估

Reliability Analysis for Artificial Rainfall System Based on Raindrop Spectrum Detector

采用德国HSO-OTT Persive132激光雨滴谱探测仪，结合中国科学院水循环与陆表过程重点实验室的人工降雨系统，从均匀性、雨强、雨滴谱、雨滴终点速度和动能5方面评估人工降雨系统模拟降雨的特征及其与自然降雨的相似性。结果表明：（1）该降雨系统模拟降雨均匀系数为0．83，降雨均匀性较好；当模拟雨强I≤1．0mm／min时降雨可靠性较高，模拟雨强I〉1．0mm／min时，受降雨系统喷头孔径等因素影响，实际雨强小于设计值，可靠性较低；短历时模拟降雨开始的第1min和结束的最后1min实际雨强远小于设计雨强，数据不可靠；建议开展短历时模拟降雨试验时恰当延长降雨时间，选取其中较可靠的数据以减少试验结果误差。（2）该模拟降雨雨滴直径在0．1～1.9mm之间，平均直径0．9mm，比自然降雨的雨滴直径0．1～6．5mm要小；该模拟降雨的雨谱分布符合自然降雨Best函数分布。（3）直径在0．3～0．7mm范围内的雨滴其终点速度与自然降雨拟合较好，当雨滴直径〈0．3mm和〉0．7mm时，雨滴终点速度可靠性较低。（4）该系统模拟降雨的雨滴动能可靠性不高，当雨滴直径≥0．6mm时，该雨滴动能小于自然降雨；当雨滴速度〉2．0m／s时雨滴动能大于自然降雨。建议通过选择合适的喷嘴内径尺寸和数量组合提高雨滴直径可靠性，从而实现雨强和降雨动能与自然降雨的一致。

By using advanced laser HSC-OTT Persivel32 raindrop spectrum detector（Germany）,raindrop size distribution under different artificial rainfall intensity was detected in Key Laboratory of Water Cycle and Related Land Surface Processes,CAS.The reliability of indoor artificial rainfall simulation was evaluated by5 properties of artificial：uniformity,rainfall intensity,raindrop size distribution,terminal velocity and kinetic energy.Results showed that（1）uniformity coefficient of the artificial rainfall was 0.83,reaching the requirement of uniformity of artificial rainfall at home and abroad.The artificial rainfall system was more reliable when artificial rainfall intensity I≤1.0mm/min.When artificial rainfall intensity I1.0mm/min,the real rainfall intensity was lower than design value because of the influence of nozzle diameter of artificial rainfall system,and the artificial rainfall system was less reliable.The rainfall intensities at the first and last minute of short duration artificial rainfall were unreliable,which were much lower than design value.Therefore,it is suggested to extend the time of short duration artificial rainfall and select reliable data to reduce the error of experimental results.（2）The raindrop diameter of artificial rainfall was in the range of 0.1to 1.9 mm,averaging 0.9 mm,which was much smaller than that of natural rainfall（0.1to 6.5 mm）.The raindrop spectrum obeyed Best distribution.（3）The raindrop terminal velocity of simulated rainfall was similar with that of natural rainfall when raindrop diameter ranged from 0.3 mm to 0.7 mm,while less reliable when raindrop diameter was smaller than 0.3mm or larger than 0.7mm.（4）The raindrop kinetic energy of artificial rainfall was unreliable,which was lower than that of natural rainfall when raindrop diameter（d）was larger than 0.6mm while greater than that of natural rainfall when raindrop terminal velocity（v）was higher than2.0m/s,mainly due to the smaller raindrop diameter.It is possible to improve reliability of intensity and raindrop kinetic energy of artificial rainfall by selecting suitable nozzle diameter and number.