基于有限公式法和流固耦合的永磁牵引电动机冷却系统设计与分析

稀土永磁电机由于其高效、高功率密度的特点,在轨道交通牵引系统的设计中受到了广泛和密切的关注。由于其全封闭式结构,牵引电动机的负载能力主要受限于冷却系统的散热能力。建立了一台永磁牵引电动机的全封闭式自循环空-空冷却系统,通过对参数散热敏感性的分析,确定了适宜的冷却结构参数范围。针对该冷却结构,应用有限公式法进行三维温度场数值计算,确定了散热系统的结构参数,并用流固耦合仿真验算了计算结果。     

Influence of blade deformation and yawed inflow on performance of a horizontal axis tidal stream turbine

For a better design of tidal stream turbines operated in off-design conditions, analyses considering the effects of blade deformation and yawed inflow conditions are necessary. The flow load causes deformation of the blade, and the deformation affects the turbine performance in return. Also, a yawed inflow influences the performance of the turbine. As a validation study, a computational fluid dynamics (CFD) simulation was carried out to predict the performance of a horizontal axis tidal stream turbine (HATST) with rigid blades. The numerical uncertainty for the turbine performance with blade deformation and a yawed inflow was evaluated using the concept of the grid convergence index (GCI). A fluid–structure interaction (FSI) analysis was carried out to estimate the performance of a turbine with flexible composite blades, with the results then compared to those of an analysis with rigid blades. The influence of yawed inflow conditions on the turbine performance was investigated and found to be important in relation to power predictions in the design stages.     

小尺度立柱水动力系数的数值分析

采用MpCCI耦合器作为ABAQUS和FLUENT的数据交换平台,对不同截面形式桥梁墩柱结构受波浪场作用过程中的流目耦合现象进行数值模拟。计算结果表明,圆形截面与方形截面立柱在波流场中的波浪力拖曳力系数与传统的波浪力计算方法中采用的拖曳力系数相吻合,为后续多柱多截面桥梁基础在流固耦合问题上的扩展研究打下了一定的基础。     

Recent fluid–structure interaction modeling challenges in IC encapsulation – A review

The rapid development of computing software has facilitated multifarious research in integrated circuit (IC) packaging. Complicated and complex processes can be visualized via simulation modeling with this software. The applications of aided software enhance the fundamental physicochemical understanding and visualization of the IC encapsulation process. In this article, fluid–structure interaction (FSI) during IC encapsulation through computer-aided simulation is reviewed based on the amount of substantial work conducted from the past decades to the present. FSI phenomena in various IC encapsulations, such as wire sweep, paddle shift, lead frame deformation, IC chip, and through-silicon via (TSV) deformation, is considered in the review. The significance and challenges of FSI analysis are also highlighted in this article.     

Study on the fluid/structure interaction at different inlet pressures in molded packaging

This paper presents the computational study of fluid/structure interaction (FSI) analysis in the molding process using the Mesh-based parallel Code Coupling Interface (MpCCI) method with finite volume coding (FLUENT 6.3) and finite element coding (ABAQUS 6.9). The FSI analysis is implemented on the molded package during the encapsulation process with different inlet pressures. Real-time flow visualization, deformation and stress of the silicon die during the encapsulation process are presented in this paper. A fluctuation phenomenon of the silicon die is found in the encapsulation process when the inlet pressure increases. The maximum deformation during the process is determined at different locations on the silicon die, calculated during the final stage of the filling process. The deformation and stress of the die is exponentially increased with increasing inlet pressure. The maximum stress on the solder bump is concentrated near to the inlet gate. Thus, the present FSI analysis approach is expected to be a guideline or reference and provides better understanding of the encapsulation process for package design in the microelectronic industry.     

基于(u_i,p)格式的U型渡槽动力特性及动力响应分析

结合沙河渡槽的设计要求,考虑渡槽在正常运行过程中槽内水体与槽身产生的动力相互作用,采用流固耦合的理论,建立了水体和结构的耦合场模型,然后对渡槽进行了振动特性分析,探讨了渡槽在6种工况下的模态变化范围,用拟静力法进行动力响应计算,得出渡槽结构在地震作用下位移和应力响应的最值及随时间变化的规律,为该渡槽的抗震设计提供依据.     

1500m3水塔流固耦合时程分析

根据工程实例,研究了塔体与水体流固耦合的边界条件和运动方程,建立水塔体系的流固耦合有限元模型。通过施加天津波与E1Centro波进行地震激励,借助ANSYS软件分析了水体晃动对水塔地震位移响应的影响。计算表明:水体的晃动可以减小地震对塔体的位移响应,当蓄水深度增大时,减震效果明显。     

端部约束悬臂输流管道的非线性动力学特性

针对悬臂端受线性弹簧支承和扭转弹簧约束的约束悬臂输流管道,采用分岔图、相平面图、Poincare截面和Lyapunov指数等非线性振动的数值仿真方法,研究其在自激-参数激励-外激励联合激励作用下的非线性动力学特性,分析系统出现周期和混沌运动响应的参数条件,揭示其通向混沌的途径,探寻各参数对输流管道振动特性的影响规律和各参数之间的相互制约关系.数值仿真结果表明,管道系统随质量比、端部约束刚度和管道粘弹性系数的不同,分别呈现周期、概周期、阵发性和混沌运动多种响应形式,系统通过倍周期分岔或阵发性进入混沌,通过倍周期倒分岔脱离混沌.     

混流式水轮机叶片强度计算及其应力特性改善

近年来，国内外一系列大型混流式水轮发电机组频繁发生转轮叶片的疲劳裂纹问题，对电站机组的安全稳定运行构成了严重威胁。本文以一混流式水轮机为研究对象，通过混流式水轮机全流道CFD计算及基于顺序流固耦合的转轮结构应力场计算，分析该转轮产生疲劳裂纹的原因；其次通过在叶片出水边和上冠连接处加应力释放三角块来降低叶片最大有效应力值和改善叶片应力分布。结果表明应力释放三角块可以明显降低叶片最大有效应力和改善叶片应力分布。本文计算结果可为其它水轮机转轮的转轮疲劳裂纹分析及应力特性改善提供参考。     

大型U形渡槽动力性能分析

以东深供水改造工程中樟洋渡槽和某小型渡槽为研究对象 ,对比分析大型预应力U形渡槽结构动力特性 ,研究渡槽结构在Mexico强震激励下的振动反应 ,以获得渡槽中动水压力资料。研究表明常规的抗震设计方法可以满足小型渡槽结构的抗震设计要求 ,而大型渡槽中水体的大幅晃动作用较大程度地改变了水压力、槽体应力的分布和数值 ,对渡槽中预应力钢筋不利 ,在渡槽的抗震设计中 ,动水压力应该作为一项主要的外荷载予以考虑。