Experimental study on the aerodynamic performance of winglets with curve edged wing of NACA 4412

Abstract

Aerodynamic drag force breakdown of a typical transport aircraft shows that lift-induced drag can be as much as 40% of total drag at cruise conditions and 80-90% of the total drag in take-off configuration. Induced drag is caused due to wingtip vortices formed bythe difference in pressure between the upper and lower surfaces of the wing. The main aim of implementing winglet is to reduce the induced drag as well as to convert them to additional thrust therefore reducing the fuel cost and increasing the efficiency of the aircraft. This thesis deals with the curved trailing edge taperedwing by adding different winglets at the wing tip. NACA 4412 aerofoilplanformis used due to its good stall properties and low roughness effect.

The experimental investigation is carried out in the wind tunnel to explore aerodynamics of wings with three winglet models. For reference curved trailing edged tapered wing is considered as base wing. Including other than base wing three winglets are used namely curved trailing edged tapered wing with blended winglet, curved trailing edgedtapered wing with double blended winglet and curved trailing edged tapered wing with spiroid winglet. All the models are designed using Solidworks. The wing and winglets are manufactured by using wood with same span and equal surface area. All the models are tested at air speed of 98.64 km/h (0.08 Mach) i.e. at Reynolds Number 2.05 x 105 in the closed circuit wind tunnel available at Turbulence Laboratory, Department of Mechanical Engineering, BUET. The Static pressure at different AOA (-4°, 0°, 4°, 8°, 12°, 16°, 20°& 24°) is measured from both upper and lower surfaces of the wing models through different pressure tapings by using a multi-tube water manometer. The aerodynamiccharacteristics (Coefficient of Lift, Coefficient of Drag and Lift to Drag ratio) for different models isdetermined from the static pressure distribution.

The experimental results show that lift to drag ratio increases and induced drag decreasesfor wing models with winglets compared to wing model without winglet for the Reynolds number considered in the present study.