Experimental Investigation on Void Fraction Distribution of Boiling Flow in 2×2 Rod Bundle Channel
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摘要: 电导探针方法是一种获取两相界面参数的重要手段。通过单探头电导探针测量并分析了2×2棒束通道内流动沸腾空泡份额的径向分布,结果表明,在当前实验工况下,从汽泡信号的波动特性来看,通道中心处的汽泡信号主体波动幅度较小,棒间隙处的汽泡信号主体波动幅度较大;空泡份额径向分布均呈现出中心峰的分布特性,中心峰呈现出下凹的现象,这是由于中心处的汽泡相对于壁面处的汽泡吸收的热量更小而发生冷凝。Abstract: The conductivity probe method is an important methodology to obtain two-phase interfacial parameters. The radial distribution of the boiling flow void fraction in the 2 × 2 rod bundle channel was measured and analyzed by a one-sensor conductivity probe. The results show that under the current experimental conditions, from the fluctuation characteristics of the bubble signal, the fluctuation amplitude of the bubble signal main body at the center of the channel is small, and the fluctuation amplitude of the bubble signal main body at the rod gap is large. The radial distribution of void fraction shows the distribution characteristics of the core peak, and the core peak shows a concave phenomenon, which is due to the bubble at the center receives less heat than that at the wall.
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Key words:
- Conductivity probe /
- Rod bundle channel /
- Boiling flow /
- Void fraction
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表 1 棒束通道实验工况
Table 1. Experimental Conditions of Rod Bundle Channel
工况
序号压力/
MPa质量流速/
(kg·m−2·s−1)入口过冷度/
K热流密度/
(kW·m−2)1 0.33 824.40 27.10 590 2 0.33 825.86 27.80 605 3 0.33 822.93 21.90 590 表 2 原始汽泡信号主体电压振幅和单个阶跃信号的时间跨度
Table 2. Time Span of Original Bubble Signal Main Body Amplitude and Single Step Signal
工况序号 测点1 测点4 电压振幅/V 时间跨度/ms 电压振幅/V 时间跨度/ms 1 0~0.5 1.2~3.0 0 0 2 0~0.5 1.5~3.0 0~1 3.0~8.0 3 0~0.5 1.0~3.0 0~1.5 5.0~8.0 表 3 滑速比模型
Table 3. Slip Ratio Model
学者 表达式 Maurer[20] $\alpha = \dfrac{1}{{1 + 0.8{{\left( {\dfrac{{1 - x}}{x}} \right)}^{0.6819 + 0.01217p}}{{\left( {\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}} \right)}^{0.6}}}}$ Fauske[21] $\alpha = \dfrac{1}{{1 + \dfrac{{1 - x}}{x}{{\left( {\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}} \right)}^{1/2}}}}$ Zivi[22] $\alpha = \dfrac{1}{{1 + \dfrac{{1 - x}}{x}{{\left( {\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}} \right)}^{2/3}}}}$ Turner-
Wallis[23]$ \alpha = \dfrac{1}{{1 + {{\left[ {{{\left( {\dfrac{{{\mu _{\text{f}}}}}{{{\mu _{\text{g}}}}}} \right)}^{0.1}}{{\left( {\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}} \right)}^{0.5}}{{\left( {\dfrac{{1 - x}}{x}} \right)}^{0.9}}} \right]}^{0.8}}}} $ Baroczy[24] $\alpha = {\left[ {1 + {{\left( {\dfrac{{1 - x}}{x}} \right)}^{0.72}}{{\left( {\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}} \right)}^{0.65}}{{\left( {\dfrac{{{\mu _{\text{f}}}}}{{{\mu _{\text{g}}}}}} \right)}^{0.13}}} \right]^{ - 1}}$ Smith[25] $\alpha = {\left\{ {1 + 0.4\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}\left( {\dfrac{1}{x} - 1} \right) + 0.6\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}\left( {\dfrac{1}{x} - 1} \right){{\left[ {\dfrac{{{\rho _{\text{f}}}/{\rho _{\text{g}}} + 0.4(1/x - 1)}}{{1 + 0.4(1/x - 1)}}} \right]}^{1/2}}} \right\}^{ - 1}}$ Wallis[26] $ \alpha = {\left\{ {1 + {{\left[ {{{\left( {\dfrac{{{\mu _{\text{f}}}}}{{{\mu _{\text{g}}}}}} \right)}^{0.1}}{{\left( {\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}} \right)}^{0.5}}{{\left( {\dfrac{{1 - x}}{x}} \right)}^{0.9}}} \right]}^{0.8}}} \right\}^{ - 0.38}} $ Chisholm[27] $\alpha = \dfrac{1}{{1 + \dfrac{{1 - x}}{x}\dfrac{{{\rho _{\text{g}}}}}{{{\rho _{\text{f}}}}}\sqrt {1 - x\left( {1 - \dfrac{{{\rho _{\text{f}}}}}{{{\rho _{\text{g}}}}}} \right)} }}$ α—空泡份额;p—压力,MPa; $ {\rho _{\text{g}}} $—气相密度,kg/m3; $ {\rho _{\text{f}}} $—液相密度,kg/m3; $ {\mu _{\text{g}}} $—气相粘度,Pa∙s; $ {\mu _{\text{f}}} $—液相粘度,Pa∙s 表 4 汽泡尺寸计算结果
Table 4. Calculation Results of Bubble Size
工况序号 测点1 测点4 时间跨
度/ms基于Fauske模型的
汽泡尺寸/mm时间跨
度/ms基于Fauske模型的
汽泡尺寸/mm1 1.2~3.0 23.7~59.2 0 0 2 1.5~3.0 29.6~59.2 3.0~8.0 59.2~157.9 3 1.0~3.0 19.7~59.2 5.0~8.0 98.7~157.9 -
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