This paper shows by the three-dimensional analyses on commercial- and laboratory-scale open cycle MHD generators that the shaped B -field configuration (SFC-type) suppresses the local Hall current distribution, which drives the secondary flow in the cross section, the magnetoaerothermal instability (MATI), and the boundary layer separation. Parabolized three-dimensional steady-state Navier-Stokes equations are used for the analyses with the k-ε turbulence model. The generalized Ohm law and the Maxwell equations are solved using the usual infinite segmentation assumption. A carbon combustion gas is considered as well as kerosine combustion plasma, since the electrical conductivity of the carbon plasma is a factor of 5-10 higher than that of the hydrocarbon combustion plasma. When the appropriate SFC-type magnetic field distribution is realized throughout the channel, particularly in the channel entrance region, the secondary flow field has different structures than those of the conventional uniform B -field configuration (UFC-type), such as the number and magnitude of vortices, which have important effects on the power output, boundary layer separation and the MATI.
Oikawa et al. (Mon,) studied this question.