Numerical study on wake vortex characteristics and aerodynamic benefits of large aircraft in formation flight

Vortex surfing formation flight, a bioinspired lift enhancement and drag reduction technique, holds potential for reducing fuel consumption and extending range, serving as a critical pathway for aviation sustainability. However, its engineering application faces challenges due to the flight-state-dependent evolution of lead aircraft wake vortices and their strong coupling with formation parameters. This study investigates wake vortex evolution characteristics and aerodynamic benefit optimization for large wide-body aircraft (CHN-T2 standard model) at various angles of attack (0°, 1.71°, 3.5°) using RANS simulations with SST turbulence model. Results reveal: Angle of attack significantly alters vortex dynamics, 1.71° induces accelerated wingtip vortex roll-up and enhanced downward convection, while 3.5° triggers an asymmetric dual-vortex system undergoing counterclockwise corotation with inner-wing vortex dominance in far-field. An innovative "wingtip-overlap and co-altitude" formation configuration is proposed, achieving lift-to-drag ratio improvements of 6.26% (0°) to 19.8% (3.5°). Systematic evaluation identifies increased lateral-directional stability risks for trailing aircraft in inboard formations, revealing an angle-dependent stability degradation trend. These findings provide critical parametric support for engineering implementation of formation flight technology.