An experimental study of rotating MHD couette flow in a coplanar field

A study of the flow regime of an electrically conducting liquid between coaxial cylinders in a coplanar magnetic field was conducted by using torque measurements. The internal cylinder was rotated, and the torque was determined from the angle of rotation of the external cylinder (which was suspended on three threads). The annular magnetic field was produced by passing a direct current through a rectilinear cylindrical conductor, which was set up coaxially with the working cylinders. The experiments show that in the flow regime the magnetic field does not prevent the formation of a known Taylor vortex flow pattern, but delays it at high Reynolds numbers after a turbulent flow was established. The experimental data approximates a linear dependence of the critical Reynolds number on the Stewart number, from which it follows that at high Reynolds numbers a critical ratio occurs between the Hartman and Reynolds numbers.