长江水位下降及降雨条件下荆江河段岸坡渗流特性研究

为了研究荆江河段岸坡土体的渗流特性及失稳机理,对荆江中州子护岸工程段河岸土样做了渗透系数和土水特征曲线室内试验,并基于Van Genuchten模型对土水曲线的试验结果进行拟合。在获得土体水力参数的基础上,根据该河段岸坡二元结构土体的特点,基于饱和—非饱和渗流理论,探讨了水位下降及降雨条件下岸坡不同粘性土层厚度对岸坡渗流场的影响规律。结果表明,地下水的下降速率随粘性土层厚度的增加而减少;粉质粘土层厚度越大,降雨对岸坡孔压场的影响范围也越大,且在一定程度上增大了土体的暂态饱和区,不利于岸坡的稳定性。     

HT-7U放电真空室支撑结构的设计和应力分析

结合ＨＴ－７Ｕ超导托卡马克核聚变装置中等离子体运行特点,提出了一种低刚性支撑结构作为放电真空室的本体支撑,并借助ＣＯＳＭＯＳ／Ｍ大型有限元分析程序,进行了全面的校核和应力分析,为结构的进一步研制提供了理论依据。     

基于单纯形法的回旋加速器平衡轨道求解

通过引入描述轨道闭合程度的目标函数,本文将求解回旋加速器平衡轨道的物理问题转换为求目标函数极小值的数学问题,利用单纯形法找到目标函数的最优解,从而实现了平衡轨道求解。该方法可在给定初始动能、初始方位角、初始半径、初始径向动量中任意两个量的条件下求解相应的平衡轨道。     

SC200超导回旋加速器磁场垫补方法研究

考虑磁铁材料的非线性、不均匀性以及有限元数值计算的精度有限,在设计主磁铁时都留有一定裕量,在完成磁铁加工组装后,根据磁场的实际测量结果对磁铁进行垫补获得理想的目标磁场分布,这样可以保证工程稳妥实施。因此磁铁垫补是加速器主磁铁设计制造的一个重要环节。本文基于SC200主磁铁模型,利用有限元分析软件TOSCA,首先研究了不同的磁极切削参数对中平面主磁场的响应影响;其次考虑到相邻切槽对中平面磁场影响的叠加效应,从理论上推导出一种求解垫补量的方法;最后通过模拟的方法验证了磁场垫补的可行性,为将来实际磁场垫补提供了有效的依据。     

EAST装置ICRF天线电特性分析与优化研究

射频波加热是磁约束核聚变装置的重要加热方式.本论文基于 EAST 装置离子回旋共振(ICRF)加热天线结构和运行参数,运用高频分析方法对 ICRF天线开展电特性分析模拟,获得 ICRF天线射频电势和电场分布特性,初步评估了天线电特性.基于天线电场分布特性和分析结果,从天线结构和运行相位两方面对 ICRF天线电特性进行了...     

Design of a Wedge-Shaped Toroidal Field Winding for KTX Device

The KTX device is a reversed field pinch(RFP)device currently under construction.Its maximum plasma current is designed as 1 MA with a discharge time longer than 100 ms.Its major radius is 1.4 m and its minor radius is 0.55 m.One of the most important problems in the magnet system design is how to reduce the TF magnetic field ripple and error field.A new wedgeshaped TF coil is put forward for the KTX device and its electromagnetic properties are compared with those of rectangular-shaped TF coils.The error field Bn/Btof wedge-shaped TF coils with6.4 degrees is about 6%as compared with 8%in the case of a rectangular-shaped TF coil.Besides,the wedge-shaped TF coils have a lower magnetic field ripple at the edge of the plasma region,which is smaller than 7.5%at R=1.83 m and 2%at R=1.07 m.This means that the tokamak operation mode may be feasible for this device when the plasma area becomes smaller,because the maximum ripple in the plasma area of the tokamak model is always required to be smaller than 0.4%.Detailed analysis of the results shows that the structure of the wedged-shape TF coil is reliable.It can serve as a reference for TF coil design of small aspect ratio RFPs or similar torus devices.     

百毫米级304不锈钢超窄间隙激光焊接头的组织及性能

采用超窄间隙激光焊对100 mm厚304奥氏体不锈钢进行了焊接试验,并研究了接头的显微组织和力学性能。结果表明,超窄间隙激光焊可以实现百毫米级及以上厚板的有效连接且焊缝的成形良好。接头的显微组织由奥氏体和少量铁素体组成,晶粒呈胞状和等轴状。接头的拉伸强度为658 MPa。拉伸断裂位于焊缝的胞状晶区,断裂形式为典型的延性断裂,断口形貌为细小均匀的韧窝和撕裂棱。焊缝组织中等轴晶区的显微硬度大于胞状晶区。     

Preload Analysis of Screw Bolt Joints on the First Wall Graphite Tiles in EAST

The first wall in the Experimental Advanced Superconducting Tokamak (EAST) used graphite tiles to withstand high thermal energy.The graphite tiles are mounted on the heat sink using screw bolts which have been preloaded to produce a clamp force.The clamp force is very important to keep the graphite tiles tightly on the surface of the heat sink so that the heat flux crosses this contacting surface in a small thermal resistor.Without the clamp force,the small gap between the graphite tiles and the heat sink will make it impossible for thermal power to be carried away by cooling water.Some bolts may even fall off with the loss of clamp force.From the mathematical models,the loss process of the clamp force has been studied.Research results explain how the different thermal expansions of three members of the screw joint makes the clamp force decrease to zero under temperature rise and external force,and how the stiffness affects the relation between the clamp force and temperature.The research also gives the critical temperature at which the clamp force can remain above zero.Analysis results indicate that the current screw joints are almost destined to lose their clamp force during the running time of EAST,so the bolt joints should be redesigned in order to improve its reliability.     

Electromagnetic and Stress Analyses of the ITER Equatorial Thermal Shield

The ITER equatorial thermal shield is located inside the cryostat and outside the vacuum vessel, and its purpose is to provide a thermal shield from hot components to the superconducting magnets. Electromagnetic analysis of the equatorial thermal shield was performed using the ANSYS code, because electromagnetic load was one of the main loads. The 40 sector finite element model was established including the vacuum vessel, equatorial thermal shield, and superconducting magnets. The main purpose of this analysis was to investigate the eddy current and electromagnetic force in the equatorial thermal shield during plasma disruption. Stress analysis was implemented under the electromagnetic load. The results show that the equatorial thermal shield can accommodate the calculated electromagnetic loads.