Numerical Study on Turbulent Flows in a Liquid Metal MHD Generator

2011 ◽  
Author(s):  
Hiroki Shionoya ◽  
Hiromichi Kobayashi ◽  
Yoshihiro Okuno
Keyword(s):  
Liquid Metal ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Mhd Generator

Numerical Study on the Two-Phase Flow for a Gas/Liquid Metal Magnetohydrodynamic Generator

2018 ◽  
Author(s):  
Meng-Ran Liao ◽  
Chun-Hui Dai ◽  
Can Ma ◽  
Yong Liu ◽  
Zheng-Xing Zhao ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Power Systems ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Phase Flow ◽  
Steam Turbines ◽  
Two Phase ◽  
Mhd Generator ◽  
Energy Conversion Systems

The gas/liquid metal magnetohydrodynamic generator (G/LM-MHD) with the mixture of gas and liquid metal as working fluids shows a promising future due to recent development of liquid metal cooled nuclear reactors. Previous efforts on the G/LM-MHD energy conversion systems have predicted a higher efficiency than traditional thermodynamics cycle. However, most of the earlier studies focus on the conception designs, feasibility analysis and preliminary experiments, while less attention paid on some specific problems such as the bubble phenomenon in the two-phase flow. Therefore, this paper deals with numerical study on the performance characteristics of the gas/liquid metal two-phase flow in an ideal Faraday-type MHD channel, of which the geometry structure is 30 × 30 × 80 mm cuboid segmentary style. The conductive mixture fluid is composed of nitrogen as the gas phase and gallium as the liquid phase (N2/Ga). The temperature at the channel inlet is about 600 K considering the heat transfer after the mixing chamber, while the inlet velocity is around 10 m/s and gas volumetric void fraction is 50%. The external magnetic field is assumed as 4 Tesla adopting the superconducting technology, which seems essential for MHD industrial practice. Then the simulation is accomplished using a modified two-phase mixture model considering the electromagnetic influence. The simulation results show that the distribution of temperature changes much weaker than pressure and velocity, which agrees with earlier one-dimension analysis. On the other hand, the results characterizes clearly the increase of the void fraction close to the electrodes, which can explain intuitively the decrease of the power-generating capacity. Besides, the power output is predicted to reach maximum 22.5 kW while the voltage is 1.2 V and the power density can be 312.5 MW/m3 which is far beyond traditional steam turbines. This study shows a promising future of the gas/liquid metal MHD generator for the small nuclear plants and power systems.

scholarly journals Numerical Study of Three-Dimensional Surface Jets Emerging from a Fishway Entrance Slot

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1079
Author(s):  
Lena Mahl ◽  
Patrick Heneka ◽  
Martin Henning ◽  
Roman B. Weichert
Keyword(s):  
Boundary Conditions ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Three Dimensional ◽  
Free Water ◽  
Lateral Wall ◽  
Lateral Spreading ◽  
Propagation Length ◽  
Vertical Slot ◽  
Surface Jets

The efficiency of a fishway is determined by the ability of immigrating fish to follow its attraction flow (i.e., its jet) to locate and enter the fishway entrance. The hydraulic characteristics of fishway entrance jets can be simplified using findings from widely investigated surface jets produced by shaped nozzles. However, the effect of the different boundary conditions of fishway entrance jets (characterized by vertical entrance slots) compared to nozzle jets must be considered. We investigate the downstream propagation of attraction jets from the vertical slot of a fishway entrance into a quiescent tailrace, considering the following boundary conditions not considered for nozzle jets: (1) slot geometry, (2) turbulence characteristics of the approach flow to the slot, and (3) presence of a lateral wall downstream of the slot. We quantify the effect of these boundary conditions using three-dimensional hydrodynamic-numeric flow simulations with DES and RANS turbulence models and a volume-of-fluid method (VoF) to simulate the free water surface. In addition, we compare jet propagation with existing analytical methods for describing jet propagations from nozzles. We show that a turbulent and inhomogeneous approach flow towards a vertical slot reduces the propagation length of the slot jet in the tailrace due to increased lateral spreading compared to that of a jet produced by a shaped nozzle. An additional lateral wall in the tailrace reduces lateral spreading and significantly increases the propagation length. For highly turbulent flows at fishway entrances, the RANS model tends to overestimate the jet propagation compared to the transient DES model.

A numerical study on combined baffles quick-separation device

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ehsan Dehdarinejad ◽  
Morteza Bayareh ◽  
Mahmud Ashrafizaadeh
Keyword(s):  
Turbulent Flows ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Turbulence Models ◽  
Complete Separation ◽  
Solid Particles ◽  
Flow Rates ◽  
Separation Device ◽  
Coupling Technique ◽  
Laminar And Turbulent Flows

Abstract The transfer of particles in laminar and turbulent flows has many applications in combustion systems, biological, environmental, nanotechnology. In the present study, a Combined Baffles Quick-Separation Device (CBQSD) is simulated numerically using the Eulerian-Lagrangian method and different turbulence models of RNG k-ε, k-ω, and RSM for 1–140 μm particles. A two-way coupling technique is employed to solve the particles’ flow. The effect of inlet flow velocity, the diameter of the splitter plane, and solid particles’ flow rate on the separation efficiency of the device is examined. The results demonstrate that the RSM turbulence model provides more appropriate results compared to RNG k-ε and k-ω models. Four thousand two hundred particles with the size distribution of 1–140 µm enter the device and 3820 particles are trapped and 380 particles leave the device. The efficiency for particles with a diameter greater than 28 µm is 100%. The complete separation of 22–28 μm particles occurs for flow rates of 10–23.5 g/s, respectively. The results reveal that the separation efficiency increases by increasing the inlet velocity, the device diameter, and the diameter of the particles.

The Role of Turbulence Models for Predicting a Thermal Stratification

2006 ◽  
Vol 128 (4) ◽  
pp. 656-662 ◽  
Author(s):  
Seok-Ki Choi ◽  
Seong-O Kim
Keyword(s):  
Liquid Metal ◽  
Thermal Stratification ◽  
Transport Model ◽  
Numerical Study ◽  
Turbulence Models ◽  
Liquid Metal Reactor ◽  
Temporal Oscillation ◽  
Elliptic Relaxation ◽  
Shear Stress Transport Model

A numerical study of the evaluation of turbulence models for predicting the thermal stratification phenomenon is presented. The tested models are the elliptic blending turbulence model (EBM), the two-layer model, the shear stress transport model (SST), and the elliptic relaxation model (V2-f). These four turbulence models are applied to the prediction of a thermal stratification in an upper plenum of a liquid metal reactor experimented at the Japan Nuclear Cooperation (JNC). The EBM and V2-f models predict properly the steep gradient of the temperature at the interface of the cold and hot regions that is observed in the experimental data, and the EBM and V2-f models have the capability of predicting the temporal oscillation of the temperature. The two-layer and SST models predict the diffusive temperature gradient at the interface of a thermal stratification and fail to predict a temporal oscillation of the temperature. In general, the EBM predicts best the thermal stratification phenomenon in the upper plenum of the liquid metal reactor.

Study on Power Converting System of Liquid Metal MHD Generator Driven by Wave Energy

2012 ◽  
Vol 229-231 ◽  
pp. 1052-1055
Author(s):  
Yu Yu Xu ◽  
Jing Bai ◽  
Yan Peng ◽  
Ran Li ◽  
Ling Zhi Zhao ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Wave Energy ◽  
Lower Cost ◽  
Mechanical Impedance ◽  
Ocean Wave ◽  
Mhd Generator

This paper firstly describes magnetohydrodynamic (MHD) generator, which makes use of liquid metal and provide an excellent match to the mechanical impedance of an ocean wave. Then a new power converting system especially for LMMHD generator is designed and simulated, the results show that the power converting system can meet the requirement of LMMHD generator and has the advantage of lower cost.

scholarly journals Numerical Study of a Liquid Metal Oscillating inside a Pore in the Presence of Lorentz and Capillary Forces

Fluids ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 12 ◽  
Author(s):  
Maria Vlachomitrou ◽  
Nikos Pelekasis
Keyword(s):  
Liquid Metal ◽  
Mesh Generation ◽  
Liquid Metals ◽  
Numerical Study ◽  
Surrounding Medium ◽  
Porous System ◽  
Plasma Facing Components ◽  
Rayleigh Taylor Instability ◽  
Operational Issues ◽  
Finite Time Singularity

In order to ensure stable power exhaust and to protect the walls of fusion reactors, liquid metals that are fed to the wall surface through a capillary porous system (CPS) are considered as alternative plasma-facing components (PFCs). However, operational issues like drop ejection and plasma contamination may arise. In this study, the unsteady flow of a liquid metal inside a single pore of the CPS in the presence of Lorentz forces is investigated. A numerical solution is performed via the finite element methodology coupled with elliptic mesh generation. A critical magnetic number is found (Bondm = 4.5) below which the flow after a few oscillations reaches a steady state with mild rotational patterns. Above this threshold, the interface exhibits saturated oscillations. As the Lorentz force is further increased, Bondm > 5.8, a Rayleigh–Taylor instability develops as the interface is accelerated under the influence of the increased magnetic pressure and a finite time singularity is captured. It is conjectured that eventually, drop ejection will take place that will disrupt cohesion of the interface and contaminate the surrounding medium. Finally, the dynamic response of different operating fluids is investigated, e.g., gallium, and the stabilizing effect of increased electrical conductivity and surface tension is demonstrated.

scholarly journals Two-dimensional Numerical Simulation on Performance of Liquid Metal MHD Generator

2004 ◽  
Vol 124 (7) ◽  
pp. 971-976 ◽  
Author(s):  
Katsunori Yamada ◽  
Tetsuhiko Maeda ◽  
Yasuo Hasegawa ◽  
Yoshihiro Okuno
Keyword(s):  
Numerical Simulation ◽  
Liquid Metal ◽  
Two Dimensional ◽  
Mhd Generator

scholarly journals Numerical Study of Turbulent Flows and Heat Transfer in Coupled Industrial-Scale Tundish of a Continuous Casting Material in Steel Production

2018 ◽  
Author(s):  
Jose Adilson de Castro ◽  
Bruno Amaral Pereira ◽  
Roan Sampaio de Souza ◽  
Elizabeth Mendes de Oliveira ◽  
Ivaldo Leão Ferreira
Keyword(s):  
Heat Transfer ◽  
Continuous Casting ◽  
Turbulent Flows ◽  
Numerical Study ◽  
Steel Production ◽  
Industrial Scale
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