绝缘方管磁流体湍流大涡数值模拟研究

发布时间：2018-06-25 09:55

本文选题：磁流体 + 湍流　；参考：《杭州电子科技大学》2017年硕士论文

【摘要】：在热核聚变反应堆包层内流动的液态金属在磁场作用下会产生磁流体动力学效应(MagnetoHydroDynamic,MHD)进而改变管内的流场,对反应堆中液态包层的热传递造成很大的影响。因此,磁流体湍流的研究对液态金属包层的应用具有重要的意义。近年来,对包层内液态金属MHD效应的研究也取得了很大发展,并且人们研究的重点也从层流研究逐渐转换到自然界和工程界更加普遍的湍流研究中。鉴于直接数值模拟(Direct numberical simulation,DNS)对网格要求比较高,而带来的计算量比较大,所以本文采用大涡模拟方法(large eddy simulation,LES)研究金属流体在方管中的流动状态。现有研究表明dynamic Smagorinsky model(DSM)在计算磁流体湍流时表现较好。所以本文研究DSM、Smagorinsky model(SM)以及dynamic one equation model(DOM)这三种模型在计算磁流体管道流中的适用性。首先基于开源CFD软件OpenFOAM开发出低磁雷诺数的磁流体湍流LES模拟的求解器,并分别研究了该求解器在低雷诺数和高雷诺数的表现;接着分别比较三种模型在磁流体管道流中的平均速度、速度均方根以及湍动能分布;研究表明DSM比其他两个模型在计算磁流体湍流时表现要好。接着通过对比平均速度、速度均方根、湍动能以及能谱来研究磁场对磁流体湍流的抑制作用和磁场对磁流体湍流的影响;随后研究不同磁场强度对磁流体湍流的影响;计算结果表明,外加磁场对磁流体湍流有明显的抑制作用,而且这种抑制作用随着磁场的增加而更加明显,直至湍流演变为层流,同时这种抑制作用还有明显的各向异性。最后通过研究壁面摩擦系数来研究金属流体管道流层流到湍流的转化机制。
[Abstract]:The liquid metal flowing in the cladding of thermonuclear fusion reactor will produce magnetohydrodynamic MHD (MagnetoHydrodynamic MHD) under the action of magnetic field, which will change the flow field in the tube and have a great influence on the heat transfer of the liquid cladding in the reactor. Therefore, the study of magnetic fluid turbulence plays an important role in the application of liquid metal cladding. In recent years, great progress has been made in the study of the MHD effect of liquid metal in the cladding, and the emphasis of the study has gradually shifted from laminar flow to the more general turbulence in nature and engineering. In view of the high demand for grid and the large amount of computation caused by direct numberical simulation, the large eddy simulation method (large eddy simulation les) is used to study the flow state of metal fluid in square tube. It is shown that dynamic Smagorinsky model performs well in calculating the turbulence of magnetic fluid. In this paper, we study the applicability of the three models, DSM Smagorinsky model (SM) and dynamic one equation model (Dom, in the calculation of MHD pipeline flow. Firstly, based on the open-source CFD software OpenFOAM, a magnetic fluid turbulence les simulation solver with low magnetic Reynolds number is developed, and the performance of the solver in low Reynolds number and high Reynolds number is studied respectively. Then, the distributions of mean velocity, root mean square velocity and turbulent kinetic energy of the three models in the MHD pipe flow are compared, and the results show that DSM performs better than the other two models in the calculation of MHD turbulence. Then, by comparing the mean velocity, the root mean square of velocity, the turbulent kinetic energy and the energy spectrum, the suppression effect of magnetic field on the magnetic fluid turbulence and the influence of the magnetic field on the magnetic fluid turbulence are studied, and the influence of different magnetic field intensity on the magnetic fluid turbulence is studied. The results show that the external magnetic field has obvious inhibitory effect on the magnetic fluid turbulence, and this inhibition effect is more obvious with the increase of the magnetic field, until the turbulence evolves into laminar flow, and the inhibition effect has obvious anisotropy. Finally, the transformation mechanism from laminar flow to turbulent flow in metal fluid pipes is studied by studying the wall friction coefficient.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O361.3

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