THEORETICAL ANALYSIS ON HYPERSONIC MHD SHOCK STAND-OFF DISTANCE OF BLUNT BODY

High speed and shock compression behind the bow shock of an aircraft head result in very high temperature, which would subsequently lead to a conductivity plasma flowfield around the vehicle. The plasma gas provides a direct working environment for the application of magnetic field. The magnetohydrodynamic (MHD) flow control, which uses the magnetic field to alter the trajectory of ions or electrons, can improve the aerodynamic characteristics of hypersonic vehicles effectively. As an intuitive aerodynamic phenomenon in the field of hypersonic MHD flow control, shock stand-off distance has attracted close attention from researchers. Under the influence of the applied magnetic field, the shock stand-off distance will change with it, of which the value can directly reflect the effect of the MHD flow control. However, the relevant theoretical models are still limited, and further development in this field is consequently needed. Focusing on dealing with this problem, MHD hypersonic shock stand-off distance of the spherical model is theoretically studied in this paper. By means of radially integrating the continuity equation and applying mathematical method of variable separation to the momentum equation, the analytical expression of MHD shock stand-off distance is obtained. The theoretical analysis was performed under the assumption of low magnetic Reynolds number, and the common-used dipole distribution of magnetic field as applied. The results show that the MHD stand-off distance of shock increases with the increase of magnetic interaction parameter. Moreover, the regularity can be found that as the speed of inflow becomes higher, magnetic interaction parameter can be viewed as the primary impact factor of shock stand-off distance under hypersonic condition. The theoretical model in this work can rapidly evaluate the effect of MHD control, and it can provide theoretical guidance to the design of experiment scheme and the analysis of results.