Aeroacoustics and Vibroacoustics

Flow instabilities, wave propagation phenomena, and structural vibrations are current topics of this research area. Let us first look at the beautiful aspects of flow acoustics, music, and speech formation of humans and animals. In classical musical instruments, energy is usually transferred in concentrated form to the acoustic wave via mechanical or fluid dynamic excitation. The produced acoustics are then amplified by a cavity (resonating body) and perceived by the ear as a distinctive and clear sound. The human voice also functions according to this principle. Speech is the most important and most basic form of human communication. People suffering from voice disorders are restricted in their everyday life and quality of life severely. Within the project "Numerical computation of the human voice source", a numerical model for the supportive treatment of voice disorders is being developed. 

Especially the fluid-structure-acoustic interaction is the basis for a multitude of parasitic effects of technical and medical applications, which influence our daily life through acoustic emissions. Applications with parasitic acoustics include

•    The transportation industry (automobile, aircraft, railroad) 
•    Moving parts of machines in production and manufacturing (furnaces, separation systems, valves). 

Each of these effects is based on the same scenario as previously presented for musical instrument. Energy is concentrated and transferred to the acoustic wave via mechanical and fluid dynamic excitation. The produced acoustics are then amplified by a cavity (resonating body) and perceived by the ear as a distinctive and clear sound. 
 

Sound sources of an axial fan

The following methods provide an overview of the capabilities using measurements and simulation:

-    MODELING: By appropriate modeling of the acoustic excitation, we use adaptable workflows and efficient methods, which reduce the calculation effort considerably. Achievement of the last years is the derivation of the scalar perturbation equation that has been applied to various applications like the sound field simulation of HVAC systems.

-    SOUND SOURCE ANALYSIS: Besides the sound field, the sound sources causing acoustics are of essential importance. We visualized and analyzed the sound sources both virtually and experimentally. The result is a 3D sound source distribution based on simulation visualization or, after measurements with a microphone array.

-    SIMULATION and VALIDATION: Considering product development, we provide a scalable, flexible, efficient, and validated simulation sequences that can boost your R&D processes. These sequences include aeroacoustic measurement methods and the simulation tool "openCFS", a high-end finite element and data transformation framework.

Generated sound of an axial fan

Our focus is physical understanding, scalability, and flexibility. We developed within fundamental and industrial research projects efficient virtual acoustic prototyping and designing tools for several application areas:

•    Private transport (automotive)
•    Public transport (aviation, railways, underground)
•    Technical applications (vehicle noise, noise vibration and harshness, heating-ventilation-air conditioning systems, turbocharger, fuel cell, fans, silencer, valves)
•    Medical applications (prothesis, human phonation, hearing aid)
•    Reducing noise source and absorbing technology (metamaterial, absorbers)