HYDRODYNAMICS AND ACOUSTICS

2018 ◊ Volume 1 (91) ◊ Issue 3 ◊ p. 334-354

S. I. Kril^*

^* Institute of Hydromechanics of NAS of Ukraine, Kyiv, Ukraine

The energy model of gas-liquid flows in airlifts

Gidrodin. akust. 2018, 1(3):334-354

https://doi.org/10.15407/jha2018.03.334

TEXT LANGUAGE: Ukrainian

ABSTRACT

An innovative energy approach to studying of general regularities of the ascending gas-liquid flow in airlift's lifting pipe is proposed as a result of developing the fundamental ideas about the airlifting dynamics. It is based on the hydraulic equations of continuity, energy balance and state of phases for steady one-dimensional isothermal motion of gas-liquid mixture in a vertical pipe. The mathematical model is developed considering not only the frictional loss of a hydrodynamic pressure, but also the loss due to phase slip. This is its principal difference from the common hydrodynamic model of similar flows derived from the differential equations of mass and momentum conservation for two-phase flows. It is shown that when determining the pressure loss, the effective density of gas-liquid mixture should be used instead of the flow density. This approach ensures equality among phase kinetic energies. For the first time, an expression is obtained for pressure loss due to phase slip that may be interpreted from a physics perspective as a ratio of specific (per unit of time) work of inter-phase hydrodynamic interaction forces and weight of gas-liquid mixture flowing through actual cross-section. The relation between the pressure loss due to phase slip and total hydrodynamic loss is obtained in the result of numerical studying of the developed energy model for the case of airlift with shell structure of air-water flow. The loss due to phase slip are shown to make 30 to 90% of the total loss. A methodology for calculating the airlift efficiency is developed, the reliability of which is validated by good coincidence of the estimated and experimental flow characteristics in a wide range of lifting conditions for an injection jet mixer.

KEY WORDS

airlift, gas-liquid flow, energy model, pressure loss due to phase friction and slip, flow rate characteristics of airlift

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