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Particle deposition in ventilation duct with convex or concave wall cavity 被引量:2
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作者 WANG Fei-fei ZHANG En-shi +2 位作者 XU Xin-hua WANG Jin-bo MI Jian-chun 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第11期2601-2614,共14页
A numerical study is carried out on particle deposition in ducts with either convex or concave wall cavity.Results show that,if compared with smooth duct,particle deposition velocitiesVd^+increase greatly in ducts wit... A numerical study is carried out on particle deposition in ducts with either convex or concave wall cavity.Results show that,if compared with smooth duct,particle deposition velocitiesVd^+increase greatly in ducts with wall cavities.More specifically,forτ+<1,Vd^+increase by about 2–4 orders of magnitude in the cases with the convex and concave wall cavities;forτ+>1,Vd^+grows relatively slower.Enhancement of particle deposition with wall cavities is caused by the following mechanisms,i.e.,interception by the wall cavities,expanded deposition area,and the enhanced flow turbulence.In general,addition of wall cavities is contributive for particle deposition,so it provides an efficient approach to remove particles,especially with small size,e.g.,PM2.5.Moreover,the convex wall cavity leads to a larger increment ofVd^+than the concave wall cavity.However,taking pressure loss into account,thoughVd^+is relatively lower,duct with the concave wall cavity is more efficient than that with the convex wall cavity. 展开更多
关键词 numerical simulation ventilation duct particle deposition deposition velocity
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A NUMERICAL STUDY OF THE TRAIN-INDUCED UNSTEADY AIRFLOW IN A SUBWAY TUNNEL WITH NATURAL VENTILATION DUCTS USING THE DYNAMIC LAYERING METHOD 被引量:17
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作者 HUANG Yuan-dong GAO Wei KIM Chang-Nyung 《Journal of Hydrodynamics》 SCIE EI CSCD 2010年第2期164-172,共9页
The objective of this study is to investigate numerically the characteristics of train-induced unsteady airflow in a subway tunnel with natural ventilation ducts.A three-dimensional numerical model using the dynamic l... The objective of this study is to investigate numerically the characteristics of train-induced unsteady airflow in a subway tunnel with natural ventilation ducts.A three-dimensional numerical model using the dynamic layering method for the moving boundary of a train is first developed,and then it is validated against the model tunnel experimental data.With the tunnel and subway train geometries in the numerical model exactly the same as those in the model tunnel experimental test,but with the ventilation ducts being connected to the tunnel ceiling and a barrier placed at the tunnel outlet,the three-dimensional train-induced unsteady tunnel flows are numerically simulated.The computed distributions of the pressure and the air velocity in the tunnel as well as the time series of the mass flow rate at the ventilation ducts reveal the impact of the train motion on the exhaust and suction of the air through ventilation ducts and the effects of a barrier placed at the tunnel outlet on the duct ventilation performance.As the train approaches a ventilation duct,the air is pushed out of the tunnel through the duct.As the train passes the ventilation duct,the exhaust flow in the duct is changed rapidly to the suction flow.After the train passes the duct,the suction mass flow rate at the duct decreases with time since the air pressure at the opening of the duct is gradually recovered with time.A drastic change in the mass flow rate at a ventilation duct while a train passes the corresponding ventilation duct,causes a change in the exhaust mass flow rate at other ventilation ducts.Also,when a barrier is placed at the tunnel outlet,the air volume discharge rate at each ventilation duct is greatly increased,i.e.,the barrier placed at the tunnel outlet can improve remarkably the ventilation performance through each duct. 展开更多
关键词 train-induced flow subway tunnel natural ventilation duct ventilation performance dynamic layering method
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A NUMERICAL ANALYSIS OF THE VENTILATION PERFORMANCE FOR DIFFERENT VENTILATION STRATEGIES IN A SUBWAY TUNNEL 被引量:8
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作者 HUANG Yuan-dong LI Chan KIM Chang Nyung 《Journal of Hydrodynamics》 SCIE EI CSCD 2012年第2期193-201,共9页
An unsteady three-dimensional analysis of the ventilation performance is carried out for different ventilation strategies to find out a ventilation method with a high performance in a subway tunnel.The natural ventila... An unsteady three-dimensional analysis of the ventilation performance is carried out for different ventilation strategies to find out a ventilation method with a high performance in a subway tunnel.The natural ventilation performance associated with a train-induced air flow in a subway tunnel is examined.The dynamic layering method is used to consider the moving boundary of a train in the current CFD method.The geometries of the modeled tunnel and the subway train are partially based on those of the Seoul subway.The effects of the structure of the ventilation duct and the geometry of the partitions on the ventilation performance are evaluated.The results show that the combined ventilation ducts (to be designed),and the partitioning blocks installed along the middle of tunnel (already in existences) are helpful for air exchange.This study can provide some guidance for the design of ventilation ducts in a subway system. 展开更多
关键词 ventilation performance subway tunnel train-induced air flow natural ventilation duct numerical analysis
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Torque characteristics in a large permanent magnet synchronous generator with stator radial ventilating air ducts
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作者 He HAO Wei-zhong FEI +2 位作者 Dong-min MIAO Meng-jia JIN Jian-xin SHEN 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2016年第8期814-824,共11页
In this study, we investigated the torque characteristics of large low-speed direct-drive permanent magnet synchronous generators with stator radial ventilating air ducts for offshore wind power applications. Magnet s... In this study, we investigated the torque characteristics of large low-speed direct-drive permanent magnet synchronous generators with stator radial ventilating air ducts for offshore wind power applications. Magnet shape optimization was used first to improve the torque characteristics using two-dimensional finite element analysis(FEA) in a permanent magnet synchronous generator with a common stator. The rotor step skewing technique was then employed to suppress the impacts of mechanical tolerances and defects, which further improved the torque quality of the machine. Comprehensive three-dimensional FEA was used to evaluate accurately the overall effects of stator radial ventilating air ducts and rotor step skewing on torque features. The influences of the radial ventilating ducts in the stator on torque characteristics, such as torque pulsation and average torque in the machine with and without rotor step skewing techniques, were comprehensively investigated using three-dimensional FEA. The results showed that stator radial ventilating air ducts could not only reduce the average torque but also increase the torque ripple in the machine. Furthermore, the torque ripple of the machine under certain load conditions may even be increased by rotor step skewing despite a reduction in cogging torque. 展开更多
关键词 Permanent magnet synchronous generator(PMSG) Radial ventilating air duct Torque ripple Step skewing Magnet shape optimization Finite element analysis Wind power
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