自然对流工况下磁流体准二维湍流结构及转捩机制研究

In fusion reactor, liquid metal blankets work in multi-physical coupled fields, which mainly composed of volumetric heat field and magnetic field. The non-uniform volumetric heat of 2-3MW/m³ deposited by the fusion neutrons would change the density distribution and cause buoyancy force in the liquid breeder. The strong magnetic field of 3~7T would form magnetohydrodynamics (MHD) flow and the flow disturbances along the magnetic field lines tend to be inhibited by the action of the magnetic field and a quasi-two-dimensional (Q2D) is promoted. The combination of Q2D turbulence with buoyant flow would greatly change the effective heat transfer coefficient of liquid blankets. This project is proposed to carry out the experimental study of the MHD Q2D turbulence under buoyancy force. The transition conditions from laminar to turbulence would be evaluated. The Q2D turbulence structure, and turbulent heat transfer would be studied. The effective heat transfer coefficients of MHD turbulence with the buoyant flow under various working parameters would be calculated and transition mechanism would be modelled, which would provide experimental data and theory basis for flow status prediction and turbulence model development of liquid blankets.

聚变堆液态包层处于强中子体积核热、强磁场等极端物理场耦合工况，使液态增殖剂呈现特殊的流动特征：2-3MW/m³中子核热呈指数分布，造成液态增殖剂密度分布不均匀，密度差形成浮力；3~7T磁场下流动的液态增殖剂切割磁感线，形成磁流体现象，磁扩散作用将磁流体湍流的结构准二维化。浮力驱动了自然对流，磁场改变了湍流结构及传热特性，二者耦合形成的浮力作用下的磁流体准二维湍流强化了液态包层有效传热，对其热工性能产生深刻影响，是液态包层应用于聚变堆需要考核的关键问题之一。本项目拟针对液态包层内浮力作用下的磁流体准二维湍流现象，在自然对流工况下开展磁流体湍流实验，评估层流湍流转捩机制，研究浮力作用下磁流体湍流的准二维结构、传热特征，建立磁流体湍流的转捩预测模型和有效传热系数关联式，为液态包层的流动状态预测和湍流模型发展提供实验依据和理论支撑。

聚变堆液态包层处于强中子体积核热、强磁场等极端物理场耦合工况，使液态增殖剂呈现特殊的流动特征：2-3 MW/m³中子核热呈指数分布，造成液态增殖剂密度分布不均匀，密度差形成浮力；3~7 T磁场下流动的液态增殖剂切割磁感线，形成磁流体现象，磁扩散作用将磁流体湍流的结构准二维化。浮力驱动了自然对流，磁场改变了湍流结构及传热特性，二者耦合形成的浮力作用下的磁流体准二维湍流强化了液态包层有效传热，对其热工性能产生深刻影响，是液态包层应用于聚变堆需要考核的关键问题之一。本项目针对液态包层内浮力作用下的磁流体准二维湍流现象，根据强磁场下MHD湍流的特征，在现有MHD湍流雷诺平均模型的基础上，开发出适用于高Hartmann数的MHD湍流模型。应用理论和实验算例对程序进行了验证，验证算例涵盖了从层流到湍流的各种工况，主要包括充分发展层流、三维层流、浮力驱动流、MHD湍流等。根据聚变堆液态包层高Hartmann数MHD流动特点，选择合适的物理模型、流场求解算法、电场求解算法、浮力计算模型，完成磁流体分析程序MTC的开发，具备完善的不可压缩磁流体及浮力驱动流计算功能，可用于聚变堆工况下液态包层磁流体流动和传热分析。