由于附壁液滴蒸发广泛应用于多种工程领域，且内在包含热质输运耦合机理，本文采用实验与物理建模相结合的方法，对置于加热基座上的三相线处于钉扎状态且接触半径大于毛细长度的附壁液滴蒸发进行了研究。

实验方面，利用实践十号蒸发对流箱，在地面一个大气压开放环境下开展了无水乙醇大滴在加热PTFE表面的蒸发实验。重力场中的附壁大滴呈现为非球冠状。蒸发大部分时间内三相线处于钉扎状态，未出现CCA（恒接触角）阶段。对于拥有相同接触半径且三相线处于钉扎状态的大液滴，平均蒸发速率与初始体积无关。准静态扩散模型因忽略了浮力对流的贡献低估了瞬时蒸发速率，而同时考虑蒸汽扩散和气相域浮力对流的经验模型的准确性依赖于实验所使用的工质。瞬时蒸发速率在短时间内迅速上升，之后长时间内基本保持稳定。热流密度演化经历了快速上升的Stage1、保持平稳的Stage2、快速下降的Stage3三个阶段。

本文对实践十号返回式科学实验卫星上的附壁液滴蒸发结果进行了分析。除了蒸发末期形成的液膜外，空间大滴在整个蒸发过程中呈现为球冠状。对于微重力环境下的钉扎大滴，扩散是蒸发的主要驱动力，对蒸发速率的贡献占比高达85%以上，Marangoni效应的贡献占比随基座温度T_s的升高而升高，随初始体积V₀的增大略有增大。

物理建模方面，建立了二维轴对称钉扎大滴蒸发模型。局部蒸发通量从液滴顶部沿气液界面到三相线逐渐升高，且在靠近三相线时急剧增大。在r＞0的rz平面内，液滴内的Marangoni对流沿逆时针方向，在气液界面及对称轴靠近液滴顶部处的流动速度大，处于10 mm/s的量级。液滴内温度场不均匀，且温度最低点位于液滴顶部中心，温度最高点落在固液界面靠近三相线的位置。气液界面最大温差△T随基座温度T_s的增大而降低，随液滴初始体积V₀的增大而增大。固液界面热流密度在对称轴和三相线处高，在靠近三相线处的温度最高点最小。随着蒸发进行，局部蒸发通量沿气液界面分布的不均匀程度加剧，Marangoni对流减弱，气液界面最大温差△T降低，温度最高点沿固液界面径向向内运动，固液界面温度整体上升，但三相线附近的温度却有所下降，固液界面热流密度分布不均匀性增大。

Due to wide applications in many engineering fields and intrinsic coupling of heat and mass transfer of sessile droplet evaporation, sessile droplet evaporation with pinned triple line and greater contact radius than capillary length on heated substrate is investigated by the means of experiment and physical modeling.

Experimentally, using SJ-10 evaporation-convection box, large sessile ethanol droplet evaporation on heated PTFE is carried out on ground and at 1 atm. A large sessile droplet on ground shows a non-spherical cap. Triple line is pinned during most of evaporation time and no CCA (Constant Contact Angle) stage is observed. Average evaporation rate is independent on initial droplet volume if two large sessile droplets have same contact radius and their triple line is pinned. Quasi-steady diffusion-limited evaporation model underestimates instant evaporation rate due to the neglect of buoyancy convection, while the accuracy of empirical model which accounts for both vapor diffusion and buoyancy convection in gas phase depends on the liquid it uses. Instant evaporation rate increases firstly and then keeps stable for a long time. Heat flux density evolution can be divided into three stages: fast increasing (Stage 1), keeping stable (Stage 2), and fast decreasing (Stage 3).

Sessile droplet evaporation results onboard SJ-10 satellite is analyzed. Except for the liquid film formed near the end of evaporation, large sessile droplet in space shows a spherical cap during evaporation. For a large droplet with pinned triple line in microgravity, diffusion is the main driving force of evaporation and its contribution to evaporation rate exceeds 85%. The contribution of Marangoni effect to evaporation rate increases with substrate temperature increasing and increases a little with droplet initial volume increasing.

Numerically, a 2D axisymmetric large sessile droplet with pinned triple line evaporation model is developed. Local evaporation flux increases from droplet apex to triple line along gas-liquid interface and increases sharply near triple line. In the rz plane where r＞0, Marangoni convection in droplet is anticlockwise. Flow velocity at gas-liquid interface and symmetry axis near droplet apex is large and is on the order of 10mm/s. Temperature field in droplet is inhomogeneous and the lowest temperature is at droplet apex while the highest temperature is at solid-liquid interface near triple line. Temperature difference at gas-liquid interface decreases with substrate temperature increasing, but it increases with droplet initial volume increasing. Heat flux density at solid-liquid interface is high both at symmetry axis and at triple line, and it is lowest near triple line where temperature is highest. When droplet is smaller and smaller, local evaporation flux distribution along gas-liquid interface becomes more inhomogeneous, Marangoni convection weakens, temperature difference at gas-liquid interface decreases, the point where temperature is highest moves inward along solid-liquid interface, temperature at solid-liquid interface increases while it decreases near triple line, and heat flux density distribution along solid-liquid interface becomes more inhomogeneous.