Free surface air entrainment and single-bubble movement in supercritical open-channel flow

View/ Open
Guo_Journal_of_Hydraulic_Engineering.pdf (2.095Mb)
Download
Publication date
2020-07Rights
This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. This material may be found at https://doi.org/10.1061/(ASCE)HY.1943-7900.0001769.Peer-Reviewed
YesAccepted for publication
2020-01-13
Metadata
Show full item recordAbstract
There has been little study on the microscopic bubble entrainment and diffusion process on the high-speed self-aerated flows although the problem under investigation is theoretically important and has important engineering application. This study presents an experimental investigation on visual processes of free surface air entrainment and single bubble diffusion in supercritical open channel flows. The typical surface deformation, single air bubble rising and penetration are recorded using a high-speed camera system. Results show that for a single bubble formation process, surface entrapment development and bubble entrainment through a deformation evolution underneath the free surface are the two main features. The shape variation of local surface deformation with time follows an identical power law for different bubble size generations. The entrained bubble size depends on both size scale and shape of entrapped free surface. As the single bubble moves downstream, its longitudinal velocity is approximately the same as that of water flow surrounded it, while its vertical velocity for rising and penetration increases with the increase of the water flow velocity. An empirical-linear relationship for the bubble rising and penetration velocity with water flow velocity is obtained. This study demonstrates that the microscopic bubble movement can improve the self-aeration prediction in the open channel flow and advance the knowledge of our understanding of the macroscopic and microscopic air–water properties in hydraulic engineering.Version
Accepted manuscriptCitation
Wei W, Xu W, Deng J et al (2020) Free surface air entrainment and single-bubble movement in supercritical open-channel flow. Journal of Hydraulic Engineering. 146(7): 04020050.Link to Version of Record
https://doi.org/10.1061/(ASCE)HY.1943-7900.0001769Type
Articleae974a485f413a2113503eed53cd6c53
https://doi.org/10.1061/(ASCE)HY.1943-7900.0001769