On Fluid-Structure Interaction and Noise Generation of an Aircraft Flap Cove Seal

Abstract

Airplane seals such as the aircraft flap cove seal in particular have to deal with the air's fluid inertial force while maintaining shape, e.g. to ensure tight and contour-fitting closing when retracting slat and flap from high-lift to clean chord cruise wing setting. The present study features an experiment which was conducted in July 2025 at the Aeroacoustic Wind Tunnel Braunschweig (AWB) as part of the EU project FALCON. The test data includes a Benchmark experiment for Fluid-Structure interaction solvers. The general research objective is to grant the seal's structural safety by avoiding an aerodynamic effect which causes the seal to curve. The effect is here characterized with help of two parameters: the gap flow inlet to outlet area ratio at rest as well as the dimensionless bending compliance of the seal against fluid inertial forces. The seal is initially operated at normal non-excited conditions, will then be excited and finally pushed to the verge of destruction. The seal excitation is accompanied with fluid-structure interaction tones. This paper focuses on the Rossiter-like open cavity tones which also characterize the noise generation mechanisms of an aircraft flap cove seal. The geometry can be described as a complexly curved cavity with overhanging flexible leading edge seal and a secondary body (i.e. the flap) whose relative distance to seal and main wing allows to distinguish between the two main Rossiter sub-effects: (A) The conventional Rossiter effect, and (C) the FSI-coupled Rossiter effect. The conventional Rossiter effect with blocked indirect return path (B) is also studied.