一种用于水电站水工建筑物缺陷检测的水下机器人系统设计

水电站水工建筑物缺陷检测目前是由观察型机器人或潜水员完成,存在检测手段少、运行受水流影响等问题。对此,文章针对水电站水工建筑物结构及缺陷特点,研制了一套水下检测机器人系统。该系统利用水动力仿真、静水力分析及稳性分析等方法,优化推力和布局布置、外形等选型和设计,解决了本体浮游和履带复合控制模式、不规则坝面吸附技术、多自由度姿态翻转和运动、缺陷位置定位等技术问题;同时,采用自主开发后处理软件,对声光电传感器数据进行融合,完成了缺陷判别与测量以及修补材料方量的估算,软件识别理论误差为7.4%,小于项目的 20%误差率要求,解决了缺陷判别与测量和修补材料方量的估算问题,最终实现了机器人在水电站水工建筑物的水平面、斜面坡、直立面及曲面环境下的水下缺陷检查、缺陷定位、缺陷尺寸测量及数据记录收集等水下无人化检测作业的目标。最后,通过水池功能试验,验证了该水下检测机器人系统的可行性。     

耦合磁场直流空气断路器栅片特性对灭弧性能的影响研究

栅片材料与结构对断路器的灭弧性能有着重要的影响。该文建立了永磁体作用下灭弧室内磁场的计算模型与电弧磁流体动力学（MHD）模型,实现了两者的耦合。在此基础上,对永磁体作用下栅片材料与栅片结构对电弧动态特性的影响进行了仿真,同时考虑电源极性的影响,得出了永磁体作用下灭弧室内磁场的空间分布、电磁耦合作用下灭弧室内温度分布与气流分布,提取了灭弧室内平均温度与电弧燃弧时间等关键参数,讨论了栅片材料与栅片结构对电弧特性的影响。结果表明,外施磁场作用下铁栅片会造成灭弧室内磁短路现象。相同仿真条件下,含铁栅片的灭弧室燃弧时间最长;动触头作为阳极更有利于弧根跃迁,燃弧时间缩短;当分断电流相同时,铜-绝缘栅片对电弧的冷却效果最佳;栅片倾角可以改变气流场分布,从而影响燃弧时间。     

氩第三谱带的研究进展

介绍了国际上对氩第三谱带的实验和理论研究工作.实验上,采用不同的泵浦方式,观察了荧光谱的谱带形状,并对时间分辨谱进行了测量.理论上,通过光谱学和动力学两方面的计算,对氩第三谱带的来源进行了研究.目前主要有两种假设,即Ar22+和Ar2+离子准分子的跃迁产生该谱带.但这两种假设都只能解释部分实验现象,因而谱带的来源至今没有确切的结论.     

Research on arc root stagnation when small current is interrupted in self-excited circuit breaker

The self-excited DC air circuit breaker (SE-DCCB) has been widely used in urban rail transit due to its excellent stability. It can realize forward and reverse interruption, but has difficulty interrupting small currents due to the phenomenon of arc root sticking at the entrance of the arc chamber in the splitting process, which is known as arc root stagnation. A coupling model of the self-excited magnetic field and magnetohydrodynamics is established for the SE-DCCB with the traditional structure. The magnetic field, temperature and airflow distribution in the arc chamber are investigated with an interrupting current of 150 A. The simulation results show that the direction and magnitude of the magnetic blowout force are the dominant factors in the arc root stagnation. The local high temperature of the arc chamber due to arc root stagnation increases the obstruction effect of the airflow vortex on the arc root movement, which significantly increases the arc duration time of small current interruption. Based on the research, the structure of the magnetic conductance plate of the actual product is improved, which can improve the direction and magnitude of the magnetic blowout force at the arc root so as to restrain the development of the airflow vortex effectively and solve the problem of arc root stagnation when the small current is interrupted. The simulation results show that the circuit breaker with improved structure has a better performance for a small current interruption range from 100 A to 350 A.