Papers by Keyword: Electromagnetic Field (EMF)

Abstract: Tungsten Inert Gas (TIG) welding is a process which an electric arc generated by the tungsten electrode to the workpiece and the welding area protected by a protective gas. Arc shape can be affected by electromagnetic force. In previous study, the use of some electromagnetic field around the arc has influenced the welding results. In this study, electromagnetic field generated from the solenoids was given to the welding arc. Welding process was conducted on Stainless Steel. The electromagnetic field made the arc becomes deflected. This deflection was controlled by the solenoid by activating it using a microcontroller. The results showed that the use of solenoid as a source of electromagnetic field has influenced the welding arc. Penetration produced by using a solenoid has deeper penetration than welding process without using solenoid. The increase of the welding power efficiency was 10.9% for arc current I = 80 A and 9.85% for arc current I = 90 A.

Abstract: In order to analyze the no-load voltage waveform and damper bars temperature of integral number slots large hydro-generator which the number of damper bars per pole increased, the 2D moving electromagnetic field-circuit coupling model of a 600MW integral number slots hydro-generator and 3D temperature field FE model of the rotor are established, and the no-load voltage waveforms and temperature are calculated. The research is helpful for improving design standard and enhancing the operation reliability of the large hydro-generator and electric network.

Abstract: In order to analyze the influence of tubular hydro-generator no-load voltage waveform by the rotor skew, the multi-slice moving electromagnetic field-circuit coupling model of a 36MW tubular hydro-generator is established, then the no-load voltage waveforms of the design scheme which skew rotor is calculated.

Abstract: The electromagnetic field and the heat generation rate distribution in the semi-infinite body which is heated by the induction coil, are obtained by solving the Maxwell equations through the analytical method. The impacts of the air gap width, induction coil width, current density and current frequency on the heat generation rate distribution in the workpiece are studied. The results show that the heat generation rate in the workpiece is in direct proportion to the square of the eddy current density and the square of the induction coil width. The heat generation rate follows the exponential attenuation law with the increase of the air gap width. The current density has effects on both the maximum heat generation and the heat generation distribution. When the effect of the air gap is neglected, the higher the current frequency, the larger the maximum heat generation rate. However, when the effect of the air gap is considered, the maximum heat generation rate will increase with the augment of the frequency when the frequency is less than the critical frequency and decrease with the augment of the frequency when the frequency is larger than the critical frequency, which is firstly reported in the paper. Moreover, the higher the current frequency, the heavier the heat generation rate attenuation in the workpiece.

Abstract: Single-sided Linear Induction Motors (SLIMs) have been widely used in various applications for demanding direct motion or wheelless contact, e.g, the maglev transportation, in which SLIMs are employed as the traction component. Due to its special structure, the SLIM will generate attractive force as it generates thrust force. Within limited input power, in order to maximize the thrust force and restrict the attractive force, a half region dynamical slip-frequency(HRDSF) control scheme for SLIM is proposed. If SLIM is operated under acceleration or deceleration operations, slip-frequency is controlled in the high slip-frequency region close to the maximum thrust point in order to obtain the maximum thrust, and if SLIM is operated under coasting operation, slip-frequency is automatically adjusted at large value to generate a particular thrust corresponding to moving resistance, and the attractive force values, meanwhile, are kept at small values. The validity of the proposed method are verified by both simulations and experimental tests.

Abstract: Ionic liquids are rising materials with unique excellence. Here the electromagnetic pump based on ionic liquids are presented. The pressure head difference is 3.2mm at 15 V_DC and 0.4T. The flow rate is 8.6μl/s at 8V_DC and 128μl/s at 21V_DC when the magnetic flux density is 0.4T. The performances obtained theoretically in single phase are compared with the experimental results.

Abstract: The magnetic field interference was studied by numerical simulation and experimental examination during dual-ingot low-frequency electromagnetic casting process. By using ANSYS software package to mesh and compute, the magnetic field distribution of semi-continuous casting mold region was simulated. The calculated results were verified with the experimental ones and the effects of current direction, shield, silicon sheet and the coil distance on the distribution of magnetic field and ingot were observed. The result indicated that: regardless of current direction, the magnetic field interference among coils appears and the magnetic flux density weakens in the neighbor part of coils. When the current direction of adjacent coils is opposite, the magnetic intensity in ingots is stronger than that of in the same direction. As the distance between coils increases, the magnetic field reduction generated by interference decreases. The magnetic field interference can be alleviated by setting silicon steel sheets or shield.

Abstract: In order to analyze the influence of integral-number slots large hydro-generator no-load voltage waveform by the number of damper bars per pole increase, the 2D moving electromagnetic field-circuit coupling model is established, and the no-load voltage waveforms of a 600MW integral-number slots hydro-generator are calculated and analyzed. The results show that the harmonics are weakened and the waveforms of the no-load voltage are improved observably when reasonable increase the number of the damper bars per pole. The research is helpful for improving design standard and enhancing the operation reliability of the large hydro-generator and electric network.

Abstract: The objective of this study was to increase flux and decomposition speed through the development of a multi-type electrical field decomposition facility that employs a more complex modulated electromagnetic field than that used in existing decomposition facilities where recalcitrant organics or heavy metals are combined together. Further, in this study, optimized foundational data was derived from the results obtained following field work. As a result, when an electrical field was applied to an electrolyzer, decomposition of the electrolyzer was carried out quickly, thereby showing higher efficiency because an electrical field was permeated to the contaminant faster compared to the case where an electrolyzer was not added. Keywords: Electromagnetic field, Heavy metal, Electrolyzer, Electrical field

Abstract: In order to analyze the influence of integral-number slots large hydro-generator no-load voltage waveform by the damper winding shift schemes, the 2D moving electromagnetic field-circuit coupling model is established, and the no-load voltage waveforms of a 600MW integral-number slots hydro-generator are calculated and analyzed. The results show that the tooth harmonics are weakened and the waveforms of the no-load voltage are improved observably when damper winding shift scheme adopted. The research is helpful for improving design standard and enhancing the operation reliability of the large hydro-generator.