Numerical modelling of imposed magnetohydrodynamic effects in hypersonic flows

TL;DR

This paper develops and validates numerical models to simulate magnetohydrodynamic effects in hypersonic flows with complex shock interactions, revealing how magnetic fields can alter flow topology and shock structures.

Contribution

It introduces a validated numerical methodology with an advanced air plasma model for simulating MHD effects in hypersonic flows around complex geometries.

Findings

Numerical models agree quantitatively with experimental data at Mach 5.6.

Magnetic fields can significantly alter shock positions and flow topology.

Flow topologies can be classified and manipulated via magnetic field configurations.

Abstract

Weakly ionised plasmas, formed in high enthalpy hypersonic flows, can be actively manipulated via imposed magnetic fields - a concept termed magnetohydrodynamic (MHD) flow control. Imposed MHD effects, within flows which exhibit multiple shock interactions, are consequential for emerging aerospace technologies: including aerodynamic control via magnetic actuation. However, numerical modelling of this flow type remains challenging due to the sensitivity of feature formation and the real gas modelling of weakly ionised, electrically conductive, air plasma. In this work, numerical simulation capabilities have been developed for the study of MHD affected, hypersonic flows, around 2D axisymmetric non-simple geometries. The validated numerical methodology, combined with an advanced 19 species equation of state for air plasma, achieves quantitative agreement between simulation and experiment for a Mach 5.6 double cone geometry with applied magnetic field. Numerical studies are conducted for varied conical surface angle and magnetic field configuration. This paper demonstrates how, for hypersonic flows with complex shock interactions, the MHD affected flow is not only augmented in terms of shock position, but may exhibit topological adaptations in the fundamental flow structure. A classification system is introduced for the emergent flow topologies. The applied numerical studies examine the mechanisms by which the magnetic field configuration influences the MHD augmented shock structure, leading to: (1) differences in magnitude of MHD enhancement effect, and (2) structural adaptations of the flow topology. Most critically, classes of conditions are identified which produce topological equivalence between the magnetic interaction effects and a generalised mechanical control surface.