降雨之模擬及雨滴特性之量測

Simulation of Rainfall and Measurements of Raindrop Characteristics

10.29417/JCSWC.199211_23(2).0001

盧昭堯(Jau-Yau Lu)；吳益裕(I-Yu Wu)

人工降雨器 ； 雨點粒徑分佈 ； 雨點落速 ； Rainfall Simulator ； Raindrop Size Distribution ； Fall Velocity

中華水土保持學報

23卷2期（1992 / 11 / 01）

1 - 12

繁體中文

人工降雨模擬裝置可控制雨滴粒徑分佈與落速，且其結果具有重覆性與連續性，因此人工降雨器是從事室內或室外土壤沖蝕研究之重要工具。本研究採用一組室內人工降雨器，該降雨器可利用旋轉頻率之改變，模擬均匀與非均匀之降雨。本文對於量測雨點粒徑分佈與落速之方法亦進行深入探討。在雨滴粒徑量測方面，本研究自行設計了一個由計時器控制快門移動速度之電動雨滴收集盒，利用苯胺藍染料法及高解析度、高灰度值並可自動分析水滴面積之彩色影像掃描處理系統，精確而迅速地推估雨點粒徑分佈。至於水滴降落速度試驗方面，本研究採用了兩種試驗方法。第一種方法係利用美製數位式高頻閃光測器，配合照相機實施攝影量測，而第二種方法係利用紅外線感應器量測。根據實驗結果，本文並針對雨滴粒徑與落速之量測方法及人工降雨器之優缺點進行評估。本研究無論對於室內沖蝕力學之基礎試驗，自然降雨特性之了解，以及土壤沖蝕之相關試驗研究皆有助益。

Rainfall simulator can simulate rainstorms with different raindrop size distribution and fall velocity. It not only can reproduce the rainstrom durations of interest at select intensities (reproducibility) but also apply raindrop nearly continuous throughout the study area (continuity). Therefore, rainfall simulator is a powerful tool for soil erosion research. This study used a rainfall simulator to simulate both the uniform and nonuniform rainfall. by changing the revolution speed of rainfall simulator. The methods of measuring both the ranidrop size distribution and fall veocity were also investigated in this study. a rainfall collector with timer and remote controller was designed for measuring the raindrop size distributions. The aniline blue method and a color image scanner analysis system with high resolution and high grayscale value were used to accurately and efficiently estimate the ranidrop size distributions. Two methods were used to measure the falling velocity of raindrops. The first method used a U.S.-made digital, high frequency strobescope with camera. The second method used an infrared sensor. The raindrop falling velocity and raindrop size distribution measuring techniques, and the advantages and disadvantages of the rainfall simulators were evaluated according to the experimental results. This study is useful for the basic research of erosion mechanics, understanding of the characteristics of natural rainfall, and other related studies.