Projectile Performance, Stability, and Free-Flight Motion Prediction Using Computational Fluid Dynamics

摘要

With the recent development of capabilities for predicting damping derivatives, it is now possible to predict the stability characteristics and free-flight motion for projectiles using data that are derived solely from computational fluid dynamics (CFD). As a demonstration of the capability, results are presented for a family of axisymmetric projectiles in supersonic flight. The particular configuration selected has been extensively tested in aeroballistic ranges, and high-quality experimental data have been obtained. Thin-layer Navier-Stokes techniques have been applied to compute the attached viscous flow over the forebody of the projectile and the separated flow in the projectile base region. Parameters that characterize the in-flight motion are subsequently evaluated using the predicted aerodynamic coefficients, including the gyroscopic and dynamic stability factors and the projectile's fast-and slow-mode frequencies and damping coefficients. These parameters are then used to predict the free-flight motion of the projectile. In each case, the computational approach is validated by comparison with experimental data, and very good agreement between computation and experiment is found. It is believed that this demonstration represents the first known instance of a viscous CFD approach being applied to predict all of the necessary data for performance of linear aerodynamics stability and trajectory analyses.