Experimental Study on Wire Melting Control Ability of Twin-Body Plasma Arc

The twin-body plasma arc has the decoupling control ability of heat transfer and mass transfer,which is beneficial to shape and property control in wire arc additive manufacturing.In this paper,with the wire feeding speed as a characteristic quantity,the wire melting control ability of twin-body plasma arc was studied by adjusting the current separation ratio(under the condition of a constant total current),the wire current/main current and the position of the wire in the arc axial direction.The results showed that under the premise that the total current remains unchanged(100 A),as the current separation ratio increased,the middle and minimum melting amounts increased approximately synchronously under the effect of anode effect power,the first melting mass range remained constant;the maximum melting amount increased twice as fast as the middle melting amount under the effect of the wire feeding speed,and the second melting mass range was expanded.When the wire current increased,the anode effect power and the plasma arc power were both factors causing the increase in the wire melting amount;however,when the main current increased,the plasma arc power was the only factor causing the increase in the wire melting amount.The average wire melting increment caused by the anode effect power was approximately 2.7 times that caused by the plasma arc power.The minimum melting amount was not affected by the wire-torch distance under any current separation ratio tested.When the current separation ratio increased and reached a threshold,the middle melting amount remained constant with increasing wire-torch distance.When the current separation ratio continued to increase and reached the next threshold,the maximum melting amount remained constant with the increasing wire-torch distance.The effect of the wire-torch distance on the wire melting amount reduced with the increase in the current separation ratio.Through this study,the decoupling mechanism and ability of this innovative arc heat source is more clearly.

Flow control performance evaluation of a tri-electrode sliding discharge plasma actuator

Tri-electrode sliding discharge(TED)plasma actuators are formed by adding a direct current(DC)exposed electrode to conventional dielectric barrier discharge(DBD)plasma actuators.There are three TED modes depending on the polarity and amplitude of the DC supply:DBD discharge,extended discharge and sliding discharge.This paper evaluates the electrical,aerodynamic and mechanical characteristics of a TED plasma actuator based on energy analysis,particle image velocimetry experiments and calculations using the Navier-Stokes equation.The flow control performances of different discharge modes are quantitatively analyzed based on characteristic parameters.The results show that flow control performance in both extended discharge and sliding discharge is more significant than that of DBD,mainly because of the significantly higher(up to 141%)body force of TED compared with DBD.However,conductivity loss is the primary power loss caused by the DC polarity for TED discharge.Therefore,power consumption can be reduced by optimizing the dielectric material and thickness,thus improving the flow control performance of plasma actuators.

Turbulent boundary layer control with DBD plasma actuators

The flat-plate turbulent boundary layer at Reτ=1140 is manipulated using a spanwise array of bidirectional dielectric barrier discharge(DBD)plasma actuators.Based on the features of no moving mechanical parts in the DBD plasma control technology and hot-wire anemometer velocity measurements,a novel convenient method of local drag reduction(DR)measurement is proposed by measuring the single-point velocity within the linear region of the viscous sublayer.We analyze the premise of using the method,and the maximum effective measurement range of-73.1%<DR<42.2%is obtained according to the experimental environment in this work.The local drag decreases downstream of the center of two adjacent upper electrodes and increases downstream of the upper electrodes.The magnitude of the local DR increases with increasing voltage and decreases as it moves away from the actuators.For the spanwise position in between,the streamwise distribution of the local DR is very dependent on the voltage.The variable-interval time-average detection results reveal that all bursting intensities are reduced compared to the baseline,and the amount of reduction is comparable to the absolute values of the local DR.Compared with previous results,we infer that the control mechanism is that many meandering streaks are combined together into single stabilized streaks.

Experimental investigation of dynamic stall flow control using a microsecond-pulsed plasma actuator

To alleviate the performance deterioration caused by dynamic stall of a wind turbine airfoil,the flow control by a microsecond-pulsed dielectric barrier discharge(MP-DBD) actuator on the dynamic stall of a periodically pitching NACA0012 airfoil was investigated experimentally.Unsteady pressure measurements with high temporal accuracy were employed in this study,and the unsteady characteristics of the boundary layer were investigated by wavelet packet analysis and the moving root mean square method based on the acquired pressure.The experimental Mach number was 0.2,and the chord-based Reynolds number was 870 000.The dimensionless actuation frequencies F+ were chosen to be 0.5,1,2,and 3,respectively.For the light dynamic regime,the MP-DBD plasma actuator plays the role of suppressing flow separation from the trial edge and accelerating the flow reattachment due to the high-momentum freestream flow being entrained into the boundary layer.Meanwhile,actuation effects were promoted with the increasing dimensionless actuation frequency F+.The control effects of the deep dynamic stall were to delay the onset and reduce the strength of the dynamic stall vortex due to the accumulating vorticity near the leading edge being removed by the induced coherent vortex structures.The laminar fluctuation and Kelvin-Helmholtz(K-H) instabilities of transition and relaminarization were also mitigated by the MP-DBD actuation,and the alleviated K-H rolls led to the delay of the transition onset and earlier laminar reattachment,which improved the hysteresis effect of the dynamic stall.For the controlled cases of F+=2,and F+=3,the laminar fluctuation was replaced by relatively low frequency band disturbances corresponding to the harmonic responses of the MP-DBD actuation frequency.

基于ZYNQ-7000的飞控计算机PC/104总线数传链路设计

针对飞控计算机面向多模块、多种类接口资源方向发展引发的原有飞控计算机固有性能不足、可拓展性差的问题,提出一种基于ARM+FPGA的软硬件协同工作、以PC/104作为多模块间通信总线的飞控计算机框架。该框架中针对PC/104总线与系统主存传输的带宽不匹配问题,设计了双通道数据缓冲路径,通过FPGA设计IP实现PC/104总线时序的控制,以DMA的方式实现总线与主存DDR之间的高速数据缓存。实验结果表明,所设计的飞控数据链路可实现模块间PC/104总线以40 Mb/s的速度进行数据传输,以及通过总线实现外设到系统主存之间微秒级别延迟的高速数据交换,保证了多模块工作时的数据传输效率。

基于PC架构的可编程控制器发展趋势及其在风电控制领域的应用

基于PC架构的可编程控制器(PC-Based PLC)是在PC平台和嵌入式操作系统基础上开发的可编程控制器。在风电机组级控制系统(包括主控系统、变桨系统、偏航系统、状态监测系统等)、风电场站级监控系统(包括SCADA系统、AGC、AVC系统等)领域,PC-Based PLC均有广泛应用。对PLC可编程控制器的PC架构、基于PC-Based PLC的风电机组控制系统技术架构等进行了阐述,结合双馈型风电机组控制系统分析了风电机组控制系统的发展现状及存在问题,同时结合云化、分布式、边缘计算等工业控制前沿方向分析了PC-Based PLC在风电控制领域的技术发展趋势。

Airfoil friction drag reduction based on grid-type and super-dense array plasma actuators

To improve the cruise flight performance of aircraft, two new configurations of plasma actuators(grid-type and super-dense array) were investigated to reduce the turbulent skin friction drag of a low-speed airfoil. The induced jet characteristics of the two actuators in quiescent air were diagnosed with high-speed particle image velocimetry(PIV), and their drag reduction efficiencies were examined under different operating conditions in a wind tunnel. The results showed that the grid-type plasma actuator was capable of producing a wall-normal jet array(peak magnitude: 1.07 m/s) similar to that generated in a micro-blowing technique, while the superdense array plasma actuator created a wavy wall-parallel jet(magnitude: 0.94 m/s) due to the discrete spanwise electrostatic forces. Under a comparable electrical power consumption level,the super-dense array plasma actuator array significantly outperformed the grid-type configuration,reducing the total airfoil friction drag by approximately 22% at a free-stream velocity of 20 m/s.The magnitude of drag reduction was proportional to the dimensionless jet velocity ratio(r), and a threshold r = 0.014 existed under which little impact on airfoil drag could be discerned.

Integrated design and performance optimization of three-electrode sliding discharge plasma power supply

The three-electrode sliding dielectric barrier discharge(TES-DBD) plasma actuator significantly enhances the ionization rate and momentum exchange between charged particles and neutral particles by incorporating a parallel DC electrode into the standard DBD design. This design improves the body force and induced jet velocity while allowing flexible control of the induced jet angle, overcoming the limitations of discharge extension and uncontrollable direction in traditional DBD plasma actuators. An integrated plasma power supply has been designed specifically for TES-DBD plasma actuators, streamlining the power supply management. The methodology involves designing the circuit topology for the TES-DBD power supply, followed by simulating and validating its operating principles using Multisim software. The operational performance of the power supply is evaluated through a comprehensive analysis of its electrical,thermal, and aerodynamic properties specific to TES-DBD plasma actuation.

High Efficiency PCS with Scan-Type MPPT Control for a Grid-Connected PV Power Generation System

For a standalone PV （photovoltaic） power generation system, the author previously proposed a new MPPT （maximum power point tracking） control method in which the I-V characteristics are scanned with a detection interval control that operates at specified intervals and monitors the maximum power point. The author has obtained satisfactory results using this new MPPT control method. This paper investigates the application of the new MPPT control method for a PCS （power conditioning system） in a grid-connected type PV power generation system. The experimental results clearly demonstrate that the developed PCS offers outstanding effectiveness in tracking the maximum power point in partially shaded environments.

双级PCS中光伏侧控制仿真

在可再生能源发电系统中,储能功率调节系统(Power Conditioning System,PCS)将光伏发电系统产生的电能进行调节、转换和储存,以满足用户用电需求。储能PCS的光伏侧直接关系到母线电压,其控制效果直接影响光伏系统的性能和稳定性。故合理的光伏侧控制策略设计对于维护平稳母线电压有重要的意义。为了优化储能PCS的光伏侧控制策略,本文提出了一种恒功率的最大功率点跟踪方法。该方法利用恒功率控制和电导增量法等技术,对光伏系统进行建模和优化。通过对实际光伏系统的数据进行分析和仿真,证明了该方法在提高光伏系统效率和稳定性方面的有效性。

PC构件施工质量控制研究

PC构件作为一种新型的建筑建材,近年来得到了广泛的应用和发展。然而,PC构件由于本身的特殊性和复杂性,其施工质量控制成为了一个备受关注的问题。例如,构件设计质量和加工精度不达标,安装、浇筑连接不规范等,不仅影响了建筑物的整体性能,也给工程质量带来了潜在的风险。对此,文章结合绿动创意之家工程实例,围绕PC构件的施工质量控制展开了研究,旨在提出有效的控制策略,为工程实践提供理论支持。

PC生产线自动布料机研究

混凝土预制件(Precast Concrete,PC)生产线是支撑建筑产业工业化和现代化发展的关键装备,布料机是PC生产线的核心设备,对生产线的自动化程度、可靠性、工作效率及构件质量有着决定性影响。通过研究自动布料机布料装置和控制系统,提供一种切实可行的自动布料解决方案,同时指出布料机未来的发展方向。

基于PCS7和Simulink的过程控制虚拟仿真实验平台开发

为了解决过程控制实验DCS硬件成本高、学生的实验效率低等问题,提出一种基于PCS7和Simulink的虚拟实验平台开发方案。该方案利用Simulink提供的子系统搭建实际工业对象模型,在PCS7中组态过程控制算法,通过OPC通信进行实时仿真。以双容水箱液位控制实验为例,介绍了整个实验平台的搭建过程。实际教学效果表明,该实验平台减少了硬件成本,激发了学生的实验兴趣,提高了实验效率。

Welding of Ti-6Al-4V alloy using dynamically controlled plasma arc welding process

A novel dynamically controlled plasma arc welding process was introduced,which is able tominimize heat input into the workpiece materials while maintaining desired full penetration,and it was used to weld Ti-6Al-4V alloy sheets.The microstructures,facture surfaces and microhardness of the welded joints were characterized by using optical microscope,scanning electron microscope （SEM） and Vickers microhardness tester.Comparing with welds such as gas tungsten arc and conventional plasma arc processes,the experimental results revealed the improvements when using the present process including：1） reducing prior-beta （β） grain size and prohibiting formation of hard martensite phases in the fusion zone due to the decreased heat input;and 2） better toughness and higher hardness.

基于PCS7的过程控制实验设计

针对传统过程控制实验存在的一些缺点,基于西门子过程控制系统PCS 7设计了电厂锅炉综合自动控制系统,其中包括了过热蒸汽出口温度控制系统、燃料和送风控制系统、给水控制系统等。利用PCS 7中连续功能图(CFC)和顺序功能图(SFC)及仿真设备SMPT1000,实现各个回路的控制策略。实验结果表明,所设计的实验系统能够进行无扰切换,稳定运行,具有较强的抗干扰能力,且超调量小,响应速度快。

基于PCS7的铜钴回收冗余控制系统设计

针对新型铜钴回收工艺仍然处于人工手动操作、自动化程度低的问题,该文在西门子PCS7过程控制系统下设计铜钴回收冗余控制系统对整个生产流程进行自动化监控,针对铜钴回收浓密机工艺机理复杂,操作环境恶劣,具有大惯性、非线性以及来料性质波动频繁等缺点,分析浓密机的结构,设计浓密机的参数自整定模糊PID控制。通过在青海某矿业集团50万吨铜钴回收项目的实际应用证明,该系统能很好地满足控制要求。浓密机运行安全可靠,提高了综合回收效率,减轻了劳动强度,实现了安全稳定的自动化生产。

低通滤波PID控制算法在PCS中的应用

PID控制是反馈控制系统中最常用的控制方法。在托卡马克装置中,等离子体的行为是很难精确预测和控制的。托卡马克等离子体控制系统中包括了对不同控制对象的PID控制。基于数字滤波技术设计的低通滤波PID算法,通过滤掉误差信号中的噪音信号从而提高了算法的控制效果。该算法在等离子体控制系统中得到了很好的应用。

基于PCS功率越限判据的独立型微电网紧急控制策略

紧急控制作为微电网系统的最后一道防线,在系统受到大扰动以后,能够维持频率稳定,对微电网的稳定运行具有重要意义。文中分析了频率紧急控制策略以及轮次减载策略在微电网中存在的定值整定难、无法精准减载的问题,提出了一种基于储能变流器(PCS)输出功率越限判据的独立型微电网紧急控制策略:在外部扰动导致PCS输出功率越限时,通过计及电池荷电状态(SOC)的均衡控制策略计算PCS的越限功率,采用负荷精准减载方案精确切除负荷,并针对工程实施采用面向通用对象的变电站事件(GOOSE)通信技术、提出小步长趋势变化采样算法和防一点大数算法,提高了控制系统的响应速度,提升了大容量独立微电网运行的稳定性。通过新疆某独立型微电网项目工程案例验证了本方案的可行性和有效性。

中原油田采油三厂PCS调驱先导试验

PCS调驱工艺技术是一种将调剖堵水与三次采油技术有机结合起来的技术。在室内实验成功的基础上,针对马寨油田的油藏条件筛选出最佳的驱油剂配方,在马寨油田W95块、W305块进行先导试验。试验证明,PCS工艺技术有一定增油潜力,PCS调驱过的井组自然递减,综合递减远远小于整个区块递减,收到较好的控水稳油效果,取得明显的经济效益。

新一代过程控制系统SIMATIC PCS 7

指出了SIMATIC PCS 7是基于全集成自动化思想的功能强大、面向生产工艺的现场总线解决方案,探讨了PCS 7系统在现代轧钢生产中的应用,以及对新型控制方法的认识。