Armature Length Research Articles

The Impact of Temperature on the Electromagnet and Structural Optimization of a Solenoid Valve

The mathematical model of the solenoid valve under varying temperatures is constructed to investigate itsperformance and enhance heat dissipation balance. The relationship between temperature and electromagnetic force isdetermined. Electrothermal coupling simulation using COMSOL is conducted, optimizing the outer diameter and lengthstructure parameters of the coil. It is established that the heat dissipation of the coil is influenced by its outer diameter.Subsequently, based on optimized coil structure parameters, an orthogonal experimental design method combinedwith Ansys Maxwell is employed for simulation solution analysis to study the impact of structural parameters such aslength, position, front and rear angles of the magnetic barrier ring in the iron core, armature length, and through-holesize on electromagnetic force. Optimal structural parameters are identified. Results indicate a decrease in steady-stateelectromagnet temperature by 3–4℃, an increase in the initial electromagnetic force by 32.63%, and a rise in the maximumelectromagnetic force by 27.10%.

Simulation and Experiment of Electromagnet for High-Speed On-off Valve for Vehicle Shifting System

The high-speed on-off valve is the core component for adjusting the oil pressure of the pressure reducing valve in the clutch shifting system of engineering vehicles, and its response speed is one of the important indicators to measure its performance. In order to improve the dynamic performance of high-speed on-off valve, the electromagnet with solid magnetic isolation structure was designed and simulated by considering the eddy current loss factor. A high-speed on-off valve electromagnetic actuator with high response speed was obtained. Firstly, the theoretical calculation and verification of the theory were carried out by using the electromagnet design theory, and the theoretical model of the electromagnet was built. Secondly, the electromagnet parameter model was brought into the finite element simulation software ANSYS Electronics to simulate and optimize the static magnetic field and the transient magnetic field respectively. The different structural parameters (guide bush thickness, outer magnetic pole thickness, magnetic isolation structure, armature length) were analyzed. And the effect of the coil parameters (number of strands) on the steady-state electromagnetic force and the dynamic displacement of the armature was analyzed. The values of the structural parameters of the electromagnet were subsequently determined. Finally, the static and dynamic characteristics experiment of the magnetically separated solid electromagnet is designed and processed. The experiment and simulation results are in good agreement. The feasibility of the high-resistance electromagnet structure design and the correctness of the simulation are verified. Reasonable optimization of structural parameters and coil parameters has obvious significance for improving the dynamic characteristics of high-speed on-off valve electromagnets.

Armature Structure Research of an Electromagnetic Reconnection Launcher

The armature of the electromagnetic reconnection launcher (EMRCL) plays a key role in accelerating large-mass loads, which have attracted extensive attention in past years. In this article, the effects of the armature thickness, length, and width on the performance of the EMRCL are analyzed for designing a high-strength and high-efficiency armature. First, according to the deformation and Von Mises’ stress distribution of the armature in the electromagnetic structure field, the armature thickness should be six times the skin depth. Then, the orthogonal experiment method results demonstrate that the armature speed tends to a saturated value with increasing length and width. Finally, a three-stage EMRCL platform with a load of 10 kg was constructed to verify the accuracy of the simulation results of three armatures with different lengths and widths. The experimental results show that the speed of 80 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times120$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> armature can reach 11.26 m/s, which is a significant increase of 23 times than the 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times120$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> armature and is consistent with the simulation results. It indicates that the optimal armature length is 1.2 times the coil length, and the optimal width is 1.3 times the coil width. This research provides a valuable reference for the armature design of EMRCL.

Study on the influence of different thickness of armature structure on the emission performance of electromagnetic induction coil launcher

In the armature structure of traditional electromagnetic induction coil launcher, the armature tail melted due to heat accumulation. In this paper, three new armature structures are proposed. Based on the finite element software maxwell2D, the single-stage electromagnetic induction coil launcher, model is established. The performance indexes of traditional and new armature structures are compared, and the influence of the thickness of traditional armature structure and the side thickness of new structure on temperature rise and electromagnetic performance is studied. On the basis of Maxwell-thermal finite element, the correctness of the temperature field conclusion is verified. The simulation results show that the traditional armature structure has the optimal thickness and the armature performance remains unchanged when the weight ratio and the mechanical strength of the armature are considered. Structure 3 and Structure 4 of the new structure significantly improve the temperature rise of the armature and enhance its emission performance. Due to the eddy current, the optimum side thickness of the new structure 3 and structure 4 is slightly larger than 1/2 of the armature length.

Research on Electromagnetic Force Performance of High Speed on-off Valve

Taking a high speed on-off valve as an example, the effects of air gap, shell thickness, armature length, guide sleeve type and armature radius on the electromagnetic force performance are studied. The results show that the air gap is negatively related to the electromagnetic force, the shell thickness, armature length and armature radius are positively related to the electromagnetic force, and the effect of pure copper guide sleeve and non-guide sleeve on the electromagnetic force is basically the same. The electromagnetic force can be increased by the guide sleeve with magnetic separation ring. The influence order of parameters on electromagnetic force is: air gap &gt; armature radius increment &gt; armature length increment &gt; shell thickness increment.

Key design parameters and optimum method of medium- and high-velocity synchronous induction coilgun based on orthogonal experimental design**Project supported by the National Natural Science Foundation of China (Grant No. 5140130).

The energy conversion efficiency of a multistage synchronous induction coilgun (MSSICG) has become one of the key factors that restricts its industrialization. To improve the launch efficiency of medium- and high-velocity MSSICG, we propose an optimization design scheme combining orthogonal experimental design (OED) and self-consistent design method in this paper. The OED is introduced to reduce the number of iterations and improve the identification accuracy and efficiency. A self-consistent design model is established to overcome a defect that the parameters that need to be optimized will multiply as the number of coil stages increases. The influence of six factors (radial thickness of armature, axial length of armature, axial length of coil, capacitance, wire diameter, and slip speed) on the launch efficiency are then evaluated by range analysis. This work presents a valuable reference for optimizing medium- and high-velocity MSSICG.

Suppression of Squeal Noise Excited by the Pressure Pulsation from the Flapper-Nozzle Valve inside a Hydraulic Energy System

Squeal noise often occurs in a two-stage electrohydraulic servo-valve, which is an unfavorable issue of modern hydraulic energy systems. The root causes of such noise from the servo-valve are still unclear. The objective of this paper is to explore the noise mechanism in a servo-valve excited by the pressure pulsations from the hydraulic energy system perspective. The suppressing capability of squeal noise energy is investigated by changing the pressure pulsation frequency and natural frequency of the flapper-armature assembly. The frequencies of the pressure pulsations are adjusted by setting different speeds of the hydraulic pump varying from 10,400–14,400 rpm, and two flapper-armature assemblies with different armature lengths are used in the tested hydraulic energy system. The first eight vibration mode shapes and natural frequencies of the flapper-armature assembly are obtained by numerical modal analysis using two different armature lengths. The characteristics of pressure pulsations at the pump outlet and in the chamber of the flapper-nozzle valve, armature vibration and noise are tested and compared with the natural frequencies of the flapper-armature assembly. The results reveal that the flapper-armature assembly vibrates and makes the noise with the same frequencies as the pressure pulsations inside the hydraulic energy system. Resonance appears when the frequency of the pressure pulsations coincides with the natural frequency of the flapper-armature assembly. Therefore, it can be concluded that the pressure pulsation energy from the power supply may excite the vibration of the flapper-armature assembly, which may consequently cause the squeal noise inside the servo-valve. It is verified by the numerical simulations and experiments that setting the pressure pulsation frequencies different from the natural frequencies of the flapper-armature assembly can suppress the resonance and squeal noise.

Analysis of superconducting linear synchronous motor for electromagnetic propulsion

There is a high demand for electromagnetic launchers in applications such as electromagnetic catapults and launch-assist systems for spacecraft, owing to their advantages in terms of controllability and reusability. This work proposes a double-sided superconducting-magnet linear synchronous motor capable of large thrust densities that can satisfy the demands of high-load launcher systems. Ring windings and narrow-toothed structures were applied to increase the density of the armature winding and reduce cogging-torque-induced fluctuations, and superconducting magnet with iron-core was first proposed to produce a strong air gap magnetic field. Numerical simulations are used to construct a simulation model of the motor, which is then used to study the relationships between the thrust characteristics of the motor and the dimensions of its armature and air-gap length. The results of this analysis provide information on the optimal thrust characteristics of linear motors in electromagnetic launcher systems.

Some Key Parameters of Monolithic C-Type Armature in Rectangular Caliber Railgun

Monolithic C-type armature is one of the most important armatures in electromagnetic railgun. Some key parameters of monolithic C-type armature in rectangular caliber railgun system—width of armature X, height of armature Y, thickness of armature’s throat $d_{0}$ , length of armature’s tail $d_{1}$ , thickness of trailing edge of armature’s tail $d_{2}$ , and angle of armature’s tail $\theta $ —are studied in this paper. By introducing current carrier margin coefficient named $\alpha $ , ratio of armature thickness to armature width named $\beta $ , ratio of armature height to armature width named $\gamma $ , and ratio of length of armature’s tail to armature height named $\kappa $ , equations of some key parameters of monolithic C-type armature in rectangular caliber railgun system are proposed. Based on analysis of mass of armature, electromagnetic contact force between armature and rail, mechanical strength of armature’s tail, and inductance gradient, relationship of some key parameters of monolithic C-type armature in rectangular caliber railgun system are proposed. Conclusion can be drawn that increase of $\theta $ can reduce mass of armature and improve mechanical strength of armature’s tail, but electromagnetic contact pressure between armature and rail will be decreased. Decrease of $\gamma $ could be a considerable way to remarkably increase inductance gradient, and then increase launch system efficiency.

A new species of Speleophriopsis (Copepoda: Misophrioida) from an anchialine cave in the Adriatic Sea, Mediterranean

A new copepod species, Speleophriopsis mljetensis, collected from an anchialine cave Bjejajka on Mljet Island (Croatia) is described. The prosome of the new species is 5-segmented; the urosome has five somites in females and six in males; the genital double-somite is symmetrical and is longer than wide; the caudal rami are symmetrical, with seta I well developed; the antennules of both sexes are 27-segmented and symmetrical; the antennal exopod is 7-segmented; the maxillule possesses 15 armature elements on the praecoxal arthrite and the proximal basal endite has three slender setae and one stout claw-like seta, the fifth legs are symmetrical, 4-segmented and uniramous, and the distal segment is elongate and armed with seven and six elements in males and females, respectively. Speleophriopsis mljetensis is comparated with similar species S. balearicus and S. canariensis. The new species is mainly distinguished by the armature of the genital operculum, the fifth legs of both sexes, maxilliped distal segment armature and total length of both sexes. This is the second report of a speleophriid copepod, otherwise thought to be a Tethyan relict, from an Adriatic anchialine cave. In the Bjejajka Cave, the salinity varied between 1.5 at the surface to 39 psu at the bottom, and the temperature ranged between 14.2 and 16.6 °C. It might be assumed that it colonised Bjejajka anchialine cave from its natural deep-sea habitat. However, the distributions of speleophriids in the Mediterranean are difficult to explain; therefore, this finding is of particular importance, contributing to our knowledge of the global biogeography of these Tethyan relicts.

New records of Anthalona acuta Van Damme, Sinev & Dumont 2011 and Anthalona brandorffi (Sinev & Hollwedel, 2002) in Brazil, with description of a new species of the simplex-branch (Crustacea: Cladocera: Chydoridae).

The range of geographical distribution of Anthalona acuta Van Damme, Sinev & Dumont 2011 and Anthalona brandorffi (Sinev & Hollwedel, 2002) in Brazil has increased by almost 2000 km to the south. New records of Anthalona verrucosa verrucosa (Sars, 1901) were also added. Populations of Anthalona brandorffi from Central Brazil showed a peculiar morphological variation, with some individuals having only a single denticle on the labral keel. A new species of the simplex-branch, Anthalona neotropica sp. nov., was described based on Brazilian material, and this is the first taxon of this branch registered in the Neotropics. It differs from Anthalona simplex Van Damme, Sinev & Dumont 2011, a Central African species, in the morphology of underneath sack of the lateral head pores, length of IDL setae and armature of first flaming-torch seta of limb IV. It could be distinguished from Anthalona sanoamuangae Sinev & Kotov, 2012 (distributed through the South- East Asia) by the morphology of the main head pores, length of IDL setae and armature of the pecten of postabdominal claw. Anthalona neotropica sp. nov. seems to have a benthic/hyporheic habit. All studied species have a wide geographical distribution and could be confused with Anthalona verrucosa Sars, 1901, thus at least some if not all previous records of this species on the continent must be revised.

Analysis of Parameter Sensitivity of Induction Coil Launcher Based on Orthogonal Experimental Method

There are many parameters that can affect the launching efficiency of the induction coil launcher (ICL), but which parameter is the most important factor to the launching efficiency still needs further study. Taking the 82-mm caliber ICL, for instance, eight parameters of the ICL were chosen to analyze based on orthogonal experimental method, and then the tables of the parameter level and orthogonal experiment were built, respectively. After that a simulation model of the ICL was built and each experiment scheme in the orthogonal table was analyzed by simulation, and then the launching efficiency of each experiment scheme was obtained. Furthermore, the range analysis method was used to analyze the parameter sensitivity of the ICL. The research results show that the parameter sensitivity of the ICL from high to low for the analysis instance above is as follows: external radius of driving coil, trigger position, capacitance, driving coil turns, armature length, charge voltage of capacitor, driving coil length, and armature inner radius, which is useful to the parameter optimization and the design of the ICL. After that, four ICLs with different parameters were designed, with which the experiments were taken and the research results obtained from the orthogonal experimental method were verified.

Modeling and Simulation of Jetpipe Servovalve Torque Motor

The torque motor is a precision mechatronic component used to convert low electric signal into linear mechanical displacement of the Jetpipe. Such torque motors are categorized under multi disciplinary engineering systems, which are complex in nature and also induces challenges to integrate with hydraulic system. This paper applies model-based system design approach of jetpipe servovalve torque motor to study the effect of critical parameters like armature length and air gap, feedback spring stiffness, and flexure tube stiffness on the dynamic performance of the were studied.

Performance Analysis of Single Inductive Coil Driver

The performance of a single inductive coil driver with six different turns of drive coils is analyzed and emulated with the emulation program in this paper. Under the condition that the integral projectile mass is 1.125 kg and the armature length is 300.0 mm, the maximum velocities of the projectile are 130.1, 134.1, and 132.8 m/s when the drive coil axial lengths are 50.0, 100.0, and 150.0 mm, respectively, and the drive coil radial thickness is 20.0 mm. By changing the drive coil radial thickness to 30.0 mm, the maximum velocities of the projectile are 112.5, 110.2, and 116.3 m/s when the drive coil axial lengths are 50.0, 100.0, and 150.0 mm, respectively. The result shows that only when the structural parameters of the drive coil and the armature are matched suitably that the maximum velocity of the projectile can be reached. This conclusion provides a reference for the engineering practice of the inductive coil driver.

Design analysis of permanent magnet DC motors with differing armature, magnet and yoke lengths

A modified magnetic circuit method and a 2-D finite element procedure are presented here for the analysis of DC permanent magnet motors with differing armature, magnet and yoke lengths including nonlinear material behavior of steel and permanent magnet. A 12 V, 120 W motor is analyzed through these methods and compared with experimental results of a prototype sample. In case of finite element analysis, commutation effects and short chording of the armature winding are treated appropriately, and cogging torque and voltage ripple are predicted.

The effect of serrated bore surfaces on plasma armatures

The use of serrated bore surface has the potential to overcome the velocity performance limitations of railgun plasma armatures. The authors evaluated several serrated bore configurations to determine their effect on plasma armature length, stability and velocity performance. They found that plasma armature length and stability are significantly influenced by bore serrations. Plasma armatures in serrated rail-serrated insulator bores are very compact and stable. Many small serrations in the rail also cause compact armatures. These micro serrations gave extremely stable armatures that were highly repeatable. The authors were unable to demonstrate the effect of serrated bores on plasma armature velocity performance. >

A triggering mechanism for secondary arcs (railguns)

It is postulated that there is local change in the magnetic field, associated with the rail joint connections, which causes a variation in the breech voltage and in the J*B force applied to the armature. Experimental data suggest that this change in force can trigger secondary arcs. A model was developed for the breech voltage variation based on the length of the perturbed region, the magnitude of the local field in the vicinity of the joints, and the length and velocity of the armature. The model suggests that the magnitude of the perturbation at both the 4-m and the 8-m joints is about the same. However, a secondary arc is formed at the 4-m joint, but not at the 8-m joint. The significant difference in the two situations is that the armature length at the 8-m joint is half that at the 4-m joint. The scenario repeats itself at the 12-m and 16-m joints with the same results. It is concluded that the development of secondary arcs in the presence of local magnetic field variations is sensitive to the armature length. >

Effect of current variation on the dynamics of railgun plasma armatures

The effect of current variations on the behavior of railgun plasma armatures is investigated with a one‐dimensional, time‐dependent model. Three typical current profiles are considered: two inductive profiles, one with a time constant of 0.5 msec and the other with a time constant of 2.0 msec, and a capacitive profile. All three calculations are for an armature in a 5 cm square‐bore railgun. It is observed that current variations create oscillations in the armature length, projectile acceleration, and projectile jerk. In addition, the current profile significantly affects the axial distribution of the plasma velocity, current density, and total pressure. The significance of these transients on the design of projectiles and the interpretation of diagnostic data is discussed, and suggestions for future calculations are outlined.

Design and modeling considerations for experimental railgun armatures

A calculational method for obtaining detailed armature parameters associated with railgun launchers has been developed. Calculated parameters are obtained for device features and operating conditions supplied as input parameters. The model was validated by reproducing several sets of experimental data from a variety of devices. Model parameters associated with armature mass loss and plasma axial profiles were obtained as part of anchoring the calculations. The data included complete sets of dynamics, armature lengths, and muzzle voltages for each case studied. From the calculations, several differences between the various types of armatures (i.e. solid, hybrid, and plasma) and bore sizes were identified and found to account for the resulting performance features.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Railgun experiments with Lexan insulators

A series of railgun experiments has been performed using Lexan insulators in both round and square bores, and with closed-breech and open-breech/injected configurations. Measured armature lengths have been roughly constant at 5-10 cm in a 1-cm bore for all Lexan insulator shots, indicating that the ablated Lexan is not swept up. Projectiles have been observed to reach peak velocity of 5.65 km/s with clean armature structures: i.e. no separated secondary arc or restrike. However, in most cases a secondary arc does occur with Lexan and limits the achievable velocity. Occasionally, stationary secondary arcs have also been observed for a particularly leaky gun assembly. The effect of insulator ablation on performance is discussed, indicating that Lexan may be useful at up to 8-10 km/s for well-sealed railguns. >