Characterization of the three-dimensional supersonic flow for the MHD generator

Abstract

A numerical procedure based on a five-wave MHD model associated with non-ideal, low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical procedure is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations, in conjunction with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would take place near the downstream edge of the second electrode, where the local adverse pressure gradient is large, and the core of the flow field is characterized as a 2-D flow due to the Hartmann effects along the direction of the magnetic field. The electric current lines would be increasingly distorted as the magnetic interactive parameter increases, and even induce an eddy current. Induced eddy current was also found in the different cross-sections along the axial direction, all of these would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the insulator cross-section, which, in turn, induces the corner eddy current at the corner. A numerical parametric study was also performed, and the computed performance parameters for the MHD generator suggest that, in order to enhance the performance of MHD generator, the magnetic interaction parameter should be elevated. MHD generator, entropy conditioned scheme, SOR, numerical simulationResearch on magnetohydrodynamics (MHD) has become increasingly active in many countries due to the potential applications in the area of hypersonic technology. In early nineties of the last century, Russian had proposed a new concept on a combined propulsion system composed of a turbojet and an MHD enhanced scramjet for hypersonic cruisers, and established the AJAX development program. The MHD enhanced scramjet engine is presently known as the MHD bypass scramjet [1] . The most essential concept in AJAX program is to take advantage of the electromagnetic force and its capacity on controlling the external and internal flow fields for the fight vehicle to improve the propulsion performances. The internal MHD generator is one of the critical components in MHD bypass scramjet system responsible for extracting the enthalpy from the main inlet flow for two purposes. The first is to lower the total enthalpy of the flow entering the combustion chamber for improving the thermomechanical performances of the scramjet, and maintaining the thermal environment of the combustion chamber to meet the constraints on the thermostructural design. The other is to convert the enthalpy into electric power. Part of the electric power is transferred to MHD accelerator placed downstream of the combustor, and the remaining will be applied to pre-ionizer to provide the required flow conductivity in the MHD channels and the onboard systems. Th...

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Research on New Type Magnetohydrodynamic Ocean Wave Energy Conversion System

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