On Aircraft Lift and Drag Reduction Using V Shaped Riblets

Reducing drag during take-off and nominal (cruise) conditions is a problem of fundamental importance in aeronautical engineering. Existing studies have demonstrated that v-shaped symmetrical riblets can effectively be used for turbulence control, with those with dimensionless depth h⁺ = 15 and dimensionless width s⁺ = 15 having the best drag reduction effect. In the present study, experimental tests have been conducted considering two models of the same size, one with smooth surface, the other with v-shaped riblets of the h⁺ = 15 and s⁺ = 15 type. The results show that for an angle of attack in the 8°~20° range (take-off stage), the maximum lift coefficient can be increased by 22%. For angle of attack between 8° and 14°, a drag reduction effect can be produced using riblets, which increases with the Reynolds number, leading to a decrease in the drag coefficient maximum of 36%. Flow visualization experiments have been carried out by means of Laser Induced fluorescence.