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Open Access
Article
Publication date: 13 October 2023

Hongmei Li, Junling Shi, Xiangdong Li, Junbo Zhang and Yunlong Chen

High-speed maglev technology can address the issues of adhesion, friction, vibration and high-speed current collection in traditional wheel-rail systems, making it an important…

507

Abstract

Purpose

High-speed maglev technology can address the issues of adhesion, friction, vibration and high-speed current collection in traditional wheel-rail systems, making it an important direction for the future development of high-speed rail technology.

Design/methodology/approach

This paper elaborates on the demand and significance of developing high-speed maglev technology worldwide and examines the current status and technological maturity of several major high-speed maglev systems globally.

Findings

This paper summarizes the challenges in the development of high-speed maglev railways in China. Based on this analysis, it puts forward considerations for future research on high-speed maglev railways.

Originality/value

This paper describes the development status and technical maturity of several major high-speed maglev systems in the world for the first time, summarizes the existing problems in the development of China's high-speed maglev railway and on this basis, puts forward the thinking of the next research of China's high-speed maglev railway.

Details

Railway Sciences, vol. 2 no. 3
Type: Research Article
ISSN: 2755-0907

Keywords

Article
Publication date: 6 November 2023

Qing Liu, Li Wang and Ming Feng

This paper aims to study the clearance compatibility of active magnetic bearing (AMB) and gas bearing (GB) to achieve a single-structured hybrid gas-magnetic bearing (HGMB), which…

Abstract

Purpose

This paper aims to study the clearance compatibility of active magnetic bearing (AMB) and gas bearing (GB) to achieve a single-structured hybrid gas-magnetic bearing (HGMB), which uses a single bearing structure to realize both the functions of gas bearing and magnetic bearing.

Design/methodology/approach

Because the radial clearance size of the AMB is typically ten times larger than that of the GB, radial clearance compatibility of GB and AMB needs to maximize the radial clearance of GB by adjusting structural parameters. Parametric analysis of structural parameters of GB is explored. Furthermore, a general structural design principle based on static analysis, rotordynamic performance and system stability is established for the single-structured HGMB.

Findings

Load capacity is vastly reduced due to the enlarged radial clearance of the GB. A minimum clearance needs to be ensured by increasing the bearing diameter or width to compensate for the reduced load capacity, yet indirectly raising the bearing load. Increased bearing load is conducive to stability, yet it raises the risk of rotor abrasion. In addition, excessively large bearing diameter leads to system instability, and inappropriate bearing width affects critical speeds. A general structural design principle is established and the designed HGMB–rotor processes optimal performances.

Originality/value

A single-structured HGMB is proposed to address the urgent demand for high-speed, cryogenic turboexpanders with frequent starts/stops. This design applies a single-bearing structure to realize the characteristics of both GB and AMB, greatly simplifying the implementation, reducing air friction loss and raising critical speeds. This paper provides a fresh perspective on the development of cryogenic turboexpanders for hydrogen liquefaction. It theoretically validates the feasibility and provides a design guide for a single-structured HGMB system.

Details

Industrial Lubrication and Tribology, vol. 75 no. 10
Type: Research Article
ISSN: 0036-8792

Keywords

Open Access
Article
Publication date: 9 August 2023

Jie Zhang, Yuwei Wu, Jianyong Gao, Guangjun Gao and Zhigang Yang

This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of…

335

Abstract

Purpose

This study aims to explore the formation mechanism of aerodynamic noise of a high-speed maglev train and understand the characteristics of dipole and quadrupole sound sources of the maglev train at different speed levels.

Design/methodology/approach

Based on large eddy simulation (LES) method and Kirchhoff–Ffowcs Williams and Hawkings (K-FWH) equations, the characteristics of dipole and quadrupole sound sources of maglev trains at different speed levels were simulated and analyzed by constructing reasonable penetrable integral surface.

Findings

The spatial disturbance resulting from the separation of the boundary layer in the streamlined area of the tail car is the source of aerodynamic sound of the maglev train. The dipole sources of the train are mainly distributed around the radio terminals of the head and tail cars of the maglev train, the bottom of the arms of the streamlined parts of the head and tail cars and the nose tip area of the streamlined part of the tail car, and the quadrupole sources are mainly distributed in the wake area. When the train runs at three speed levels of 400, 500 and 600 km·h−1, respectively, the radiated energy of quadrupole source is 62.4%, 63.3% and 71.7%, respectively, which exceeds that of dipole sources.

Originality/value

This study can help understand the aerodynamic noise characteristics generated by the high-speed maglev train and provide a reference for the optimization design of its aerodynamic shape.

Details

Railway Sciences, vol. 2 no. 3
Type: Research Article
ISSN: 2755-0907

Keywords

Article
Publication date: 25 April 2023

Ali Hashemi, Parsa Yazdanpanah Qaraei and Mostafa Shabanian

An excessive increase in temperature will reduce the lifespan and even burn the coil. The variety of materials in the structure of the electromagnet along with its multi-layer…

Abstract

Purpose

An excessive increase in temperature will reduce the lifespan and even burn the coil. The variety of materials in the structure of the electromagnet along with its multi-layer winding creates a complex and heterogeneous thermal structure. There are very few researches that are completely focused on the thermal analysis of electromagnets. The purpose of this paper is to provide an accurate, yet fast and simple method for the thermal analysis of cylindrical electromagnets in both transient and steady-state modes. For this purpose, a thermal equivalent circuit (TEC) is presented based on the nodding approach.

Design/methodology/approach

The results of TEC analysis of cylindrical electromagnet, for two orthogonal and orthocyclic winding coil technologies, were compared with the results of the thermal simulation in COMSOL. The authors also built a laboratory model of the cylindrical electromagnet, similar to those analyzed and simulated, and measured the temperature in different parts of it.

Findings

The comparison of the results obtained from different methods for the thermal analysis of the cylindrical electromagnet indicates that the proposed TEC has an error of less than 2%. The simplicity and high accuracy of the results are the most important advantages of the proposed TEC.

Originality/value

Comparing the information and results related to winding schemes, indicates that the orthogonal winding has less cost and weight due to the shorter length of the wire used. On the other hand, orthocyclic winding generates lower temperature and has more lifting force, and is simpler to implement. Therefore, in practice, orthocyclic winding technology is usually used.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 42 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 26 February 2024

Leonardo Valero Pereira, Walter Jesus Paucar Casas, Herbert Martins Gomes, Luis Roberto Centeno Drehmer and Emanuel Moutinho Cesconeto

In this paper, improvements in reducing transmitted accelerations in a full vehicle are obtained by optimizing the gain parameters of an active control in a roughness road…

Abstract

Purpose

In this paper, improvements in reducing transmitted accelerations in a full vehicle are obtained by optimizing the gain parameters of an active control in a roughness road profile.

Design/methodology/approach

For a classically designed linear quadratic regulator (LQR) control, the vibration attenuation performance will depend on weighting matrices Q and R. A methodology is proposed in this work to determine the optimal elements of these matrices by using a genetic algorithm method to get enhanced controller performance. The active control is implemented in an eight degrees of freedom (8-DOF) vehicle suspension model, subjected to a standard ISO road profile. The control performance is compared against a controlled system with few Q and R parameters, an active system without optimized gain matrices, and an optimized passive system.

Findings

The control with 12 optimized parameters for Q and R provided the best vibration attenuation, reducing significantly the Root Mean Square (RMS) accelerations at the driver’s seat and car body.

Research limitations/implications

The research has positive implications in a wide class of active control systems, especially those based on a LQR, which was verified by the multibody dynamic systems tested in the paper.

Practical implications

Better active control gains can be devised to improve performance in vibration attenuation.

Originality/value

The main contribution proposed in this work is the improvement of the Q and R parameters simultaneously, in a full 8-DOF vehicle model, which minimizes the driver’s seat acceleration and, at the same time, guarantees vehicle safety.

Details

Engineering Computations, vol. 41 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 14 December 2023

Ali Hashemi and Parsa Yazdanpanah Qaraei

This paper aims to present an accurate magnetic equivalent circuit for modeling the cylindrical electromagnet so that by analyzing it, the magnetic flux density in different parts…

Abstract

Purpose

This paper aims to present an accurate magnetic equivalent circuit for modeling the cylindrical electromagnet so that by analyzing it, the magnetic flux density in different parts of the electromagnet, as well as its lifting force, can be calculated.

Design/methodology/approach

The structure of the electromagnet is divided into parts that can be modeled by lumped element parameters. Mathematical equations for calculating these elements are presented and proved. The axial symmetry of the cylindrical electromagnet made it possible to use planar circuits for its modeling. To increase the accuracy of the proposed equivalent circuit, attention has been paid to the leakage flux as well as the nonlinear behavior of the ferromagnetic core. Also, the curvature of the magnetic flux path is considered in the calculation of the corner permeances of the core.

Findings

The magnetic flux density in different parts of the electromagnet was calculated using nodal analysis of the circuit and compared to the results of the finite element method. Also, a test bed was established to measure the lifting force of the electromagnet. Comparing the results shows a difference of less than 3% which indicate the good accuracy of the proposed circuit. In addition, due to the curvature of the flux path, there is a no-flux region in the center of the disk, the extent of which depends on the thickness of the disk and the diameter of the middle leg.

Originality/value

Magnetic equivalent circuit is a new contribution to analyze the cylindrical electromagnet and calculate its lifting force with good accuracy. The circuit lumped elements can be quickly calculated using mathematical equations and software such as MATLAB according to the actual path of the magnetic flux. Compared to other methods, the proposed circuit analyzes the electromagnet in a shorter period of time. This is the most important advantage of the proposed circuit model.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering , vol. 43 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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