Magnetohydrodynamic pressure drops in geometric elements forming a HCLL blanket mock-up

Mistrangelo, C.; Bühler, L.

doi:10.1016/j.fusengdes.2011.03.011

Cited by 16 publications

(10 citation statements)

References 5 publications

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“…The measurement points have been chosen at the location where the internal walls are connected with the Hartmann wall. As a consequence, the potential difference between two sensors gives the mean velocity in the considered sub-channel according to (2). The outcomes agree well with numerical simulations of fully developed MHD flow in the middle of the module [7].…”

Section: Resultssupporting

confidence: 81%

“…The present measurements of electric potential are an extension of previous investigations [1] and should be considered complementary to [2] where the focus is placed on pressure measurements. For liquid-metal flows when exposed to intense magnetic fields like in a fusion reactor, electric potential measurements give information on the flow structure in the breeder units, since the recorded quantity can be interpreted as an approximate flow streamfunction.…”

Section: Introductionmentioning

confidence: 87%

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Determination of flow distribution in a HCLL blanket mock-up through electric potential measurements

Bühler

Mistrangelo

2011

Fusion Engineering and Design

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Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 87%

Determination of flow distribution in a HCLL blanket mock-up through electric potential measurements

Bühler

Mistrangelo

2011

Fusion Engineering and Design

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“…These rectangular boxes are fed and drained by a single manifold system. Experiments for a simplified geometry of a HCLL blanket module have shown that the largest MHD pressure drop occurs in the manifolds [15] [16]. Figure 2(left top) shows the design of a HCLL blanket mock-up and the model geometry used for the numerical study.…”

Section: Effects Of Electromagnetic Coupling On Mhd Flow In Parallel mentioning

confidence: 99%

Magnetohydrodynamic flows in liquid metal blankets for fusion reactors

Mistrangelo

Bühler

2017

Proc Appl Math and Mech

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Liquid metal blankets will be tested in the experimental fusion reactor ITER. Three main concepts are currently under development. In the water-cooled and in the helium-cooled lead lithium blankets the PbLi alloy serves only as breeder material for producing the fuel component tritium used to generate the magnetically confined fusion plasma. The fusion heat is removed by a separated water or helium cooling system and therefore the liquid-metal could be practically at rest. However, for tritium extraction and liquid metal purification a weak circulation (1 mm/s) is required. Instead in the dual coolant lead lithium blanket the liquid metal serves both to produce tritium and to remove the volumetric heat deposited in the breeding zone, while helium is employed to cool first wall and blanket structure. In this concept PbLi has to flow faster (10 cm/s) than in the separately cooled blanket designs to allow efficient cooling of the breeding zone.In all liquid metal blankets there are issues related to the specific characteristics of the liquid metal. The interaction of the electrically conducting fluid with the strong magnetic field induces electric currents and electromagnetic forces that influence velocity and pressure distribution in the blanket. Lorentz forces are balanced by pressure gradients and these additional magnetohydrodynamic (MHD) pressure losses are proportional to the electric current density induced in the fluid. The electrical coupling of adjacent fluid domains that results from the presence of leakage currents crossing common conducting walls, has also to be taken into account. Two examples of MHD flows typical in fusion blankets are discussed in this paper.

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“…Understanding transition in coolant ducts is important for ensuring sufficient heat transfer at the plasma-facing (Shercliff) wall [9][10][11][12][13] and to establish the feasibility of selfcooled reactor designs [7]. Limits on maximum pressure gradient [9,14,15] and pumping efficiency [11,[16][17][18] motivate seeking the most efficient route to turbulence. However, quasitwo-dimensional turbulence is unlikely to arise in blankets via strongly three-dimensional turbulence [7].…”

Section: Introductionmentioning

confidence: 99%

Subcritical route to turbulence via the Orr mechanism in a quasi-two-dimensional boundary layer

Camobreco¹,

Pothérat²,

Sheard³

2020

Preprint

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A subcritical route to turbulence via purely quasi-two-dimensional mechanisms, for a quasi-twodimensional system composed of an isolated exponential boundary layer, is numerically investigated. Exponential boundary layers are highly stable, and are expected to form on the walls of liquid metal coolant ducts within magnetic confinement fusion reactors. Subcritical transitions were detected only at weakly subcritical Reynolds numbers (at most ≈ 70% below critical). Furthermore, the likelihood of transition was very sensitive to both the perturbation structure and initial energy. Only the quasi-two-dimensional Tollmien-Schlichting wave disturbance, attained by either linear or nonlinear optimisation, was able to initiate the transition process, by means of the Orr mechanism. The lower initial energy bound sufficient to trigger transition was found to be independent of the domain length. However, longer domains were able to increase the upper energy bound, via the merging of repetitions of the Tollmien-Schlichting wave. This broadens the range of initial energies able to exhibit transitional behaviour. Although the eventual relaminarization of all turbulent states was observed, this was also greatly delayed in longer domains. The maximum nonlinear gains achieved were orders of magnitude larger than the maximum linear gains (with the same initial perturbations), regardless if the initial energy was above or below the lower energy bound. Nonlinearity provided a second stage of energy growth by an arching of the conventional Tollmien-Schlichting wave structure. A streamwise independent structure, able to efficiently store perturbation energy, also formed.

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Magnetohydrodynamic pressure drops in geometric elements forming a HCLL blanket mock-up

Cited by 16 publications

References 5 publications

Determination of flow distribution in a HCLL blanket mock-up through electric potential measurements

Determination of flow distribution in a HCLL blanket mock-up through electric potential measurements

Magnetohydrodynamic flows in liquid metal blankets for fusion reactors

Subcritical route to turbulence via the Orr mechanism in a quasi-two-dimensional boundary layer

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