Bubble Coalescence Characteristics in Micro-Scale Nucleate Boiling
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摘要: 从微观角度深入探究汽泡的生长、聚合及传热规律,采用数值仿真的方法,建立相变物理模型。将建立的模型嵌入计算流体动力学(CFD)软件,利用流体体积函数(VOF)相界面追踪方法,对汽泡的生长、运动、聚合及脱离进行探究。设立1个尺寸为3 mm×2 mm×2 mm的三维微型通道,底部壁面设置5个单元,用于加热并对汽泡底部热流密度进行监测。获得微通道加热条件下汽泡的合并运动形态和底面热流密度分布,并与实验观测值比较。通过对汽泡形态的模拟和底部热流密度的监测,建立汽泡动力学规律与底面热流密度分布的关系,进一步深化对汽泡合并的动力学规律和沸腾传热机理的认识。Abstract: Micro-scale bubble growth, coalescence and heat transfer characteristics are numerically investigated. Bubble interface is tracked with VOF（Volume of Fluid） method in CFD（Computational Fluid Dynamics） software. A 3 mm×2 mm×2 mm 3-D micro-channel is set up and 5 heating elements are arranged at the bottom surface. These elements can measure the local heat flux as well as provide the power for the bubble nucleation. Bubble growth and coalescence characteristics and heat flux distributions under bubbles are analyzed and compared with the experimental observations. The heat transfer mechanisms in nucleate boiling are better interpreted by developing the correlations of bubble dynamics and heat flux variations at different positions.
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Key words:
- Nucleate boiling /
- Bubble coalescence /
- Numerical simulation /
- Two phase /
- Heat and mass transfer
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