双垂尾对边条翼布局大迎角升力影响机理研究

A study on the effects of the twin-tails on the lift of a LEX-wing configuration at high AOA

对边条翼双垂尾布局的垂尾导致大迎角升力减小现象的机理进行了研究。采用CFD方法分析一个类似于F-22战斗机的模型,发现在低速大迎角条件下,脱体涡流经垂尾外侧;垂尾下部附近气流方向向后并向外;垂尾外侧存在低压区,而垂尾内侧和垂尾间的机身上表面存在高压区。认为脱体涡在垂尾外侧表面产生吸力,在涡核下方诱导出向外的速度分量,致使垂尾处于"侧滑"气流中,从而使其表面压力内高外低,除了产生指向外侧的法向力外,也传递内侧高压至机身上表面。外倾垂尾上向外的法向力和机身上表面的高压区,是减小大迎角升力的直接原因。

It was often seen in the wind tunnel tests that a leading edgy extension wing（LEX-wing） configuration suffered a significant reduction of the lift at high AOA when twin-tails was incorporated.To find the reason,a CFD method was used on a model similar to F-22 fighter.It was found that at high AOA the LEX vortices passed through the field outside both vertical tails and induced the airflow below outboard.It was also found that the pressure was lower on the outboard surfaces of the tails and higher on the inboard surfaces and the fuselage upper surface between the tails.The analyses show that the suction of the LEX vortices acts on the outboard surfaces of tails and that while located in a ＂sideslip＂ flow field induced by the vortices,the tails have circulations surrounded which cause higher pressure on the inboard surfaces of tails and vice versa.The sum of the pressure of each tail is a normal force outboard.When twin-tails incline outboard,the normal forces incline downwards.This contributes a negative lift.Besides,the higher pressure on the inboard surfaces of tails tends to spread over the upper surface of the fuselage.This contributes a negative lift too.