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Experimental Investigation of Effect of Viscosity on Aperiodic Bubbling from Submerged Capillary-Tube Orifices in Adiabatic Liquid Pools

Deora, Aakash
http://orcid.org/0000-0001-6229-4356
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563271814185849

Abstract Details

2019, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
This thesis focuses on experimental investigation and subsequent regime mapping of the aperiodic bubbling from submerged capillary orifices through quiescent adiabatic liquids with varying viscosities. A high-speed and high-resolution digital camera is used to capture formation, departure, and coalescence of air bubbles in static liquids. Water and five glycerol-water mixture with 36%, 48%, 65%, 77%, and 87% glycerol by volume are used to alter dynamic viscosity while keeping density and surface tension nearly the same. Five stainless steel orifices with diameter- 0.8 mm, 1 mm, 1.4 mm, 1.8 mm and 2.4 mm are used to vent compressed air through the liquids with air Reynolds number ranging from 100 to 1800. With increase in the flow rate, bubble frequency increases and beyond a critical value wake effect of the preceding bubble affects the formation and departure of trailing bubble. Due to this wake effect trailing bubble rises faster and coalesces with the leading bubble. In this flow regime fluid dynamics is conducive to coupling. With further increase in the flow rate, wake effect grows in strength and facilitates coalescence of two already coalesced bubbles. This regime is called quadrupling regime. For water, a tripling regime is also observed for orifice diameters 1 and 1.8 mm, where a single trailing bubble coalesces with a coupled bubble. Effect of viscosity on aperiodic bubbling is investigated using different glycerol-water solutions. Mathematical analysis of experimental data shows that Capillary number is an appropriate physical parameter for the characterization of different bubbling regimes. Effect of orifice diameter is also studied and for smaller orifice diameters, bubbles are seen to coalesce closer to orifices and coalescence takes place at larger Capillary numbers. For quadrupling, a high value of Ca is obtained for the smallest orifice and this is almost thrice the value for the largest orifice. A correlation between Capillary Number and non-dimensional orifice diameter is derived from the experimental data for the coupling regime; which can be used to predict transitional Ca values for liquids of varying viscosity. The correlation uses Morton Number to factor in the balance of forces i.e. viscous force, buoyancy and surface tension, in bubble dynamics to predict the transitional Ca with an accuracy of 35%. Similar effort was made to understand and analyze the experimental data in the quadrupling regime. But, due to the strong non-linear effect of viscous drag along with experimental limitation of analyzing both wake effect and inertia force of the surrounding liquid involved in this regime, it would require further experimentation with more glycerol solutions. This is recommended for future experimental investigation.
Milind Jog, Ph.D. (Committee Chair)
Je-Hyeong Bahk, Ph.D. (Committee Member)
Raj Manglik, Ph.D. (Committee Member)
93 p.
Mechanical Engineering
glyceol solutions; aperiodic bubbling; effect of viscosity; coalescence distance; coupling regime; quadrupling regime

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Citations

  • Deora, A. (2019). Experimental Investigation of Effect of Viscosity on Aperiodic Bubbling from Submerged Capillary-Tube Orifices in Adiabatic Liquid Pools [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563271814185849

    APA Style (7th edition)

  • Deora, Aakash. Experimental Investigation of Effect of Viscosity on Aperiodic Bubbling from Submerged Capillary-Tube Orifices in Adiabatic Liquid Pools. 2019. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563271814185849.

    MLA Style (8th edition)

  • Deora, Aakash. "Experimental Investigation of Effect of Viscosity on Aperiodic Bubbling from Submerged Capillary-Tube Orifices in Adiabatic Liquid Pools." Master's thesis, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563271814185849

    Chicago Manual of Style (17th edition)

ucin1563271814185849
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This open access ETD is published by University of Cincinnati and OhioLINK.