Zonal-detached-eddy simulation of projectiles in the subsonic and transonic regimes

This paper presents nonspinning-projectile computations with advanced turbulence modeling to demonstrate the relevance of using a hybrid method in projectile simulations. A zonal-detached-eddy simulation methodology is used to improve the base-How prediction without deteriorating the incoming attached flow upstream of the base in the subsonic and transonic regimes. The numerical results are found to compare fairly well with the available experimental wall-pressure data. Both time-averaged and unsteady features are then discussed. Particular attention was paid to the near-wake flowfield and its dependency upon the freestream Mach number. In these calculations, some classical features of massively separated flows, such as the pressure evolution along the base or the wake centerline characteristics, are poorly predicted with the Spalart-Allmaras model. The use of a hybrid method leads to promising results and allows for a physical analysis of the separated flowfield. The flow appears to exhibit selfsimilar properties, even in the recirculation area, independently of the Mach number value in the range of freestream conditions investigated. Moreover, the instability process leading to the shear-laver growth is found to be similar in the range of parameters investigated and is in accordance with previous results concerning the compressibility effects in free shear flows. Finally, base-pressure spectra are reported and compared with axisymmetric base-flow data.