Numerical simulations of rarefied gas flow over an aero-spiked hypersonic blunt body using the second-order Boltzmann-Curtiss constitutive model

Abstract

Hypersonic vehicles experience significant aerodynamic drag and aerothermal heating while traveling through the atmosphere. One technique involves reducing these aero-thermodynamic loads by adding an aerodynamic tip to the blunt nose of the hypersonic vehicle. In highly rarefied gas regimes, the conventional Navier-Stokes-Fourier (NSF) equations may not accurately predict aerothermodynamic loads acting on these vehicles. To overcome these shortcomings, the second-order Boltzmann-Curtiss kinetic equations, in conjunction with the Maxwell slip and Smoluchowski jump conditions, are considered in this study. Further, an explicit mixed-type modal discontinuous Galerkin (DG) method for the unstructured triangular and tetrahedral meshes is adopted to ascertain numerical accuracy. The effect of aerospike for varied ratios of spike length (L) to the diameter (D) of the blunt body is examined at high degrees of rarefaction. The aerospike placed in front of the vehicle replaces the more substantial detached shock wave with weaker oblique shock waves, thus reducing the total drag and wall heat flux. A comprehensive analysis suggests that the L/D ratio and the rotational mode of energy transfer for diatomic gases substantially affect the hypersonic vehicle's drag, heat flux, and stability. © 2024 Author(s).