Project UNLIMITED - Applied Liner Research in Germany

In the field of noise reduction of aero-engines passive acoustic silencers, so-called liners still seem to have some potential for improvement. UNLIMITED is a transfer project funded by the German Research Foundation (DFG) and deals with UNiversal Liner Impedance Modelling based on Improved Tests and EDuction methods. Partners from university (TU Berlin) and German Aerospace Center (DLR) work together with the liner manufacturer PFW Aerospace AG to combine knowledge in experimental testing, CAA techniques and production know-how. The special production process of the investigated liners results in non-locally reacting behaviour which is one of the main issues of the project. Possibly, this behaviour could be used to improve the damping characteristics of liners. Besides, the research is used to gain a better understanding of non-linear effects and influences due to higher order mode excitation on liners under grazing flow conditions