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Multiple-degree-of-freedom damping characteristics evaluation of dual halbach array eddy current damper for turbopump in cryogenic environment

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INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 2024年第1-2期76卷 111-120页

作者： Heya, Akira Inoue, Tsuyoshi Nagoya Univ Dept Mech Syst Engn Nagoya Japan

Liquid hydrogen turbopumps are used in large high-performance rockets. Stable high-speed rotation is required for rocket turbopumps. The damping mechanism of the pump must suppress vibration not only in the radial direction but also in the axial direction. However, conventional damping elements using oil or rubber cannot be used due to the cryogenic temperature of liquid hydrogen. Therefore, the application of eddy current dampers to liquid hydrogen turbopumps is focused on in this paper. Although various structures of eddy current dampers have been developed, the multi-degree-of-freedom damping characteristics of dual halbach array type eddy current dampers for liquid hydrogen turbopumps have not yet been investigated. The variation of damping characteristics with temperature has also not yet been verified. In this paper, we propose a novel dual halbach array type eddy current damper for liquid hydrogen turbopumps. The proposed damper can generate high damping force and can be operated maintenance-free at the cryogenic temperature. The analysis results show that the damping characteristics strongly depend on temperature and that the amplitude reduction effect is greater at low temperatures. It was also found that the proposed damper has a higher damping force density than conventional dampers.

关键词： Eddy current damper magnetic damper dual halbach array cryogenic environment turbopump

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A LOW FREQUENCY VIBRATION DRIVEN, MINIATURIZED AND HYBRIDIZED ELECTROMAGNETIC AND TRIBOELECTRIC ENERGY HARVESTER USING dual halbach array 19

A LOW FREQUENCY VIBRATION DRIVEN, MINIATURIZED AND HYBRIDIZE...

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19th International Conference on Solid-State Sensors, Actuators and Microsystems (Transducers)

作者： Salauddin, M. Park, J. Y. Kwangwoon Univ Dept Elect Engn Seoul 139701 South Korea

ISBN: (纸本)9781538627327

We have proposed and experimentally validated a highly miniaturized and hybridized electromagnetic (EM) and triboelectric (TE) energy harvester for scavenging low frequency vibration using dual halbach array. The halbach array enhances the magnetic flux density and reduces the overall volume as well as facilitates high power generation at low frequencies. In particular, the proposed dual halbach array allows the concentrated magnetic flux lines to interact with the same coil in a way where maximum flux linkage occurs. To obtain high output power in low amplitude and low frequency vibrations, the proposed harvester was comprised of a dual halbach array, TE generator, and magnetic springs. The fabricated hybrid energy harvester delivered an output power of 2.1mW, corresponding to a volume power density of 68W/m(3) under a loading resistance of 112 Omega at 10Hz resonant frequency and 0.5g acceleration.

关键词： Low frequency vibration dual halbach array electromagnetic triboelectric

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Design and experiment of human hand motion driven electromagnetic energy harvester using dual halbach magnet array

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SMART MATERIALS AND STRUCTURES 2017年第3期26卷

作者： Salauddin, M. Park, Jae Y. Kwangwoon Univ Dept Elect Engn 447-1 Wolgye dong Seoul 139701 South Korea

We present a dual halbach array electromagnetic energy harvester that generates significant power from hand shaking vibration. The magnetic-spring configuration is employed for generating sufficient power from the hand motion of irregular and low-frequency vibrations. However, significant power generation at low-frequency vibrations is challenging because the power flow decreases as the frequency decreases;moreover, designing a spring-mass system that is suitable for low-frequency-vibration energy harvesting is difficult. In this work, our proposed device overcomes both of these challenges by using a dual halbach array and magnetic springs. During the experiment, vibration was applied in a horizontal direction to reduce the gravity effect on the halbach-array structure. To achieve an increased power generation at low-amplitude and low-frequency vibrations, the magnetic structure of the dual halbach array and the magnetic springs were optimized in terms of the operating frequency and the power density. A prototype was fabricated and tested both using a vibration exciter and by manual hand-shaking. The fabricated device showed resonant behavior during the vibration exciter test. For the vibration exciter test, the prototype device offers a maximum average power of 2.92mW to a 62 Omega optimum load, at a 6 Hz resonance frequency and under a 0.5 g acceleration. The prototype device is capable of delivering a maximum average power of 2.27mW from hand shaking. The fabricated device exhibited a normalized power density 0.46 mW cm(-2) g(-2) which is very high compared to the current state-of-the-art devices, representing its ability in powering portable and wearable smart devices from extremely low frequency vibration.

关键词： electromagnetic dual halbach array low frequency vibration human hand motion resonant

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Analysis of double side ironless permanent magnet linear synchronous machine with low normal force

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Scientific Reports 2025年第1期15卷 1-14页

作者： He, Xinghua Sun, Qixin Yan, Liang Xiang, Pengjie Zheng, Tao School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China Science and Technology on Aircraft Control Laboratory Beihang University Beijing 100191 China Ningbo Institute of Technology Beihang University Ningbo 315800 China Beijing Aerospace Control Instrument Research Institute Beijing 100854 China

An electromagnetic linear machine is an energy conversion device that can convert electrical energy into linear motion. Conventional study of electromagnetic linear machines mainly focuses on the axial thrust, because it can be used to act on external payloads directly. However, due to manufacturing error and mechanical deformation of mover, the double side permanent magnet linear synchronous machine (DPMLSM) often generates unbalanced normal force on mover. This unwanted force may aggravate the mover deformation and lead to unequal airgap, which increases the normal force further, consequently leading an increase of friction, vibration and noise of the system. Therefore, the normal force in also important that is ignored. The purpose of this article is to study the normal force of DPMLSM to provide theoretical support for the design. The normal force of DPMLSM is analysed systematically and the magnetic field distribution is formulated analytically. The normal force for different mover deformation and different number of halbach segments are analysed. It is found that the offset of normal installation has a significant impact on the normal force, and the more segments there are, the smaller the normal force. The width of the pole is optimized and an experimental prototype is fabricated to verify the accuracy of analytical and numerical calculations through experiments. © The Author(s) 2025.

关键词： dual halbach array Electromagnetic normal force Permanent magnet machine

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