The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low s...The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h, H=60 m, n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head(NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model(κ-ε). It is found that axial force of pump with radical reflux balance holes of5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.展开更多
Turbine generators play a pivotal role in efficiently converting gas internal energy into electrical energy,finding extensive applications in diverse green energy and power equipment.The adoption of a high-speed direc...Turbine generators play a pivotal role in efficiently converting gas internal energy into electrical energy,finding extensive applications in diverse green energy and power equipment.The adoption of a high-speed direct-drive structure eliminates mechanical losses associated with the reducer between the turbine and generator,enhancing system efficiency and compactness.However,this configuration introduces challenges in design and manufacturing.This article explores the various application scenarios of high-speed direct-drive power generation systems,examining their roles in organic Rankine cycle power generation,gas turbine power generation,supercritical CO_(2) power generation,vehicle exhaust turbine power generation,and natural gas pressure reduction power generation.Considering the high-speed,high-pressure,high-temperature,and high-efficiency challenges in turbine power generation systems,the key technologies are reviewed including high-speed bearings,rotor dynamics,high-speed motors,high-frequency variable frequency technology,sealing technology,axial force adjustment,thermal management,turbine aerodynamic design,and system control strategies.The article further delves into the current research and development status of high-speed direct-drive power generation systems across different application scenarios.Finally,the article presents prospects for the future development of efficient,reliable and widely adaptable high-speed direct-drive generators,offering valuable insights for researchers and practitioners in the field.展开更多
基金Project(51179075)supported by the National Natural Science Foundation of ChinaProject(BK20131256)supported by the Natural Science Funds of Jiangsu Province,ChinaProject supported by the Priority Academic Program Development of Jiangsu High Education Institutions,China
文摘The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h, H=60 m, n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head(NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model(κ-ε). It is found that axial force of pump with radical reflux balance holes of5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.
基金supported by the National Major Science and Technology Project (2019-Ⅱ-0009-0029)the 2022 Jiangsu Province Carbon Peak Carbon Neutral Science and Technology Innovation Special Major Innovation Carrier Construction Project (BM2022001)+2 种基金the National Natural Science Foundation of China(52202324)supported by the Hundred Talents Program of the Chinese Academy of Sciencesthe Nanjing Future Energy System Research Institute independently deploys research projects (E3550101)
文摘Turbine generators play a pivotal role in efficiently converting gas internal energy into electrical energy,finding extensive applications in diverse green energy and power equipment.The adoption of a high-speed direct-drive structure eliminates mechanical losses associated with the reducer between the turbine and generator,enhancing system efficiency and compactness.However,this configuration introduces challenges in design and manufacturing.This article explores the various application scenarios of high-speed direct-drive power generation systems,examining their roles in organic Rankine cycle power generation,gas turbine power generation,supercritical CO_(2) power generation,vehicle exhaust turbine power generation,and natural gas pressure reduction power generation.Considering the high-speed,high-pressure,high-temperature,and high-efficiency challenges in turbine power generation systems,the key technologies are reviewed including high-speed bearings,rotor dynamics,high-speed motors,high-frequency variable frequency technology,sealing technology,axial force adjustment,thermal management,turbine aerodynamic design,and system control strategies.The article further delves into the current research and development status of high-speed direct-drive power generation systems across different application scenarios.Finally,the article presents prospects for the future development of efficient,reliable and widely adaptable high-speed direct-drive generators,offering valuable insights for researchers and practitioners in the field.
