A numerical model for the unsteady flow under a pulsed magnetic field of a solenoid is developed, in which magnetohydrodynamic flow equations decouple into a transient magnetic diffusion equation and unsteady Navier–...A numerical model for the unsteady flow under a pulsed magnetic field of a solenoid is developed, in which magnetohydrodynamic flow equations decouple into a transient magnetic diffusion equation and unsteady Navier–Stokes equations in conjunction with two equations of the k–ε turbulent model. A Fourier series method is used to implement the boundary condition of magnetic flux density under multiple periods of a pulsed magnetic field （PMF）. The numerical results are compared with the theoretical or experimental results to validate the model under a time-harmonic magnetic field; it is found that the toroidal vortex pair is the dominating structure within the melt flow under a PMF. The velocity field of a molten melt is in a quasi-steady state after several periods; changing the direction of the electromagnetic force causes the vibration of the melt surface under a PMF.展开更多
With the emergence of urban sentry boxes and capsule hotels,the development of tiny spaces with the concept of a reasonable minimum occupied space has attracted widespread attention from society.The ventilation mode t...With the emergence of urban sentry boxes and capsule hotels,the development of tiny spaces with the concept of a reasonable minimum occupied space has attracted widespread attention from society.The ventilation mode that fits with the limited geometric characteristics of tiny spaces is worth exploring.Combined with the respective ventilation requirements of two types of tiny spaces,i.e.,sentry box space and tiny sleeping space,this paper proposes two attached ventilation modes.A full-scale experiment cabin was established,and the simulation method was optimized through experimental data.The airflow pattern and distribution performance of the two attached ventilation modes in two types of tiny spaces were studied by the CFD method.The results showed that the airflow attached to the vertical wall could form an air curtain at the opening windows of the sentry box space,but there is a phenomenon of air leakage.The installation of the deflector can improve the integrity of the air curtain,and the best installation angle of the deflector is 60 degrees.The double side-attached ventilation mode in the tiny sleeping space can not only relieve the draught of the occupants(DR<15%),but also firstly deliver fresh air to the occupied zone(expiratory zone MAA<92 s).The research conclusions will add new ideas to the diversity of ventilation modes in tiny spaces.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51034012)
文摘A numerical model for the unsteady flow under a pulsed magnetic field of a solenoid is developed, in which magnetohydrodynamic flow equations decouple into a transient magnetic diffusion equation and unsteady Navier–Stokes equations in conjunction with two equations of the k–ε turbulent model. A Fourier series method is used to implement the boundary condition of magnetic flux density under multiple periods of a pulsed magnetic field （PMF）. The numerical results are compared with the theoretical or experimental results to validate the model under a time-harmonic magnetic field; it is found that the toroidal vortex pair is the dominating structure within the melt flow under a PMF. The velocity field of a molten melt is in a quasi-steady state after several periods; changing the direction of the electromagnetic force causes the vibration of the melt surface under a PMF.
基金This study was jointly funded by the National Natural Science Foundation of China(No.51408477)the Opening Fund of Key Laboratory of Plateau Green Building and Ecological Community in Qinghai Province(No.KLKF-2020-005)the Natural Science Foundation of Education Department of Shaanxi Province(No.21JK0712).
文摘With the emergence of urban sentry boxes and capsule hotels,the development of tiny spaces with the concept of a reasonable minimum occupied space has attracted widespread attention from society.The ventilation mode that fits with the limited geometric characteristics of tiny spaces is worth exploring.Combined with the respective ventilation requirements of two types of tiny spaces,i.e.,sentry box space and tiny sleeping space,this paper proposes two attached ventilation modes.A full-scale experiment cabin was established,and the simulation method was optimized through experimental data.The airflow pattern and distribution performance of the two attached ventilation modes in two types of tiny spaces were studied by the CFD method.The results showed that the airflow attached to the vertical wall could form an air curtain at the opening windows of the sentry box space,but there is a phenomenon of air leakage.The installation of the deflector can improve the integrity of the air curtain,and the best installation angle of the deflector is 60 degrees.The double side-attached ventilation mode in the tiny sleeping space can not only relieve the draught of the occupants(DR<15%),but also firstly deliver fresh air to the occupied zone(expiratory zone MAA<92 s).The research conclusions will add new ideas to the diversity of ventilation modes in tiny spaces.
