Unsteady flow and wing rock characteristics of low aspect ratio flying-wing

The low aspect ratio flying-wing layout is one of the options of new fighter aircraft，and its dynamic charac⁃ teristics are particularly important. Aiming at the unsteady flow and wing rock of the low aspect ratio flying-wing stan⁃ dard model at a large angle of attack，we employ the Delay Detached Eddy Simulation（DDES）method and the Dy⁃ namic Modal Decomposition（DMD）method to study the unsteady flow，fluctuating pressure and wing rock character⁃ istics of flying-wings. The instability mechanism is analyzed and the method of instability motion control is explored. The results show that the unsteady flow characteristics（Ma=0. 6）of the flying-wing model at a large angle of attack are mainly reflected in the concentrated vortex，vortex breakdown，and spiral wave. The vortex breakdown point oscillates along the vortex axis at the frequency of St=0. 12-0. 23，and the spiral wave frequency is within the range of St=1. 16-2. 33. The wing rock characteristics of the flying-wing model obtained through numerical simulation are in good agree⁃ ment with those of the wind tunnel test. The wing rock phenomenon appears at the angle of attack of 24. 5°-26°，and the roll angle balance position is 28°. It is found that the balance between concentrated vortex flow on the leeward side and separated flow on the windward side is the physical mechanism for the occurrence and maintenance of wing rock. When the upper spoiler is opened for 30°，the control effect of wing rock is not obvious. When the outer aileron is de⁃ flected for 30° downward，the wing rock phenomenon can be well restrained. © 2023 AAAS Press of Chinese Society of Aeronautics and Astronautics. All rights reserved.