Fundamentals of Unsteady Aerodynamics

Course content

The students define unsteady motion, parameters, and aerodynamic load. Students understand and classify the sources of unsteadiness: impulsive motion, simple harmonic motion, gust, and arbitrary motion. The students know the classical theory of unsteady incompressible flow about an airfoil. The students can distinguish between the various corresponding theories: Theodorsen’s theory of a harmonically pitching and plunging airfoil, Wagner’s step response, Küssner’s sharp-edged gust, and Sear’s sinusoidal gust. The students know about the limitations of unsteady aerodynamics classical theory, unsteady aerodynamics modeling, and various engineering applications. The students discuss research and modern topics in unsteady aerodynamics and review selected literature in these topics, e.g.: static stall, dynamic stall, the vortex lift, and flapping wing theory. The students apply this knowledge to choose the approach and tools to analyze unsteady flow for various engineering applications.

• Introduction and review: history review, steady airfoil characteristics- Lift, drag, pitching moment, source of unsteady aerodynamic loading, definitions of unsteadiness parameters: e.g. reduced frequency and reduced time
• Unsteady incompressible flow about an airfoil: Unsteady attached flow, Classical potential flow theory of unsteady aerodynamics, principles of quasi-steady thin airfoil theory, Impulsive motion, Simple harmonic motion: Theodorsen’s theory, indicial response: Wagner’s problem, gust response: Sharp-edged gust: Küssner’s problem, sinusoidal gust: sear’s problem, Duhamel integral
• Unsteady compressible flow: Subsonic and transonic flow
• Modern topics in unsteady aerodynamics: Flow past finite wing, the vortex lift, bio-inspired unsteady aerodynamic (flapping-wing theory at low Reynolds number, dynamic stall, static stall), applications and numerical modeling