战损飞翼布局飞行器气动特性分析

Aerodynamic characteristics of battle-damaged flying-wing aircrafts

关键词:  飞翼布局飞行器  战损  风洞试验  LES  气动特性

Key words:  flying-wing aircraft  battle-damaged  wind tunnel tests  LES  Aerodynamic characteristics

摘要:

为分析飞翼布局飞行器受到防空系统打击后的气动特性,采用风洞试验与数值模拟相结合的方法,对Re=1.47×10⁵条件下战损飞翼布局飞行器进行了风洞试验测力分析,并采用LES方法对部分工况流场特性进行了研究,揭示了战损孔导致飞翼布局飞行器滚转特性和侧向特性出现变化的原因。首先,通过风洞试验发现战损对飞翼布局飞行器的纵向气动特性影响较小,对飞翼布局飞行器的滚转气动特性和侧向气动特性影响较大。其次,迎角10°~30°范围内有战损情况下飞翼布局飞行器的滚转力矩系数明显比未战损情况下大,其中model2战损形式飞翼布局飞行器的滚转力矩系数和侧向力系数绝对值最大。model3~model5一类战损形式的飞行器在迎角10°~24°范围内其滚转力矩系数和侧向力系数绝对值随战损孔向梢弦方向移动而减小。最后,通过LES方法对飞翼布局飞行器流场进行高精度模拟发现:机翼下表面气流会经过战损孔流至上表面,诱导机翼被风区流动提前分离,从而导致飞翼布局飞行器机翼表面的非对称流动分离,引起飞行器滚转力矩系数和侧向力系数绝对值的增大。且战损孔越靠近根弦,其诱导出机翼背风区的流动分离面积越大,飞翼布局飞行器背风区非对称流动现象越明显。结果表明:通过对飞翼布局飞行器的尾涡进行分析发现战损孔会在其后方诱导出多个涡系,且各个涡系之间的距离较近并相互缠绕；随着战损孔向机翼的梢弦移动,战损孔诱导出的脱落涡也向梢弦移动,并与翼尖涡相互融合。

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.