Novel liner concepts

  • F. BakeEmail author
  • K. Knobloch
Original Paper


Modern, low-emission aero-engine concepts, such as, for instance, Ultrahigh-Bypass Ratio (UHBR) designs, claim higher demands on the damping performance of acoustic wall treatment, called liner, installed in the engine. New liner concepts are needed providing a more broadband damping efficiency ranging explicitly to the low-frequency range. However, space and weight constrains are still also one of the crucial criteria which need to be fulfilled by the liner structure. To overcome this challenge, two novel liner concepts are presented here. One concept, the hybrid ZML, combines the classical Single-Degree-of-Freedom (SDOF) liner with a Zero-Massflow-Liner (ZML) principle. The other one, the FlexiS concept, takes advantage of the intrinsic material damping of flexible walls within the liner structure. A proof of concepts study of both novel concepts is provided highlighting the enhanced damping performance with respect to broadband capacity and low-frequency damping.


Aeroacoustics Acoustic damping Liner Wall treatment Novel liner concepts 



The authors gratefully acknowledge the valuable contributions of Anita Schulz, Albert Bauer and the LAKS consortium as well as the fruitful discussions with Christoph Richter from Rolls-Royce Deutschland LTD & Co KG. The research leading to these results has received funding from the German Federal Ministry for Economic Affairs and Energy (Luftfahrtforschungsprogramm V) within the framework of the LIST (‘Das Leise InStallierte Triebwerk’) project under grant agreement no. 20T1307B and within the framework of LAKS (‘Lärmabsorbierende Kunststoffstrukturen’) project under grant agreement no. 20E1502A.


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Copyright information

© Deutsches Zentrum für Luft- und Raumfahrt e.V. 2019

Authors and Affiliations

  1. 1.Department of Engine Acoustics, Institute of Propulsion TechnologyGerman Aerospace Center (DLR)BerlinGermany

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