Duct acoustic analysis of an acoustic liner in a flow duct with grazing flow

Abstract

Resonant acoustic liners for noise reduction in aircraft jet engines consist of several small liner elements. These elements interfere with each other acoustically and exhibit complex behavior. In addition, the grazing flow also affects the acoustic characteristics. A one-dimensional duct acoustic analysis similar to the transfer matrix method was attempted for this phenomenon, and the results simulated the experimental results well. This indicates that once the characteristics of one resonator are obtained, the characteristics of the entire acoustic liner with multiple resonators in a row can be estimated with a simple calculation. This method may also provide a clue to understanding why and how the impedance of acoustic liners changes with grazing flow.