Numerical Simulation of Critical Flow in a Narrow Rectangular Channel
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摘要: 冷却剂通过细微裂缝泄漏的主要机理为临界流流动，准确预测临界流流量是实现破前漏（LBB）应用的关键。基于空化模型对窄矩形通道的临界流进行了数值模拟，探讨了表征气泡半径和气化核心密度的常数项（C）对于临界流的影响。结果表明，当C=1.25时模拟结果与实验值符合良好；在实验工况范围内，临界流质量流速的模拟结果与实验值的误差在±15%以内；修正后的空化模型可用于模拟计算上游温度、压力工况下的临界流质量流速以及归纳临界流流量变化规律。Abstract: The main mechanism of coolant leakage through micro-cracks is critical flow, and accurate prediction of critical flow is the key to realize the application of Leak-Before-Break (LBB). Based on the cavitation model, the critical flow in a narrow rectangular channel is numerically simulated, and the influence of the constant term (C) representing the bubble radius and nucleation site density on the critical flow is discussed. The results show that when C=1.25, the simulation results are in good agreement with the experimental values; Within the range of experimental conditions, the error between the simulation results of critical flow and the experimental values is within ± 15%; The modified cavitation model can be used to simulate and calculate the critical flow under upstream temperature and pressure conditions.
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Key words:
- Critical flow /
- Cavitation model /
- Bubble radius /
- Nucleation site density /
- Mass flow
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图 1 实验件连接和测点布置
Φ—直径
Figure 1. Experimental Piece Connection and Measuring Point Arrangement
图 4 压力随轴向距离变化关系图
Figure 4. Relationship Diagram of Pressure Varying with Axial Distance
图 5 不同粒径尺寸时压力随轴向距离变化关系图
Figure 5. Relationship Diagram of Pressure Varying with Axial Distance under Different Bubble Sizes
图 6 不同粒径尺寸时空泡份额随轴向距离变化关系图
Figure 6. Relationship Diagram of Void Fraction Varying with Axial Distance under Different Bubble Sizes
图 7 修正的空化模型计算结果与实验值对比
Figure 7. Comparison between the Calculated Results of the Revised Cavitation Model and the Experimental Values
图 8 临界质量流速随上游参数的变化
Figure 8. Critical Mass Flow Rate Variation with Upstream Parameters
表 1 湍流模型敏感性分析
Table 1. Sensitivity Analysis of Turbulence Models
湍流模型 质量流量/(kg·s−1) 相对误差/% 计算值 实验值 标准 k−ε 0.145 0.167 13.17 RNG k−ε 0.146 12.57 Realizable k−ε 0.147 11.98 标准 k−ω 0.143 14.37 BSL k−ω 0.142 14.97 SST k−ω 0.144 13.77 
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表 2 计算工况表
Table 2. Calculation Condition Table
工况 rb/mm ${\alpha _{{\text{nuc}}}}$ Fvap C 工况1 0.01 0.0005 50 2.50 工况2 0.02 1.25 工况 3 0.03 0.83 工况 4 0.04 0.63 工况 5 0.05 0.50 工况 6 0.06 0.42
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