【摘要】 为了探究异质蒸气氛围对附壁液滴蒸发过程的影响，采用实验观测的方式分析了低压乙醇蒸气氛围中水滴蒸发热动力学特性。实验结果表明，液滴蒸发冷却效应诱导产生气液界面处的切向温度梯度及液滴内部的法向温度梯度。液滴蒸发初期，切向温度梯度诱导产生的Marangoni流动占据主导地位，自由界面近三相线处温度分布呈齿轮状。随着蒸发的进行，齿轮状热流型逐渐演变为多流胞状结构，并逐渐脱离三相线朝自由界面中心处移动。随着液滴高度的降低，法向温度梯度逐渐占据主导地位，浮力效应诱导产生Bérnard-Marangoni流胞。在低压乙醇蒸气氛围中，乙醇在液滴界面生成溶解热，使得界面热质传递过程更为复杂，观察到多类不稳定流型演化过程。随着初始时刻乙醇蒸气压力的降低，液滴蒸发速率增加，流动不稳定性增强。更多还原

【Abstract】 In order to explore the influencing mechanism of heterogeneous vapor environment on the sessile droplet evaporation process, a series of experiments are carried out to analyze the evaporation characteristics of water droplet in ethanol vapor environment under low-pressure condition.Results indicated that droplet evaporation induces the temperature gradients in tangential and normal directions. During the initial stage of the evaporation process, the Marangoni convection induced by tangential temperature gradient is dominant, leading to the emergence of the gear-like thermal pattern nearby the three-phase-contact-line region. Subsequently, the gear-like thermal pattern gradually transforms into the multi-cells thermal pattern, which depart the three-phase-contact-line region and move towards the apex of the free surface. With the reduction of the droplet height,the normal temperature gradient is increased, which produces the buoyance flow, and results in the formation of the Bérnard-Marangoni cell. The energy and mass transport are more complicated in ethanol vapor environment under low-pressure condition, and various flow instabilities are observed. As the decreased initial pressure of ethanol vapor, the evaporation rate is increased, and flow instabilities are enhanced.更多还原