Suppression of the wake steady asymmetry of an Ahmed body by central base bleed

The injection of fluid into the wake of a bluff body, commonly referred to as base bleed, is a well-known method of drag reduction. In the current paper we demonstrate that this method provokes a complete suppression of the steady asymmetry which otherwise dominates the natural Ahmed body wake and causes additional drag. Independent force measurements corroborate the suppression of the wake asymmetry. Different scales of base blowing reveal similar maximum drag reduction and asymmetry suppression, where the optimal blowing coefficient is found to scale with bleed-to-base area ratio as (Sⱼ/S)1/2.