Numerical study on hydraulic loss characteristics of seawater MHD thruster under electromagnetic field

Abstract

Under the action of an external electromagnetic field, the velocity distribution of seawater in the MHD thruster channel changes significantly compared with the distribution without an electromagnetic field, which will affect the original hydraulic loss characteristics of the channel. Based on Fluent numerical simulation, the distribution characteristics and generation mechanism of flow in the MHD thruster are analyzed first and then the effects of current density, channel structure, and inlet Reynolds number on the channel flow field distribution and hydraulic loss characteristics are further studied. The results show that (i) the M-type velocity distribution also appears in the channel of the seawater MHD thruster, but due to the low conductivity of seawater, its source is different from the traditional Hartmann effect, which is mainly caused by the combined action of the external electromagnetic field. (ii) There will be an additional hydraulic loss in the thruster channel under the action of the electromagnetic field. With the increase of the interaction coefficient N (the ratio of electromagnetic force to inertial force), the hydraulic loss coefficient ratio ξ/ξ0 of the channel monotonically increases. (iii) When the thruster operates at a high interaction coefficient (N > 1), the additional hydraulic loss caused by the electromagnetic field in the channel cannot be ignored. Key words: Seawater MHD thruster, linear channel, hydraulic loss, interaction coefficient, numerical simulation. Tables 1, Figs 21, Refs 15.