Aerodynamic characteristics of battle-damaged flying-wing aircrafts

Abstract:

To analyze the aerodynamic characteristics of flying-wing aircrafts after being hit by air defense systems, a combination of wind tunnel test and numerical simulation was used to conduct force measurement analysis on a battle-damaged flying-wing aircraft under the condition of Reynolds number Re=1.47×10⁵, and the LES method was used to study the flow field characteristics of some working conditions, which reveals the reasons of the changes in roll and lateral characteristics of flying-wing aircraft caused by battle damage holes. It is found through the wind tunnel test that the battle damage has less influence on the longitudinal aerodynamic characteristics of the flying-wing aircraft, and more influence on the roll and lateral aerodynamic characteristics. The rolling moment coefficient of the battle-damaged flying-wing aircraft within the angle-of-attack range of 10°~30° within the angle-of-attack range obviously larger than that of the undamaged aircraft, and the absolute values of the rolling moment coefficient and lateral force coefficient of battle-damaged flying-wing aircraft of model2 are the largest; within the angle-of attack range of 10°~24°, the absolute values of the rolling moment coefficient and lateral force coefficient of battle-damaged flying-wing aircraft of model3~model5 decrease as the battle damage holes move towards the tip chord direction. The high-precision simulation of the flow field of the battle-damaged flying-wing aircraft through the LES method reveals that the airflow on the lower surface of the wing will flow to the upper surface through the battle damage holes, which induces the flow separation of the wing by the wind area in advance, thus leading to the asymmetric flow separation on the wing surface of the flying wing layout aircraft, and causing an increase in the absolute values of the rolling moment coefficient and lateral force coefficient of the aircraft. And the closer the battle damage hole is to the root chord, the larger the flow separation area induced out of the wing leeward area is, and the more obvious the asymmetric flow phenomenon in the leeward area of the flying wing layout aircraft is. By analyzing the wake vortices of a battle-damaged flying-wing aircraft, it is found that the battle damage hole induces multiple vortex systems behind it, and each vortex system is close to each other and entangles with each other. The vortices induced by the damage holes move towards the tip chord and merge with the tip vortices as the damage holes move towards the tip chord.