膜态沸腾的汽化成核与界面演化研究

Bubble Nucleation and Interface Evolution During Film Boiling

与对流换热相比,沸腾传热通过相变汽化潜热带走更多热量,能显著提升换热能力。以CFD软件为技术手段,通过构建UDF函数以满足假定条件下膜态沸腾的气泡界面演化过程,采用VOF模型在微观层面对汽化成核与单气泡演化进行模拟研究。研究表明:气泡成核主要包含膨胀及拉伸两个阶段;气泡上升诱导形成的涡流增强了与周围的热质交换能力;液体表面张力及液体黏度增加会延长气泡脱离时间,且气泡直径增加。研究结果有助于深入理解膜态沸腾的换热机理,并可指导相关的相变传热工程应用。

Compared with convective heat transfer,boiling heat transfer takes more heat away from the latent heat of gasification,which can significantly improve the heat transfer.In this paper,CFD software was used to construct the UDF function to trace the bubble interface evolution during film boiling,and the VOF model was used to simulate the bubble nucleation and single bubble evolution at the microscopic level.The results showed that bubble nucleation included the growth and extension stages.The rising bubble-induced vortex enhanced the heat and mass transfer with the surrounding media.The increase in surface tension and viscosity would extend the bubble separation time and increase the bubble diameter.This study has scientific significance for understanding the heat transfer mechanism of film boiling and is expected to guide the related engineering designs of heat transfer.