【作者】 倪陈宵；

【导师】 程旭；

【作者基本信息】 上海交通大学 ， 核能科学与工程， 2011， 硕士

【摘要】 能源问题是当今人类社会面临的重要问题之一,目前主要使用的化石能源热值低、资源匮乏并且对环境造成很大的污染,不适合长期使用。核能是新能源家族中的重要成员,包括裂变能和聚变能两种主要形式。裂变能是重金属元素的原子通过裂变所释放出的巨大能量,目前已经实现商用化。核能的另一种形式就是目前尚未实现商用化的聚变能。聚变反应的燃料在自然界中大量存在,几乎“取之不尽,用之不竭”,并且其反应产物放射毒性较低,也不产生污染环境的硫、氮氧化物,不释放温室气体,所以聚变能被看成是清洁、安全和可再生的新型能源。在产生聚变能的聚变反应堆中,包层是实现高环境适应性和低发电成本的聚变能应用的关键能量转换部件,作为堆内构建它包裹着等离子体,由第一壁和增殖区构成。聚变堆包层的主要功能是:产生和输运聚变反应所需的氚;将聚变中子的能量转换成热能并通过其内部的冷却通道将包层内的热量载出;第一壁材料还要抵御高温等离子体的热流;同时还要起到部分屏蔽作用。在众多包层设计和冷却方案中,超临界水冷包层是其中的一种,采用25MPa下的超临界水作为冷却剂。本文主要研究了超临界水冷包层第一壁结构材料中的温度和应力分布,以及增殖区冷却剂通道内的混合对流换热。本文针对聚变反应堆超临界水冷包层第一壁结构,通过商用计算流体力学软件CFX和有限元分析软件ANSYS Workbench中的SIMULATION模块进行单向流固耦合,对现有设计的超临界水冷包层第一壁温度和应力进行数值模拟,验证了流固耦合分析手段的可行性。在此基础上,进一步研究了不同湍流模型对计算结果的影响,以及比较了不同冷却方案下第一壁结构材料中的最高温度和最大应力。同时,研究了流道截面对结构材料中最高温度和最大应力的影响,综合这些影响因素对第一壁结构作了优化设计,有效降低了结构材料中的最高温度和最大应力。本文针对超临界水冷包层增殖区,利用商用计算流体力学软件CFX研究了冷却剂质量流量对通道内对流换热效果的影响。数值模拟结果表明超临界水在过拟临界点时剧烈的物性变化给冷却通道内的对流换热带来了一定的影响;更大的冷却剂流量能够带来的更好的对流换热效果,这一现象随着沿程高度的增加越来越明显。同时,还分析了不同流量下浮升力对混合对流换热的影响。数值模拟结果表明,随着流量大小和流动方向(顺浮升力方向和逆浮升力方向)的变化,浮升力作用下的对流换热出现“换热加强”和“换热弱化”的现象。更多还原

【Abstract】 Nowadays energy issue is one of the most serious issues. The mostly used chemical energy is not recommended for long-term use due to its low caloric value and pollution potential to the environment. Nuclear energy is a vital member of new energy family, including fission and fusion. Fission energy comes from the fission of heavy metal atoms releasing enormous energy. Nuclear fission has been currently achieved commercial operation. Fusion energy is not yet commercially utilized. The fuel for fusion reaction is almost inexhaustible in nature, and its reaction products are less radioactive. Therefore, fusion energy is considered to be clean, safe and renewable.In fusion reactor, blanket is the key component for energy transformation. It enwraps components in plasma reactor and made up by the first wall and breeder zone. The primary functions of fusion reactor blanket are as follows: producing and transporting tritium; transferring neutron energy into heat energy and removing heat by coolant flowing through the cooling channel. The first wall has to withstand the heat flux from high-temperature plasma and also partially achieve shielding effect. Supercritical water (SCW) cooled blanket is one kind of blanket design proposals. It is cooled by supercritical water at pressure of 25MPa.This paper investigates the thermo-structural performance of the first wall and convective heat transfer in breeder zone cooling channel of SCW cooled blanket. In this study, a coupled code ANSYS CFX /ANSYS Workbench is used to analysis the temperature and stress distribution of structural material by one-way coupling approach. Firstly the temperature and stress in the first wall structural material of the existing SCW cooled blanket design is simulated to verify the fluid-structure interaction analysis method. Then different turbulence models are used in numerical simulation to find out their influence on temperature and stress distribution in the first wall. Different cooling schemes and different geometrical configurations of flow channel of the first wall are taken into consideration. Based on the results achieved so far, an optimized design solution is suggested on the modification of the design structure and geometric configuration of flow channels, which can effectively reduced the maximum temperature and stress of the structural material.Furthermore, convective heat transfer in the cooling channel of breeder zone is investigated by CFX simulation. Numerical results show heat transfer reduction near the pseudo-critical temperature due to the dramatic change of physical properties of SCW. The results also indicate that larger coolant flow rate leads to improved heat transfer, which becomes more apparent along the flow pass. At the same time, the influence of buoyancy force on the heat transfer reduction at mixed convection conditions is studied. Simulation results show that phenomenon of“heat strengthened" and "heat weakened" occur alternatively according to the changes of flow rate and flow direction (along or again buoyancy direction).更多还原