Research On Aerodynamic Shape Optimization Of Winglet

The induced drag caused by the wingtip vortices accounts for more than 30% of the total drag during the flight,and it can even reach 70% during the take-off,landing and climb phases.In the research on reducing the induced drag of the wing,the winglet structure design occupies the main part.Reducing the induced drag caused by the wingtip vortex can not only extend the endurance of the aircraft and reduce fuel consumption,but also improve the performance of the aircraft.For China’s large passenger aircraft’s lift and drag reduction technology,it is extremely important to study the influence of the winglet on the lift and drag of the aircraft during flight,and to explore the winglet device with lift and drag characteristics.In this paper,a large passenger aircraft wing model is established based on the RAE2822 airfoil,and the main wing structure is drawn.Five kinds of wing tip,end plate,fusion type,oblique cutting type and double-feathered type,are selected to install on the main wing structure,which are equal span wing tip extension.k-ω SST two equation model is used to simulate the pressure distribution cloud,pressure isosurface and flow field characteristics of the same span wingtip in cruise and medium high speed flight,and the drag reduction effect and aerodynamic characteristics of them and Wingtip extension are compared and analyzed..The results show that the tip winglet of the end plate has a significant effect on improving the lift,but the drag is significantly increased compared with other winglets.At low angle of attack,the blended winglet has a good performance in the wake and lift drag characteristics.The double feathered winglet can effectively clean up the air flow on the upper and lower wings,but the drag reduction effect is not obvious.However,the lift coefficient is relatively low.Based on the comparative study of flow field characteristics and lift drag characteristics of existing commercial winglets,a winglet with tip splitting deformation is designed,which has the characteristics of different tip types.The surface pressure distribution and lift drag ratio of the winglet with deformation angles of 0 °,30 °,60 ° and 90 ° under different flight conditions are compared.It is found that the 0 ° and 90 ° deformed wing tip has the best lift and drag characteristics at 2 ° attack angle.The results show that the 0 ° and 30 ° deformed wingtips have higher lift drag ratio at 2 ° attack angle and high speed.At 5 ° angle of attack,the lift and drag characteristics of 0 °,30 ° and 90 ° deformed wingtip are increased by 6%-7% compared with 90 ° deformed wingtip in cruise and medium high speed flight.