航空機主翼の翼型変更による複数枚ウィングレット下面の圧力回復効果

抄録

This study examined the effect of pressure recovery on the underside of multi-winglets due to changing the main wing airfoil of an aircraft. Winglets play a role in suppressing the generation of the wingtip vortex and reducing induced drag. Previous research has shown that changing to multiple winglets disperses the wingtip vortex and decreases the induced drag compared to the conventional single winglet. In addition, multi-winglets reduce drag by scattering the wingtip vortices and gain lift by narrowing the gaps between winglets. It seems to be because air flowing through the gaps accelerates and reduces the pressure on the upper surfaces of the following winglets. However, if the winglet’s lower surface pressure decreases due to the shock-wave expansion on the winglet’s underside, the flow rate through the gap would decline; the effect must not emerge. Thus, we applied a main wing airfoil design, which did not generate shock waves on the lower surface, to compare the aerodynamic characteristics and the pressure distribution before and after the airfoil change using numerical analysis. The comparison employed a single wing without winglets in the same way. Consequently, the negative pressure region narrowed on the winglet’s lower surface; the pressure recovered. Accordingly, this contributed to an increase in the lift coefficient of the winglets.