“…In this section, the evolution of gas-liquid flow shape and development of gas-liquid two-phase flow in the nozzle exit region are studied to reveal the gas-liquid characteristics of different upstream flow regimes. There are three typical flow regimes (slug, bubbly, or churn flow) in the effervescent atomizer determined by bubble generation and bubble dynamics, as shown in Figure 9 which was observed by the previous experiment, 19 and the gas-liquid structures of the three flow regimes could be well described by Hewitt and Hall Taylor 22 : In slug flow, some of the gas bubbles have nearly the same cross-section as that of the channel and move along in the characteristic bullet-shaped bubbles as illustrated in Figure 9(a). The bubbles of gas are separated by lengths occupied mainly by liquid which may or may not contain a dispersion of smaller gas bubbles.…”
Section: Flow Behavior Under Different Flow Regimesmentioning
“…The detailed operating conditions for investigated case are shown in Table 1, and the upstream flow regime of cases 1,2,6,8 in the flow regime map is shown in Figure 2 (right). Figure 2.The upstream flow regimes of cases in the flow regime map (Right) by previous experiments 19 with the same geometries (Left).…”
Section: Methodsmentioning
confidence: 91%
“…The upstream flow regimes of cases in the flow regime map (Right) by previous experiments 19 with the same geometries (Left).…”
Section: Methodsmentioning
confidence: 99%
“…[16][17][18] The upstream flow regime and initial flow morphology parameters such as the liquid film and bubble size were determined through the visualization experiments. 19 The atomizer geometries (mixing chamber diameter, exit orifice diameter, exit orifice length) are same with the visualization experiments, as can be seen in Figure 2 (left). The diameter of upstream entrance region is same with the mixing chamber diameter.…”
Section: Solvability Conditions and Verificationmentioning
The pressure drop and particular geometric structure of the nozzle exit region of an effervescent atomizer cause complex changes in the flow pattern, which could affect the spray performance. In this study, the gas-liquid twophase flow behavior in the nozzle exit region of the effervescent atomizer was investigated numerically. The results show that the flow behaviors in the nozzle exit region have disparate characteristics with different upstream flow regimes. For upstream churn flow, the liquid film morphology is closely related to fluctuation in the gas-liquid velocity, and the flow parameters (fluids' velocities and gas void fraction) at the exit section vary regularly with time. For upstream bubbly flow, the instantaneous gas void fraction is determined by the bubble distribution inside the mixing chamber. The bubble will form a tadpole-like shape as a result of the complex flow field and the surface tension. The flow parameters at the exit section are in an oscillatory decay, and the fluctuation amplitude is larger than for churn flow. For upstream slug flow, the gas void fraction varies significantly with time. The discrete characteristic of the gas-liquid flow parameters at exit section is very obvious.
“…In this section, the evolution of gas-liquid flow shape and development of gas-liquid two-phase flow in the nozzle exit region are studied to reveal the gas-liquid characteristics of different upstream flow regimes. There are three typical flow regimes (slug, bubbly, or churn flow) in the effervescent atomizer determined by bubble generation and bubble dynamics, as shown in Figure 9 which was observed by the previous experiment, 19 and the gas-liquid structures of the three flow regimes could be well described by Hewitt and Hall Taylor 22 : In slug flow, some of the gas bubbles have nearly the same cross-section as that of the channel and move along in the characteristic bullet-shaped bubbles as illustrated in Figure 9(a). The bubbles of gas are separated by lengths occupied mainly by liquid which may or may not contain a dispersion of smaller gas bubbles.…”
Section: Flow Behavior Under Different Flow Regimesmentioning
“…The detailed operating conditions for investigated case are shown in Table 1, and the upstream flow regime of cases 1,2,6,8 in the flow regime map is shown in Figure 2 (right). Figure 2.The upstream flow regimes of cases in the flow regime map (Right) by previous experiments 19 with the same geometries (Left).…”
Section: Methodsmentioning
confidence: 91%
“…The upstream flow regimes of cases in the flow regime map (Right) by previous experiments 19 with the same geometries (Left).…”
Section: Methodsmentioning
confidence: 99%
“…[16][17][18] The upstream flow regime and initial flow morphology parameters such as the liquid film and bubble size were determined through the visualization experiments. 19 The atomizer geometries (mixing chamber diameter, exit orifice diameter, exit orifice length) are same with the visualization experiments, as can be seen in Figure 2 (left). The diameter of upstream entrance region is same with the mixing chamber diameter.…”
Section: Solvability Conditions and Verificationmentioning
The pressure drop and particular geometric structure of the nozzle exit region of an effervescent atomizer cause complex changes in the flow pattern, which could affect the spray performance. In this study, the gas-liquid twophase flow behavior in the nozzle exit region of the effervescent atomizer was investigated numerically. The results show that the flow behaviors in the nozzle exit region have disparate characteristics with different upstream flow regimes. For upstream churn flow, the liquid film morphology is closely related to fluctuation in the gas-liquid velocity, and the flow parameters (fluids' velocities and gas void fraction) at the exit section vary regularly with time. For upstream bubbly flow, the instantaneous gas void fraction is determined by the bubble distribution inside the mixing chamber. The bubble will form a tadpole-like shape as a result of the complex flow field and the surface tension. The flow parameters at the exit section are in an oscillatory decay, and the fluctuation amplitude is larger than for churn flow. For upstream slug flow, the gas void fraction varies significantly with time. The discrete characteristic of the gas-liquid flow parameters at exit section is very obvious.
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