Slot Shape Research Articles

Simulation Analysis of the Effect of Slit/Slot Pintle Geometry on Atomization of Bipropellant Engine

In order to optimize the slit/slot geometry design of a bipropellant pintle injector, the impinging spray development of a pintle injector was numerically investigated. The VOF (volume of fluid) and LES (large eddy simulation) methods were employed for an analysis to capture the gas–liquid interface by means of the AMR (adaptive mesh refinement) method. In those simulation cases, different flowrates, slot numbers, pintle diameters, slot thicknesses and slot shapes were compared for an analysis. In a comparison of visualization and quantification, a high flowrate and large pintle diameter were shown to be more positive features for improving the atomization quality and mixing effect. As for the slot parameters and shape, the spray development was mainly determined by the flow proportion between the slit jet and slot jet. The simulation results indicated that dominant slot jets cause a more dispersed spatial distribution, which is more conducive to the subsequent improvement of combustion efficiency in a limited space. However, an excessive increase in the number of slot jets can weaken the overall atomization quality and mixing effect, so it is suggested to ensure a balance for geometry design optimization.

Equivalent circuit model‐based design and analysis of microstrip line fed electrically small patch antenna for sub‐6 GHz 5G applications

SummaryIn this paper, an equivalent circuit model‐based electrically small patch antenna is designed for sub‐6 GHz 5G application (3.5 GHz) using 50‐Ω microstrip line feed. The overall size of the proposed antenna is 0.33λ0 × 0.4λ0 × 0.019λ0 (28 × 34 × 1.6 mm3) at 3.50 GHz frequency. The proposed antenna has a tilted Y‐shape slot, two rectangular shape slots, and two rectangular shape notches in the radiating patch. The proposed antenna is resonating from 3.21 to 3.74 GHz covering the entire sub‐6 GHz 5G band (3.3–3.8 GHz). The impedance bandwidth (simulated) of the proposed antenna has been obtained 530 MHz resonating at 3.50 GHz frequency. The good return loss of −23.62 dB is also obtained at 3.50 GHz resonant frequency. The simulation results and geometry of the proposed antenna are validated with equivalent circuit model and experimental measurement of prototype antenna using vector network analyzer (VNA) and anechoic chamber. In the whole operating frequency range, the measured findings show reasonable agreement with the simulated ones. The measured impedance bandwidth of the proposed antenna has been obtained 480 MHz (3.21–3.69 GHz) resonating at 3.48 GHz frequency with a return loss of −21.61 dB, while the theoretical impedance bandwidth of the proposed antenna has been obtained 720 MHz (3.18–3.90 GHz) resonating at 3.58 GHz frequency with a return loss of −21.5 dB. The peak gain of 3.39 (simulated) and 3.2 dB (measured) is obtained at 3.50 GHz frequency. Moreover, the antenna shows 97% (simulated) and 95% (measured) efficiency at 3.50 GHz frequency.

Dependence of starting characteristics on the shape of rotor slots

At present, induction motors with a squirrel-cage rotor drive based on them are widely used. The breadth of the field of use of induction electric motors is so great due to the large power range, simple design, reliability and high technical and economic indicators, the possibility of producing these machines with various degrees of protection, which allows them to be used both under normal operating conditions and under harsh environmental conditions. The review of technical literature was carried out and various forms of stator and rotor slots were considered. The calculations of an induction electric motor with a squirrel-cage rotor are considered in two different ways: using the technique presented in [1], and using the ANSYS finite element analysis program Maxwell.

Vibration and Noise Optimization of Rotor Structure of Permanent Magnet Synchronous Motor for Vehicles

In order to improve the vibration and noise level of permanent magnet synchronous motor, based on the ANSYS workbench multi-physical field coupling platform, the motor structure is designed and simulated to optimize the vibration and noise of the motor. The spatial and temporal order of the vibration noise caused by the first order tooth harmonic is analysed, and the vibration noise caused by the first order tooth harmonic is reduced by slotting the rotor. By analysing the influence of rotor slots with different positions and different size parameters on the air gap magnetic flux density of the motor, the most suitable optimization method is found, and the optimization level of air gap magnetic flux density of rotor slots with different shapes under the same position and slot area is analysed and compared, so as to select the most suitable rotor slot shape. The simulation analysis shows that the air gap magnetic density and torque ripple of the optimized motor have been significantly improved, and the electromagnetic noise of 48-time order caused by 12 times the electromagnetic frequency of the motor in the 0 space order has been significantly reduced, which proves the reliability of the optimized scheme.

Numerical study on the influence mechanism of different types of burst disc on high pressure hydrogen spontaneous combustion in tube

High-pressure transportation and storage are the current main methods for storing hydrogen. Burst discs, which are common in high-pressure storage devices, can cause hydrogen leaks to ignite and create serious accidents when certain conditions are met. To investigate this, this paper studies the effect of different blasting slot shapes on the spontaneous combustion of leaked high-pressure hydrogen. Numerical simulations, using LES, EDC model, Ten-Step Burst Disc Opening Method and 19-Step Detailed Hydrogen Combustion Mechanism, were conducted to analyze the spontaneous combustion of hydrogen with annular grooves, star grooves, cross grooves and grooveless burst discs. The results of the study show that the shape of the groove in the bursting disc will significantly affect the shock wave structure and spontaneous combustion time of leaked high pressure hydrogen in the tube. Among the four types of bursting discs, the order of spontaneous combustion in the tube is annular groove (approximately 90 μs), star groove (approximately 110 μs), cross groove (approximately 120 μs), and grooveless bursting disc (approximately 130 μs). Secondly, the double spherical shock waves produced by annular groove bursting disc collide with each other, resulting in a higher rising speed of pressure and temperature in the tube than with other bursting discs. Finally, the spontaneous combustion time of the leaked hydrogen is proportional to the open area of the bursting disc. When the opening area is the same, the smaller the exit shape coefficient is, the shorter the spontaneous combustion time is. The research results can provide some reference for the design and application of bursting disc in high pressure hydrogen storage equipment.

Compact modified hourglass-shaped aperture-coupled antenna for radar applications

AbstractThis paper furnishes a compact modified hourglass-shaped aperture-coupled antenna for radar applications. The effect of slots of various shapes and various slot lengths on the input impedance, radiation pattern, and gain of the antenna are analyzed. The proposed antenna, designed using a modified hourglass-shaped aperture, offers a gain of 8.214 dBi for an compact antenna with a dimension of 20.4 × 20.4 × 1.041 mm3 and an aperture area of 2.495 mm2. Implementation of this proposed modified hourglass-shaped aperture offers a high gain per unit radiating patch area of 40.26 dB/$\lambda _g ^2$ and a high gain per unit aperture area of 1324.84 dB/$\lambda _g ^2$. The proposed aperture feeds a circular patch which radiates at its resonant frequency of 10.5 GHz. The proposed design is fabricated and the simulated results are verified experimentally. Equivalent circuit analysis is also done. A measured gain of 7.2 dBi is observed at 10.5 GHz. The physical area of the antenna is reduced without compromising the gain by judiciously choosing the shape of slot with more degree of freedom for impedance matching. The proposed antenna is well suited for the unit cell of phased array antennas for X-band missile radar applications.

Impact of Stator Slot Shape on Cogging Torque of BLDC Motor

Brushless DC (BLDC) motors have a wide range of applications in these modern days, such as electric vehicles, industrial robots, washing machines, pumps, and blowers. The brushless DC motors have many advantages when compared to induction motors and conventional DC motors, such as better speed control, noiseless operation, high efficiency, less maintenance, and a long life. Along with these benefits, there is one major disadvantage known as cogging, which causes undesirable effects in the motor such as noises and vibrations. BLDC motors have been widely used in automation and industrial applications due to their attractive features. There are certain parameters to be considered while designing a BLDC motor, such as its dimensions, number of windings turns, type of magnetic materials used, required torque, output current, slot-to-depth ratio, efficiency, temperature rise, etc.

Design and analysis of square shape slot cut high gain Sierpinski carpet fractal antenna for wireless applications

AbstractIn this paper, a fractal antenna is proposed for wideband application. It has a resonance frequency of 5 GHz, and has been designed using an FR4 substrate with a width and a length of 40 mm and patch with a width, length of 35.288 mm. The proposed antenna has been made with five iterations, and the result obtained multiband behavior and agrees with the various efficient wireless applications. In the proposed antenna, there are four bands response at frequencies 1.6, 2.9,5.2, and 6 GHz, and bandwidth percentage are 4.56%, 7.89%, 12.13%, and 4.6%. It also covers application in 1.5–1.7, 2.8–3.1, 4.8–5.4, and 5.9–6.2 GHz. The gain and the directivity of the proposed antenna is measured as 15.885 dBi greater than other fractal antennas to date, and 7.422 dBi respectively. The proposed antenna has been implemented successfully using IE3D and the result has been tested successfully using a key sight vector analyzer.

A compact channel patch antenna with reconfigurable circularly polarized pattern for mobile satellite communications

A compact dual-band circularly polarized antenna with a characteristic of pattern reconfiguration is proposed for S-band satellite handsets. The antenna works as a patch antenna in a channel shape with no ground beneath reaching an overall size of 0.55λ × 0.14λ × 0.1λ. The dual-band performance is realized through multi-branch slots of the patch. The antenna mainly consists of a channel metal patch, a channel dielectric, and a simple feeding network. The overall shape of slot can be changed by the PIN diode on the patch to adjust the surface current direction, which in turn achieves 180° switching of the left-hand circularly polarized radiation beam direction. In addition, by combining the quadrifilar helical antenna, which is switchable in the end-fire beam direction, the designed antenna can realize the switching of four main beam directions to achieve 360° 3D spatial coverage. The proposed antenna is fabricated and measured to verify the proposed design. The test results show that the designed antenna obtains circularly polarized radiating characteristics in S-band with the center frequency of 1.98 GHz and 2.2 GHz, and the test results and simulation results are basically consistent, which indicates the superior performance of the designed antenna.

Design and Evaluation of Linear Primary Permanent Magnet Vernier Machines for Urban Railway Transportation

Linear induction machine (LIM) is used as a driving machine in urban railway transportation because of its simple structure and mature technology. However, low thrust force and efficiency have always been a difficult problem to be solved. In the last decade, linear primary permanent magnet vernier machine termed as LVM in this paper has been extensively investigated owing to its potential application prospect in urban railway transportation. However, there is a lack of investigation on the feasibility of rendering the LVM the same size as existing LIM used in urban railway transportation. Therefore, in this paper, a large-sized LVM is designed and evaluated according to the requirement. Firstly, the LIM used in practical urban railway transportation are introduced. Secondly, the LVMs with the same size as the LIM counterpart are established by finite element method. Then, effects of consequent-pole Halbach permanent magnet structure, secondary tooth number and primary slot shape on performances are investigated. Thirdly, a LVM is optimized and compared with the LIM. The results revealed that the LVM exhibits higher thrust force and efficiency. Finally, a small-sized prototype of LVM is constructed to validate the simulation.

A Compact Quad-Port UWB MIMO Antenna With Improved Isolation Using a Novel Mesh-Like Decoupling Structure and Unique DGS

The progress in mobile communication and the Internet of Things facilitates multiple features. The trending technology demands wider bandwidth so that user experiences uninterruptedly. The wider bandwidth and the isolation are two key characteristics of modern device antennas. The design of an ultrawideband (UWB) and four-port MIMO antenna is presented in this brief. The semicircular monopole patch is modified by including a guitar shape slot on a radiator and a half-circle slot in the lowered ground plane. The structural transformation affects the current path and enhances impedance matching, resulting in a broader bandwidth. The UWB monopole is replicated to construct a four-port multiple input and multiple output (MIMO) antenna. The separation between the interelement is less than the quarter wavelength. As a decoupling structure, the implicit mutual coupling in the MIMO elements is minimized by parasitic elements on the radiator and defected ground plane (DGS). A novel mesh-like structure embedded in radiating plane and DGS couples the current from an excited antenna and suppresses through the DGS correspondingly and improves the isolation. The overall geometry of the antenna is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$45 {\times } 45 {\times }1$ </tex-math></inline-formula> .6 mm3. The UWB MIMO has a measured impedance bandwidth of 113% between 4.5-16.4 GHz and greater than 20 dB of isolation throughout the bandwidth. Besides the mutual coupling reduction, radiation characteristics and all MIMO diversity parameters are studied. The performance of MIMO diversity characteristics is relatively good, with envelope correlation coefficient<0.002, diversity gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathbf {\mathrm {\simeq }}10$ </tex-math></inline-formula> , mean effective gain<−3 dB, total active reflection coefficient<−10 dB, channel capacity loss <0.2 bps/Hz, and multiplexing efficiency<−0.5. The experimental and simulated findings are in line and make the projected design suitable for UWB MIMO applications.

A Comprehensive Analysis, Design, and Experimental Evaluation of Single-Loop Polygonal Slotted RF Resonators and WPT Systems

A thorough analysis of slotted ground plane (SGP)-based resonators designed for wireless power transfer (WPT) applications is reported in this paper. For the first time, some new findings that relate a resonator and WPT performance metrics to the slot shape, quality factor (Q), and radiation loss are presented in a very comprehensive manner. As a case study, a single-loop polygonal shape was considered to carry out all analyses and investigations. It has been identified that the slot shape has no impact on the performance of resonators and, hence, developed WPT. Instead, the performance is hugely dependent on Q of resonators regulated by the chosen slot area. These findings allow the conceptualization of systematic analysis of WPT systems and the development of design schemes that are readily realizable, and they also enable significant improvement in power transfer efficiency (PTE). The developed prototypes conforming to the industrial, scientific, and medical frequency bands show an enhancement in PTE to the extent of 11% during the measurements. The proposed analysis and design approach are very important steps in advancing state-of-the-art radio-frequency WPTs. In essence, this has the potential to reinvigorate the stagnated SGP-based WPT systems so as to facilitate the requirements of low-power applications.

DUAL-BAND HALF-CIRCULAR RING IMPLANTABLE ANTENNA WITH METAMATERIAL SRR FOR BIOMEDICAL APPLICATIONS

This paper presents a half-circular ring antenna with a rectangular slot that operates in the industrial, scientific, and medical (ISM) band at 2.45 GHz. A metamaterial (MTM) split-ring resonator operating in the lower ISM band at 0.9 GHz is added to the proposed implantable antenna in order to obtain a dual-band frequency result of 0.9 and 2.45 GHz. Some methods of miniaturization are used in the design of the proposed antennas, such as the addition of a MTM resonator to the antenna, the use of the Roger 3010 with its high permittivity, the shorting pin to connect the patch and the ground plane, and slot shapes. To check the presence of the MTM, the permeability is extracted by the Nicolson method. A high-frequency structure stimulator is used to design and simulate the proposed antenna in free space, one-layer, and three-layer tissue models. The specific absorption rate values and the maximum input power for the antenna with and without the MTM resonator are also calculated.

Compact Single Band Suppression Monopole Antenna for SWB Application

This article describes the design of a miniatured monopole antenna with a band notch for use in super-wideband applications. The suggested antenna is fed by a triangular tapered micro-strip feed line and has a frequency range of 2.88 to 60 GHz (bandwidth ratio: 20.83:1) with |S11|&lt;−10 dB, with the exception of the notched band for WLAN band at 4.35–6.45 GHz. The antenna’s overall dimensions are 23 × 14.5 × 1 mm3 which consists of F4B substrate having permittivity of 2.65 and 1mm thickness, a round-cornered beveled-shaped radiating element, and a roundcornered partial ground plane. To realize the band notch characteristic an inverted crescent shape slot is introduced in the radiator. This paper presents the simulated results for the suggested antenna. The results shows that the suggested antenna operates well over the whole operational BW (181.7%), making it a good choice for SWB applications.

Analytical and FEM Methods for Line Start Permanent Magnet Synchronous Motor of 2.2kW

This paper has developed electromagnetic equations based an analytical model to design a three-phase line start permanent magnet synchronous motor (LSPMSM) of 2.2 kW. In order to enhance the torque and efficiency of this machine, an optimized slot shape of rotor permanent magnet is proposed. The analytical model is first presented to evaluate the magnetic characteristics, and then analytical expressions are derived under the open circuit condition. The influence of the magnet size variables on the analytical model is considered to investigate the magnetic leakage flux and flux density distribution in air gaps. Moreover, the variation of design has a significant impact on the steady-state performance characteristics of this motor. In addition, in order to check the output results from the analytical model, a finite element method is developed to evaluate these solutions. Finally, experimental and simulation results have been compared and analyzed to validate the development of method.

Design of Compact Bow-Tie Slotted Antenna for Satellite Communication

A printed antenna using the slot-loading technique is adapted in the design to achieve multiband. A rectangular microstrip (printed) antenna with a Bow-Tie shape slot embedded on the radiating patch using a glass epoxy substrate with dimensions 3.34 x2.47 x 0.16 cms. The antenna is simulated using high-frequency structure simulator software and fabricated using a photolithography process. Experimental results are measured using a vector analyzer. the proposed antenna is resonating at three different frequencies 4.62 GHz, 8.14 GHz, and 12.41 GHz with a return loss of -20.00 dB, -25.09 dB, and -26.45 dB respectively. The antenna is resonating between 4.62 GHz to 12.41 GHz frequency which covers applications in the field of satellite (space to earth)5.441 and mobile communication 5.463.

Magnet Slotting Design to Reduce High Order Electromagnetic Force and Vibration of Permanent Magnet Motor

In this paper, a new method is proposed to suppress the vibration caused by the modulation effect of high-order electromagnetic forces in permanent magnet (PM) motors. Firstly, the modulation effect of the radial force was investigated, which indicated that the higher-order electromagnetic force could cause modulated vibrations through the modulation effect. Then, auxiliary slots on the magnet surface and their effect on vibration reduction were investigated. The optimal shape of the auxiliary slot was found to minimize the noise of motor vibration. Finally, the method was verified experimentally.

Super‐UWB MIMO Antenna With Dual Band‐Notched and High Gain

AbstractA 2 × 2 multiple‐input multiple‐output (MIMO) antenna with super‐ultra wideband (super‐UWB), dual band‐notched characteristics and high gain is proposed. The antenna element consists of a circular slot shape radiator fed by a tapered feedline on the top side of the substrate, whereas defected ground structure (DGS) is etched on the bottom ground plane. The DGS and tapered feedline has been designed to produce the super‐UWB performance. Dual‐band notch is achieved by etching a J‐shape slot in the radiator and an I‐shape slot at the edges of the ground plane. The dual‐band notch prevents the electromagnetic interference allocated for other wireless applications. High isolation is realized by incorporating a plus‐shape decoupling structure with four small arm shape stubs at the center of the ground plane. A prototype was fabricated to verify the simulated and measurement results. The proposed design achieves a super‐ultra wide bandwidth of 165% (3.4 ∼ 35 GHz), isolation of 21 dB, and a peak gain of 13 dBi. The notched bands are at 6.6 and 10 GHz. The envelope correlation coefficient is less than 0.01. The overall size of the MIMO design is 0.58λ0L × 0.34λ0L (λ0L is the free‐space wavelength at the lowest operating frequency).

Implementation and Experimental Validation of Efficiency Improvement in PM Synchronous Hub Motors for Light Electric Vehicles

The efficiency of permanent magnet synchronous hub motors (PMSHM) used in light electric vehicles (EVs) is lower than that used in commercial EVs. Therefore, in this study a high-efficiency radial-flux outer-rotor PMSHM was designed for light EVs. The high-efficiency motor will contribute to the reduction of the power consumption demand from the batteries of EVs, the longer life of the batteries and the longer uninterrupted operation of the system. The optimization objectives, such as motor sizing, number of slots and poles, air gap length, material selection, stator winding structure, stator slot shape, magnet thickness, and cutting method for stator sheets were considered to ensure high efficiency and low cogging torque. In this study, three validation stages were followed; electromagnetic analyzes with FEM, analytical calculations, and finally experimental validation. First, the design parameters of the motor were determined based on the analyses results obtained using ANSYS Maxwell software, and then validated both with the analytical calculations and experimental results. The comparison results show that the design data of the motor at the rated speed agree well with the analytical calculations and test results. After obtaining the optimized motor design, the motor was installed on a prototype electric car for the road test. During the test drive, the motor performed successfully and operated compatibly with the rest of the electric vehicle systems such as the motor driver and the battery.

Design of a hexagonal slot rectenna for RF energy harvesting in Wi‐Fi / WLAN applications

This work proposes a single port hexagonal slotted rectenna operating at 2.45 GHz Wi-Fi bands, using a hexagonally slotted shape of microstrip radiator surface followed by a voltage rectifier circuit using Schottky diode. A symmetrically extended ground plane and rectangular slots help in obtaining the desired resonance characteristics with improved antenna bandwidth. Three different antenna designs have been compared and analyzed. Best gain and wide most bandwidth is seen in the newly designed rectangular and hexagonal slotted design having symmetrically extended ground plane. A RF capacitor and inductor based matching network has been designed to maximize the wireless power transmission at 2.45 GHz. This also helps to enhance the rectifier efficiency for various values of load resistance and input power. Furthermore, for maintaining the small size and ensuring least amount of energy loss, the rectifier's ground has been directly connected to the antenna's ground plane. The proposed design has been simulated in HFSS and ADS software, prototyped, and measured. It has been seen in the results that, the proposed radio frequency (RF) power receiving antenna is performing very well at 2.45 GHz with a wide bandwidth ranging from 1.25 to 2.63 GHz. The proposed rectenna is having a maximum efficiency of 62.4% at 2.45 GHz with an input power of 0 dBm. Furthermore, with variations in the load resistance across a wide range of values from 4 to 12 kΩ $$ \mathrm{k}\Omega $$ under a wide range of low input power, the rectenna maintains an efficient power conversion, which is found to be an important parameter when the ambient RF signal input to the antenna is weak. As a result, the rectenna may be adaptable to a variety of low-power electronic circuits by harvesting RF energy at 2.45 GHz Wi-Fi Band. Furthermore, the proposed antenna can also be used for wireless medical telemetry, satellite phone and Wi-Fi applications used for the frequency band 1.45 GHz as well.