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Feasibility evaluation for excavation of Naghshe Jahan Square subway station by underground methods 被引量:3
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作者 Morteza Abdi Cherlo Hamid Hashemolhosseini +1 位作者 Masoud Cheraghi Saeed Mahdevari 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2013年第6期452-459,共8页
In recent years, in reaction to the increasing usage of urban areas, the excavation of underground spaces has been developed. One of the most challenging issues encountered by engineers is the construction of subway s... In recent years, in reaction to the increasing usage of urban areas, the excavation of underground spaces has been developed. One of the most challenging issues encountered by engineers is the construction of subway stations as large underground spaces at shallow depth with soft surrounding soils. In this paper, Naghshe Jahan Square subway station located in Isfahan, Iran, has been simulated by geomechanical fnite difference method(FDM). This station is located under important historical structures. Therefore, the ground displacement and surface settlement induced by the excavation of the subway station should be strictly controlled. Many of such problems are affected by selected excavation method. For these reasons, different underground excavation methods associated with construction have been studied. In this study, sequential excavation method and large-diameter curved pipe roofng method are used and the numerical results of the two methods are compared. The presence of groundwater table obliges us to choose special techniques for the stability of the ground around the subway station during construction; hence compressed air and ground freezing techniques are utilized in the simulations of the subway station. Finally, after choosing appropriate support systems, the large-diameter curved pipe roofng method with 1.5 m spacing between curved pipes is proposed. 展开更多
关键词 Subway station Sequential excavation method Compressed air Ground freezing Large-diameter curved pipe roofng method
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Numerical investigation of frictional drag reduction with an air layer concept on the hull of a ship 被引量:4
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作者 Jun Zhang Shuo Yang Jing Liu 《Journal of Hydrodynamics》 SCIE EI CSCD 2020年第3期591-604,共14页
A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bu... A novel air bubble lubrication method using the winged air induction pipe (WAIP) device is used to reduce the frictional drag of the hull of the ship and hence increase the efficiency of the propulsion system. This bubble lubrication technique utilizes the negative pressure region above the upper surface of the hydrofoil as the ship moves forward to drive air to the skin of the hull. In the present study, the reduction rate of the drag by applying the WAIP device is numerically investigated with the open source toolbox OpenFOAM. The generated air layer and the bubbles are observed. The numerical results indicate that the reduction rate of the drag closely depends on the depth of the submergence of the hydrofoil, the angle of attack of the hydrofoil, and the pressure in the air inlet. It is also proportional to the air flow rate. The underlying physics of the fluid dynamics is explored. 展开更多
关键词 Winged air induction pipe(WAIP) drag reduction frictional resistance reduction hull of ship OPENFOAM
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Numerical investigation of gas-particle flow in the primary air pipe of a low NO_x swirl burner-The DEM-CFD method 被引量:3
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作者 Hao Zhou Yu Yang Lingli Wang 《Particuology》 SCIE EI CAS CSCD 2015年第2期133-140,共8页
The gas-particle flow in the primary air pipe (PAP) of a low NOx swirl burner was investigated using the computational fluid dynamics (CFD) coupled with the discrete element method (DEM). The mathematical models... The gas-particle flow in the primary air pipe (PAP) of a low NOx swirl burner was investigated using the computational fluid dynamics (CFD) coupled with the discrete element method (DEM). The mathematical models were validated using the measured values obtained at the outlet of the primary pipe through a phase Doppler anemometer (PDA) system. Particles of different Stokes numbers in the primary air pipe (PAP) were investigated, and the effects of the structure of the primary air pipe and the particle-particle interaction on particle dispersion were analyzed. The results indicate that particles under the combined effects of the Venturi pipe and the spindle body are concentrated into a narrow band area and that the PAP structure can more efficiently concentrate particles with large Stokes numbers. The formed fuel rich/lean jet persists for a long distance out of the burner, thereby favoring of air-staged combustion and NOx reduction. The particle collision frequency and its fluctuation range increase as the particle Stokes number increases. The collisions among particles result in an increase of the spanwise dispersion of particles. Experimental results indicate that the models that take particle-particle collision into consideration are more able to predict particle concentration. 展开更多
关键词 DEM CFD Gas-particle Swirl burner Primary air pipe
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