Abstract
Monodisperse droplet streams are used to study the droplet wall interaction of ethanol droplets in the micrometer range. Qualitative results are given for different regimes of droplet wall interaction. The phenomena observed range from complete wetting to almost elastic reflection of the droplets. Complete wetting is observed for low wall temperatures, whereas reflection occurs for wall temperatures above the Leidenfrost temperature. For high impact velocities and high wall temperatures above the Leidenfrost temperature the formation of secondary droplets can be observed. Image processing is used to obtain quantitative results for the loss of momentum during wall interaction for cases of droplet reflection without formation of secondary droplets.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Abbreviations
- d :
-
droplet diameter
- d G :
-
orifice diameter
- f G :
-
excitation frequency for droplet production
- r :
-
ratio of velocity components after collision and before collision
- s :
-
droplet spacing
- t W :
-
wall temperature
- u J :
-
velocity of the liquid jet
- u :
-
= √ v2+w2 droplet velocity
- v :
-
droplet velocity component perpendicular to the wall, normal velocity
- w :
-
droplet velocity component parallel to the wall
- We :
-
Weber number
- β :
-
angle between droplet stream and wall
- σ :
-
surface tension of the liquid with respect to the surrounding gas
- ϱ :
-
density of the liquid
- 1:
-
incident
- 2:
-
reflected
- n :
-
normal to the wall
- p :
-
parallel to the wall
- *:
-
measured in the image plane
References
Anders, K.; Roth, N.; Frohn, A. 1991: Simultaneous in situ measurements of size and velocity of burning droplets. Part. Part. Syst. Charact. 8, 136–141
Anders, K.; Roth, N.; Frohn, A. 1992: Operation characteristics of vibrating-orifice generators: The coherence length. Part. Part. Syst. Charact. 9, 40–43
Berglund, R. N.; Liu, B. Y. H. 1973: Generation of monodisperse aerosol standards. Env. Sci. Tech. 7, 147–153
Choi, K. J.; Hong, J. S.1990: Heat transfer characteristics of water droplets interacting with a rotating hot surface. Int. Comm. Heat Mass Transfer 17, 419–429
Gottfried, B. S.; Lee, C. J.; Bell, K. J. 1966: The Leidenfrost phenomenon: Film boiling of liquid droplets on a flat plate. Int. J. Heat Mass. Transfer 9, 1167–1187
Mizikar, E. 1970: Spray cooling investigations for continuous casting of billets and blooms. Iron and Steel Engineer 47, 53–60
Pedersen, C. O. 1970: An experimental study of the dynamic behavior and heat transfer characteristics of water droplets impinging upon a heated surface. Int. J. Heat Mass. Transfer 13, 369–381
Lord Rayleigh 1878: On the stability of liquid jets. Proc. London Math. Soc. 10, 4–13
Wachters, L. H. J.; Westerling, N. A. J. 1966: The heat transfer from a hot wall to impinging water drops in the spheroidal state. Chem. Eng. Sci. 21, 1047–1056
Xiong, T. Y.; Yuen, M. C. 1991: Evaporation of a liquid droplet on a hot plate. Int. J. Heat mass transfer 34, 1881–1894
Yao, S. C.; Choi, K. J. 1987: Heat transfer experiments of monodispersed vertically impacting sprays. Int. J. Multiphase Flow 13, 639–648
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Anders, K., Roth, N. & Frohn, A. The velocity change of ethanol droplets during collision with a wall analysed by image processing. Experiments in Fluids 15, 91–96 (1993). https://doi.org/10.1007/BF00190948
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00190948