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Experimental Study of Chamber Volume Effect on Bubble Growth from Orifice Plates Submerged in Liquid Pools

Gokhale, Omkar S
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1554217036036588

Abstract Details

2019, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Experimental study of the air bubble formation from orifice plates submerged in pools of water and aqueous glycerin solutions has been carried out. Air is forced through the orifice by supplying it to a chamber connected to the orifice plate to form isolated bubbles. The chamber volume affects the bubble growth time as well as bubble size and shape at departure. The effect of chamber volume is generally correlated in term of a dimensionless parameter, capacitance number (Nc), which is proportional to the chamber volume and is inversely proportional to the square of the orifice diameter. To better understand and characterize this effect, experimental measurements of the size and shape of bubble are carried out using high speed videography for capacitance numbers from 0.2 to 24. This large range of Nc was achieved by using ten orifice plates of diameter ranging from 0.61 mm to 2.261 mm with six different chamber volumes between 12 cc and 59 cc. Also, to study the interplay of surface wettability and chamber volume, orifice plates made of acrylic glass (hydrophilic) and Teflon (hydrophobic) are used. Furthermore, to understand the effect of viscosity, bubble growth dynamics was captured in the pools of aqueous glycerol solutions of three different concentrations with viscosities of 730 cp, 372 cp and 127.5 cp, respectively. First, experiments were conducted with acrylic glass orifice plates in pure water. It was observed that the value of the critical capacitance number or Nc* above which the bubble evolution is affected by the gas chamber volume, is around 0.85. Above Nc > ~ 0.85, this effect manifests in producing more spherical bubbles with shorter growth times. Above Nc > 10, the chamber effects plateau and further increase in gas chamber volume does not alter bubble size and shape at departure. The study confirms that at low capacitance number (Nc ~0.85), the bubbles formed in viscous liquid pools are only slightly larger than those formed in pure water. The viscosity effects are dominant in case of smaller orifice diameters. The shape of the bubble is elliptical in viscous pools at all chamber volumes as compared to the bubbles with sharp apex in case of water. Experiments are conducted with water and glycerin solutions using five Teflon orifice plates to study the interplay of the chamber volume effect and contact angle effect. Due to the spreading of the bubble on the orifice substrate, the bubble departure diameter is itself larger in case of hydrophobic substrates. However, the departure size does not change with varying chamber volume. At larger Nc, the air flow in the bubble is faster. This increased bubble frequency provides a shorter time for surface de-wetting. In essence, the two effects neutralize each other, and bubble size remains unchanged with a change in the chamber volume. This behavior is elucidated in this thesis through high speed photographs of the process.
Milind Jog, Ph.D. (Committee Chair)
Raj Manglik, Ph.D. (Committee Member)
Sanjivan Manoharan, PhD (Committee Member)
119 p.
Mechanical Engineering
Bubble dynamics; Chamber volume; Hydrophilic; Hydrophobic

Recommended Citations

Citations

  • Gokhale, O. S. (2019). Experimental Study of Chamber Volume Effect on Bubble Growth from Orifice Plates Submerged in Liquid Pools [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1554217036036588

    APA Style (7th edition)

  • Gokhale, Omkar. Experimental Study of Chamber Volume Effect on Bubble Growth from Orifice Plates Submerged in Liquid Pools. 2019. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1554217036036588.

    MLA Style (8th edition)

  • Gokhale, Omkar. "Experimental Study of Chamber Volume Effect on Bubble Growth from Orifice Plates Submerged in Liquid Pools." Master's thesis, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1554217036036588

    Chicago Manual of Style (17th edition)

ucin1554217036036588
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