Fluid Mechanism of Wing Rock for Configurations with Chine-Shaped Forebodies

Abstract

The increasing demand to employ sharp-edged geometries in airframe design of advanced fighters to meet stealth requirements has nudged research to explore the new aerodynamic and dynamic characteristics of such configurations. In this paper, the wing rock oscillation is numerically simulated for a generic wing-body model consisting of cropped delta wing of 65°-sweep and chine-shaped forebody. The purpose is to develop a complete understanding of the complex flow interactions that drive the wing rock oscillation. The numerical simulation is based upon coupling the unsteady Euler fluid dynamic equations with the rigid-body dynamic equations in roll. A subiteration algorithm is employed to simultaneously solve the coupled equations. The numerical model exhibits a limit cycle oscillation in roll at an angle of attack of 35° with 16° peak-to-peak amplitude in roll angle. The complex interactions of the forebody-induced flow and the wing leading-edge vortices during wing rock are fully investigated and visualized. Analysis of the observed vortex breakdown dynamics during one entire cycle of the oscillation is also presented.