A numerical procedure based on a five-wave MHD model associated with non-ideal,low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypa...A numerical procedure based on a five-wave MHD model associated with non-ideal,low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical procedure is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations,in conjunction with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would take place near the downstream edge of the second electrode,where the local adverse pressure gradient is large,and the core of the flow field is characterized as a 2-D flow due to the Hartmann effects along the direction of the magnetic field. The electric current lines would be increasingly distorted as the magnetic interactive parameter increases,and even induce an eddy current. Induced eddy current was also found in the different cross-sections along the axial direction,all of these would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the insulator cross-section,which,in turn,induces the corner eddy current at the corner. A numerical parametric study was also performed,and the computed performance parameters for the MHD generator suggest that,in order to enhance the performance of MHD generator,the magnetic interaction parameter should be elevated.展开更多
Influences of Hall effects on the flow characteristics and performance of the magnetohydrodyanmic (MHD) converging channel as an MHD generator are studied numerically in the present study. The numerical algorithm used...Influences of Hall effects on the flow characteristics and performance of the magnetohydrodyanmic (MHD) converging channel as an MHD generator are studied numerically in the present study. The numerical algorithm used is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations, in conjunction with an SOR method for solving the elliptic equation governing the electrical potential of the electric field. It is found that Hall effects may lead to distortions in both the flow field and electric field in the MHD converging channel. The electric current lines are distorted and induce eddy currents, which will be mitigated by Hall effects. Comparisons of parameters characterizing the performance of the MHD generator for different geometry also reveal that the Hall effects may deteriorate the performance of MHD generator, especially for converging channel.展开更多
A numerical procedure based on a five-wave model associated with non-ideal,low magnetic Reynolds number magnetohydrodynamic(MHD)flows was developed.It is composed of an entropy conditioned scheme for solving the non-h...A numerical procedure based on a five-wave model associated with non-ideal,low magnetic Reynolds number magnetohydrodynamic(MHD)flows was developed.It is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations,in conjunction with an SOR method for solving the elliptic equation governing the electrical potential of flow field.To validate the developed procedure,two different test cases were used which included MHD Rayleigh problem and MHD Hartmann problem.The simulations were performed under the assumption of low magnetic Reynolds number.The simulated results were found to be in good agreement with the closed form analytical solutions deduced in the present study,showing that the present algorithm could simulate engineering MHD flow at low magnetic Reynolds number effectively.In the end,a flow field between a pair of segmented electrodes in a three dimensional MHD channel was simulated using the present algorithm with and without including Hall effects.Without the introduction of Hall effects,no distortion was observed in the current and potential lines.By taking the Hall effects into account,the potential lines distorted and clustered at the upstream and downstream edges of the cathode and anode,respectively.展开更多
针对液态金属磁流体(Liquid metal magnetohydrodynamic,LMMHD)发电系统,设计出四种气—液态金属两相混合器,对液态金属(镓铟锡合金)和二氧化碳气体在混合器及发电通道内的两相流场进行模拟和对比分析,同时对具有最佳混合效果的混合器...针对液态金属磁流体(Liquid metal magnetohydrodynamic,LMMHD)发电系统,设计出四种气—液态金属两相混合器,对液态金属(镓铟锡合金)和二氧化碳气体在混合器及发电通道内的两相流场进行模拟和对比分析,同时对具有最佳混合效果的混合器所连接的发电通道的发电性能进行研究。结果表明,利用诱导磁场法预测计算得到的空载电压计算值与理论值相比,误差小于5%;在相同气液入口压力(pl=pg=1.5 MPa)条件下,不同气液两相混合器结构可以产生搅拌流、环状流、弹状流和分散流等流型;在不同气液入口压力下,综合考虑发电通道内的两相流型、液态金属的平均体积分数、平均速度和均匀度,发现双喷嘴式混合器(model 4)的混合效果最佳;此外,发电通道内的电流密度和平均电磁功率密度的大小均与液态金属的体积分数呈正相关。展开更多
The study on the application of Genetic Algorithms(GA) to numerical simulation has been carried out. The simulation with GA is aimed at to realize the operation optimization of the coal fired MHD generator channel. Th...The study on the application of Genetic Algorithms(GA) to numerical simulation has been carried out. The simulation with GA is aimed at to realize the operation optimization of the coal fired MHD generator channel. The computer program for this purpose has been developed. By simulating numerically the operation optimization of IEE’s 25MWt coal fired experimental MHD generator, the feasibility of the application of GA procedure to the MHD power generation field has been verified.展开更多
文摘A numerical procedure based on a five-wave MHD model associated with non-ideal,low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical procedure is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations,in conjunction with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would take place near the downstream edge of the second electrode,where the local adverse pressure gradient is large,and the core of the flow field is characterized as a 2-D flow due to the Hartmann effects along the direction of the magnetic field. The electric current lines would be increasingly distorted as the magnetic interactive parameter increases,and even induce an eddy current. Induced eddy current was also found in the different cross-sections along the axial direction,all of these would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the insulator cross-section,which,in turn,induces the corner eddy current at the corner. A numerical parametric study was also performed,and the computed performance parameters for the MHD generator suggest that,in order to enhance the performance of MHD generator,the magnetic interaction parameter should be elevated.
文摘Influences of Hall effects on the flow characteristics and performance of the magnetohydrodyanmic (MHD) converging channel as an MHD generator are studied numerically in the present study. The numerical algorithm used is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations, in conjunction with an SOR method for solving the elliptic equation governing the electrical potential of the electric field. It is found that Hall effects may lead to distortions in both the flow field and electric field in the MHD converging channel. The electric current lines are distorted and induce eddy currents, which will be mitigated by Hall effects. Comparisons of parameters characterizing the performance of the MHD generator for different geometry also reveal that the Hall effects may deteriorate the performance of MHD generator, especially for converging channel.
文摘A numerical procedure based on a five-wave model associated with non-ideal,low magnetic Reynolds number magnetohydrodynamic(MHD)flows was developed.It is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations,in conjunction with an SOR method for solving the elliptic equation governing the electrical potential of flow field.To validate the developed procedure,two different test cases were used which included MHD Rayleigh problem and MHD Hartmann problem.The simulations were performed under the assumption of low magnetic Reynolds number.The simulated results were found to be in good agreement with the closed form analytical solutions deduced in the present study,showing that the present algorithm could simulate engineering MHD flow at low magnetic Reynolds number effectively.In the end,a flow field between a pair of segmented electrodes in a three dimensional MHD channel was simulated using the present algorithm with and without including Hall effects.Without the introduction of Hall effects,no distortion was observed in the current and potential lines.By taking the Hall effects into account,the potential lines distorted and clustered at the upstream and downstream edges of the cathode and anode,respectively.
文摘针对液态金属磁流体(Liquid metal magnetohydrodynamic,LMMHD)发电系统,设计出四种气—液态金属两相混合器,对液态金属(镓铟锡合金)和二氧化碳气体在混合器及发电通道内的两相流场进行模拟和对比分析,同时对具有最佳混合效果的混合器所连接的发电通道的发电性能进行研究。结果表明,利用诱导磁场法预测计算得到的空载电压计算值与理论值相比,误差小于5%;在相同气液入口压力(pl=pg=1.5 MPa)条件下,不同气液两相混合器结构可以产生搅拌流、环状流、弹状流和分散流等流型;在不同气液入口压力下,综合考虑发电通道内的两相流型、液态金属的平均体积分数、平均速度和均匀度,发现双喷嘴式混合器(model 4)的混合效果最佳;此外,发电通道内的电流密度和平均电磁功率密度的大小均与液态金属的体积分数呈正相关。
文摘The study on the application of Genetic Algorithms(GA) to numerical simulation has been carried out. The simulation with GA is aimed at to realize the operation optimization of the coal fired MHD generator channel. The computer program for this purpose has been developed. By simulating numerically the operation optimization of IEE’s 25MWt coal fired experimental MHD generator, the feasibility of the application of GA procedure to the MHD power generation field has been verified.
