Aerodynamic analysis of variable cant angle winglets for improved aircraft performance

TLDR

Aircraft performance is heavily influenced by induced drag from wingtip vortices, which winglets mitigate to enhance fuel efficiency. The study aims to compare aerodynamic characteristics and assess the performance of winglets at cant angles of 0°, 30°, 45°, and 60° over a range of angles of attack. A rectangular wing prototype with NACA 653218 aerofoil was tested in a closed‑loop wind tunnel at sea‑level conditions (35 m/s) and simulated in ANSYS CFX using the Spalart‑Allmaras turbulence model on a 3‑D unstructured tetrahedral mesh. Results show that lift, drag, and lift‑to‑drag ratios vary with winglet configuration and angle of attack, indicating that fixed winglets cannot deliver optimal performance across all flight phases.

Abstract

Aircraft performance is highly affected by induced drag caused by wingtip vortices. Winglets, referred to as vertical or angled extensions at aircraft wingtips, are used to minimise vortices formation to improve fuel efficiency. This paper describes a wind tunnel experiment and a Computational Fluid Dynamics (CFD) analysis, performed on a rectangular wing prototype (with and without winglet) of NACA 653218 aerofoil section. The objectives of the analysis were to compare the aerodynamic characteristics and to investigate the performance of winglet at cant angles 0°, 30°, 45° and 60° at various angles of attack (AOA). The experimental analysis was performed in a closed-loop wind tunnel at sea-level conditions and free-stream velocity of 35 m/s. The CFD simulations were performed at low subsonic flow speed in ANSYS CFX solver using Finite Volume Method. Spalart-Allmaras turbulence model and 3-dimensional unstructured tetrahedral mesh were used to compute the flow around the model. The aerodynamic characteristics of lift coefficient (CL), drag coefficient (CD) and lift-to-drag ratio (L/D) were compared and it was found that each winglet configuration at a particular AOA had different CL, CD and L/D values, indicating that fixed winglets do not provide optimum aircraft performance at different phases of flight.