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实验观察分析直径25及100μm微细铂丝上过冷池沸腾微小汽泡射流现象,利用高速摄影和PIV技术获取汽泡周围射流形态及流场,发现小尺寸汽泡具有明显的顶部射流,大尺寸汽泡则可以在汽泡两侧出现多股射流.通过分析汽泡界面相变换热以及热毛细力效应(Marangoni),建立了近壁面汽泡计算模型并数值模拟汽泡周围流场,模拟射流结构及喷射强度等与实验结果一致吻合.分析证明,热毛细效应引起汽泡界面快速流动并带动周围液体形成射流;汽泡直径对于射流结构有重要影响,决定着汽泡射流多样性结构.
Experiments were carried out to analyze the phenomenon of micro bubble bubbling in subcooled pool on 25 and 100 μm diameter platinum wires. The jet shape and flow field around the bubble were obtained by high-speed photography and PIV technique. It was found that the small-size bubble had obvious jet at the top. Bubbles can generate multiple jets on both sides of the bubble.By analyzing the phase transition heat transfer and the thermal capillary effect (Marangoni) on the bubble interface, a model of near-surface bubble calculation is established and the flow field around the bubble is numerically simulated. The jet structure and jet intensity are in good agreement with the experimental results. The results show that the hot capillary effect causes rapid flow at the bubble interface and drives the surrounding liquid to form a jet. The bubble diameter has an important influence on the jet structure, which determines the structure of the bubble jet.