Numerical Investigation of Blended and Raked Winglets Characteristics

MOHAMMED HUSSAIN FAROOK, VISHNU KUMAR G. C.

Department of Aeronautical Engineering

Hindustan Institute of Technology and Science

Chennai

INDIA

Abstract: - This research compares the efficiency of various winglet designs to reduce lift-induced drag by

for increasing the lift coefficient while lowering the contributions of frictional and vortex drag components. It

was observed that the lift increased with the winglet tips, the increase in frictional drag caused by the wetted

surface area is a barrier to aerodynamic efficiency. The findings indicate that the chevron-type tips is best in

reducing drag. It is outperformed by wings without chevron winglets in terms of lift-to-drag ratio. It is determined

that chevron tips are the best winglet as their aerodynamic efficiency is essential for increasing flight range and

endurance. Overall, it is observed that winglets are more efficient at lower aspect ratios and that a moderate aspect

ratio of 10 offers the greatest increase in aerodynamic efficiency.

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Key-Words: - Winglets, Blended type, Raked type, CFD, Vortices

Received: March 14, 2023. Revised: November 25, 2023. Accepted: December 27, 2023. Published: January 31, 2024.

distributions across a wing. Owing to the wing's

finiteness, the circulation creates tip vortices,

which are three-dimensional effects near the

wingtips, as seen in Fig. 1. These vortices create

lift-induced drag known as vortex drag. The lift-

induced drag impacts the three-dimensional

vortex flow around the wingtip region. Hence the

winglets can stop the flow on the upper surface

of the wing from flowing over it, which

eliminates the wing tip vortices. As a result, the

aerodynamic effectiveness of a wing tip sail, to

analyze the winglets to reduce the lift-induced

drag. Many tip-device combinations have

potential benefits; however, [3] studies that

include all pertinent variables have not revealed

any one configuration to have a clear overall

advantage over the others. On par with changes

that could result from the implementation of a

modified few locations on the wingtip can be

modified without having a significant effect on

areas may come together to form a single vortex.

This lone vortex travels in a straight line behind

the wing and interacts favorably with the other

components of the fuselage, increasing the

aircraft's range as shown in Figure 1.

2 Problem Formulation

The commercial CFD tool Ansys Fluent 19.2 has

been used to simulate the exterior flow

aerodynamics numerically. Using a second-

order centered difference technique for the

diffusive terms, the variable values are

interpolated at the face positions from their cell-

centered values. A second-order upwind

technique is used to interpolate the convective

terms at cell faces. The least squares cell-based

The pressure checkerboard instability is avoided

by using the Rhie-Chow interpolation approach

since the solution occurs in collocated meshes.

For the turbulence modeling, k – ω and SST

model is used [5]. By resolving stable Reynolds

averaged three-dimensional Navier Stokes

equations, the current case's solution is sought.

The Spalart Allmaras, k - ɛ, and k – ω and SST

RANS CFD models were taken into

consideration before the k - omega shear stress

model was selected. This choice was taken after

taking into account how well the K-omega model

could depict the impacts of turbulence. This is

because the higher-order stress relaxation terms

were correctly predicted. The near-field viscous

greater flow resolution with the available

computing resources. The two-equation model

that was used in the current study's mathematical

formulation is stated as,

Turbulence Kinetic Energy

(1)

(2)

3 Methodology

computational fluid dynamics (CFD) on two

modified shapes of winglets: blended and raked.

To determine the significance of a winglet, the

results of these comparisons are made with wing

without winglets. The Ansys Fluent Solver is

used to do the CFD simulation for an angle of

three-dimensional wing with a 3m span, 0.25

m chord at the root, and 0.2m chord at the

wingtip and 0.15m height of the blended winglet

was modelled using the NACA 2412 airfoil [8,

4]. The calculated wing area is 0.6 m2. It should

be mentioned that the majority of the studies in

design its geometry. The blended, raked, and

modified winglets depicted in Figure 2 & 3 are

attached to the baseline wing. The study's

[4] Gautham Narayan, Bibin John, 2016, Effect of

[5] Wilcox, D.C. Turbulence Modeling for CFD;

[6] F. R. Menter, “Zonal Two Equation k-ω

[8] Abbott, Ira H., Albert E. von Doenhoff, and

[9] Jason E. Hicken and David W. Zingg, Induced-

[10] Shollenberger, C.A. Application of an

Optimized Winglet Configuration to an

Advanced Commercial Transport; Technical

Report NASA-CR-159156; NASA:

Washington, DC, USA, 1979.

[11] Smith, L.; Campbell, R. Effects of Winglets on

the Drag of a Low-Aspect-Ratio Configuration;

Washington, DC, USA, 1996.

[12] Joel H, Daniel P, Thomas Y, Aerodynamic