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

Abstract

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.

Keywords

• droop leading edge
• internally blown flap
• stall characteristics
• circulation control
• coanda effect