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RISS 인기검색어
- 검색키워드
- 저자 : Yili Zhu (검색결과 3 건)
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Yili Zhu,Yanhong Zhang,Chengtao Yu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6
A new-type active touchdown bearing (TDB) system integrated with a centering device to eliminate the protective clearance after rotor drop in an active magnetic bearing (AMB) system is proposed. A rotor dynamic model is established on the basis of rigid rotor theory. A collision model between the support base and outer race of the ball bearing and a real-time ball bearing elastic supporting force model are established on the basis of Hertz contact theory. The dynamic model of the new-type TDB is established on the basis of vibration theory. Using these established theoretical models, the dynamic responses after rotor drops onto the new-type TDB are simulated and compared with the responses after rotor drops onto traditional TDB. Relevant experiments are conducted on an AMB test platform to verify the simulation results. The results show that the proposed new-type TDB can rapidly eliminate the protective clearance after rotor drop and can thus effectively reduce the following rotor vibrations and impacts.
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Yi Li,Guangwei Feng,Xiaojun Li,Qiaorui Si,ZuChao Zhu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10
Cavitation is a challenging flow abnormality that leads to undesirable effects on the energy performance of the centrifugal pump and the reliable operation of the pump system. The onset and mechanism of a phenomenon that results in unsteady cavitation must be realised to ensure a reliable operation of pumps under the cavitation state. This study focuses on cavitation instability at normal flow rate, at which point the unsteady cavitation occurs as the available net positive suction head (NPSHa) falls below 5.61 m for the researched pump. An ameliorative algorithm–united algorithm for cavitation vibration analysis is proposed on the basis of short time Fourier transform (STFT) and Wigner–Ville distribution (WVD). The STFT–WVD method is then tested using vibration data measured from the centrifugal pump. The relationship between vibration and suction performance indicates that the inception and development of cavitation can be effectively detected by the distribution and intensity of the united algorithm at the testing points. Intermediate frequency components at approximately 6 kHz fluctuate initially with the development of cavitation. A time–frequency characteristic is found to be conducive to monitoring the cavitation performance of centrifugal pumps.
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Analysis of particle motion and wear characteristics for mixed particle sizes in centrifugal pumps
Yi Li,Haiyang Zhang,Zhe Lin,Guang Zhang,ZuChao Zhu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9
In this study, we investigated the effect of particle size distribution (PSD) variations on the particle motion characteristics and wear in centrifugal pumps. We used computational fluid dynamics (CFD) and the discrete element method (DEM) to conduct simulations for one single particle size and five mixed particle sizes. The variation of the PSD had a significant effect on the wear rate of the impeller pressure surface and the volute surface. When the proportion of small particles near the impeller increased, the wear rate decreased. Specifically, at the middle of the impeller, the wear rate changed the most significantly. For volute surfaces 6-7 and 7-8 and the diffusion section, the velocity vectors of the near-wall volute surface showed a greater accumulation of small particles, and the buffering effect on the impact of large particles increased. Thus, the addition of small particles caused the wear rate of the volute surface to decrease.
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