界面切应力和重力驱动下受热过冷薄膜的破断模型研究

Breakdown model of locally heated and subcooled films driving by interfacial shear and gravity

液膜破断过程的内在机理受流体物性、流动状态和界面边界条件的影响而有所不同。针对界面切应力和重力驱动下的受热过冷液膜性破断过程,基于控制体内的力平衡方程,建立了受热过冷液膜破断力平衡模型,模型包含了滞止压力、重力、表面张力、切应力、热毛细力和蒸汽压力的影响。在重力驱动、重力和切应力协同驱动和切应力驱动下,分别推导出层流和紊流的临界液膜厚度和最小润湿量的理论关系式,为分析受热过冷液膜的破断特征提供了一种可借鉴的理论模型。

The breakdown mechanism of liquid films is distinctly influenced by fluid properties, flow regime and boundary conditions. Based on the force balance equation in control volume, the theoretical force balance model is established for breakdown of the subcooled films driving by interracial shear stress and gravity under the sensible heating condition. The effects of the stagnant pressure, gravity, surface tension, shear stress, thermocapillarity and vapour pressure are included in present model. The relations of the critical film thickness and minimum wetting rate with the contact angle, the film temperature, the interracial shear and heat flux are formulated raider driving by gravity, the combination of gravity and interracial shear, and interracial shear, respectively. The present models provide a theoretical method for better understanding for film dryout under complex boundary conditions.