雨滴物理特性的粒子成像测量技术研究

Measurement of Raindrop Physical Properties with Particle Imaging Measurement Technology

雨滴形状、直径、降落速度等是表征雨滴特性的重要物理量。为了获取雨滴物理特性参数,基于粒子成像的瞬态测量可视化技术,研制了降雨环境下拍摄雨滴影像的光路系统和成像系统,开发了雨滴影像的识别、提取、量测等软件系统,设计了一种基于面阵电荷耦合元件的自然降雨成像测量系统。钢珠洒落实验发现该技术观测误差小。外场观测实验发现本次降雨主要以中等粒子为主,雨滴直径和降落速度均值分别为2.00 mm和3.52 m/s。雨滴降落速度可由雨滴直径的线性回归方程表达,且该方程的预测准确度和精度较高。可见,该测量技术可以准确地获取雨滴物理特性参数,为降雨特征和土壤侵蚀研究开辟了新途径。

The shape, diameter and fall velocity are the key physical characteristics of raindrops. Thus it is imperative that we begin to focus on the direction of physical characteristics of raindrops. In order to obtain physical properties of raindrops, light field and imaging system were designed based on the particle imaging transient visual measurement technology. The software for image identification, extraction and measurement were investigated, and a natural precipitation imaging measurement system based on a charge coupled device sensor was established. The result of the experiment on steel ball showed that the measurement technology had small relative error. By the field experiment, we found that medium-sized particles were the predominant contributor in the single rainfall, with the diameter of 2. 00 mm and average fall velocity of 3.52 m/s. Mathematic model was developed to calibrate fall velocity and diameter by using linear regression, and the prediction accuracy and precision were reliable. In conclusion, characteristics of raindrops can be measured precisely by the proposed technology, which is a novel method for observing rainfall properties and further researching soil erosion.