Experimental study on two-phase flow in rod bundle channels based on wire mesh sensor
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摘要: 为研究压水堆棒束通道内气液两相流型特性及演变规律,基于双层丝网传感器(WMS)在常温常压下开展了3×3棒束通道内的空气-水两相流型测量实验,流型包含泡状流、泡-帽状流和弹状流。结果表明:常温常压下横向升力方向发生反转的临界气泡直径范围为4~5.8 mm。此外,对于泡状流,气相表观速度较低时,空泡份额呈现“壁峰”分布;气相表观速度较高时,呈现“中心峰”分布。对于泡-帽状流,相邻子通道内,帽状气泡交叉分布,并引发液相在相邻子通道间的大尺度交混,空泡份额呈现“中心峰”分布。对于弹状流,大尺寸气泡沿轴向发展会跨越子通道间隙并聚合为弹状气泡,空泡份额“中心峰”分布更为明显。将实验数据用以评价部分漂移流模型,其中Bestion漂移流模型因高估漂移速度,导致空泡份额预测结果偏小;Ozaki漂移流模型对空泡份额预测较为精准,其平均相对误差为9.8%。Abstract: To study the characteristics and evolution of the gas-liquid two-phase flow pattern in the rod bundle channel of pressurized water reactor, based on the double-layer wire mesh sensor, the air-water two-phase flow pattern experiment of the 3×3 rod bundle channels was carried out at room temperature and pressure. The flow patterns include bubble flow, cap flow and slug flow. The experimental results show that, the critical bubble diameter range for the reversal of lateral lift direction under normal temperature and pressure is 4 to 5.8 mm. In addition, for bubbly flow, the time-averaged void fraction exhibits a “wall peak” distribution at lower superficial gas velocities and a “central peak” distribution at higher superficial gas velocities. For the cap flow, the cross distribution of cap shaped bubbles within adjacent subchannels triggers large-scale mixing of the liquid phase between adjacent subchannels, and the time-averaged void fraction exhibits a “central peak” distribution. For slug flow, large-sized bubbles develop along the axis and cross subchannel gaps to aggregate into slug shaped bubbles, with a more pronounced distribution of the central peak of void fraction. The experimental data are used to evaluate three drift-flux models. The Bestion’s drift-flux model overestimates the drift velocity, resulting in underestimated void fraction predictions. The Ozaki’s drift-flux model provides more accurate predictions of void fraction than the Xu Han model, with an average relative error of 9.8%.
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Key words:
- two-phase flow /
- wire mesh sensor /
- void fraction /
- bubble size distribution /
- drift-flux model
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表 1 典型工况参数
Table 1. Typical operating condition parameters
No. superficial liquid velocity/(m·s−1) superficial gas velocity/(m·s−1) void fraction 1 1.34 0.023 0.015 2 1.34 0.138 0.104 3 1.34 0.207 0.143 4 1.34 0.277 0.170 5 1.34 0.322 0.187 6 1.34 0.414 0.210 7 1.34 0.737 0.264 -
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