Experimental investigation of the influence of liquid physical properties and channel dimensions on gas-liquid flow patterns in rectangular microchannels


Аuthors

Bartkus G. V.1, 2*, Kuznetsov V. V.1, 2

1. Novosibirsk State University, Novosibirsk, Russia
2. Kutateladze Institute of Thermophysics, Siberian Branch of RAS, Novosibirsk, 630090, Russia

*e-mail: germanbartkus@gmail.com

Abstract

The influence of microchannel cross section size and physical properties of liquids on the local characteristics of gas-liquid flow in a horizontal microchannel with rectangular section were investigated in this paper. Microchannels with rectangular cross-sections 269×362 and 200х2000 µm and internal T-shaped mixers for forming two-phase flow were used in the expe- riments. The feature of this work consists in application of liquids with various physical proper- ties such as viscosity, surface tension, and density. The distilled water and the aqueous solutions of the ethanol with volume fractions 47.4% and 95% and gas-nitrogen were used. The flow characterization and the local film thickness measurement of the fluid inside the channel were carried out using contactless visualization methods: the high-speed imaging, the laser scanning and the laser-induced fluorescence (LIF). High-speed imaging allowed distinguishing the cha- racteristic flow patterns obtained in the microchannels for the given gas and liquid flow rates. The characteristic flow patterns for the microchannel with cross section 269×362 µm are a perio- dic, a transition (non-periodic) and annular flow regimes. The periodic and the transition flow patterns were observed for the microchannel with cross-section 200×2000 µm for the given speed range. Flow patterns and their boundaries were also confirmed using the laser scanning method. Using the LIF method the dynamics of the liquid distribution along the microchannel long side (362 µm) was obtained for the annular flow of 95% ethanol-nitrogen mixture. It was found that most of the liquid flow in the meniscus, there is also a thin liquid film in the center. The liquid film thickness in the center is increased with the passage of perturbation waves on the meniscus and then decreased before the passage of a new wave. Based on the measurements made by the high-speed video and the laser scanning, flow patterns maps were plotted for the channels with different aspect ratio and liquids with different physical properties. The maps plotted in dimensionless coordinates by Waelchli demonstrate that the dimensionless complex Re0.2We0.4 takes into account the liquid properties and gives a good generalization of the experimental data, but the data for the channels with different aspect ratios are not generalized in these coordinates.

Keywords:

two-phase flow, gas-liquid flow, microchannel, flow pattern map, LIF

References


  1. Kozilin I.A., Kuznetsov V.V. Eksperimental'noe izuchenie struktury gazozhidkostnogo techeniya v pryamougol'nom mini-kanale opticheskimi metodami [Experimental study of structure of gas-liquid flow in rectangular minichannel by optical methods]. Vestnik NGU. Seriya: Fizika – Vestnik NSU. Series: Physics, 2015, vol. 10, no. 3, pp. 63–69. In Russ.

  2. Chinnov E.A., Ron’shin F.V., Kabov O.A. Regimes of two- phase flow in micro- and minichannels (review). Thermophysics and Aeromechanics, 2015, vol. 22, no. 3, pp. 265–284. DOI: 10.1134/S0869864315030014

  3. Bartkus G.V., Kuznetsov V.V. Eksperimental'noe izuchenie detal'noj struktury gazozhidkostnogo techeniya v pryamougol'nom mikrokanale [Experimental investigation of detailed structure of gas-liquid flow in rectangular micro- channel]. Vestnik NGU. Seriya: Fizika – Vestnik NSU. Se- ries: Physics, 2016, vol. 11, no. 1, pp. 73–79. In Russ.

  4. Yagodnitsyna A.A., Kovalev A.V., Bilsky A.V Vizualizatsiya rezhimov techeniya nesmeshivayushhikhsya zhidkostej v mikrokanale T-tipa [Flow pattern visualisation of immiscible liquid-liquid flow in a T-shaped microchannel]. Sovremennaya nauka: issledovaniya, idei, rezul'taty, tekhnologii – Modern science: research, ideas, results, technology, 2015, no. 1, pp. 207–210. In Russ.

  5. Günther A., Jensen K. F. Multiphase microfluidics: from flow characteristics to chemical and materials synthesis. Lab Chip, 2006, vol. 6, pp. 1487–1503. DOI: 10.1039/b609851g

  6. Kozilin I.A., Kuznetsov V.V. Statistical characteristics of two-phase gas-liquid flow in a vertical microchannel. Journal of Applied Mechanics and Technical Physics, 2011, vol. 52, no. 6, pp. 956–964. DOI: 10.1134/S0021894411060149

  7. Boyarshinov B.F., Fedorov S.Yu. Measurement of temperature and concentration of OH radicals in combustion of hydrogen and ethanol by the laser-induced fluorescence technique. Combustion, Explosion, and Shock Waves, 2004, vol. 40, no. 5, pp. 511–515. DOI: 10.1023/B:CESW.0000041402.12524.07

  8. Waelchli S., Rudolf von Rohr P. Two-phase flow characteristics in gas-liquid microreactors. Int. Jour. of Multiphase Flow, 2006, vol. 32, pp. 791–806. DOI:10.1016/j.ijmultiphaseflow.2006.02.014

  9. Vargaftik N.B. Spravochnik po teplofizicheskim svojstvam gazov i zhidkostej [Handbook of thermophysical properties of gas and liquids]. Moscow: Science, 1972. 720 p. In Russ.


mai.ru — informational site of MAI

Copyright © 2009-2024 by MAI