Numerical study of the magnetohydrodynamic flow instability and its effect on energy conversion in the annular linear induction pump

Abstract

A numerical model of annular linear induction pump with a full-scale pump channel is created to study the scale-dependent instability of the magnetohydrodynamic flow. The magnetic-fluid coupling effect is implemented by modifying the underlying governing equations and constraints. The model authenticity is validated by comparing the simulated pressure difference, as well as the pressure pulsation, with the previous experimental data. The flow patterns at different flow rates corresponding to different magnetic Reynolds numbers are depicted from both the azimuthal and meridian viewpoints, and the periodicity of the occurring vortex flows is found in the pump. By analyzing the different mechanisms contributing to the fluid kinetic energy, it is found the competition between the axial components of the Lorentz force and pressure gradient dominates the flow evolution in the pump channel. The magnetic-fluid coupling effect is found to amplify the disturbances in either the magnetic field or the fluid field. It is even effective within the uniform externally imposed magnetic field and inlet velocity only if a disturbance exists in the initial flow. Increase in the cycle number of disturbance can enhance the flow stability and induce smaller vortex flows. Finally, different mechanisms of energy conversion in the pump are analyzed and it is found that the sudden occurrence of vortex flows can induce large current density, which significantly increases the Ohmic dissipation and decreases the efficiency of energy conversion from magnetic field into the fluid. The relatively large Ohmic dissipation in the fluid is the main reason for the low efficiency of such a device.

Active Flow Control of the Magnetohydrodynamic Flow in an Annular Linear Induction Pump by Modifying the Driving Electromagnetic Field

“…Its detailed description will be presented in the following paragraph. The expressions for defining the EM boundary conditions on the flow channel of ALIP were employed and proved in several previous studies [9,16,24]. It can create the induced magnetic field and current density in the liquid metal with reasonable accuracy while the simulations of stators, coiling windings, and ducts can be ignored.…”

“…However, the flow instability was not analyzed in the model for that the full-scale flow channel was not simulated in this work and the unstable flow was not observed. Zhao et al built a 2D coupling numerical model [23] and further a 3D fullscale numerical model to study the internal unstable flows [24]. It is found that the competition between the axial components of the Lorentz force and pressure gradient in the flow dominates the vortical evolution, and the magneticfluid coupling can amplify the small disturbance in either the magnetic field or the fluid.…”

Investigation of biomagnetic nanofluid flow configured by a stretchable surface in the presence of magnetic dipole

“…The significance of MHD hybrid nanofluids on the flow by employing an activation energy concept throughout a rotating disc was investigated by Reddy et al [24]. Zhao et al [25] explored the scale-dependent instabilities of MHD flow, a computational model of an annulus linear inductive pump with full-scale pump channels. The analysis of MHD flow in nanofluid is recently illustrated by many researchers [26][27][28][29][30][31].…”

“…Zhao et al. [25] explored the scale‐dependent instabilities of MHD flow, a computational model of an annulus linear inductive pump with full‐scale pump channels. The analysis of MHD flow in nanofluid is recently illustrated by many researchers [26–31].…”

One-stage simplified lattice Boltzmann method for two- and three-dimensional magnetohydrodynamic flows

“…Indeed, its area of employment is impressively wide. The design of electromagnetic pumps 2,3 and cooling systems for nuclear reactors 4 , the predictions of solar flares 5,6 , the measurement of flow velocities in hot and aggressive liquids 7,8 , and drop-ondemand printability 9 are just few compelling examples of the most challenging applications of MHD.…”