Interaction Mechanism of Vortex System Generated by Large Civil Aircraft Afterbody

摘要

The evolution of vortex system in the wakes of the simplified large civil aircraft afterbody is simulated with the improved delayed detached eddy simulation (IDDES) method and adaptive mesh refinement technology. First of all, the physical characteristics of afterbody vortex system are presented to perform qualitative analysis. Results based on two-dimensional kinematic analysis demonstrate that three phases show up in vortical interaction including formation, wake evolution and wake interaction. Further, two patterns of vortical interaction are clearly identified as follows: strong straining interaction (SSI) and strong rotating interaction (SRI). Compared with SRI, SSI features considerable circulation decrease of 20% in formation phase and interaction intensity reduction of up to 45% at downstream wake location of eight-characteristic length. It is attributed to that the circulation of afterbody primary vortex pair (APVP) has declined in formation phase due to the remarkable stress deformation imposed by horizontal tail root vortex pair (HRVP) in SSI, whereas the tip vortex pair (HTVP) obtains a circulation augmentation for more dramatic convective diffusion and fluid entrainment in SRI. Above all, the inner connection between kinematic characteristics and vortex induced drag is revealed quantitatively, which offers a novel perspective to reduce crusing resistance of aircraft afterbody.