Comparison of Gas–Liquid Flow Characteristics in Geometrically Different Swirl Generating Devices

Abstract

The gas–liquid flow characteristics for blade, single, and the double-helical swirl elements were numerically investigated and compared in this work. The Euler–Euler model assuming bi-modal bubble size distributions was used. The experiment, conducted in a vertical pipe equipped with a static blade swirl element, was used as the basis for the computational fluid dynamics (CFD) simulations. In the experiment, high-resolution gamma-ray computed tomography (HireCT) was used to measure the gas volume fractions at several planes within the blade swirl element. The resulting calculated profiles of the pressure, liquid and gas velocities as well as the gas fraction showed a large influence of the swirl elements’ geometry. The evolution and characteristics of the calculated gas–liquid phase distributions in different measurement planes were found to be unique for each type of swirl element. A single gas core in the center of the pipe was observed from the simulation of the blade element, while multiple cores were observed from the simulations of the single and double helix elements. The cross-sectional gas distribution downstream of the single and double helical elements changed drastically within a relatively short distance downstream of the elements. In contrast, the single gas core downstream of the blade element was more stable.

Numerical simulation of the gas-liquid flow inside a horizontal static mixer

“…Rotating flow can be found in nature, such as ocean whirlpool [1], tropical cyclones and tornadoes [2] as well as in many engineering applications such as heat transfer [3], combustion [4], phase separation and mixing [5], [6]. In the case of gas-liquid flow, a static swirl element can be used inside a pipe to generate the rotating flow responsible either for mixing or separating the gas and liquid phases [6], [7]. In contrast to a single-phase flow, the gas-liquid flow inside a static mixer is a complex phenomenon [8].…”

“…The computational fluid dynamics (CFD) simulations using the Euler-Euler approach based on the experiment of [6] and [8] were performed by [9] and [8], respectively. A numerical study to compare the gas-liquid flow characteristics for a different type of static swirl elements (i.e., the blade type, the single helix, and the double helix swirl elements) using CFD was performed by [7]. A numerical investigation by [10] demonstrated that the gas distribution inside the vertical static mixer is also influenced by the length to diameter ratio of the static swirl.…”

Experimental and Numerical Study on Flow Resistance and Bubble Transport in a Helical Static Mixer

“…Nevertheless, the flow resistance increases as well [4]. Therefore, many researchers investigated and optimized the hydrodynamic and mixing performance of static mixers with helical flow channels in recent years [10]. Lei et al [11] numerically studied the fluid flow and heat transfer of pipe flow in a modified helical static mixer with perforated holes on the staggered twisted tapes (Figure 1b).…”

Gas-Liquid Flow in a Vertical Pipe Equipped with a Double Helical Swirl Separator Element

“…Swirl elements with different geometries can be found in the open literature e.g. [9]. Figure 1 shows a double helical swirl element [9] used in our preliminary experiment at the Laboratory of Fluid Mechanics, Department of Mechanical and Industrial Engineering, Universitas Gadjah Mada.…”

“…[9]. Figure 1 shows a double helical swirl element [9] used in our preliminary experiment at the Laboratory of Fluid Mechanics, Department of Mechanical and Industrial Engineering, Universitas Gadjah Mada. The element was placed in a vertical pipe to generate swirling flow for the separation between gas and liquid.…”