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屏蔽电机内冷却循环流场及水力损失数值研究

水力发电学报 2024年第10期43卷 53-62页

作者：郭苗刘宇唐学林刘树红左志钢李小芹华北电力大学水利与水电工程学院北京102206 中国农业大学水利与土木工程学院北京100083 清华大学水圈科学与水利工程全国重点实验室北京100084 清华大学能源与动力工程系北京100084

本文采用RNG k-ε湍流模型对一屏蔽电机内部流动进行数值模拟,同时运用多孔介质模型及Ergun方程计算近似电机定子区域内流动,最终构建了基于能量守恒定律的水力损失分析理论模型,揭示了屏蔽电机内部水力损失演化过程,并结合相应流场现... 详细信息

本文采用RNG k-ε湍流模型对一屏蔽电机内部流动进行数值模拟,同时运用多孔介质模型及Ergun方程计算近似电机定子区域内流动,最终构建了基于能量守恒定律的水力损失分析理论模型,揭示了屏蔽电机内部水力损失演化过程,并结合相应流场现象进行了分析。计算结果表明,转子与多孔介质两者间隙内流体成螺旋形流动,同时较大的多孔介质阻力将导致冲击水流在此间隙前出现多个轴对称漩涡;推力轴承径向流道间的进口处出现类似叶片绕流的轴对称漩涡,同时推力轴承外流场还存在强环流;研究结果揭示了复杂的几何结构会导致产生较多漩涡,且造成较大水力损失,尤其是在推力轴承与滑动轴承间。以上计算结果可为相似电机内部冷却循环流动开展相关几何参数和结构优化提供一定参考。

关键词：多孔介质流水力损失漩涡推力轴承屏蔽电机

Analytical Solutions of Cracks Emanating from an Elliptic Hole in an Infinite Plate under Tension

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 1057-1063页

作者： liu shuhong DUAN Shijie Department of Engineering Mechanics Shijiazhuang Tiedao University The Key Laboratory for Health Monitoring and Control of Large Structures of Hebei Province Department of Adult Education Shijiazhuang Tiedao University

It is a common phenomenon that the cracks originating from a hole can cause structural damage in ***,the fracture mechanics studies of hole edge crack problems are not *** problem of an elliptical hole with two collinear edge cracks of unequal length in an infinite plate under uniform tension at infinity is *** on the complex variable method,the analytical solutions of stress functions and stress intensity factors are *** stress distribution along the axes and the edge of the elliptical hole is given *** numerical results show that there is obvious stress concentration near the hole and cracks,and the stresses tend to applied loads at distances far from the defect,which conform to Saint-Venant’s ***,the stress functions are proved to be *** special conditions,the present configuration becomes the Griffith crack,two symmetrical cracks emanating from an elliptical hole,two cracks of unequal length emanating from a circular hole,a crack at the edge of a circular hole,or a crack emanating from an elliptical *** with available results,stress intensity factors for these special shapes of ellipses and cracks show good *** stress intensity factor for two cracks of unequal length at the edge of an elliptical hole increases with the crack length and the major-to-minor axis ratio of the elliptical *** stress distribution in an infinite plate containing an elliptic hole with unsymmetrical cracks is given for the first time.

关键词： hole crack stress distribution stress intensity factor

Analytical solutions of cracks emanating from an elliptical hole under shear

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Chinese Journal of Aeronautics 2014年第4期27卷 829-834页

作者： liu shuhong Duan Shijie Department of Engineering Mechanics Shijiazhuang Tiedao University Department of Adult Education Shijiazhuang Tiedao University

Based on the complex variable method, the analytical solutions of stress functions and stress intensity factors（SIFs） are provided for the plane problem of two collinear edge cracks emanating from an elliptical hole in an infinite plate under shear. The stress distribution along the horizontal axis is given in graphical forms, which conforms to Saint-Venant＇s principle. The influences of crack length and ellipse shape on the stress intensity factors are evaluated. Comparing the analytical solutions with finite element method（FEM） results shows good coincidence. These numerical examples show that the present solutions are accurate.

关键词： Conformal mapping Cracks Hole Shearing Stresses Stress intensity factors

Exact Solutions for Piezoelectric Materials with an Elliptic Hole or a Crack under Uniform Internal Pressure

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Chinese Journal of Mechanical Engineering 2012年第4期25卷 845-852页

作者： liu shuhong SHEN Yingming liu Jinxi Department of Engineering Mechanics Shijiazhuang Tiedao University Shijiazhuang 050043 China Department of Science and Technology Shijiazhuang Tiedao University Shijiazhuang 050043 China

The existing investigations on piezoelectric materials containing an elliptic hole or a crack mainly focus on remote uniform tensile *** order to have a better understanding for the fracture behavior of piezoelectric materials under different loading conditions,theoretical and numerical solutions are presented for an elliptic hole or a crack in transversely isotropic piezoelectric materials subjected to uniform internal pressure and remote electro-mechanical *** the basis of the complex variable approach,analytical solutions of the elastic and electric fields inside and outside the defect are derived by satisfying permeable electric boundary condition at the surface of the elliptical *** an example of PZT-4 ceramics,numerical results of electro-elastic fields inside and outside the crack under various electric boundary conditions and electro-mechanical loads are given,and graphs of the electro-elastic fields in the vicinity of the crack tip are *** non-singular term is compared to the asymptotic one in the *** is shown that the dielectric constant of the air in the crack has no effect on the electric displacement component perpendicular to the crack,and the stresses in the piezoelectric material depend on the material properties and the mechanical loads on the crack surface and at infinity,but not on the electric loads at *** figures obtained are strikingly similar to the available *** the existing work,the existence of electric fields inside an elliptic hole or a crack is considered,and the piezoelectric solid is subjected to complicated electro-mechanical loads.

关键词： piezoelectric material elliptic hole crack boundary condition electro-elastic fields

Investigation of Anti-Plane Shear Behavior of a Piezoelectric Material Containing an Impermeable Edge Crack

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上海交通大学学报 2004年第Z2期38卷 124-129页

作者： Shijie Duan shuhong liu Jin liu School of Adult Education Shijiazhuang Railway InstituteShijiazhuang 050043 China Department of Mechanics and Engineering Science Shijiazhuang Railway InstituteShijiazhuang 050043 China Department of Mechanics and Engineering Science Shijiazhuang Railway InstituteShijiazhuang 050043 China

The problem involving an edge-crack in a rectangular material under the anti-plane mechanical loading and in-plane electric loading is analyzed under the impermeable conditions. By using the series expansion, the general solutions of electromechanical fields are obtained, which satisfied both governing equations and crack sufrace boundary conditions, and the unknown constants in which can be obtained by the boundary collocation method. Numerical results are given to show the effect of electromechanical interaction on energy release rate.

关键词： piezoelectric material mode-Ⅲ edge-crack intensity factor energy release rate boundary collocation method

Flow-Induced Instabilities in Pump-Turbines in China

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Engineering 2017年第4期3卷 504-511页

作者： Zhigang Zuo shuhong liu State Key Laboratory of Hydro Science and Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

The stability of pump-turbines is of great importance to the operation of pumped storage power （PSP） stations. Both hydraulic instabilities and operational instabilities have been reported in PSP stations in China. In order to provide a reference to the engineers and scientists working on pump-turbines, this paper summarizes the hydraulic instabilities and performance characteristics that promote the operational instabilities encountered in pump-turbine operations in China. Definitions, analytical methods, numerical and experimental studies, and main results are clarified. Precautions and countermeasures are also provided based on a literature review. The gaps between present studies and the need for engineering practice are pointed out.

关键词： Pump-turbines Flow-induced instability Pressure fluctuations S-shaped characteristics Positive slopes

论大中小学爱国主义教育一体化建设的理论内涵及实践探索

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现代教育科学 2024年第1期 40-46页

作者：侯玉童刘树宏中央民族大学北京100081

推进大中小学爱国主义教育一体化建设是理论和实践相统一的重要课题。大中小学爱国主义教育一体化建设的内涵重点在“大中小学”和“一体化建设”,其实质是对大中小学爱国主义教育体系的系统构建。深刻理解大中小学爱国主义教育一体化... 详细信息

推进大中小学爱国主义教育一体化建设是理论和实践相统一的重要课题。大中小学爱国主义教育一体化建设的内涵重点在“大中小学”和“一体化建设”,其实质是对大中小学爱国主义教育体系的系统构建。深刻理解大中小学爱国主义教育一体化建设的内涵和实质,遵循整体性与层次性相统一、主导性和主体性相统一、思想性、理论性和亲和力、针对性相统一,以及理论与实践相结合、宏观与微观相统一等原则,从打造教育共同体的组织架构、建立健全各学段既有序衔接又螺旋上升的课程和教材体系、打造各要素同向同行的横向教育格局、牢牢占领网络阵地等方面着手,打造虚实相融的教育模式。

关键词：大中小学爱国主义教育一体化教育共同体思想政治教育横向教育格局

铸牢中华民族共同体意识的实践路径——从社会心态说开去

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贵州民族大学学报（哲学社会科学版） 2024年第2期 42-56页

作者：刘树宏侯玉童中央民族大学马克思主义学院北京100081 中央民族大学马克思主义学院思想道德与法治教研中心北京100081

中华民族共同体意识是一种积极健康的社会心态。铸牢中华民族共同体意识就是调动社会各方面的力量,通过心理建构和行为模铸,促进中华民族共同体意识成为各族干部群众广泛认同和长期保持的心理特点和行为模式。合理借鉴社会心态理论,探... 详细信息

中华民族共同体意识是一种积极健康的社会心态。铸牢中华民族共同体意识就是调动社会各方面的力量,通过心理建构和行为模铸,促进中华民族共同体意识成为各族干部群众广泛认同和长期保持的心理特点和行为模式。合理借鉴社会心态理论,探讨新时代铸牢中华民族共同体意识的实践路径,可以从五个方面“深耕细作”:以自我归类促进对中华民族共同体的身份认同;在“五个认同”中助力汇聚效应的发生与拓展;以“四个与共”为重点涵养良好的社会行为意向;在“四个正确把握”中激发互动模仿;建立网络预警机制为正向共享现实性生成营造风清气正的网络环境。这五条路径内外兼修、知行统一、虚实融合,共同构成铸牢中华民族共同体意识的实践系统。

关键词：社会心态铸牢中华民族共同体意识中华民族共同体

胃肠微环境下吻合钉仿生表面对细菌黏附的微流场仿真

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医用生物力学 2024年第2期39卷 339-345页

作者：冯荣川胡亚辉马言张春秋刘淑红刘帮付蔚华天津理工大学天津市先进机电系统设计与智能控制重点实验室天津300384 机电工程国家级实验教学示范中心(天津理工大学) 天津300384 天津市骨植入物界面功能化与个性化研究企业重点验室天津300190 天津医科大学总医院胃肠肛肠外科天津300052

目的模拟在吻合钉植入人体以后,吻合钉表面与肠壁组织之间的微流场环境,研究其仿生疏水化表面对细胞外液流速和壁面处流体剪切力的影响,进而通过流场的变化调控细菌的黏附。方法观察鲨鱼皮肤微结构,建立细菌在微流场环境中的简化二维运... 详细信息

目的模拟在吻合钉植入人体以后,吻合钉表面与肠壁组织之间的微流场环境,研究其仿生疏水化表面对细胞外液流速和壁面处流体剪切力的影响,进而通过流场的变化调控细菌的黏附。方法观察鲨鱼皮肤微结构,建立细菌在微流场环境中的简化二维运动模型。通过计算流体动力学数值仿真,模拟静态流场和动态流场中,细菌分别在光滑表面和微织构表面的运动,比较两种表面环境下细菌周围的流场特征和流体剪切力,分析流体剪切力影响细菌黏附的内在机制。结果仿生微织构的加入增强了微流场内细胞外液的流速,在静态流场中流体对细菌的黏滞作用较小;动态流场中流体对细菌的推动作用更强;一定范围内的微坑宽度使微织构壁面所受流体剪切力更大。结论吻合钉的仿生微织构表面,加快了细胞外液的流速,提高了微织构壁面和细菌所受流体剪切力,对细菌的附着有一定影响。研究结果为吻合钉抑菌表面的研究提供了理论依据。

关键词：仿生鲨鱼皮肤结构吻合钉抑菌性细胞外液流速壁面剪切力