Study on fall velocity of continuously ejected micro inkjet droplet
- PDF / 739,899 Bytes
- 5 Pages / 595.22 x 842 pts (A4) Page_size
- 23 Downloads / 175 Views
DOI 10.1007/s12206-020-0723-1
Journal of Mechanical Science and Technology 34 (8) 2020 Original Article DOI 10.1007/s12206-020-0723-1 Keywords: · DOD (drop-on-demand) print · Piezoelectric inkjet · Successive droplet · Terminal velocity
Correspondence to: Han Seo Ko [email protected]
Citation: Kang, S.-H., Kim, S., Lim, J. W., Sohn, D. K., Ko, H. S. (2020). Study on fall velocity of continuously ejected micro inkjet droplet. Journal of Mechanical Science and Technology 34 (8) (2020) ?~?. http://doi.org/10.1007/s12206-020-0723-1
Received October 2nd, 2019 Revised
June 2nd, 2020
Accepted June 14th, 2020 † This paper was presented at AJKFluids2019, Hyatt Regency, San Francisco, CA, USA, July 28 August 1, 2019. Recommended by Guest Editor Seongwon Kang and Hyoung-gwon Choi
Study on fall velocity of continuously ejected micro inkjet droplet Seung-Hwan Kang1, San Kim2, Jong Woo Lim2, Dong Kee Sohn2 and Han Seo Ko2 1
Aaeropropulsion Research Division, Korea Aerospace Research Institute, 169-84 Gwahak-ro, Daejeon, 2 Korea, School of Mechanical Engineering, Sungkyunkwan University, 2066, Seobu-ro, Suwon, Korea
Abstract
One of the most important design parameters for the inkjet printing device is the inkjet drop velocity, which changes along the falling path from the ejection out of a nozzle to the impact on a substrate. Therefore, in this study, the droplet velocity of the piezoelectric drop-ondemand inkjet was measured. The nozzle diameter was 70 μm and polyethylene glycol aqueous solution was used as ink. The inkjet droplets were generated within a range from 500 to 10000 Hz of frequencies at a reference piezoelectric input voltage. The successive inkjet droplets were captured by the high-speed camera with 100000 fps, then the inkjet droplet velocities were analyzed visually at each falling location. The velocity change of a drop up to its terminal velocity was calculated theoretically to be compared with the experimental results. This study found that the velocity of the continuously ejected droplets depended on the interval of the droplets, as well as the density and diameter of the droplet which are essential factors of the general velocity change of a falling drop. The inkjet droplets with the long interval can be considered as an independent droplet so that it can follow the terminal velocity curve of the general drop. However, the inkjet droplets with short interval have the higher velocity than the general terminal velocity curve. It is considered that each droplet gets into the wake field of the former droplet so that its drag force can decrease and the velocity can increase.
1. Introduction The inkjet technology has been developed with micro-sized droplets not only for graphic printing but also for many other applications especially such as printed electronics. For this purpose, a drop-on-demand (DOD) method, one of the inkjet technologies, which prints the ink drop by drop at required instant and location, is being widely used. The piezoelectric element is used to generate the droplets. In order to ma
Data Loading...
