INVESTIGATION OF WING STALL DELAY EFFECT DUE TO AN UNDULATING LEADING EDGE: AN LES STUDY

Abstract

We present LES simulations of the flow over a wing with sinusoidal leading edge undulations. The undulations act as a passive flow control device, offering superior poststall aerodynamic performance relative to the unmodified wing with the same mean chord. The baseline case of a regular wing is also presented for comparison. In all cases the Reynolds number based on bulk velocity and mean chord is equal to 120,000, and the angle of attack is set to 20◦. The study explores the details of the flow physics and the mechanisms by which the post-stall aerodynamic benefit is gained. For the particular set of geometrical and aerodynamic parameters considered, a hitherto unreported physical mechanism by which the undulation offers their benefit is observed. This increased understanding of the flow physics for the current configuration is an important step towards a more general understanding and the incorporation of the technology into practical designs. Potential applications include vertical axis wind turbines, unmanned air vehicles, helicopter blades, and canard surfaces; the present Reynolds number is of particular relevance to the first two of these applications. Introduction Inspired by the high maneuverability of the humpback whale, there has been a surge in interest in the mammal’s hydrodynamic performance, with a view towards capitalising on findings in the field of biomimetics. A key contributing factor to this high maneuverability is the form of the pectoral flippers; specifically the presence of protuberances A