Aerodynamic coupling effects of high-speed spin and angle of attack on supersonic projectiles based on overset mesh

Accurately predicting the aerodynamic response of supersonic projectiles under the coupled effects of high-speed spin and non-zero angles of attack (AoA) is critical for trajectory optimisation and submunition dispensing. This study systematically investigates the aerodynamic coupling effects of a 12.7 mm supersonic carrier projectile during its natural velocity decay phase (830 m/s to 610 m/s) under minor AoA perturbations (0° to 2°). A high-fidelity numerical framework was established utilising the realizable k - ε turbulence model and overset mesh technology. The initial kinematic boundary conditions were rigorously extracted from ballistic gun experiments and subsequently validated against wind tunnel test data. The results reveal that high-speed rotation significantly modifies the flow topology around the projectile. At an AoA of 2°, the rotation-induced circumferential flow reduces the characteristic wake recirculation region by approximately 70%, contributing to a 20.65% reduction in aerodynamic drag and a 4.26% attenuation of base negative pressure compared with the non-rotating condition. Furthermore, quantitative analysis indicates that the lift exhibits an approximately linear increase with increasing AoA, whereas the rotation-induced Magnus force demonstrates a pronounced saturation characteristic, with its growth rate decreasing by 81.76%. Based on the revised force and moment decomposition, the lift primarily governs the pitching response through its pressure-distribution-induced moment, while the Magnus force mainly contributes to the lateral/yawing aerodynamic response. During the velocity decay process, the reduction in flow energy weakens the shock-wave intensity and the rotation-induced swirling flow, leading to a progressive decrease in drag, lift, and Magnus force. Overall, high-speed rotation not only improves aerodynamic efficiency through wake-flow regulation and base-pressure recovery but also provides gyroscopic stability that suppresses excessive AoA growth and enhances flight stability.