C. Breitsamter

Unsteady aerodynamic excitation of aircraft wing and tail surfaces may evoke from separated and turbulent flows induced by shock boundary layer interactions, burst leading-edge vortex flow structures or airbrake turbulent wake flow. The corresponding excitation of the wing and/or tail structures due to unsteady aerodynamic forces is referred to as ‘buffet’. While for transonic transport aircraft shock induced flow separation at off-design conditions constitutes buffet, the separated flow associated with burst leading-edge and strake vortices is the dominant mechanism for buffet at high agility aircraft. The dominating turbulent flow fields associated with shock induced flow separation or burst large-scale vortices can cause severe surface pressure fluctuations both on the wing itself and on downstream components, particularly, the horizontal and/or vertical stabilizers. The structural response of the aircraft is denoted as "buffeting". Buffeting can have serious impacts on the aircraft, resulting in increased structural vibrations and high accelerations in the area of wing and tail tip sections, structural maximum and fatigue loads, and degraded flight characteristics. Buffeting, with its interaction of unsteady aerodynamic forces, inertia forces, and elastic forces, represents a dynamic aeroelastic response problem. It is treated as limitation of the flight envelope in verification and certification processes. Unsteady aerodynamic forces consists of flow separation dependent aerodynamic forces (shock induced or due to vortex bursting) and motion induced aerodynamic forces (oscillations of the elastic structures in their eigenmodes). Due to its significance as a flight envelope limit and the complex coupling mechanisms between flow scenarios and structural properties, buffeting has been a subject of research in the field of aeroelasticity from the very beginning. This overview paper addresses some main mechanisms of vortex-induced and shock-induced buffet flow. Associated fluctuation intensities of surface pressures are reported and surface pressure frequency characteristics related to fluid mode instabilities are analyzed. Semi-empirical relations to quantify buffet onset and buffet intensity levels are further given.

Deutscher Luft- und Raumfahrtkongress 2025, Augsburg

Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn, 2025

Conference Paper

englisch

21,0 x 29,7 cm, 13 Seiten

urn:nbn:de:101:1-2511031355087.510761656261

Buffeting, FOR 2895

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Breitsamter, C. (2025): Buffet and Buffeting Characteristics of High Agility and Transport Aircraft. Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V.. (Text). urn:nbn:de:101:1-2511031355087.510761656261.

03.11.2025