Instability of homogeneous velocity distribution in an induction-type MHD machine

A. Gailitis - O. Lielausis

Institute of Physics, Latvian Academy of Sciences, Salaspils-1, LV-2169, Latvia

Abstract
A cylindrical MHD machine is investigated in the regimes in which the magnetic field gets considerably lowered by the currents induced in the fluid. The machine is regarded as a combination of many elementary machines connected in parallel hydraulically and in series electrically. It is shown that in a number of cases the homogeneous flow is unstable. The operating cross section is then divided into several zones with significantly different velocities. The conditions of instability are derived. The consequences of the multivelocity flow are demonstrated by the computation of the p(Q) characteristics as an example. The characteristics of hydraulically parallel operation of two independent machines are investigated in detail. The parallel combination of two narrow machines is put forward as an elemetary model of the phenomena occurring inside a wide machine.