Initial liquid metal magnetohydrodynamic thin film flow experiments in the McGA-loop facility at UCLA

Morley, Neil B.; Gaizer, Alexander A; Tillack, M. S.; Abdou, Mohamed

doi:10.1016/0920-3796(95)90189-2

Cited by 3 publications

(5 citation statements)

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“…To date, there have been several reviews on the subject of free surface liquid metal film flow under the influence of a magnetic field [28,29]. Under the aegis of the APEX project [30,31], experiments and numerical simulations have been performed on experimental systems, such as the MeGA-loop facility, the MTOR facility, and the HIMAG numerical simulation platform, respectively [32][33][34]. Their results indicated that the existence of a spanwise magnetic field induced a MHD drag, which acts on the film flow and results in an increasing film height [32,35], jump, and sidewall detachment [36,37].…”

Section: Introductionmentioning

confidence: 99%

“…Under the aegis of the APEX project [30,31], experiments and numerical simulations have been performed on experimental systems, such as the MeGA-loop facility, the MTOR facility, and the HIMAG numerical simulation platform, respectively [32][33][34]. Their results indicated that the existence of a spanwise magnetic field induced a MHD drag, which acts on the film flow and results in an increasing film height [32,35], jump, and sidewall detachment [36,37]. In order to obtain as much experimental data as possible, Li et al [38] first introduced the multi-channel ultrasonic transmission technique to measure the instantaneous local film thickness of vertically falling NaK film flow in a transverse magnetic field, observing film thickening and flow stabilization effects due to turbulence suppression by the magnetic field, which was subsequently validated by Ji et al [39], and Nornberg et al [40] via theoretic and experimental studies relating to the MHD surface waves of GaInSn liquid metal.…”

Section: Introductionmentioning

confidence: 99%

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Magnetohydrodynamic effects on liquid metal film flowing along an inclined plate relating to plasma facing components

Yang

Ren

et al. 2020

Nucl. Fusion

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The liquid metal film plasma facing component (PFC) is considered to be one of the most promising ways to realize a PFC capbable of operating for long periods. However, in the presence of a magnetic field, magnetohydrodynamic effects appearing in the liquid metal film flow directly influence the reliability of the flowing liquid metal limiter or divertor. In the present study, we consider the influence of flow rate, transverse magnetic field, and inclination angle, and conduct experiments on a liquid metal film flowing along an inclined conducting stainless steel plate. A laser profilometer (LP) and a high-speed camera are respectively adopted to obtain the local film thickness quantitatively, and its free surface structures qualitatively. We observe the magnetohydrodynamic effects of liquid metal film flow, such as the nonmonotonic change of film thickness, the reduction of film flow velocity, and the weakening of free surface waves in the direction of magnetic lines. Moreover, the film thickness increases with an increasing flow rate, whereas it decreases with an increasing inclination angle at a constant value of the magnetic field. When plotting the relative film thickening δ en, and the reduction of flow velocity against the Stuart number N, we find that there is a critical N, N cr ≈ 0.1, at which δ en begins to increase dramatically. The δ en sinβ with 1 • ≤ β ≤ 5 • , based on all of the experimental data, collapses into one line, which can be scaled as δ en sinβ ∼ N. The present experimental data and its scaling law may prove useful for estimating magnetohydrodynamic effects on liquid metal film flows when considering the design of liquid metal film PFCs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic effects on liquid metal film flowing along an inclined plate relating to plasma facing components

Yang

Ren

et al. 2020

Nucl. Fusion

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“…The experimentally achieved Hartmann numbers (formally defined in section 2.1) <∼100 were relatively low, and the relatively high Reynolds number led to turbulent flow. Based on the assumed achievement of fully developed flow, the LM height along the flow (streamwise) direction calculated by 1D or 2D theoretical methods qualitatively matched experimental results [31,32,36]. It is unknown if the steady, fully developed film flow regime can be realized in a practical LM freesurface divertor application.…”

Section: Introductionmentioning

confidence: 82%

“…Results of experiments on LM flow under the influence of magnetic fields are presented in past studies [26,31,32,[34][35][36]. The experimentally achieved Hartmann numbers (formally defined in section 2.1) <∼100 were relatively low, and the relatively high Reynolds number led to turbulent flow.…”

Section: Introductionmentioning

confidence: 96%

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

Sun

Al-Salami

Khodak³

et al. 2023

Nucl. Fusion

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While flowing liquid metal plasma-facing components (PFCs) represent a potentially transformative technology to enable long-pulse operation with high-power exhaust for fusion reactors, magnetohydrodynamic (MHD) drag in the conducting liquid metal will reduce the flow speed. Experiments have been completed in the linear open-channel LMX-U device [Hvasta et al., Nucl. Fusion. 58 (2018) 01602] for validation of MHD drag calculations with either insulating or conducting walls, with codes similar to those used to design flowing liquid metal PFCs for a Fusion Nuclear Science Facility [Kessel et al., Fusion Science Technol. 75 (2019) 886]. We observe that the average channel flow speed decreased with the use of conducting walls and the strength of the applied transverse magnetic field. The MHD drag from the retarding Lorentz force resulted in an increase of the liquid metal depth in the channel that ‘piled up’ near the inlet, but not the outlet. As reproduced by OpenFOAM and ANSYS CFX calculations, the magnitude and characteristics of the pileup in the flow direction increased with the applied traverse magnetic field by up to 120%, as compared to the case without an applied magnetic field, corresponding to an average velocity reduction of ~ 45%. Particle tracking measurements confirmed a predicted shear in the flow speed, with the surface velocity increasing by 300%, despite the 45% drop in the average bulk speed. The MHD effect makes the bulk flow laminarized but keeps surface waves aligned along the magnetic field lines due to the anisotropy of MHD drag. The 3D fringe field and high surface velocity generate ripples around the outlet region. It was also confirmed that the MHD drag strongly depends on the conductivity of the channel walls, magnetic field, and volumetric flow rate, in agreement with the simulations and a developed analytical model. These validated models are now available to begin to determine the conditions under which the ideal liquid metal channel design of a constant flow speed and fluid depth could be attained.

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“…Several concepts of moving divertors are proposed for high heat load applications using liquid metal thin film flows [2], droplets [3] and carbon fibre belts [4,5]. A 'pebble drop' divertor is a new concept applicable to the environment of very high heat load (>20 MW/m 2 ) and particle loading (>10 24 atoms/(m 2 s)).…”

Section: Introductionmentioning

confidence: 99%

Multilayer pebbles for application to new divertor systems

et al. 2000

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A `pebble drop' divertor concept is proposed for future commercial fusion reactors. The marked feature of this system is the use of multilayer pebbles that consist of a central kernel and some coating layers. By using multilayer pebbles the pebble drop divertor has advantages such as steady state wall pumping with low bulk tritium retention. The performance of the whole divertor system depends on the characteristics of the multilayer pebble. In particular, the maximum heat load of the system is determined by the dimensions, the layer structure and the material of the kernel. The kernel also has an important role in determining surface temperature, which affects the wall pumping efficiency. Numerical results for the maximum allowable heat load and the surface temperature of the divertor pebble are presented. From the numerical estimation of thermal stress and surface temperature, it is found that the radius of a divertor pebble with a ceramic kernel should be 0.5-1 mm.

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Initial liquid metal magnetohydrodynamic thin film flow experiments in the McGA-loop facility at UCLA

Cited by 3 publications

References 2 publications

Magnetohydrodynamic effects on liquid metal film flowing along an inclined plate relating to plasma facing components

Magnetohydrodynamic effects on liquid metal film flowing along an inclined plate relating to plasma facing components

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

Multilayer pebbles for application to new divertor systems

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