Supersonic Unsteady Flow around a Capsule-shaped Abort System with Angle of Attack

Supersonic flow over a capsule-shaped abort system with angle of attack (AoA) of α, which is boosted by supersonic aerodynamic interference, is investigated numerically through the 3D simulation. The objective of this study is to examine the effects of AoA on aerodynamic stability. In the previous study, the flowfield around this system at α = 0 is unsteady and has a strong periodic flow oscillation in the case without the clearance between the capsule and rocket. In the present study, this system has the angle of attack and a disk is installed to enhance the abort separation. The self-sustaining flow oscillation in the case with AoA is described and is visualized using the phase-averaged analysis of simulated results. With increasing AoA, the oscillating flow is divided into two parts, which correspond to the lower and upper surfaces of the cone. These two flows have a phase difference which becomes larger with increasing AoA. The present findings show it is about 0.28π and 0.4π, respectively. At the same time, the lower flow oscillation is out of step with the upper one, and an inharmonic flow oscillation occurs because of strong aerodynamic interaction in the lower flow. This unstable flow will lead to a risky abort separation and this phenomenon is analyzed in detail in this paper.