© Fraunhofer IBP
In many technical applications, flow noise is the principle source of noise. Through experiments and numerical computational fluid dynamics (CFD) and computational aero acoustics (CAA) simulations, we investigate flow-induced noise in order to identify ways to reduce it and to optimize products.
Based on metrological investigations, simulations and our extensive acoustic know-how, we develop product-specific suggestions for improvement that are tailored to customer requirements. Within the scope of our project work, we also build functional samples and models and conduct extensive tests on them in our laboratories.
In our wind tunnel, we systematically measure the flow noise generated by all types of duct and pipe components (e.g., valves, throttle valves, air outlets, silencers, weather protection grilles). The tests can be performed both on original components as well as models (façade sections, chassis models, etc.).
Systems with their own integrated fan as a flow generator can be set up, operated and investigated under diffuse sound field conditions in the reverberation chamber or under free-field conditions in anechoic chambers, depending on the individual application and issue concerned. Microphone arrays, acoustic camera systems and near-field holography are used to localize and identify dominant noise sources.
From the sound levels and spectra ascertained, we derive sound power parameters and carry out further calculations and analyses, which form the basis for the development of suggestions for improvement.
For detailed measurement and flow dynamics investigations, we have a particle image velocimetry system (PIV) at our disposal.
With the increasing availability of computing power, sophisticated and computationally-intensive numerical simulation methods such as computational fluid dynamics (CFD) and computational aero acoustics (CAA) have become useful tools for supplementing measurement-based analyses of flow characteristics and flow noise.
Against this background, we have strengthened our expertise in CAA and CFD simulation in recent years. So far, these methods have mainly been used to address aircraft construction issues in the context of EU-funded “Clean Sky” research projects. We also successfully transfer these skills to other areas of noise control. Thus, flow noise can be investigated both through measurement-based analyses and simulations at Fraunhofer IBP, enabling us to develop product optimization concepts for our customers.