气液相变是自然界中的常见现象，利用沸腾相变的高效换热设备在电子设备、核能堆芯、火电、制冷等领域广泛应用。表面润湿性通过影响过热表面上气液相互作用影响沸腾换热。本文结合可视化实验、理论分析和数值模拟对两种广泛应用的沸腾形式——池沸腾和液滴沸腾进行研究，探究表面润湿性在两种沸腾形式中对气液相变的作用进而分析其对沸腾换热的影响机理。本文旨在阐明不同润湿性表面沸腾过程气泡/液滴行为特征，揭示其对沸腾换热的影响机理，明确表面润湿性对沸腾换热的影响规律，进而为调控表面润湿性以强化沸腾换热提供理论指导。本文采用涂层法和化学刻蚀再修饰两种方法制备了多种热稳定性良好的不同润湿性表面。研究了表面润湿性对池沸腾换热及气泡行为的影响。结果表明，表面越亲水，沸腾起始点越高且临界热流密度越大；在低热流密度下疏水表面换热较好，而在高热流密度下亲水和裸铝表面换热较好。可视化实验得到疏水表面上，气泡经拉伸生长、颈缩后脱离并在表面残留小气泡，接触角滞后越大则残留气泡越大，换热越弱。与一般表面不同，超疏水表面的沸腾曲线，热流密度随表面过热度的增加单调增大，既未出现临界热流密度点也未出现最小热流密度点。可视化观测了超疏水表面沸腾气泡行为特征。建立了沸腾气泡行为数值模拟模型，分析了表面接触角和接触角滞后对气泡行为的影响及其对周围液体流动和换热的影响。研究了表面润湿性对液滴沸腾特征的影响。建立了四种液滴沸腾的典型模式，分析了表面润湿性对液滴沸腾模式的影响机制。实验得到，表面越亲水液滴的蒸发时间越短且液滴的Leidenfrost温度越高。超疏水表面上液滴的蒸发时间随表面温度的升高而缩短，且液滴蒸发曲线未出现过渡态沸腾。建立了液滴转变为膜态沸腾的模型，并分析了表面润湿性对液滴Leidenfrost温度的影响机理。建立了膜态沸腾液滴蒸发模型，在其基础上拟合获得了液滴蒸发时间半经验关联式。研究了表面润湿性对液滴冲击沸腾特征的影响。观测了液滴冲击过热表面的动态行为，分析了表面温度、倾角、润湿性和液滴Weber数的影响。观测了液滴雾化现象，实验得到表面润湿性越好、液滴铺展越大则液滴雾化程度越强，随着表面温度的升高液滴雾化先增强后减弱。建立了六种典型的液滴冲击沸腾模式，对不同润湿性表面构建了液滴冲击沸腾模式的表面温度Ts-液滴Weber数相图，分析了表面润湿性、表面温度和液滴Weber数等对液滴冲击沸腾模式的影响机理。

Liquid-vapor phase change is a common phenomenon in nature. The boiling heat transfer is widely used in electronic equipment, nuclear reactor core, thermal power, refrigeration and other fields. The surface wettability affects the boiling heat transfer by affecting the liquid-vapor interaction on the superheated surface. In this paper, two widely used boiling forms, pool boiling and droplet boiling, were studied by means of visualizations, experimental measurent, theoretical analysis and numerical simulation. The effect of surface wettability on liquid-vapor phase change was explored and the mechanism of its influence on boiling heat transfer was analyzed. The purpose of this paper is to clarify the characteristics of bubble/droplet behavior on the surfaces with various wettabilities during boiling, to reveal the mechanism of the influence of bubble/droplet behavior on boiling heat transfer, to clarify the law of the influence of surface wettability on boiling heat transfer, and to provide design guidance for boiling heat transfer enhancement by surface wettability design.In this paper, surfaces with various wettabilities and good thermal stability were prepared by spray coating and chemical etching and remolding methods. The effect of surface wettability on pool boiling heat transfer and bubble behavior was studied. The onset nucleate boiling temperature is higher and the critical heat flux is higher on the surface with better surface wettability. The heat transfer is better on the hydrophobic surface with low heat flux, while it is better on the hydrophilic surface and bare aluminum surface with hight heat flux. Visualizations shows that on the hydrophobic surface, the bubbles break away after stretching growth and necking and remain small bubbles on the heated surface. However, the residual bubbles are larger on the surface with larger contact angle hysteresis on the hydrophobic surface. The heat flux of boiling curve on superhydrophobic surface increases with the increase of surface superheat, and neither the critical heat flux nor the minimum heat flux appears. The bubble behavior characteristics on superhydrophobic surface were observed and the influence of bubble behavior on boiling heat transfer was analyzed. A numerical simulation model of bubble behavior in pool boiling was established, and the effects of surface contact angle and contact angle hysteresis on bubble behavior, liquid flow and boiling heat transfer ware analyzed.The effect of surface wettability on droplet boiling was investigated. Four typical modes of droplet boiling were established, and the influence of surface wettability on the droplet boiling mode was analyzed. The droplet evaporation curve was measured. The droplet evaporation time decreases and the Leidenfrost temperature increases with the increase of surface wettability. On the superhydrophobic surface, droplet evaporation time decreases with the increase of surface temperature. Therefore, no droplet transition boiling occurs on the superhydrophobic surface. The model of the transition to droplet film boiling was established and the mechanism of the influence of surface wettability on Leidenfrost temperature was analyzed. A droplet film boiling was proposed to relate the droplet evaporation time， initial droplet size and surface superheat with a semi-empirical correlation developed for the droplet evaporation time.The effect of surface wettability on droplet impacting and boiling was investigated. The dynamic behavior of single droplet impacting the superheated surface was observed, and the effects of Weber number, surface temperature, inclination and wettability were analyzed. The phenomenon of droplet atomization was observed. It was found that the droplet atomization was stronger on the surface with better wettability and with larger spread of the impacting droplet. The droplet atomization intensity first increased and then decreased with the increase of surface temperature. Six typical droplet impacting and boiling modes were observed and classified. The Ts-We regime map was used to illustrate the droplet impacting and boiling modes on the surfaces with various wettibilities. The influence mechanism of surface wettability, temperature and droplet Weber number on the droplet impacting and boiling mode was analyzed.