Parameter Optimization and Three-dimensional Flow Topology of a Cavity in a Blunt-nose Projectile

Trajectory correction provides an effective means for enhancing the accuracy of conventional ammunition. This study investigated a cavity-based passive flow control method for trajectory correction and refined the cavity geometry using Orthogonal Array Testing (OAT) and Response Surface Methodology (RSM). The aerodynamic characteristics of the resulting cavity configurations were examined through Computational Fluid Dynamics (CFD) simulations. The orthogonally refined cavity achieved a drag coefficient of 0.289 and a correction force coefficient of 0.263, representing increases of 32% and 181% relative to the initial design. The RSM-refined cavity achieved a correction force coefficient of 0.275 and a drag coefficient of 0.288, corresponding to increases of 193% and 35%, respectively. Compared to the orthogonally refined configuration, the RSM design produced a 12.3% higher correction force and a 0.6% lower drag. The coupling among geometric parameters was examined to elucidate the physical mechanism governing correction force generation. Finally, a three-dimensional flow topology model of the blunt-nose cavity was established. This research provides significant reference value for the understanding of three-dimensional flow topology model and the design of passive correction devices.