Research on the characteristics of the leeward vortex flow field on a blunt-headed rotating body at high angles of attack

Abstract

Detached eddy simulation was used to numerically compute the leeward vortex flow field on a blunt-headed rotating body. The effects of changes in the angle of attack and flight velocity on the evolutionary law of the counter-rotating vortexes and the fluctuation characteristics of the lateral force coefficient were analyzed. The results show that the counter-rotating vortexes on the leeward surface of the blunt-headed rotating body gradually separate from the wall along the direction from the tail to the head of the projectile as the angle of attack increases. In addition, it shows a periodic variation law of alternating expansion and detachment of the unilateral separated vortex. When the angle of attack is greater than 30°, the fluctuation amplitude of the lateral force coefficient initially rises and then drops with an increase in the angle of attack, while the fluctuation frequency keeps increasing. The maximum amplitude and corresponding frequency of the lateral force coefficient under the main fluctuation remain in the range of 100–230 Hz and have a linear positive feedback relationship with the flight Mach number. With the angle of attack and flight velocity as independent variables, the fittings were performed on the varying laws of maximum amplitude and the corresponding frequency of the lateral force coefficient under the main fluctuation. An unsteady calculation equation for the lateral force coefficient under the change in coupling with the angle of attack and flight velocity was established.