DRESDYN
The DREsden Sodium facility for DYNamo and thermohydraulic studies (DRESDYN) is an infrastructure project devoted both to large scale liquid sodium experiments with geo- and astrophysical background, as well as to investigations of various energy related technologies. Figure 1 shows a photograph of the building.
Precession driven dynamo
The most ambitious installation in the framework of DRESDYN is a precession driven dynamo experiment (Figures 2 and 3), which aims at clarifying whether precession could be a viable source of planetary magnetic fields. Basically, it consists of a liquid sodium filled container of 2 m diameter, with a central cylinder of 2 m height and two conical end pieces, rotating around its central axis with up to 10 Hz, and around an inclined axis with up to 1 Hz. Depending on the precession ratio, and on the angle between the rotation and the precession axis, different flow structures appear and will be tested with respect to their suitability for magnetic field self-excitation.
In November and December 2024, first water experiments were carried out with a rotation rate of 1 Hz and a precession rate of up to 0.1 Hz (see video). Transitions between laminar and turbulent flow regimes were detected at the expected precession ratio.
MATISSE (MAgnetically Triggered flow Instabilities in disks and Stars: A Sodium Experiment)
The goal of a second experiment (Figure 4) is to study various combinations of the magnetorotational instability (MRI) and the Tayler instability (TI). The MRI is widely believed to trigger turbulence and angular momentum transport in accretion disks around protostars and black holes, thereby allowing mass concentration onto these central objects. The TI is thought to play a role in the angular momentum transport in neutron stars, and is also discussed as a key ingredient of an alternative stellar dynamo model, the Tayler-Spruit dynamo. After having investigated the helical and the azimuthal MRI, as well as the pure TI in much smaller experiments with the eutectic alloy GaInSn, the new liquid sodium experiment will allow to studying the combinations of these instabilities, as well as the standard version of MRI.
In addition to its astrophysical significance, TI may also play an important role in a ‘terrestrial’ application (Figure 5). This involves large-scale liquid metal batteries, which are being discussed as promising storage systems for highly fluctuating renewable energies. As the cost per stored kilowatt hour decreases with increasing battery size, the aim is to maximise the size of the battery from an economic perspective. However, this results in currents in the battery at which the TI starts in the form of vortices, which can destroy the stable layering of the anodic material (Mg, Li, Na), the thin electrolyte and the cathodic material (Pb, Sb, Bi). Various measures developed at the HZDR to suppress TI are to be validated in a special test stand.
Further experiments within the DRESDYN programme are dedicated to the development of measurement techniques for thermohydraulic applications of liquid sodium.
Publications
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Stefani, F.; Anders, S.; Eckert, S.; Freyer, N.; Gerbeth, G.;
Giesecke, A.; Gundrum, Th.; Kaever, K.; Kumar, V.; Pizzi, F.;
Räbiger, D.; Šimkanin, J.; Steglich, C.; Vogt, T.; Wagner, N.;
Wedel, G.
The DRESDYN precession experiment
Comptes Rendus. Physique, Online first (2024), 1-19. -
Stefani, F.
Liquid-metal experiments on geophysical and astrophysical phenomena
Nature Reviews Physics 6 (2024), 409-425 -
Mishra, A.; Mamatsashvili, G.; Stefani, F.
Nonaxisymmetric modes of magnetorotational and possible hydrodynamical instabilities in the upcoming DRESDYN-MRI experiments: Linear and nonlinear dynamics
Physical Review Fluids 9 (2024), 033904 -
Giesecke, A.; Vogt, T.; Pizzi, F.; Kumar, V.; García González, F.; Gundrum, T.; Stefani F.
The global flow state in a precessing cylinder
Journal of Fluid Mechanics 998 (2024), A30 -
Kumar, V.; Pizzi, F.; Giesecke, A.; Šimkanin, J., Gundrum, Th.; Ratajczak, M.; Stefani, F.
The effect of nutation angle on the flow inside a precessing cylinder and its dynamo action
Physics of Fluids 35 (2023), 014114 -
Mishra, A.; Mamatsashvili, G.; Stefani, F.
Nonlinear evolution of magnetorotational instability in a magnetized Taylor-Couette flow: Scaling properties and relation to upcoming DRESDYN-MRI experiment
Physical Review Fluids 8 (2023), 083902 -
Mishra, A.; Mamatsashvili, G.; Stefani, F.
From helical to standard magnetorotational instability: Predictions for upcoming liquid sodium experiments
Physical Review Fluids 7 (2022), 064802 -
Pizzi, F.; Giesecke, A.; Simkanin, J.; Stefani, F.
Prograde and retrograde precession of a fluid-filled cylinder
New Journal of Physics 23 (2021), 123016 -
Stefani, F.; Gailitis, A.; Gerbeth, G.; Giesecke, A.; Gundrum, T.; Rüdiger, G.; Seilmayer, M.; Vogt, T.
The DRESDYN project: liquid metal experiments on dynamo action and magnetorotational instability
Geophysical and Astrophysical Fluid Dynamics 113 (2019), 51-70 -
Giesecke, A.; Vogt, T.; Gundrum, T.; Stefani, F.
Kinematic dynamo action of a precession driven flow based on the results of water experiments and hydrodynamic simulations
Geophysical and Astrophysical Fluid Dynamics 113 (2019), 235-255 Online First (2018) -
Giesecke, A., Vogt, T., Gundrum, Th., Stefani, F.
Nonlinear Large Scale Flow in a Precessing Cylinder and Its Ability To Drive Dynamo Action
Phys. Rev. Lett. 120 (2018), 024502 -
Stefani, F., Galindo, V., Kasprzyk, C., Landgraf, S., Seilmayer, M., Starace, M., Weber, N., Weier, T.
Magnetohydrodynamic effects in liquid metal batteries
IOP Conf. Ser.: Mater. Sci. Eng. 143 (2016), 012024. -
Stefani, F., Albrecht, T., Gerbeth, G., Giesecke, A., Gundrum, T., Herault, J., Nore, C., Steglich, C.
Towards a precession driven dynamo experiment
Magnetohydrodynamics 51 (2015), 275-284
arXiv:1410.8373 -
Giesecke, A., Albrecht, T., Gundrum, T., Herault, J., Stefani, F.
Triadic resonances in non-linear simulations of a fluid flow in a precessing cylinder
New J. Phys. 17 (2015), 113044 -
Herault, J., Gundrum, T., Giesecke, A., Stefani, F.
Subcritical transition to turbulence of a precessing flow in a cylindrical vessel
Phys. Fluids 27 (2015), 124102 -
Stefani, F., Eckert, S., Gerbeth, G., Giesecke, A., Gundrum, Th., Steglich, C., Weier, T., Wustmann, B.
DRESDYN - A new facility for MHD experiments with liquid sodium
Magnetohydrodynamics 48 (2012), 103-113
arXiv:1201.5737