Numerical Investigation of Magnetohydrodynamics Flow Control
When the aircraft flies at hypersonic speed,the high Mach number incoming flow passes through the shock wave and the temperature rises sharply.The internal energy mode of gas molecules is excited at high temperatures,leading to reactions such as dissociation,ionization,and neutral exchange,forming weakly ionized plasma with a certain conductivity.Reasonably arranging the magnetic field and electric field,the conductive fluid in the shock layer interacts with the external electromagnetic field to generate induced current,further generating Lorentz force and Joule heat,achieving the impact on the aerodynamic heat of the aircraft and achieving the purpose of flow control.This paper conducts numerical simulation research on two flow control methods:MHD heat flux mitigation and MHD energy extraction.Firstly,this paper investigates the influence of incoming Mach number,flight altitude,and magnetic field intensity on MHD heat flux mitigation.And the following conclusion has been obtained:at a certain flight altitude,the Mach number of the incoming flow needs to make the total temperature of the incoming flow close to 10000K in order to make the MHD heat flux mitigation effect significant.Subsequently,this paper conducted conceptual design and parameter impact research on the MHD energy extraction device.And the following conclusion is obtained:under typical re-entry flight conditions(altitude of 46km,speed of 7000m/s),the MHD energy extraction device proposed in this paper can provide megawatt level electrical power output under an external magnetic field intensity of 0.2T.The electrical energy extracted by the device and the working efficiency of the energy extraction device show a trend of increasing first and then decreasing with the increase of load voltage,indicating that for the given inflow conditions,there is an optimal load voltage that maximizes the power and efficiency of the magnetic fluid energy extraction device.The results in this paper can provide guidance for the design of magnetohydrodynamic thermal protection technology and energy extraction technology in hypersonic flight.
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