穿流回转干燥机目前大多采用直线型抄板的形式,其作用仅为物料抄动用,不具备内部物料混合作用,这使得物料因转筒内部风场分布不均导致干燥不均匀加剧,基于EDEM仿真软件,采用Hertz-Mindlin with JKR模型表征颗粒的接触力,对颗粒物料在穿...穿流回转干燥机目前大多采用直线型抄板的形式,其作用仅为物料抄动用,不具备内部物料混合作用,这使得物料因转筒内部风场分布不均导致干燥不均匀加剧,基于EDEM仿真软件,采用Hertz-Mindlin with JKR模型表征颗粒的接触力,对颗粒物料在穿流回转干燥机中的混合分散情况进行模拟,并运用后处理网格划分方法来直观展现回转干燥机中物料的分布情况。结果证明,优化后的抄板能有效提高穿流回转干燥机内部物料的混合度,提升物料干燥均匀度。展开更多
A 3-D numerical simulation with CFX software on physical field of multi-air channel coal burner in rotary kiln was carried out. The effects of various operational and structural parameters on flame feature and tempera...A 3-D numerical simulation with CFX software on physical field of multi-air channel coal burner in rotary kiln was carried out. The effects of various operational and structural parameters on flame feature and temperature distribution were investigated. A thermal measurement was conducted on a rotary kiln (4.5m in diameter, 90m in length) with four-air channel coal burner to determine the boundary conditions and to verify the simulation results. The calculation result shows that the distribution of velocity near burner exit is saddle-like; recirculation zones near nozzle and wall are useful for mixture primary air with coal and high temperature fume. A little central airflow can avoid coal backing up and cool nozzle. Adjusting the ratio of internal airflow to outer airflow is an effective and major means to regulate flame and temperature distribution in sintering region. Large whirlcone angle can intensify disturbution range at flame root to accelerate ignition and mixture. Large coal size can reduce high temperature region and result in coal combusting insufficiently. Too much combustion air will lengthen flame and increase heat loss.展开更多
We have investigated the properties of cellulose diacetate in solution by using laser light scattering. The cellulose diacetate molecules can form micelles and micellar clusters in acetone besides the individual chain...We have investigated the properties of cellulose diacetate in solution by using laser light scattering. The cellulose diacetate molecules can form micelles and micellar clusters in acetone besides the individual chains. As the concentration increases, the average hydrodynamic radius （Rh） linearly increases, whereas the ratio of gyration radius to hydrodynamic radins 〈Rg〉/〈Rh〉 linearly decreases. It indicates that the micelles associate and form micellar clusters due to the intermolecular interactions.展开更多
The central region model (CRM) cyclotron is the experimental platform for the key technology study of a high intensity beam cyclotron.In this paper we introduce the spiral inflector and central region designed for the...The central region model (CRM) cyclotron is the experimental platform for the key technology study of a high intensity beam cyclotron.In this paper we introduce the spiral inflector and central region designed for the CRM cyclotron,including the physical design,the numerical control machining and the installation precision control techniques.The shape of electrodes is complex,and machining with a strict tolerance must be done by a numerical control machine tool with the number of its axles no less than 4.The electrodes of central region were finished by using 3-axle machine tools.The size of gaps between the ground and Dee tip is very important,a special device was made to guarantee the installation precision,and the error of gaps was controlled within±0.05mm.展开更多
This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/t...This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/turbulent wind.In this paper,the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode,and the performances and the flow conditions were investigated numerically and experimentally.The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model.While providing the pump unit for the turbine mode,the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclu-sively for the turbine mode.Besides,the runner/impeller of the unit works evidently so as to coincide the angularmomentum change through the front runners/impellers with that through the rear runners/impellers,namely to take the axial flow at not only the inlet but also the outlet without the guide vanes.These results show that this type of unit is effective to work at not only the pumping but also the turbine modes.展开更多
文摘穿流回转干燥机目前大多采用直线型抄板的形式,其作用仅为物料抄动用,不具备内部物料混合作用,这使得物料因转筒内部风场分布不均导致干燥不均匀加剧,基于EDEM仿真软件,采用Hertz-Mindlin with JKR模型表征颗粒的接触力,对颗粒物料在穿流回转干燥机中的混合分散情况进行模拟,并运用后处理网格划分方法来直观展现回转干燥机中物料的分布情况。结果证明,优化后的抄板能有效提高穿流回转干燥机内部物料的混合度,提升物料干燥均匀度。
文摘A 3-D numerical simulation with CFX software on physical field of multi-air channel coal burner in rotary kiln was carried out. The effects of various operational and structural parameters on flame feature and temperature distribution were investigated. A thermal measurement was conducted on a rotary kiln (4.5m in diameter, 90m in length) with four-air channel coal burner to determine the boundary conditions and to verify the simulation results. The calculation result shows that the distribution of velocity near burner exit is saddle-like; recirculation zones near nozzle and wall are useful for mixture primary air with coal and high temperature fume. A little central airflow can avoid coal backing up and cool nozzle. Adjusting the ratio of internal airflow to outer airflow is an effective and major means to regulate flame and temperature distribution in sintering region. Large whirlcone angle can intensify disturbution range at flame root to accelerate ignition and mixture. Large coal size can reduce high temperature region and result in coal combusting insufficiently. Too much combustion air will lengthen flame and increase heat loss.
基金ACKNOWLEDGMENTS This work was supported by China Tobacco Guangdong Industrial Co., Ltd., National Natural Science Foundation of China （No21234003 and No.51303059）, and the Fundamental Research Funds for Central Universities.
文摘We have investigated the properties of cellulose diacetate in solution by using laser light scattering. The cellulose diacetate molecules can form micelles and micellar clusters in acetone besides the individual chains. As the concentration increases, the average hydrodynamic radius （Rh） linearly increases, whereas the ratio of gyration radius to hydrodynamic radins 〈Rg〉/〈Rh〉 linearly decreases. It indicates that the micelles associate and form micellar clusters due to the intermolecular interactions.
文摘The central region model (CRM) cyclotron is the experimental platform for the key technology study of a high intensity beam cyclotron.In this paper we introduce the spiral inflector and central region designed for the CRM cyclotron,including the physical design,the numerical control machining and the installation precision control techniques.The shape of electrodes is complex,and machining with a strict tolerance must be done by a numerical control machine tool with the number of its axles no less than 4.The electrodes of central region were finished by using 3-axle machine tools.The size of gaps between the ground and Dee tip is very important,a special device was made to guarantee the installation precision,and the error of gaps was controlled within±0.05mm.
基金co-sponsored by Japan Society for the Promotion of Science KAKENHI23860035
文摘This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/turbulent wind.In this paper,the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode,and the performances and the flow conditions were investigated numerically and experimentally.The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model.While providing the pump unit for the turbine mode,the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclu-sively for the turbine mode.Besides,the runner/impeller of the unit works evidently so as to coincide the angularmomentum change through the front runners/impellers with that through the rear runners/impellers,namely to take the axial flow at not only the inlet but also the outlet without the guide vanes.These results show that this type of unit is effective to work at not only the pumping but also the turbine modes.
