具有密度极值流体Rayleigh-Bénard-Marangoni（R-B-M）对流传热与晶体生长、相变储能等实际应用中的流动控制与传热密切相关。相比常规流体，具有密度极值流体R-B-M对流的流动及传热特性更加复杂，而这方面研究还较缺乏。项目拟以冷水和硅熔体这两种典型的具有密度极值流体的R-B-M对流为研究对象，采用线性稳定性分析、数值模拟与实验观测结合的方法展开系统研究，具体而言：（1）根据线性稳定性理论确定流动发生及失稳的临界条件，预示可能的流动结构及流动最先失稳的区域；（2）通过数值模拟研究远离临界点时流动的非线性演变规律，建立各流动结构与传热性能间的对应关系，揭示流动失稳的物理机制；（3）进行系统的实验观测，验证理论分析与数值模拟结果，补充传热数据，获取传热关联式。研究成果对认知具有密度极值流体R-B-M对流传热的基本规律具有重要的学术价值，而且可为晶体生长等实际应用提供有益参考。

Rayleigh-Bénard-Marangoni (R-B-M) convection for the fluids with density extremum is closely related to the flow control and heat transfer in many engineering applications, such as crystal growth, heat storage system etc. Compared with the common fluid, the flow and heat transfer characteristics of R-B-M convection of fluid with density extremum behaves much more complex. However, the research about this subject is lacked. Aiming at the complex R-B-M convection problem of cold water and silicon melt, the two typical fluids with density extremum, a systematic study is performed by means of linear stability analysis, numerical simulation and experimental observation, particularly: (1) According to the linear stability theory, the critical condition for the onset of convection and the instability of the flow is determined, and the possible flow structures and instability flow areas are indicated; (2) A series of numerical simulation is carried out to obtain the nonlinear evolution rules of flow apart from the critical point. The correspondence between the various flow structures and heat transfer performance is established, and the mechanism of the flow instability is investigated; (3) An experiment is conducted to validate the results of the linear stability analysis and numerical simulation. Additional heat transfer data is also provided by the experiment. Then, several heat transfer correlations are proposed. Research results in this project are of important academic values for understanding the fundamental law of R-B-M convective heat transfer of fluids with density extremum, and can also provide valuable reference for the application of crystal growth etc.