Aerodynamic characterization of low-aspect-ratio swept wings at $Re=400$

TL;DR

This study uses direct numerical simulations to analyze how sweep angles affect the unsteady aerodynamics of low-aspect-ratio wings at Reynolds number 400, revealing lift enhancement due to vortical structures.

Contribution

It provides the first detailed laminar aerodynamic characterization of low-aspect-ratio swept wings at low Reynolds number, highlighting the effects of sweep on lift and drag.

Findings

Sweep increases lift for low-aspect-ratio wings due to vortical structures.

Lift-to-drag ratios improve with sweep angle for low-aspect-ratio wings.

Higher aspect ratio wings show less sensitivity to sweep effects.

Abstract

We perform unsteady three-dimensional direct numerical simulations to study the aerodynamic characteristics of finite-aspect-ratio swept wings with a NACA 0015 cross-section at a chord-based Reynolds number of 400. The effects of the sweep angle ($\Lambda=0^{\circ}-45^{\circ}$) on the aerodynamic force coefficients are examined for finite-aspect-ratio wings ($sAR=0.5$, 1, and 2) over a wide range of angles of attack ($\alpha=0^{\circ}-30^{\circ}$). The unsteady laminar separated flows exhibit complex aerodynamic characteristics with respect to these parameters. The introduction of sweep enhances lift for wings with low aspect ratios of $sAR=0.5$ and 1, due to the lift generated by the vortical structures near the midspan. For these cases, the dependence of drag coefficients on the sweep angle is less noticeable, particularly at lower angles of attack. The lift-to-drag ratios for low-aspect-ratio wings increase with the sweep angle. However, such favorable effects of sweep angle on the lift coefficients and lift-to-drag ratios are not observed for wings with higher aspect ratios, where the midspan effects are relatively weaker over the wing span. The results herein provide a laminar aerodynamic characterization of the low-aspect-ratio wings and complement the unsteady low-Reynolds-number aerodynamic database with highlight on the effect of sweep.