Turbulent transport of momentum and heat in magnetohydrodynamic rectangular duct flow with strong sidewall jets
This paper presents an experimental study of the momentum and heat transport in a turbulent magnetohydrodynamic duct flow with strong wall jets at the walls parallel to the magnetic field. Local turbulent flow quantities are measured by a traversable combined temperature-potential-difference probe. The simultaneous measurements of time-dependent velocity and temperature signals facilitates the evaluation of Reynolds stresses and turbulent heat fluxes. Integral quantities such as pressure drop and temperature at the heated wall are evaluated and compared with results from conservative design correlations. At strong enough magnetic fields the destabilizing effect of strong shear generated at the sidewalls wins the competition with the damping effect by Joule's dissipation and turbulent side layers are created. Due to the strong non-isotropic character of the electromagnetic forces, the turbulence structure is characterized by large-scale two-dimensional vortices with their axis aligned in the direction of the magnetic field. As most of the turbulent kinetic energy is concentrated in the near-wall turbulent side layers, the temperatures at the heated wall are governed by the development of the thermal boundary layer in the turbulent flow.(Received August 17 1998)
(Revised October 28 1999)
p1 Present address: Institut für Hydromechanik und Wasserwirtschaft, Eidgenössische Technische Hochschule Zürich, ETH Hönggerberg, CH-8093 Zürich.