Study of instabilities in a quasi-2D MHD duct flow with an inflectional velocity profile

• We investigate inflectional instabilities in quasi-2D MHD duct flows.
• A velocity profile is artificially induced in a channel through current injection.
• The Q2D velocity field is measured via the electric potential on a Hartmann wall.
• Results are compared to numerical simulations of the same geometry/conditions.
• Similar experimental and computed results suggest a Q2D approximation is valid.

The mechanisms responsible for instabilities and a transition to turbulence in liquid metal duct flows of a fusion blanket are not understood very well, which limits predictive capabilities for heat and material transport in a blanket. In order to elucidate such mechanisms in quasi-two-dimensional (Q2D) magnetohydrodynamic flows with inflection points, an experimental and computational effort is underway to electromagnetically induce a Q2D turbulent flow through the injection of current at the Hartmann walls. In such a flow, inflectional instabilities arise at the two locations where current is supplied. In the experiments, Hartmann wall inductive velocimetry is employed as the main flow diagnostics. The electric potential field is measured using an array of small probes embedded in the wall material, and the fluctuating velocity field is reconstructed from the potential data using Ohm's law. First experimental data have been taken, which are in qualitative agreement with the pre-experimental analysis, where the flows are numerically simulated using a Q2D flow model.