Investigation of secondary flows in magnetohydrodynamic channels

Abstract

In magnetohydrodynamic (MHD) channel flows, electromagnetic body forces may create significant secondary flows with resultant effects on axial velocity and turbulence distributions, electrical conductivity, boundarylayer voltage drops, electrode temperatures, and wall heat transfer. An investigation of the influence of electromagnetic interaction parameter, and channel electrical configuration on the magnitude and structure of MHD secondary flow is reported. Two electrode configurations were utilized. The first was a simulated Hall generator configuration in which an axial current was driven through the plasma. In this configuration, a two-cell secondary flow pattern with peak transverse velocities of approximately 13% of the freestream axial velocity was observed. The secondary flow was initially a sensitive function of electromagnetic interaction level, but became insensitive at high interaction levels. For all interaction levels, the secondary flow was concentrated in the upper two-thirds of the channel cross section. The second configuration was a simulated segmented Faraday channel in which transverse currents were driven through the plasma. A two-cell secondary flow structure was again observed, whereas a first-order model for an infinitely finely segmented channel would predict a six-cell structure. Current streamline curvature due to finite electrode segmentation may explain this discrepancy.