Experimental study on morphology and flow structure of liquid cone in flow focusing

KANG Peng; GUO Jianfeng; MU Kai; SI Ting

doi:10.11729/syltlx20210159

Volume 36 Issue 2

May 2022

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KANG P，GUO J F，MU K，et al. Experimental study on morphology and flow structure of liquid cone in flow focusing[J]. Journal of Experiments in Fluid Mechanics, 2022，36（2）：74-81. doi: 10.11729/syltlx20210159

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Experimental study on morphology and flow structure of liquid cone in flow focusing

doi: 10.11729/syltlx20210159

Department of Modern Mechanics, University of Science and Technology of China, Hefei　230027, China

Received Date: 2021-10-25
Accepted Date: 2022-02-08
Rev Recd Date: 2022-01-13

Available Online: 2022-05-26

Publish Date: 2022-05-19

Abstract

Abstract

Flow focusing is one of capillary flow techniques that can produce monodisperse droplets, particles and capsules at micro-/nano-scales. In flow focusing, the formation of a stable liquid cone upstream of the small orifice is a prerequisite for further jet generation and efficient preparation of microdroplets. In this work, dimensional analysis is first used to analyze the effects of the focused phase flow rate, driving gas pressure difference, and the distance between the capillary and the focusing orifice on the stability of the liquid cone. Based on the aspirating flow focusing experimental platform, the morphology and stability of the liquid cone are observed, verifying the theoretical analysis. In addition, the stable parameter range of the liquid cone is obtained by adjusting the main process parameters. Moreover, the flow field is visualized by adding tracer particles into the fluid of the focused phase, and the high-speed photography is employed to capture the flow field images, which are analyzed quantitatively to explore the structure of the recirculation zone inside the liquid cone. It is found that the generation of the recirculation cell is closely related to the tangential velocity distribution on both sides of the cone interface, and the size of the recirculation cell is affected significantly by the driving gas pressure difference, the flow rate of focused phase, and the geometric parameters.
- flow focusing,
- cone morphology,
- cone stability,
- recirculation cell

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References(44)

References

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