双垂尾不利影响改善措施研究

采用一个典型的双垂尾鸭式布局模型,利用CFD手段对垂尾导致大迎角升力减小现象的机理进行了研究.发现在低速大迎角条件下,前体脱体涡在机身后体诱导出向外的速度分量,致使垂尾处于“侧滑”气流中,增大了垂尾内侧压力,与此伴生的逆压梯度,削弱了前体涡强度和稳定性,从而使飞机升力减小.根据这一发现,设计了减小垂尾面积、垂尾前缘内偏和变化外倾角3种改善措施.通过风洞试验验证,减小垂尾面积和垂尾前缘内偏具有明显的改善大迎角升力特性的效果.

A study on the measures to cut down twin-tails' unfavorable influences

The research was done on a typical canard configuration with twin-tails to find why tails always reduce the lift at high angle-of-attack by using CFD method.It was found that the vortices passing above induced a "sideslip" flow field in the region tails located.The tails thus had higher pressure on the inboard side which put an adverse pressure gradient in the field.It was this gradient to weaken and destabilize the vortices and then to reduce the vortex lift on the whole model.Based on the findings,three improving measures were designed,which were small size vertical tails,toe-in vertical tails and different tail incline angles.The wind tunnel test results showed that the first two received expected effects.