Preliminary Study of the Effects of Leading-Edge Serration on a Two-Section Planar Wing in ground-effect at Low Reynolds Number

TL;DR

The paper investigates how serrated leading-edges affect a two-element trapezoidal wing operating in ground and non-ground conditions at a low Reynolds number ($Re \approx 2.0\times 10^{5}$). It combines wind-tunnel experiments in a large closed-return facility with RANS simulations (ANSYS Fluent) to evaluate aerodynamic performance and flow structures for straight and serrated leading edges, across out-of-ground- and in-ground-effect configurations at $H=0.4c_{MAC}$. The results show that serrations increase $C_{L,\max}$ and $\alpha_{stall}$ in free air due to counter-rotating vortex pairs, and ground effect generally improves efficiency for both geometries, though high-AoA lift can degrade in-ground due to complex trailing-edge interactions. Overall, the study provides preliminary, experimentally validated insights into serrated leading-edge benefits for low-Re, two-section WIG-like wings and highlights areas for improved numerical modeling of vortex-dominated near-leading-edge flow.

Abstract

A preliminary study has been conducted on the effects of serration on the leading-edge of a two-element trapezoidal wing placed both out-of- and in-ground effect. Aerodynamic performance and flow behaviour were evaluated numerically and validated experimentally. Results indicate an increase in maximum lift coefficient and stall angle obtained implementing a serrated leading-edge geometry due to the flow being re-energized by the formation of a series of counter-rotating pairs of vortices. Results from the analysis of the wing in ground effect appear less well defined. Both leading-edge geometries -- straight and serrated -- show an increase in efficiency due to the proximity to the ground. The wing with the straight leading-edge geometry shows constant improvement up to stall, whilst numerical results show a significant decrease in lift performance at high angles of attack. This may be caused by the lower-fidelity numerical model implemented at higher angles of attack, thus yielding less accurate results.

Figures (13)

• Figure 1: Schematic of the Morkovin Tunnel Gravante2003 - Adapted
• Figure 2: (a) Angle of Attack Mechanism; (b) Wing in the Test Section.
• Figure 3: Instrumented Wings
• Figure 4: Acquisition System Diagram
• Figure 5: Representative meshes for the Straight Wing (a) and the Serrated Wing (b) in ground-effect