Effect of magnetohydrodynamic control on the self-starting ability of hypersonic inlets
Numerical simulations of a generic hypersonic inlet were conducted under the influence of an external electromagnetic field to demonstrate the feasibility of enlarging the envelope of self-starting operation.Numerical and analytical models of self-starting ability control in an electromagnetically controlled inlet were established.The analysis demonstrates that the performance of electromagnetic boundary layer flow control is mainly determined by the Lorentz force in the flow direction by applying an external electromagnetic field.Moreover,the low-velocity fluid in the boundary layer can be accelerated,thus enhancing the ability of the boundary layer to resist separation.Furthermore,the Lorentz force in the streamwise direction could increase the shear stress and the skin friction coefficient.The most prominent characteristic of the unstarted inlet flowfield is the large-scale separation bubble.With an external electromagnetic field applied,the separation bubble is subjected to additional streamwise Lorentz forces.To maintain force balance at the separation zone,the pressure plateau decreases,and the location of the separation point moves downstream,resulting in a decrease in the size of the separation bubble.During the accelerating start process,the Lorentz force directed along the stream can reduce the self-starting Mach number of the background inlet,thereby expanding the operating Mach range remarkably.
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