Influences of muzzle jets of aircraft guns on aerodynamic performance of wings

The core components of an aircraft and the source of its lift are its wings, but lift generation is disrupted by the high temperature and pressure generated on the wing surface when an aircraft gun is fired. Here, to investigate how this process influences the aerodynamic parameters of aircraft wings, the k – ω shear-stress-transport turbulence model and the nested dynamic grid technique are used to analyze numerically the transient process of the muzzle jet of a 30-mm small-caliber aircraft gun in high-altitude (10 km) flight with an incoming Mach number of Ma = 0.8. For comparison, two other models are established, one with no projectile and the other with no wing. The results indicate that when the aircraft gun is fired, the muzzle jet acts on the wing, creating a pressure field thereon. The uneven distribution of high pressure greatly reduces the lift of the aircraft, causing oscillations in its drag and disrupting its dynamic balance, thereby affecting its flight speed and attitude. Meanwhile, the muzzle jet is obstructed by the wing, and its flow field is distorted and deformed, developing upward toward the wing. Because of the influence of the incoming flow, the shockwave front of the projectile changes from a smooth spherical shape to an irregular one, and the motion parameters of the projectile are also greatly affected by oscillations. The present results provide an important theoretical basis for how the guns of fighter aircraft influence the aerodynamic performance of the wings.