基于CFD仿真的雨量计雨滴收集效率及其订正模型研究

论文总字数：21496字

目 录

1 引言 4

1.1 选题背景及意义 4

1.2 国内外研究现状 4

1.3 研究目标与方法 5

2 研究方法 6

2.1 翻斗式雨量计的结构，原理与建模 6

2.1.1 翻斗式雨量计结构特征 6

2.1.2翻斗式雨量计的工作原理 6

2.1.3翻斗式雨量计3D建模 6

2.2 固流耦合（计算域和网格划分） 7

2.3 雨量计风场特征仿方案 8

3 结果与分析 9

3.1 流场特征 9

3.2 粒子研究 14

3.2.1 雨滴下落末速度与雨滴粒径的关系 14

3.2.2 雨量计对不同粒径雨滴的收集效率仿真与结果 15

3.3 收集效率拟合分析 18

3.4 订正模型 22

4 总结与展望 23

参考文献： 24

致谢 26

基于CFD仿真的雨量计雨滴收集效率及其订正模型研究

蔡乐天

，China

Abstract： Measuring the amount of precipitation in an area can provide a reliable basis for the calculation and analysis of water resources utilization and disaster warning, and it is of important reference value for flood forecasting, urban road planning, and the degree of dryness and humidity in the area. Rain gauge is the most common and most important meteorological instrument for surface precipitation observation. Environmental wind is the main reason for its impact. Correcting this error has important implications. Based on 3D numerical simulation, this paper conducts 3D modeling of tipping bucket rain gauge, simulates and calculates the velocity field and turbulent flow field around the rain gauge outer cylinder with wind speed between 0 and 12m/s, and sets and simulates the falling process of raindrops of different particle sizes. To obtain the collection efficiency of raindrops for raindrops with different particle sizes at different wind speeds. The results show that：1） the wind field is deformed near the rain gauge. The wind in the parallel horizontal plane flows semi-elliptically around the rain gauge cylinder, and the wind in the vertical plane flows clockwise around the inner cylinder.2) With the increase of wind speed and the decrease of droplet size, precipitation measurement error increases. 3)And when the droplet size is 300um and below, the collection efficiency is significantly affected by the wind speed, and with the decrease of the droplet size, the maximum wind speed value corresponding to the minimum value of collection efficiency is smaller. 4)When the diameter of raindrops is larger than 1000um, the wind field has little effect on the collection efficiency, especially for raindrops with a particle size of more than 2000um, the raindrop's raindrop collection efficiency is greater than 99%. 5) The collection efficiency of raindrops with diameters of 300 μm to 1000 μm is a linear function of the wind speed, and the slopes corresponding to the raindrop collection efficiency functions of different sizes are distributed as a power function with the diameter of the raindrops. According to the collection efficiency of different particle size raindrops, the corresponding revised model equations are obtained.

Key words： Rain gauge; wind speed; particle size; raindrop collection efficiency; revised model

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