Effects of Leading-Edge Tubercles on Structural Dynamics and Aeroelasticity

Abstract

The design of tubercles has both aerodynamics and structural considerations. In this chapter, we discuss structural design, stability and aeroelasticity of lifting surfaces that are modified with leading-edge (LE) tubercles. With LE tubercles, bending and torsional frequencies are slightly lower due to the combined effects of spanwise stiffness and inertia variations from spanwise chord length variation and mass redistribution. In the pre-stall regime, lifting surfaces are likely to encounter instability (flutter) due to flexibility and rear placement of the centre-of-gravity. The structural dynamics and unsteady aerodynamics with LE tubercles have opposite influence on margins-of-stability with the latter having the dominant effect. Numerical investigations show that the flutter speed is consistently mildly higher with LE tubercles and they have reduced effect on the margins for stability when concentrated inboard of the wing or on sweptback wings as the sweep angle is increased.