Title: Effects of trailing edge design on flow around a two-element airfoil placed near a wall

Authors: Dilip Lalchand Parmar; Deepak Kumar Singh; Arjun Sharma

Addresses: Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi – 110016, India ' Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi – 110016, India ' Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi – 110016, India

Abstract: Effects of presence of a wall on aerodynamics of two-element airfoils are studied at Reynolds number of 5 × 10⁴, angle of attack of 5 degrees and varying flap overlap. The primary geometry of airfoil has NACA0012 section as the main element along with a slotted flap. A second geometry for the main element is obtained by local modifications, in the form of downward tilt at the trailing edge and shaping of overlap region. Lift coefficients increase significantly with reduction in wall-distance for both geometries. Geometric modifications at the trailing edge of main element cause higher pressure due to flow blocking on the lower side as well as higher exit speed with flow alignment along the flap surface on the upper side. Improvements in lift coefficients due to geometric changes vary from 7% to 11% when the wall-distance decreases from 1 to 0.15 times the chord length of main element.

Keywords: high-lift system; two-element airfoil; ground effects; shape modifications; adjoint-based gradient.

DOI: 10.1504/PCFD.2026.151112

Progress in Computational Fluid Dynamics, An International Journal, 2026 Vol.26 No.1, pp.20 - 31

Received: 23 Oct 2024
Accepted: 05 Jan 2025
Published online: 14 Jan 2026 *

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