Vibro-acoustic calculations - Structural vibro-acoustic response to turbulent flow excitation

Turbulent fluids can cause severe vibrations in the structures around which they flow. Ship hulls, aircraft wings, heat exchanger tubes, submarine cables, etc.: many industrial systems are affected. Vibrations induced by turbulent flows can reach unacceptable levels, in terms of noise and wear, for example. Estimating the vibration levels of flow-excited structures helps to limit the acoustic impact or increase the service life of the above-mentioned systems.

This article provides an introduction to vibro-acoustic computation for the vibratory response of a structure subjected to turbulent boundary layer excitation. It is aimed primarily at students of mechanical engineering and, more generally, at scientific computing engineers and plant designers concerned with this issue.

After recalling some background elements (flow-induced vibrations, description of the turbulent boundary layer, auto-correlation and inter-correlation spectra), the paper offers an analysis of the various representations of pressure loading, discussing their assumptions and limitations, and the different ways of obtaining them (empirically or numerically). It then presents a numerical method for calculating a parietal pressure spectrum in more general configurations than those prevailing for analytical models. Finally, a method for calculating the vibratory response of a deformable structure is presented, with a step-by-step approach.

The subject complements numerous presentations on aero-acoustics, hydro-acoustics and numerical simulation in fluid and structural mechanics. These subjects are covered in specific articles available in the Techniques de l'Ingénieur documentation resources. Readers will find these references in the documentation section of this article. An additional bibliography and links to websites provide useful resources for furthering your knowledge of the subject.

At the end of the article, readers will find a glossary of important acronyms, as well as a table of symbols used.