Title: Flow sensitivity to trailing edge design for a two-element airfoil at low Reynolds numbers

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: The sensitivity of flow past a two-element airfoil to changes in the geometry of trailing segment of the main element is studied using Reynolds-averaged-Navier-Stokes simulations at Reynolds numbers, 5 × 10⁴ and 1.5 × 10⁵ and angles of attack in the range 0 to 7 degrees. Adjoint-based gradient data are used to make systematic changes to the shape in a localised region around the trailing edge of the main element with the objective of maximising the lift-to-drag ratio. The introduced shape changes tend to modify the converging-diverging flow passage that forms in the overlap region between main element and flap such that separation on the flap suction surface is delayed. Improvements in lift-to-drag ratio of 28% and 10% are obtained at angles of attack 0 and 5 degrees respectively at lower Reynolds number of 5 × 10⁴ whereas the improvements at higher Reynolds number are comparatively lower.

Keywords: high-lift system; boundary layer separation; boundary layer reattachment; passive flow control; shape modification; adjoint-based gradient.

DOI: 10.1504/PCFD.2025.145999

Progress in Computational Fluid Dynamics, An International Journal, 2025 Vol.25 No.3, pp.159 - 175

Received: 25 May 2024
Accepted: 01 Sep 2024
Published online: 01 May 2025 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article