Modelling the vibrational response of structures to high-frequency turbulent boundary layer excitation

Abstract

Modelling the response of complex built-up structures under the influence of distributed and correlated high-frequency force fields is an important aspect in many structural dynamics applications. A prime example of such a forcing is the pressure field applied by a Turbulent Boundary Layer (TBL) on an aircraft in flight. Previous studies focus on the total vibrational power input into the structure and do not consider spatial variations or directional components of the energy input introduced due to correlated forcing. We will close this gap by demonstrating how correlated force fields can be implemented as the source term in a Dynamical Energy Analysis (DEA) treatment determining the resulting vibrational energy distribution in a complex structure. Using Wigner-transformation techniques, we convert force-correlation functions (such as those routinely used to describe TBL excitations) into directional ray-source terms which then provide the source for a DEA treatment. Results are presented for the vibrational energy distribution across a flat plate excited by a fully formed, stationary TBL under a variety of flow conditions. We note that even though the excitation is spatially uniform across the plate, there is a preference for energy to flow in the downstream direction. This leads to a marked enhanced of the vibrational excitation at the trailing edge of the plate.