前缘下垂结合内吹式襟翼失速特性研究

Research on Stall Characteristics of Droop Leading Edge Combined with Internal-blowing Flaps

内吹式襟翼具有高效的增升能力,但失速迎角在较高的吹气动量系数下下降明显,为改善其失速特性,研究内吹式襟翼加装前缘下垂后的失速特性。对前缘下垂结合无缝襟翼的亚声速翼型在环量控制作用下的流场进行数值模拟,研究吹气动量系数对失速特性的影响规律,前缘刚性偏转、弯度变化和厚度变化对失速特性的改善作用,以及改变襟翼偏角研究前缘下垂的作用效果。结果表明:随着吹气动量系数的增加,失速迎角先迅速下降再略微增加;前缘下垂装置减小了翼型上表面逆压梯度,延缓了翼型边界层动量厚度随迎角增加而增加的趋势,能有效提高失速迎角;通过逐渐改变前缘表面曲率,实现了前缘下垂设计对失速特性改善的最好效果。

The internally blown flap is of efficient lift enhancement ability,but stall angle of attack drops significantly at a higher jet momentum.In order to improve the stall characteristics,the stall characteristics of the internally blown flap with the droop leading edge is studied.The numerical simulation of flow fields of a subsonic airfoil with droop leading edge combined with seamless flaps under the effect of circulation control are conducted.The influence rules of the blowing momentum coefficient on the stall characteristics are studied.The effects of leading edge rigid deflection,camber and thickness changes on the improvement of stall characteristics are studied.The effects of doop leading edge with different flap angle are also studied.The results show that,with the increase of the blowing momentum coefficient,the stall angle of attack is firstly droped rapidly and then slightly increased.The pressure gradient on the upper surface of the airfoil is reduced by the leading edge droop devices,the trend of the momentum thickness of the foil boundary layer increasing with the angle of attack is delayed,and the stall angle of attack is increased effectively.By gradually changing the curvature of the leading edge surface,the target that the leading edge droop design has the best effect on the improvement of stall characteristics is realized.