Discussion on the application prospect of the transient electromagnetic method based on the dual launcher and mine advanced detection

The dual transmitter implements the equivalent anti-magnetic flux transient electromagnetic method, which can effectively reduce the scope of the transient electromagnetic detection blind area. However, this method is rarely reported in the detection of pipelines in urban geophysical exploration and the application of coal mines. Based on this, this paper realizes the equivalent anti-magnetic flux transient electromagnetic method based on the dual launcher. The suppression effect of this method on the blind area is analyzed by physical simulation. And the detection experiment of underground pipelines is carried out outdoors. The results show that the dual launcher can significantly reduce the turn-off time, thereby effectively reducing the impact of the blind area on the detection results, and the pipeline detection results verify the device’s effectiveness. Finally, based on the ground experimental results, the application prospect of mine advanced detection is discussed. Compared with other detection fields, the formation of blind areas is mainly caused by the equipment. If the dual launcher can be used to reduce the blind area, the accuracy of advanced detection can be improved more effectively. The above research results are of great significance for improving the detection accuracy of the underground transient electromagnetic method.

Trigger control characteristics of fuze-recoil simulation system based on electromagnetic launcher

Fuze is the information processing and control unit of the ammunition, so the quality of the fuze becomes one of the most important aspects of ammunition detection. Since using recoil force is a common method to the arm fuze, its dynamic simulation test has always been the focus of the fuze test research. A new fuze recoil environmental simulation method is proposed based on the electromagnetic launcher. Then the trigger control characteristics of the fuze recoil simulation system and the influence of the trigger position on the recoil force are studied. The results of the study show that although the pulse width of the armature force curve can be changed by adjusting the trigger position, due to the limit of the range, there also exists the contradiction that the electromagnetic pulse width gets narrow with the increase of electromagnetic force peak. Thus, it cannot meet the requirements of the fuze launch recoil simulation. In order to make the recoil force close to the actual environment, the multi-stage trigger control characteristics are analyzed, and the influence of trigger position on recoil environmental force characteristics is studied. Then a fuze launch recoil environmental simulation platform is established and continuous electromagnetic force is achieved by using the trigger strategy. Finally, the experiment is performed to simulate the fuze launch recoil environment and show the feasibility and effectiveness of the proposed theoretical analysis. The major research work of this paper includes studying the composition and basic principle of the simulation system, establishing a launch model to analyze the single-stage and multi-stage coil fuze launch recoil characteristics, designing the test device to verify the correctness and validity of the research. This paper draws the conclusions that the feasibility of the fuze launch environmental simulation based on the electromagnetic launcher is verified, the trigger position has a great influence on force peak continuity, the problems of low maximum overload peak and short peak duration in the multi-stage coil fuze launch environmental simulation can be effectively solved through adjusting the trigger position, the system has creative and extensive application prospects.

Dynamic response of electromagnetic launcher's rail subjected to harmonic magnetic pressure

In order to extend the rail life and improve the firing accuracy,the electromagnetic launcher's rail can be modeled as a beam on elastic foundation with simply supported beam with moving load.Euler beam theory is applied to build the mechanical model and the analytical solution of the equation subjected to harmonic magnetic pressure is derived in details,which has successfully avoided the errors caused by using the uniform pressure to approximately replace the variable force.Numerical analysis of the dynamic response on rail by using the MATLAB software shows that the peak values of maximal deflection and vibration velocity increase gradually as the exciting frequency increases.Taking the same speed of load into account,the dynamic response of rail is obviously smaller than that under constant force.Therefore the reliable theory basis is provided for the design and control of rail to promote the practical application of electromagnetic launcher.

Mechanical Analyses of Rails and Panels in a Rectangular Electromagnetic Rail Launcher

In the present work,rails and panels in a rectangular electromagnetic rail launcher were simulated as finite-length bi-layer elastic foundation beams. Mechanical equilibrium equations were established for these bi-layer beams under the electromagnetic and contact forces between armatures and rails. With the application of Generalized Krylov function,analytical expressions of rails( upper beam) and panels( lower beam) 'deformation and stress were generated. The analytical results agree well with ANSYS calculations even in the presence of electromagnetic and armature's forces,a strong indication of the reliability of the analytical approach. The current work lays the foundation for mechanical analyses of rectangular electromagnetic rail launchers,and offers help in future designs and calculations in marine,aerospace,and civil engineering.

Researches on End Effects of Permanent Magnet Electromagnetic Launchers

Brushless DC linear motors have considerable advantages of simpler structure,higher efficiency,higher thrust density and so on.They are well suited for many domains such as electromagnetic launch and launch-assist,but it is inevitable that there exist longitudinal end effects in the mover of the motor caused by longitudinal discontinuities.The serious trouble caused by longitudinal end effects is the thrust ripple.Firstly,by using the method of finite element simulation,this paper studies the distribution of magnetic field and energy in the end region when the mover is in different positions in the range of a polar pitch and discusses the effective methods of reducing the longitudinal end effects.Then the law of the influence of different mover length on the longitudinal end effects has been studied by using analytic methods,and the influences of the mover length and its end geometry shape on the longitudinal end effects have been verified for the test model by using the method of finite element simulation.

电磁发射装置的温升特性研究

为了研究电磁发射装置的损耗与温升特性,基于COMSOL有限元仿真软件建立了电磁发射装置的动态计算模型,并用有限元方法模拟了电磁发射装置损耗和温度分布的时空演变过程。仿真结果表明:发射过程中电枢会产生熔化现象,导轨和电枢发生接触的内侧,尤其是靠近棱线部分的导轨温升较大。通过该模型建立了激励源大小、导轨材料、导轨结构、导轨尺寸与温度变化的关系,为电磁发射装置热管理提供了参考。

身管外壳对电磁轨道发射装置发射性能影响分析

电枢在发射过程中,瞬时变化的导轨电流会在金属身管外壳上感应出巨大的涡流,身管涡流会产生额外的损耗,同时外壳涡流的去磁效应会改变电枢、导轨等器部件的应力分布从而影响装置发射性能。该文建立了电磁轨道发射装置的数学模型,并针对整体式、上下分断式以及叠压式三种外壳结构有限元模型进行了电磁场-结构场联合仿真,获得了发射装置电磁参数和各部件应力分布。有限元电磁仿真结果表明,叠压式外壳结构外壳涡流最小、电感梯度最大、器部件应力最大,整体式外壳结构外壳涡流最大、电感梯度最小、器部件应力最小。全系统电气仿真和对比试验证明,在满足外壳支持强度和装置各部件应力条件下,选用高磁导率、低电导率的材料并设计抑制涡流的身管外壳结构,有利于提高发射装置电枢出口速度和系统效率,从而获得优良的发射性能。

磁阻型线圈发射器电路拓扑优化与性能提升

为提高线圈发射器的发射速度及能量利用率,研究了磁阻型电磁线圈发射器不同放电电路结构对发射性能的影响。对晶闸管式(SCR)、半桥式、阻容(RCD)吸收式、Boost-Buck式四种不同结构放电电路进行分析,使用有限元方法研究了四种电路对发射性能的影响。结果表明,相同条件下,相比SCR式电路,三种可关断电路中,Boost-Buck式电路下电枢出口速度提升最少,为78.77%;RCD式电路下系统能量利用率提升最少,为220.66%。可关断电路中电流的衰减速率会影响电枢的加速度,存在最优电流衰减速率曲线;单级可关断电路中出口速度与系统能量利用率搭配最均衡的为半桥式放电电路;Boost-Buck式放电电路更具灵活性,更适合应用于多级线圈发射器中。

电磁轨道发射器高速下电流密度场预测

通过有限元方法计算发射过程中电流密度场,是实现电磁轨道发射器结构精细化设计的必要条件之一,但存在计算时间长、高速计算困难甚至无法计算的问题。该文首先以激励电流、电枢电导率、轨道结构参数和时间t为输入,建立了基于条件生成对抗网络(CGAN)的电流密度场预测模型;然后,为提高对复杂场分布的预测能力,构建ResUnet-Trans网络作为CGAN的特征生成器;最后进行计算验证。以低速电磁轨道发射器实例验证模型内插预测精度,结果表明,模型在测试集上的平均绝对百分比误差(MAPE)小于1.5%;以高速电磁轨道发射器实例验证模型外推预测能力,结果表明,使用由低电导率向高电导率的迁移学习训练策略可以提高模型外推预测精度和泛化能力,在测试集上外推预测MAPE小于2.5%。该文提出的预测方法可实现电流密度场的秒级计算,为高速电磁轨道发射器的优化设计和数字化提供了一种新的思路。

基于桥式驱动电路的磁阻型电磁发射器仿真与实验

在磁阻型线圈电磁发射器中,驱动线圈的剩余电流会影响抛体的发射效率。将磁阻型线圈电磁发射器驱动电路中的电容器用桥式电容电路替代,通过桥式电容电路能够快速降低发射器中驱动线圈的剩余电流,避免抛体在运动时受到反向的回吸力。该文介绍了桥式驱动电路在磁阻型线圈电磁发射器中的工作原理,通过仿真与实验对比分析磁阻型线圈电磁发射器在传统驱动电路与桥式驱动电路中的发射性能。实验和仿真的结果表明:采用桥式驱动电路后,磁阻型线圈电磁发射器的效率得到了提高,剩余电流的能量回收到电容器降低了系统能量的损耗。仿真和实验结果的规律具有一致性,验证桥式驱动电路在磁阻型线圈电磁发射器的可行性,为解决驱动线圈剩余电流及反向力的抑制提供了参考。

电枢及导轨几何参数对电磁轨道发射器电感梯度的影响

电枢是电磁轨道发射器的关键部件,但以往对电感梯度的研究认为电枢距离炮尾部无穷远,忽略了电枢对导轨电感梯度的影响。为此,首先分别建立电磁轨道发射器的二维和三维模型,对比分析了无电枢部分导轨的电感梯度和电枢附近部分导轨电感梯度之间的差异;然后,基于有电枢的电磁轨道发射器三维模型,探究了U形电枢尺寸对电磁轨道发射装置电感梯度的影响。研究结果表明:随着导轨宽度,导轨间距,导轨厚度的增加,无电枢部分导轨的电感梯度和电枢附近部分导轨电感梯度之间的误差均逐渐增加;随着两种电枢宽度的增加,电磁轨道发射器电感梯度呈减小趋势,但变化量较小。

磁阻型电磁发射器剩余能量回收电路的仿真与实验

对于传统磁阻型电磁发射器,驱动线圈中的剩余电流会对弹丸产生反向电磁力,这会直接影响弹丸出口速度和发射效率。针对这一问题,提出了一种具有剩余能量回收功能的磁阻型电磁发射器驱动电路。通过在电容放电支路设置调节电感,使放电完成后的电容产生反向电压,对晶闸管施加逆流脉冲使其自然关断,以切换电流流通路径来实现驱动线圈中剩余能量到电容器中的转移。回收的能量被储存在电容器中,可作为磁阻型电磁发射器下一个工作周期的初始储能,减少了电容预充电时间。对提出的剩余能量回收电路的工作原理进行了介绍,并与传统电路进行了仿真与实验对比。仿真与实验结果表明:此电路可以迅速回收驱动线圈中的剩余能量,减少了能量损耗,消除了反向电磁力,提高了弹丸出口速度与发射效率。

磁阻型线圈发射减速力研究

磁阻型线圈发射对铁磁体弹丸有吸引力作用能够实现加速发射,本文通过对磁阻型线圈发射弹丸受力情况的理论分析和仿真计算,发现磁阻型线圈发射在弹丸高速度、驱动线圈强磁场的发射条件下会出现较强作用的涡流减速力,弹丸速度不会增加反而减小。文中提出减小铁磁弹丸的电导率和对弹丸进行开槽处理,仿真结果表明这两种方法可以有效地减弱涡流对磁阻型线圈发射弹丸减速力的影响。

线圈型电磁发射器磁场构型的设计与分析

在线圈型电磁发射器的设计中,驱动线圈磁场构型的设计是基础和关键问题。提出磁场构型的概念和设计准则,推导出线圈型电磁发射模型的加速力表达式,通过有限元方法仿真分析了不同厚长比矩形截面螺线管线圈的磁场形态,考虑驱动线圈与抛体之间的互感及作用力随位置变化的趋势,比较不同截面形状螺线管线圈的磁场构型,同时计算截面形状对作用力的影响。结果表明,在静磁场中,相同截面安匝电流的情况下,驱动线圈采用正方形截面螺线管,能够对抛体产生较大的电磁力。

电磁驱动线圈的力学特性及制作方法

为给线圈式电磁发射装置提供可耐高压的高强度电磁驱动线圈,对驱动线圈的实时电磁力、结构特性及制作方法进行了研究。首先采用ANSOFT软件对线圈绕组时变电磁力进行分析。结果表明,径向电磁力集中到线圈截面的中心右侧,轴向电磁力集中在线圈截面中心偏下部,线圈径向电磁力远大于轴向电磁力,因此litz线制作较带状线圈更适合制作高强度线圈。然后采用ANSYS软件对线圈的接触特性进行分析,结果表明,绕组受到径向电磁力往线圈外侧挤压,形变集中在绕组外侧;上下层绕组沿轴向方向向中间挤压;总电磁力的作用使线圈绕组向外部封装的中间处挤压。设计并制作了高强度驱动线圈,测试结果表明:该线圈满足耐高压、高强度的应用要求。研究结果可为高强度线圈的制备提供理论依据和指导。

电磁发射用13 MJ脉冲功率电源系统研究

随着电磁发射技术的发展,对脉冲功率电源特性的要求也越来越高,需要脉冲电流具有兆安级幅值、数毫秒脉宽、上升快速且有平顶波特点,为此研制了1套13 MJ、额定工作电压10 k V的电容储能型脉冲电源。电源系统采用多模块并联结构,由13个储能1 MJ脉冲成形子系统组成,每个子系统包含20个50 k J脉冲电源模块,单个模块短路放电电流最大可达65 k A;充电系统由基于串联谐振变换器的高压充电机组成;控制系统具有两级控制结构,使用同步编码信号对各电源模块进行时序放电控制;测量系统采用PXI系统,主从式网络结构,可满足分布式测量需求。系统在模拟负载上进行了性能测试,在电磁发射装置上进行了实验研究。实验结果表明,13 MJ脉冲功率电源系统输出电流波形灵活可调、可靠性高,可以满足电磁发射实验的需求。

电磁轨道发射装置隔离式分压器

研制了一套用于测量电磁发射装置轨道电压信号的隔离式分压器,实现了测量回路与被测回路之间的电隔离,简化了电磁发射装置测试系统的复杂性。并对影响隔离式分压器频率响应的元件参数进行了参数扫描,结果表明:研制的分压器在-3dB区间的频率响应范围为14Hz～18MHz,满足电磁发射装置轨道电压信号的测试要求。使用P6015A高压探头进行比对标定,输出信号的前沿约1μs,频率响应满足电磁轨道发射装置轨道电压信号的测量要求。同时用隔离式分压器及电阻分压器测量轨道电压信号,两者波形符合较好。

触发放电位置对重接型线圈推进器加速性能影响的仿真分析

为了使重接型线圈推进器获得较大的出口速度和较高的能量转化效率,需要对其触发放电位置和脉冲电流波形进行优化设计。首先从物理机理上解释了推进过程,然后根据电路方程分析了推进效率,最后采用电磁场有限元仿真分析了不同触发放电位置对重接型线圈推进器加速力、出口速度和推进效率的影响。仿真结果表明,存在一个最佳的触发放电发位置,使得抛体能够在较大范围内获得较大的加速力,从而获得最大出口速度。同时分析发现,重接型线圈推进器在发射过程中存在减速制动力,最大出口速度并不一定对应最大推进效率。在多级重接型线圈推进器的设计中,随着各级抛体入口速度的增大,触发放电位置需要相应优化,同时使驱动线圈中脉冲电流波形与互感梯度变化曲线匹配,才能获得最大的推进效率。

电磁线圈发射器相似模型研究

模型实验是研究电磁线圈发射器工作特性的有效方法,将模型实验结果应用于电磁线圈发射器原型的研究,必须要弄清模型与原型各物理参数间的相似关系。以电磁线圈发射器数学模型为基础,根据相似理论推导出电磁线圈发射器模型与原型各物理参数的相似关系,设计一种新型的电磁线圈发射器并对该发射器的相似模型进行仿真研究。研究结果表明:电磁线圈发射器各物理参数的相似系数均可由尺度比例系数表示且与尺度比例系数成函数关系,电磁线圈发射器相似模型是成立的。

线圈炮(电磁同轴发射器)综述

文中主要包括:1、线圈炮的基本原理;2、主要的结构型式,每种类型举出几个有代表性的装置,说明其运行机制与性能;3、应用前景。