Experiment and Analysis of the Drag Force of Freely-Falling Liquid Droplets in Air

• Main Authors: Chen yen-wen, 陳彥文
• Other Authors: C. H. Wang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/61478820771518499845

碩士 === 國立臺灣大學 === 機械工程學研究所 === 90 === In this study we investigated the effect of freely-falling droplets on drag force. A single stream of mono-sized stable droplets were generated by piezo-electric transducer and fell into quiescent surrounding air, then we recorded the trajectory of droplets by CCD camera. The species of droplets included water, hexadecane and heptane. By measuring the velocity and diameter of droplet with time, we got the acceleration profile of droplets and the drag force of droplet along the path. Our experiments included two parts. One was the effect of acceleration and properties on the drag coefficient in isolated droplet；the other was the influence of droplet spacing on the drag coefficient in steady, monodisperse droplet stream. We then tried to nondimensionalize the experiment data as CD, Re, Ac, and S/d ratio. The range of Reynolds numbers were from 5 to 200 and experimental uncertainties were typically less than 5 percent.