Study on leading-edge vortex/shock interaction and unsteady characteristics of a transonic low-aspect-ratio flying wing

In the transonic flow over a delta wing, the interaction between shock waves and leading-edge vortex (LEV) can cause oscillations in the vortex breakdown position. However, for real aircraft, due to their complex geometries and three-dimensional effects, the characteristics of shock-vortex interactions and the mechanisms underlying vortex breakdown remain to be further investigated. To address this issue, a comprehensive study was conducted using wind tunnel experiments and numerical simulation methods to analyze the aerodynamic characteristics for a low-aspect-ratio flying wing configuration at Mach 0.9. Based on these analyses, the interaction laws and unsteady characteristics between LEV and crossflow/termination shocks were thoroughly investigated, revealing the underlying mechanisms of vortex breakdown. The results demonstrate that as the angle of attack increases, the suction surface of the flying wing successively develops flow structures such as attached flow, LEV, and vortex breakdown, which lead to significant nonlinear characteristics in the lift coefficient. Through detailed flow field analysis, it was identified that crossflow shocks play a pivotal role in triggering secondary vortex formation, while termination shocks are primarily responsible for inducing vortex breakdown. Notably, at an angle of attack of 14°, oscillations in the vortex breakdown position exhibit periodic characteristics. This phenomenon is attributed to the interaction between LEV and the second shock wave on the wing surface, which induces unsteady variations in shock strength and pressure downstream of the second shock wave, consequently causing oscillations in shock position. This study provides valuable insights into the aerodynamic characteristics of complex flying wings under transonic conditions.