In order to effectively prevent the diffusion and pollution of highly concentrated PM2.5, the roadway full-section water curtain device has been developed in this paper. Based on our water spray experiments, a type II nozzle that was suitable for the water curtain device was selected. This roadway full-section water curtain device was optimized through a numerical simulation using Fluent software. The wind -droplet numerical simulation results showed that the water curtain device could achieve the optimal spray parameters. When the water pressure Pw was 7 MPa and the nozzle was inclined to the upwind side at theta = 15 degrees, a high-quality spray field with the concentration greater than 10 g m(-3) covered 93.1 % of the cross-sectional area of the entire roadway. The settlement of harmful particulates of PM2.5 in the air-return pathway of the Bailu Coal Mine's 4307 coal mining face, using three roadway full-section water curtain devices, was then measured. The results showed that the ideal level of dust settlement can be achieved by consuming less water. It was also found that the settling rate of PM2.5 at the air-return pathway 200 m away from the coal mining face was as high as 95.7 %, indicating that the roadway full-section water curtain device had settled and controlled the PM2.5 in the roadway's airflow effectively. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

To accurately calculate the core loss of medium frequency transformer(MFT) under nonsinusoidal excitation,we comparatively study several correction methods based on original steinmetz equation(OSE).Firstly,the correction methods are comparatively analyzed from the correction principle.Secondly,Square waveform is a typical voltage waveform for MFT,and triangular waveform is close to the sinusoidal one.Equations of the correction methods for these two voltage waveforms are derived.Finally,measurement system for hysteresis loop of the core is set up,and coefficients of OSE for a nanocrystalline ring core are fitted in the medium frequency range.Thereby,the calculated values of each correction methods are compared with the measured values of the core loss density under square and triangular waveform excitations.It is found that the error of the coefficient Steinmetz equation(WcSE) is the minimum.When calculating the core loss of nanocrystalline in the medium frequency range,WcSE is the most accurate.The research results can provide a reference for the accurate calculation of the core loss of medium frequency transformer at its design and optimization stage.

分析了大功率中频变压器绕组高频损耗与铁心高频损耗的解析计算方法,建立了算优化设计流程.采用自由参数扫描法,对一台面向电力机车轻量化应用的300kW中频变压器进行了优化设计.通过建立评价系数公式,最优方案兼顾了变压器的损耗与重量.利用电磁有限元仿真计算软件Ansoft Maxwell,分别在二维涡流场与瞬态场中,对其中6组设计方案的绕组损耗与铁心损耗进行了仿算验证.对比解析设计与有限元仿真计算结果,两者误差在可接受范围内,验证了优化设计方法的正确性与有效性.

When hollow conductors are applied to high power medium frequency transformer (MFT), both utilization ratio of the conductor material and cooling efficiency of the transformer can be improved. However, because of the unique shape, it is difficult to evaluate AC resistance of hollow conductors by analytical calculation directly. To solve this problem,this paper combined the analytical and numerical method. Relationship between AC resistance of hollow and the solid conductors in MFT was got by abundant finite element models calculation. The relationship was concluded as a new defined parameter, hollow resistance factor. Through the analysis of the relationship between hollow resistance factor and relevant parameters, the classic Dowell analytical equation can be extended to AC resistance calculation of hollow conductor windings. A MFT prototype with hollow conductors was manufactured. The results comparison of the analytical, finite element numerical, and experimental calculation verified the correctness and effectiveness of the proposed evaluation method.

为了对电力电子牵引变压器300 kW功率单元中的中频变压器(HPMFT)进行优化设计,分析了大功率中频变压器绕组高频损耗、铁芯高频损耗以及漏感参数的计算方法.在此基础上,利用自由参数扫描法建立了其设计流程,依据综合评价系数选择了兼顾变压器损耗、漏感与质量的最优方案.按照最优方案制造了样机,并对其参数进行了测试.对比解析设计与实验测试结果可知,样机铜耗、铁耗、漏感与质量的误差分别为7.99％、12.75％、6.98％和2.21％,均在可接受范围内,验证了该设计方法的正确性与有效性.

为在设计阶段对大功率中频变压器漏感值进行准确法估算,基于中频变压器一维等效模型,根据漏磁场分布特征,通过能量法进行了变压器漏感参数解析公式推导。在此基础上,根据理想漏磁场模型与实际的差异,修正了解析公式中绕组的电导率与漏磁场的计算高度。通过比较两台样机在50 Hz~10 k Hz频段下的漏感实测与计算结果,证实了对这2个参数同时进行校正,可使变压器漏感计算误差减小到5%以内,并进一步分析了仍然存在的误差产生的原因。通过样机1与样机2的漏感值对比,证明了绕组交叉换位技术可有效减小变压器漏感。

Based on a one-dimensional magnetic field model of medium frequency transformers (MFT),the analytical equation for the leakage inductance of the MFT is derived with the flux linkage partition method which is based on the characteristics of the magnetic field distribution.On this basis,this paper assumes that the flux is not link or entirely link with the winding which belongs to its region.The derivation process and the final equation of the leakage inductance are simplified by using the average value of these two postulated conditions.The correctness and effectiveness of the method is verified by the comparison of the calculated and measured values.

电缆连接器高压端部对箱体四壁放电影响动车组可靠运行,对连接器端部进行合理优化,可降低故障频次.分析绝缘护层加装位置、绝缘护层结构和绝缘护层厚度对电场强度分布的影响规律.仿真结果表明,电缆连接器高压端加装绝缘护层可有效改善电场分布,绝缘护层应紧贴连接器端部金属部件并延伸至靠近高压端的首个伞裙根部.试验结果表明:优化后的电缆连接器雷电冲击电压耐受值满足高海拔地区运行要求.

绝缘子表面污秽受潮和水分侵入瓷体均可导致瓷支柱绝缘子出现异常发热,比较二者所引起的温升规律具有重要的实际应用价值。为此,选取具有相同运行年限和气象环境条件的试品,发热试品在现场局部有明显发热,不发热试品表面温度分布均匀。研究结果表明:发热试品经干燥处理后发热点暂时性消失,浸泡后的试品温升最大值约为浸泡前数值的2倍,浸泡后高湿和自然风干两种状态下温升变化趋势一致,差值<1℃。浸泡后的发热试品温升最大值出现在加压时长为180~240 min,浸泡时长>72 h时的局部温升变化幅值增加不明显。不发热试品在退网、干燥处理等两种状态下各部位温升值均<0.4℃,浸泡后在表面湿润状态下最大温升仅为1.2℃。发热试品表面污秽受潮湿润后的局部温升值远小于水分侵入瓷体后的温升值,浸泡前的发热试品热点位于7号伞瓷柱附近,浸泡后发热点迁移到3号伞瓷柱附近。发热试品异常发热系绝缘子低压端金具同瓷体胶装处有明显的裂纹和凹坑,该缺陷导致水分侵入瓷体后会引起瓷体局部出现异常发热。

Compact main insulation structure of a power electronic traction transformer(PETT) is designed in this paper. Angle ring and electrostatic ring are set on the end of the high voltage winding to reduce the maximum electric field intensity value and improve the electric field distribution. A model of the end insulation structure is established in ANSYS. By the scanning method, the distance between the electrostatic ring and iron yoke is reduced to 13mm, and the optimal values of the end insulation structure are found.

动车组运行过程中的高速气流影响绝缘子表面污秽分布特性。为在试验室内有效模拟雾霾天气对动车组车顶支柱绝缘子积污及闪络特性的影响,研究在严重污染气候条件下在网运行动车组绝缘子表面污秽分布规律具有重要的工程实用价值。应用比较分析方法,采集不同空气质量指数(AQI)条件下的污秽样本,分析等值附盐密度(ESDD)、不可溶物密度(NSDD)、等值灰盐比KN/E和上下表面污秽不均匀度KNSDD、KESDD分布规律。研究结果表明:针对SC-400C型环氧树脂基复合绝缘子,其NSDD、ESDD、KN/E及KNSDD、KESDD最大值均出现在绝缘子中部伞裙处,不同部位伞裙表面污秽分布具有明显的波动性。除7号伞裙上下表面污秽量无明显差异外,其余伞裙上表面污秽量均大于下表面污秽量。伞裙表面脏污程度同空气质量指数AQI呈现出正相关关系,AQI指数对ESDD有显著影响。

This paper discusses the reduction of torque ripple in interior permanent magnet (IPM) machine. We find that the torque ripple can be minimized by optimizing two key parameters of rotor based on the principle of virtual displacement. The effectiveness of the proposed method is proved by the analytical and finite element analysis (FEA) results. Finally, a prototype was built, and the test result was compared with predicted torque waveform as a mean of confirming the model accuracy.

砌碹巷道长期受临近采区巷道放炮震动及工作面采空区的压力影响,如碹顶与顶板岩石接触不实,容易形成顶板岩石离层冒落,造成隐患。本文介绍了采用固邦特新型充填加固材料对碹顶内部空洞进行充填、再配合锚网索重新支护,对砌碹老巷道的维修与加固起到了良好效果。

In order to solve the problem of the high dust concentration which caused by the speeded advance of coal road using the ABM20 development machine,a kind of method which was suitable to China's speeded advance of coal road was proposed.By using the mathematic model method to contrast the wind current field,dust field of the drivage face which using the enclosure dust-laying system under different drivage velocity,an optimized drivage velocity of the fully-mechanized development machine was got.On the optimized drivage velocity,put their theories into industry experiment.On the analysis of the data which collected by the experiment,the result indicates that the enclosure dust-laying system proposed can significantly lower the dust concentration of the heading face.Also it has some advantages in the accomplishment of the effective advance of coal mines.

针对目前综掘面在采用综掘机内、外喷雾及抽出式除尘风机整体除尘效果不理想的情况,提出了综掘面封闭式除尘系统,该系统利用空气幕控尘原理有效地将粉尘控制在掘进机前方,且设备布置简单、操作方便;根据综掘面的产尘规律和设备、工艺特点,优化了空气幕喷嘴位置和数量、除尘风机吸尘口位置等参数;通过现场应用,验证了该封闭式除尘系统的设计科学、合理,能有效地降低综掘面的粉尘浓度.

巷道顶板采用BHW-3-280-3500型W钢带进行加强支护。钢带的作用是:一方面能保持顶板的平整,另一方面将顶板锚杆连结起来,形成一个支护结构,当顶板某一锚杆失效时,因钢带的作用仍能保持对顶板围岩的有效支护。

Recently, people pay much more attention to the research on gas movement law because more and more gas explosion accidents take place. The paper establishes mathematical model and simulate the distribution rule of gas in gob which is based on the air dynamic dispersion theory of the gob as well as the actual situation at H2103 fully mechanized coal face of BeiZao coal mine.

该文详细介绍了利用Excel进行U型钢拱形可缩性支架设计的过程和公式,首先从计算的角度简化了设计过程,使计算公式更简洁易懂,而且计算准确无误,然后充分利用Excel强大的计算和函数功能,使计算更快捷、准确,而且具有模拟和校对功能,非常实用。

In order to overcome the well ventilated measure of resistance the error and the blunder error to the result of the influence, we put forward the method of recognition and disposal to blunder err or with the practice of resistance measurement, researching of the mathematics method and the analysis of the source of error of colliery ventilation. Enabling the relative error to have obvious depressed, it can do some help to the resistance measurement of colliery ventilation.