Calculation of drag coefficients for hypersonic spherical projectiles initiating oblique detonation wave or shock-induced combustion

A CFD study is carried out to estimate the drag coefficients of a hypersonic projectile in detonable gases initiating shock-induced combustion (SIC) or oblique detonation wave (ODW) to apply the detonation initiation criterion for the classification of OSIC and ODW regimes. The drag coefficients of a spherical body in non-reacting flow is well known, but it is a questionnaire whether it can be apply for the present case involving strong overdriven detonation ahead of projectile surrounded by hot burned gas. Numerical model is based on the Navier-Stokes equations for multispecies reacting flows Menter's shear-stress transport (SST) turbulence model. The present CFD results reproduce the experimental visualization quite well and show good agreements with observations. The drag coefficients predicted from the CFD seems to be in the reasonable range and give the explanation on the effects of the detonative combustion around the projectile. It is shown that the detonation initiation criterion is shown to be effective for the spherical projectile with the drag coefficient estimated presently.