Study on flow pattern and transition mechanism of gas-liquid two-phase flow in swirl field under pulsating flow

doi:10.11949/0438-1157.20220769

Abstract

Abstract:

Using high-speed camera technology, the dynamic behavior of bubbles and gas-liquid two-phase flow pattern in the cyclone separator were studied under the condition of flow pulsation. It was found that the flow fluctuated in the range of 3.62—4.18 m³/h during the full pulsation cycle. In the flow-enhancing section, the gas core migrates toward the overflow as a whole. And the gas core migrates toward the bottom cone as a whole in the flow-decreasing section, and the size and shape of the gas core changes periodically. Through the analysis of special frames in the pulsation period, it is concluded that the gas-liquid two-phase flow patterns in the swirl field under the condition of flow pulsation mainly include: bubble flow, plug flow, slug flow, silk flow and wavy flow. According to the experiment, the converted velocity of gas-liquid two-phase is obtained. And the limit diagram of the flow pattern conversion of gas-liquid two-phase flow is determined under pulsating conditions. The coalescence and fragmentation behavior between bubbles is the main reason for generating the gas-liquid two-phase flow pattern. Ultimately, an evaluation model was constructed to characterize the relationship between cross-section gas content and separation efficiency.

Key words: pulsating flow, bubble, hydrodynamics, gas-liquid two-phase flow, flow pattern, coalescence and breakage

摘要：

运用高速摄像技术对流量脉动条件下旋流分离器内气泡动力学行为及气液两相流流型展开研究。研究发现，在完整脉动周期内，流量在3.62~4.18 m³/h范围内波动，流量增大段的气核整体向溢流口方向运移，流量减小段的气核整体向底流口方向运移，气核大小及形态变化呈现周期往复性。通过脉动周期内特殊帧的分析，得出流量脉动条件下旋流场内气液两相流流型主要包括：气泡流、塞状流、弹状流、丝状流及波状流等五种形式。根据实验得出的气液两相折算速度，确定了脉动条件下气液两相流流型转换界限图，而气泡间的聚并破碎行为是产生气液两相流型的主要原因，最终构建了表征截面含气量和分离效率之间关系的评价模型。

关键词: 脉动, 气泡, 流体动力学, 气液两相流, 流型, 聚并破碎

CLC Number:

TE 329

Rui YANG, Baojin ZHU, Chao LYU, Lei ZHANG, Yingsong XIAO. Study on flow pattern and transition mechanism of gas-liquid two-phase flow in swirl field under pulsating flow[J]. CIESC Journal, 2022, 73(10): 4389-4398.

杨蕊, 朱宝锦, 吕超, 张磊, 肖迎松. 脉动条件下旋流场内气液两相流流型及其转变机理[J]. 化工学报, 2022, 73(10): 4389-4398.

Figures/Tables 18

Fig.1 Cyclone separator

Table 1 Dimension parameters

参数	数值/mm
混合相入口管尺寸a×b	15×5
溢流管直径D₁	26
柱段直径D₂	70
底流管直径D₃	12
小柱段直径D₄	24
分离器总长度L₁	746
柱段长度L₂	218
分离器锥段长度L₃	236
小柱段长度L₄	111
底锥长度L₅	247

Fig.2 Experimental process

Fig.3 High-speed camera test observation area

Fig.4 Gas-liquid two-phase supply equipment

Fig.5 Image contour extraction

Fig.6 Flow pattern in complete pulsating period

Fig.7 Flow fluctuation curve

Fig.8 The overall flow pattern of flow enhancement section

Fig.9 The overall flow pattern of flow weakening section

Fig.10 Gas-liquid two-phase flow pattern

Table 2 Conversion speed

f /帧	气相折算速度v_sg/(m/s)	液相折算速度v_s_l /(m/s)
1	0.793	5.707
150	0.621	5.686
190	0.274	5.652
230	0.506	5.475
314	0.171	4.811
420	0.159	3.815
450	0.342	4.701
528	0.613	4.725
628	0.913	4.838

Fig.11 Flow pattern conversion boundaries

Fig.12 The coalescence of multiple bubbles

Fig.13 Bubble breaking behavior

Table 3 Parameter values and errors

参数	数值	标准误差	t值	概率＞ $t$	相关性
A₁	76.08032	0.34724	219.10098	3.75824×10^-11	0.6802
A₂	87.91143	0.60443	145.44468	2.91471×10^-10	0.86843
$l g x 0$	0.0845	0.00296	28.53214	9.90679×10^-7	0.75051
p	-23.94055	3.78331	-6.32794	0.00145	0.81657

Table 3 Parameter values and errors

参数	数值	标准误差	t值	概率＞ $t$	相关性
A₁	76.08032	0.34724	219.10098	3.75824×10^-11	0.6802
A₂	87.91143	0.60443	145.44468	2.91471×10^-10	0.86843
$l g x 0$	0.0845	0.00296	28.53214	9.90679×10^-7	0.75051
p	-23.94055	3.78331	-6.32794	0.00145	0.81657

Fig.14 Fitting curve of separation efficiency

Table 4 Fitting effect

评价指标	数值
Reduced Chi-Sqr	0.15034
R²(COD)	0.99571
调整后R²	0.99314

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