微重力单气泡池沸腾传热及气泡热动力学研究

Study on bubble thermal dynamics and heat transfer of pool boiling in microgravity is important to reveal the mechanism of heat transfer of pool boiling. In the present project, the experimental data of both single bubble boiling mode and normal pool boiling mode obtained from the flight experiments aboard the Chinese recoverable satellite SJ-10 will be analyzed in detail to develop a basic understanding of the local convection, vapor removal, and heat transfer processes that take place during nucleate boiling from a well characterized surface in microgravity. Experiments both in normal gravity on Earth and in short-term microgravity by utilizing the drop tower Beijing will also be conducted, to expand the scope of parameters in the space flight experiment. Theoretical analysis and numerical simulations are also used for in-depth study of local processes of pool boiling in different gravity conditions. These processes included bubble thermal dynamical behavior, micro flow structure and local heat transfer performance around the growing bubble, transient heat conduction inside the heating wall, endothermic/exothermic effect of the superheated liquid layer near the wall. It will be helpful to reveal the coupling effect of bubble dynamics and heat transfer, to provide insights into pool boiling phenomenon, and then enhance the understanding of boiling heat transfer mechanism.

微重力沸腾传热及其中气泡热动力学研究对于揭示沸腾传热内在机制具有重要意义。本项目将利用SJ-10返回式科学实验卫星飞行实验所获得的单气泡沸腾和常规池沸腾模式下的实验数据，开展细致的数据整理与分析，提供对微重力条件下核态池沸腾现象中局部对流、蒸汽迁移与传热等过程的基本认识；利用地面常重力实验和地基短时微重力落塔实验开展补充的实验观测，拓展空间飞行实验参数范围并弥补空间数据中的不足；同时，利用理论分析和数值模拟，深入研究不同重力条件下池沸腾现象中的气泡热动力学行为特征、围绕生长气泡的细观流动结构及局部传热性能、加热固壁内部瞬态导热和近壁区过热液层蓄/放热效应等，揭示气泡热动力学与局部热量传输过程间的耦合作用及其对沸腾传热性能的影响机制，加深对沸腾传热内在机理的理解。

本项目基于SJ-10卫星SOBER-SJ10沸腾实验数据和地面补充实验结果，针对微重力沸腾传热中的气泡热动力学及其与传热性能之间的关联机制展开研究。修订并完善了集成微加热器温度传感器同步标定方法，能正确反演SJ-10卫星空间飞行实验科学数据的真实特征；构建了基于双目视觉原理的双CCD图像3维重构算法，正确提取并重构了气泡生长过程的基本特征（气泡尺寸、接触区大小与表观接触角等）；分析了空间实验中气泡生长过程特征和加热面局部温度时空演化特征，揭示了生长气泡底部干斑变化规律及其与加热固壁内部瞬态导热和近壁区过热液层相互作用特征；采用连续介质模型（CMM）和格子玻尔兹曼方法模型（LBM），模拟了不同重力沸腾传热现象和气泡生长过程，研究了气泡周围细观流动结构及重力、液体过冷度和壁面过热度等因素对传热特性的影响；综合分析和对比空间长时间微重力、地面常重力和地基短时微重力实验结果及数值模拟结果，研究了重力对沸腾气泡热动力学特征及传热性能的影响机制，提出了一个新的重力标度模型。本项目通过空间飞行实验所获得的长期稳定微重力沸腾数据的处理与分析、地面补充实验以及基于连续介质模型（CMM）和格子玻尔兹曼方法模型（LBM）的沸腾传热数值模拟研究等，深入挖掘空间飞行实验数据的科学价值，加深对沸腾传热现象内在规律的理解，推动沸腾传热学自身的发展，服务于我国航天事业以及地面工业应用技术研发的需求。