Effect of Leading-Edge Slats at Low Reynolds Numbers

Lance Traub,Mashaan Kaula

doi:10.3390/aerospace3040039

Abstract

One of the most commonly implemented devices for stall control on wings and airfoils is a leading-edge slat. While functioning of slats at high Reynolds number is well documented, this is not the case at the low Reynolds numbers common for small unmanned aerial vehicles. Consequently, a low-speed wind tunnel investigation was undertaken to elucidate the performance of a slat at Re = 250,000. Force balance measurements accompanied by surface flow visualization images are presented. The slat extension and rotation was varied and documented. The results indicate that for small slat extensions, slat rotation is deleterious to performance, but is required for larger slat extensions for effective lift augmentation. Deployment of the slat was accompanied by a significant drag penalty due to premature localized flow separation.

Highlights

The stall of an airfoil or wing is a viscous phenomenon attributed to flow separation [1]
The clean wing denotes that the slat is fully retracted.◦Figure 2 presents the effect of attenuate lift in the attached flow regime
A low-speed wind tunnel investigation was conducted to explore the behavior of a leading-edge slat at a Reynolds number of 250,000

Summary

Introduction

The stall of an airfoil or wing is a viscous phenomenon attributed to flow separation [1]. Representative devices include leading-edge slats, fixed slots and auxiliary airfoils ahead and above the leading-edge, as well as flaps [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. An auxiliary airfoil [2,17] uses a low drag “vane” (typically an airfoil) placed ahead of and above the airfoil/wing. These devices commonly suffer from excessive drag at low angles of attack, but avoid the complication of a retraction mechanism required for a slat. Leading-edge stall control devices work by attenuating the loading over the main wing section and moving the loading peak aft

Methods

Results

Conclusion