Magnetic Flux Intensity Research Articles

Design Analysis of a Dual Rotor Permanent Magnet Machine driven Electric Vehicle

Electric bike in urban countries such as Europe and China commonly used the brushless direct current machine (BLDC) as it able to produce high torque to transport the user from one place to another. However, BLDC torque density can’t be improving due to limitation magnetic flux generated by the permanent magnet. Therefore, the performance of electric bike can’t be improved. Outer rotor BLDC machine design able to improve the torque density of the motor due to increase radius of the motor which can be explained by simple physics equation (Torque = Force x radius). However, an outer rotor machine only generates constant speed, which is not suitable for operating under tractive load condition, especially electric bike. The proposed model is a new novel of double layer outer rotor BLDCPM machine which able to amplify the magnetic flux density and improve the torque density of the machine. The mutual magnetic coupling between the inner and outer rotor of the proposed model increase the magnetic flux intensity as both of them acts as individual parts. Thus, the magnetic flux generated by both rotors are double which resulted in improving the performance of the E-bike. Designing parameters and analysing the performance of the proposed 2D model is done using FEA tools. Evaluation of the conventional and proposed model by comparing torque performance, magnetic flux density and motor constant square density. Other than that, speed torque graph also is evaluated to justify either it can operate similarly to ICE engine with gears. Two model is designed which is Single Outer Rotor Brushless Direct Current (SORBLDC) and Double Outer Rotor Brushless Direct Current (DORBLDC) operated with the same cases of 27 Amp current supplied to it and operate under various speed from 500 rpm to 2000 rpm. The average torque produce by the conventional and proposed model are 2.045439 Nm and 3.102648 Nm. Furthermore, improvement of the proposed model to conventional model in terms of motor constant square density by 24.92%. Therefore, the proposed model able to improve the magnetic flux by amplifying which resulted to increase the torque density of the machine. Furthermore, the speed-torque graph of the proposed machine shows similarity with speed torque graph of ICE engine. Thus, the proposed machine is suitable to operate for bike application

Effect of flow, heat transfer and magnetic energy on the grain refinement of 7A04 alloy under electromagnetic pulse

Abstract In this paper, a transient numerical simulation method was used to analyze the direct chill casting process of 7A04 alloy under electromagnetic pulse treatment. The distribution and evolution of the electromagnetic force, fluid and thermal fields were studied to determine their effect on the solidification characteristics of alloy ingots. A modified nucleation theory for the refinement of grain size was presented considering the effect of electromagnetic energy on the critical Gibbs free energy Δ G * $\Delta {G^*}$ of the unity, which was verified by the corresponding experiments. The results showed that the swirl rings of the axial section in the melt were restrained and a lower temperature gradient was formed in the radial section when the magnetic flux intensity was increased. Under these conditions for nucleation, the grain refinement could be explained by the electromagnetic pulse energy that reduced the energy barrier and improved the nucleation rate, either heterogeneous nucleation or homogeneous nucleation.

Experimental study on rise velocities of single bubbles in liquid metal under the influence of strong horizontal magnetic fields in a flat vessel

The ascent of single argon bubbles with equivalent diameters (deq) between 3.43 and 6.28 mm is investigated at room temperature in a flat, rectangular vessel by means of ultrasound Doppler velocimetry (UDV). GaInSn is used as a working liquid and magnetic flux intensities up to B ≈ 0.918 T are applied. A decelerating effect on the rise velocity is observed at lower, an accelerating effect at medium and a reduction at higher field strengths. Maximum velocities are achieved when the ratio of N/CD ≈ 1, bubble paths are substantially rectilinear at N/CD > 2. The mean ascent velocities are compared with literature and data of this work as well as other publications is provided in tables.

A Novel Non-destructive Testing Method by Measuring the Change Rate of Magnetic Flux Leakage

The application of magnetic sensors in the traditional magnetic flux leakage (MFL) technique has a significant influence on the detection results. The sensor is typically used to directly measure the amplitude of the magnetic leakage flux intensity as the detection signal. In view of noise effects on the detection result and the subsequent misinterpretation of defect signals, a new non-destructive testing method is proposed. The proposed method intends to measure the magnetic flux change rate using two sensors. A mathematical model is first established to present the principle of the change rate measurement. Based on the magnetic dipole theory, it is inferred that the new method is applicable and sensitive to the detection and location of defects. Moreover, this method is advantageous as it inhibits the interference of MFL noises such as the distension noise, background noise, and vibration noise. The model predictions are then verified by a series of simulations. Finally, an experimental platform is set up to practically detect the defect of a steel plate, and the results agree with the demonstrations and simulations.

A Fiber Optic Accelerometer–Magnetometer

A fiber optic accelerometer–magnetometer (FOAM), which can measure acceleration and magnetic field simultaneously, based on fiber laser sensing is proposed. The principle of the FOAM and the theory of the mixed signal of acceleration and magnetic field are presented. To verify the theory, an FOAM was fabricated and tested. The measured acceleration sensitivity and the sensitivity of magnetic flux intensity were 9.75 pm/g (19.78 dB, re: 0 dB = 1 pm/g) within 100–250 Hz, and 0.955 pm/T/mA@725 Hz, respectively, which were close to the theoretical values. A test of simultaneously measuring acceleration and magnetic field was performed. The results show that the responding mixed signal achieves a good SNR. It proves that the function of the sensor has been realized and the theory of mixed signal is reliable.

Conversion of glycerol into syngas by rotating DC arc plasma

One of the most stable byproducts of biodiesel industry is glycerol, for which there’s lack of a large-scale application currently. Thermal plasma treatment is a potentially viable means of recycling glycerol by converting it into syngas. In this work, a rotating DC arc plasma reactor was used to decompose glycerol in order to produce syngas. The effect of plasma input power, glycerol feed rate, and water content in feedstock on the syngas conversion was investigated. It was found that the product gas stream, on an argon-free basis, contained 38% CO and 56% H2, with the balance being methane, ethylene, and little C4 hydrocarbons. Complete carbon conversion and energy conversion efficiency of 66% could be obtained with sufficient input power. Water content of feedstock influenced the amount of CO and H2 in the product gas. Magnetic flux intensity of the reactor showed negligible effect on the composition of the product gas, carbon conversion and energy conversion efficiency, but could prevent the anode and plasma reactor from severe erosion.

Structural analysis for the joint of the ITER ELM coil

The joint is an important component of the Edge Localized Modes (ELM) coils in fusion reactor, which is used to connect the ELM coils. Like the ELM coils, the joints work in an environment with high radiation levels, high temperature and high magnetic field. These joints are mainly subject to nuclear heat from the plasma and cyclic electromagnetic (EM) loads induced by the interaction of ELM coil current with magnetic fields. Take the joint of ITER ELM coil for example. In order to assure the structural integrity of joints under these loads, it is necessary to estimate the strength and fatigue of the joints. As a local model, the joint without ELM coil is investigated by the sub-model method. Results show that the finite element sub-model method is feasible and rapid for the joint design. The maximum magnetic flux intensity occurs in the axial direction for the joint local reference, which parallels with the current and corresponds to the toroidal direction of the ITER. The two areas at the top of the Inconel sleeve appear high temperature. For the joint, the conductor, jacket and sleeve can meet the static and fatigue criteria and the joint design is valid and feasible. The thermal load from the nuclear heat is the key factor for the joint design.

Optimal design of a new multipole bilayer magnetorheological brake

This article presents a new high-torque multipole bilayer magneto-rheological brake (MRB). This MRB has a unique structural design with multiple electromagnetic poles and multiple media layers of magnetorheological fluid (MRF). The MRB has two rotors located on the outer and inner sides of a six-pole stator, and therefore, it can provide higher torque and a larger torque-to-volume ratio (TVR) than conventional single- or multipole single-layer MRBs can. Moreover, the problem of potential MRF leakage is solved by using cylindrical separator rings around the stator. In this study, first, the structure of the proposed MRB is introduced. An analog magnetic circuit was built for the MRB to investigate the effects of the MRB parameters on the magnetic field intensity of the MRF layers. In addition, a 3D electromagnetic model of the MRB was developed to simulate and examine the magnetic flux intensity and corresponding braking torque. An approximate optimization method was then applied to obtain the optimal geometric dimensions for the major dimensional parameters of the MRB. The MRB was manufactured and tested to validate its torque and dynamic characteristics. The results showed that the proposed MRB exhibited great enhancement of the braking torque and TVR.

Performance enhancement of the synchronous micropump based on experimental and numerical investigations of the magnetic field flux density in planar microcoils

This study presents numerical and experimental investigations targeting enhancing the magnetic field flux magnitudes in electroplated copper microcoils. Improved designs are used in the development of a new generation of the electromagnetic-based synchronous micropump in order to enhance its performance (i.e. the maximum achievable output pressure and flow rate). The synchronous micropump concept is based on managing the movement of two magnets in an annular fluidic channel. The magnets’ rotation is achieved by sequentially activating a set of three-dimensional microcoils to repel or attract one magnet (travelling piston) through the channel, whereas the second one is anchored between the inlet and the outlet ports (valve piston). At the end of each pumping cycle, the magnets exchange their functions. To achieve the maximum achievable output pressure and flow rate, higher magnetic fields without exceeding the material temperature limitation are required. The stronger the magnetic fields that can be generated, the higher the hydraulic power that the pump can deliver. The microcoil conductor width and height were optimized to generate higher magnetic field flux intensity within the pump limitation parameters (i.e. pump footprint and coils’ maximum heat dissipation limit). The new generation of the synchronous pump was run at a rotational speed of up to 800 rpm and provided a maximum flow rate of 3.56 ml/min and a maximum pressure head of 687 Pa.

Separation of primary Si and impurity boron removal from Al-30%Si-10%Sn melt under a traveling magnetic field

Separation of primary Si phase and removal of boron in the primary Si phase during the solidification process of the Al-30%Si-10%Sn melt under a traveling magnetic field (TMF) were investigated. The results showed that the agglomeration layer of the primary Si can be formed in the periphery of the ingot while the inner microstructures mainly consist of the eutectic α-Al+Si and β-Sn phases. The intense melt flow carries the bulk liquid with higher Si content to promote the growth of the primary Si phase which is first precipitated close to the inner wall of crucible with a relatively lower temperature, resulting in the remarkable segregation of the primary Si phase. The content of impurity B in the primary Si phase can be removed effectively with an increase in magnetic flux intensity. The results of electron probe microanalysis (EPMA) clearly indicated that the average intensity of the B Ka line in the α-Al phase region of Al-Si-Sn alloy is higher in the case of solidification under TMF than that of normal solidification condition, suggesting that the electromagnetic stirring can promote the B removal from the primary Si phase.

Improved mechanical properties of magneto rheological elastomeric composite with isotropic iron filler distribution

In this work, mechanical property of magneto rheological elastomeric (MREs) composite is investigated using iron as filler distribution. The MREs composite were fabricated using irregular shaped iron particles with size range varies from 50 -150μm in matrix of elastomeric polymer. The matrix such as ZA22 was considered with 1:1 catalyst ratio as the binder with 30 Vol % of filler content. The fillers were incorporated within the matrix of elastomer using silicon oil as additive binder in the composite. The open circuit solenoid coil was designed as the magnetic circuit for magnetic flux intensity. Various magnetic field intensities were induced to observe the mechanical properties of the MREs composites. Hysteresis loss was observed in MRE samples due to dissipation of energy during compression of the composite material. Improved engineering strength of the MRE is observed on varying magnetic field of intensity and constant at 0.3 Tesla.

Vibration analysis and optimal design of multi-layer plates partially treated with the MR fluid

The vibration characteristics of a sandwich plate partially treated with the Magneto-Rheological (MR) fluid are investigated numerically and experimentally considering different boundary conditions and intensities of the magnetic flux. A cantilevered sandwich plate consisting of an aluminum host layer with nine equal cavities for the MR fluid treatments and a constraining layer was fabricated for experimental characterizations and validations of the finite-element (FE) model. The dynamic responses of the untreated plate and the partially treated plate, where only one of the nine cavities in the core layer was filled with the MR fluid (MRF 132DG), were measured under harmonic excitation applied at the fixed support. The finite element model of the sandwich plate, developed using the classical plate theory (CPT) and first-order shear deformation theory (FSDT) is verified using the experimental data. The FE model considers the effect of slippage between the top and bottom layers of the structure. The validated FE model is subsequently used to investigate the effects of partial MR fluid treatments, magnetic flux intensity and boundary conditions on the dynamic response characteristics of the structure. The effect of shear deformation on the vibration properties of the MR sandwich plate is further highlighted. Finally, three optimization problems are formulated to identify optimal locations for the MR fluid treatments so as to maximize the variations in the natural frequencies and damping ratios in response to magnetic field. The solution of the optimization problem, attained using the genetic algorithm (GA) suggested that the MR fluid applied to locations with noticeable shear strain can maximize the stiffness variations and damping of the structure, significantly.

A new method to determine magnetic properties of the unsaturated-magnetized rotor of a novel gyro

A new method is proposed to determine magnetic properties of the unsaturated-magnetized, small and irregular shaped rotor of a novel gyro. The method is based on finite-element analysis and the measurements of the magnetic flux density distribution, determining magnetic parameters by comparing the magnetic flux intensity distribution differences between the modeling results under different parameters and the measured ones. Experiment on a N30 Grade NdFeB magnet shows that its residual magnetic flux density is 1.10±0.01T, and coercive field strength is 801±3kA/m, which are consistent with the given parameters of the material. The method was applied to determine the magnetic properties of the rotor of the gyro, and the magnetic properties acquired were used to predict the open-loop gyro precession frequency. The predicted precession frequency should be larger than 12.9Hz, which is close to the experimental result 13.5Hz. The result proves that the method is accurate in estimating the magnetic properties of the rotor of the gyro.

磁性流体を用いた気体流量制御

A novel method of controlling gas flow rate using magnetic fluid is proposed. Magnetic fluids under non-uniform magnetic field have strong dynamic pressure distribution along the magnetic field gradient at the gas-liquid interface with bulk magnetic body force. The principle of proposed gas flow rate control technique is based on controlling the pressure distribution, which can be controlled by magnetic field. In this report, controlling technique is introduced and the accuracy of the flow rate control with resolution of the control technique is reported. From measured data (giving a reference for measuring the small gas flow rate), it was found that the flow rate decreases with increasing magnetic flux intensity, and is largely dependent on the magnetic pressure which acts on magnetic fluid, particularly to the interface of gas-liquid phase. The flow rate and the magnetic pressure have a definite relation with the flow coefficient, so that, the flow rate can be controlled only by the magnetic pressure. It was satisfactory verified from the proposed controlling technique that the proposed gas flow controlling method is useful to control the low gas flow rate as low as 0.3×10-5m3/s with the excellent resolution.

The Effect of Magnetic Field on Magnetorheological Composites - Artificial Neural Network Based Modelling and Experiments

Looking for new applications of the available materials, such as magnetorheological elastomers (MERs) is an important element of machine design process. To this end it is necessary to determine their fundamental mechanical properties, including Young’s modulus and shear modulus. These properties are determined experimentally by testing the material in compression, tension and shear. In the case of the analysed group of materials the above-mentioned constants depend, inter alia, on the parameters of magnetic field acting on them. Therefore, it is necessary to determine the character and the extent of variation of the mechanical properties as a function of the physical constants characterising the active magnetic field, namely magnetic flux and magnetic intensity (field strength).This paper presents the results of static compression tests carried out on magnetorheological elastomers. The parameters measured during the static compression test were force and displacement at a pre-set magnetic flux. The maximum strength of the induced magnetic field was limited by the design parameters of the test set-up. In order to determine the behaviour of the material at greater values of magnetic strength and flux the properties of a real material were modelled with a neural network. The simulation was carried out using a simple, one-layer neural network. The chosen network training approach was error backpropagation. This approach enables approximation and predicting of changes of the properties of the tested material. The output results will enable deriving an analytical model of the tested MREs.

Stick-slip behavior of magnetorheological fluids in simple linear shearing mode

The stick-slip motion of magnetorheological (MR) fluids under a simple linear shear mode has been experimentally reported. The critical shear strain for the onset of the stick-slip motion decreases logarithmically with the magnetic flux intensity applied. The rate of energy accumulation and releasing during stick-slip motion changed in a power law of the viscosity of the continuous phase in a range of 0.01~1000 mPa S. Different carrier fluids led to different stick-slip characteristics. The stick-slip motion can be fully suppressed with certain carrier fluids. When the MR fluids are in a shear-thickening state, the critical shear strain of the onset of the stick-slip motion is larger than a normal state. But, the relative spike amplitude of the stick-slip remains similar.

Simulation research of eddy current separation technology in scrap copper based on ANSYS finite element method

Copper mineral resources are seriously insufficient in China. Scrap copper recycling is an inevitable choice to solve the shortage problem of the copper resources. To achieve rational utilization of the scrap copper in high quality, it's greatly significant to separate the scrap copper finely. In this paper, modeling and simulation analysis for the separation of the scrap copper with different materials by eddy current sensor based on ANSYS finite element method are made. The detection model for three situations such as the surface of the scrap copper is smooth and clean, coating and concavo-convex about four kinds of scrap copper materials (red copper, brass, manganin and bronze) are involved respectively in magnetic field lines, contour of magnetic flux intensity and equivalent impedance of sensor coil. Intercomparison and analysis of the simulation results testify that eddy current separation technology of the scrap copper is feasible. The simulation results are validated by the experiments.

Voltage-Source Finite-Element Model of High Temperature Superconducting Tapes

A voltage-source finite-element model of high-temperature superconducting tapes is presented in this paper. This model is a combined model built on both MATLAB and COMSOL, and it is used to study the overcurrent characteristics of non-uniform HTS tapes. The electrical parameters, magnetic distribution, and temperature distribution are separately calculated by different software. The temperature, magnetic flux intensity, and generated heat are set as the intermediate exchange variables. The model accuracy is calibrated and verified by short-circuit experiments of a uniform five-turn HTS solenoid. Then, the basic model is expanded and used to simulate the overcurrent characteristics of nonuniform HTS tapes. Conclusions are provided by considering both simulation and experimental results from these non-uniform tapes, and the results of this study can be used for the design of superconducting devices.

Fano resonances in hexagonal zigzag graphene rings under external magnetic flux

We study transport properties of hexagonal zigzag graphene quantum rings connected to semi-infinite nanoribbons. Open two-fold symmetric structures support localized states that can be traced back to those existing in the isolated six-fold symmetric rings. Using a tight-binding Hamiltonian within the Green's function formalism, we show that an external magnetic field promotes these localized states to Fano resonances with robust signatures in transport. Local density of states and current distributions of the resonant states are calculated as a function of the magnetic flux intensity. For structures on corrugated substrates we analyze the effect of strain by including an out-of-plane centro-symmetric deformation in the model. We show that small strains shift the resonance positions without further modifications, while high strains introduce new ones.

Design of Magnetic Fields for Half and Full Type Electromagnetic Swirl Flow Generators

In this work, the placement of an electromagnetic swirl flow generator (EMSFG) around a submerged entry nozzle (SEN) was proposed as a method for generating a rotating electromagnetic field in a continuous casting (CC) process of steel. First, two kinds of a full type EMSFG and a half type EMSFG were designed based on mathematical modeling. Then, distributions of magnetic flux intensity in an EMSFG as well as distributions of Lorentz force in molten steel were simulated. It was found that the EMSFG structure and electromagnetic parameters have an important effect on magnetic flux intensity and Lorentz force distributions. For both a full type and a half type EMSFG, the magnetic flux intensity and Lorentz force increases as the magnetomotive force increases. Especially, for a full type EMSFG, the magnetic flux intensity is distributed evenly in molten steel. Moreover, the Lorentz force increases along a radial direction in the molten steel in the SEN. However, for a half type EMSFG, the magnetic flux intensity and Lorentz force decreases gradually towards the region without an EMSFG. Consequently, a full type EMSFG with a 44 000 AT magnetomotive force and a 50 Hz frequency is more suitable to apply in the operation of an EMSFG under actual production conditions.