Large size hydrogen neutral beam injectors （NBI） used a negative ion source （NNBI） as well as a proton source （PNBI） were developed for the large helical device （LHD）. The injected power from NNBI and PNBI hav...Large size hydrogen neutral beam injectors （NBI） used a negative ion source （NNBI） as well as a proton source （PNBI） were developed for the large helical device （LHD）. The injected power from NNBI and PNBI have reached 16 MW and 6.8 MW, respectively, These injected powers have outstripped the nominal beam powers. A diagnostic system of beam-emitted hydrogen visible spectrum has been installed along the beam injection axis to estimate the energy fraction on PNBI. The full energy beam component is about half which is equivalent to 70% of injected beam power. The attenuation of high energy neutral beam is also observed on NNBI. The peak density distribution is effective to increase beam deposition power.展开更多
We are pleased to introduce this special thematic section on Nanofluid Mechanics and Heat Transfer that is being included in Acta Mechanica Sinica(AMS).This thematic issue consists of 6 papers selected from papers tha...We are pleased to introduce this special thematic section on Nanofluid Mechanics and Heat Transfer that is being included in Acta Mechanica Sinica(AMS).This thematic issue consists of 6 papers selected from papers that were presented at the 18th International Symposium on Numer-ical Analysis of Fluid Flows,Heat and Mass Transfer-Nu-merical Fluids 2023,held in Heraklion,Crete Greece,11-17 September 2023,and invited through a general call.The symposium covers various subjects:from new numerical methods and fundamental research until engineering appli-cations,and it is a part of the International Conference of Numerical Analysis and Applied Mathematics(ICNAAM),held annually.展开更多
A hybrid approach based on the immersed boundary method(IBM)is developed for computation of flow-induced sound around moving bodies.In this method,a high-fidelity direct numerical simulation(DNS)solver is used to simu...A hybrid approach based on the immersed boundary method(IBM)is developed for computation of flow-induced sound around moving bodies.In this method,a high-fidelity direct numerical simulation(DNS)solver is used to simulate the incompressible flow field.The sound field is predicted by discretizing acoustic perturbation equations(APEs)with dispersionrelation-preserving space scheme and low-dispersion and low-dissipation Runge-Kutta time integration.A sharp-interface IBM based on ghost-cell is implemented for present two-step DNS-APE approach to deal with complex moving bodies with Cartesian grids.The present method is validated through simulations of sound generation caused by flow past a rotating cylinder,an oscillating cylinder,and tandem oscillating and stationary cylinders.The sound generated by typical kinds of complicated bio-inspired locomotions,i.e.,flapping flight by wings of varied shapes and collective undulatory swimming in tandem,are investigated using present method.The results demonstrate potential of the hybrid approach in addressing flowinduced sound generation and propagation with complex moving boundaries in a fluid medium,especially for the sound characteristics of bio-mimetic flows,which might shed lights on investigations on bio-acoustics,ethology of complex animal system,and related bio-mimetic design for quietness.展开更多
基金the budget for NIFS08ULBB501 of Japanthe JSPS-CAS Core-University program in the field of Plasma and Nuclear Fusion
文摘Large size hydrogen neutral beam injectors （NBI） used a negative ion source （NNBI） as well as a proton source （PNBI） were developed for the large helical device （LHD）. The injected power from NNBI and PNBI have reached 16 MW and 6.8 MW, respectively, These injected powers have outstripped the nominal beam powers. A diagnostic system of beam-emitted hydrogen visible spectrum has been installed along the beam injection axis to estimate the energy fraction on PNBI. The full energy beam component is about half which is equivalent to 70% of injected beam power. The attenuation of high energy neutral beam is also observed on NNBI. The peak density distribution is effective to increase beam deposition power.
文摘We are pleased to introduce this special thematic section on Nanofluid Mechanics and Heat Transfer that is being included in Acta Mechanica Sinica(AMS).This thematic issue consists of 6 papers selected from papers that were presented at the 18th International Symposium on Numer-ical Analysis of Fluid Flows,Heat and Mass Transfer-Nu-merical Fluids 2023,held in Heraklion,Crete Greece,11-17 September 2023,and invited through a general call.The symposium covers various subjects:from new numerical methods and fundamental research until engineering appli-cations,and it is a part of the International Conference of Numerical Analysis and Applied Mathematics(ICNAAM),held annually.
基金supported by the National Natural Science Foundation of China(Grant Nos.52301380 and 11602277).
文摘A hybrid approach based on the immersed boundary method(IBM)is developed for computation of flow-induced sound around moving bodies.In this method,a high-fidelity direct numerical simulation(DNS)solver is used to simulate the incompressible flow field.The sound field is predicted by discretizing acoustic perturbation equations(APEs)with dispersionrelation-preserving space scheme and low-dispersion and low-dissipation Runge-Kutta time integration.A sharp-interface IBM based on ghost-cell is implemented for present two-step DNS-APE approach to deal with complex moving bodies with Cartesian grids.The present method is validated through simulations of sound generation caused by flow past a rotating cylinder,an oscillating cylinder,and tandem oscillating and stationary cylinders.The sound generated by typical kinds of complicated bio-inspired locomotions,i.e.,flapping flight by wings of varied shapes and collective undulatory swimming in tandem,are investigated using present method.The results demonstrate potential of the hybrid approach in addressing flowinduced sound generation and propagation with complex moving boundaries in a fluid medium,especially for the sound characteristics of bio-mimetic flows,which might shed lights on investigations on bio-acoustics,ethology of complex animal system,and related bio-mimetic design for quietness.
