Innovative liner concept for enhanced acoustic damping: hybrid Zero Massflow Liner (ZML)

Kurzfassung

Modern aero-engines require due to their architecture an enhanced damping performance of passive, acoustically absorbing wall treatment, called liner. The concept in thispaper aims on the improvement of the broadband damping compared to the narrow damping behavior of conventional Single-Degree-of-Freedom (SDOF) liner. This study investi- gates a new liner concept based on an additional acoustical excitation of the liner cavity below the liner face sheet. This so-called Zero-Mass ow-liner (ZML) concept was investigated earlier in the framework of combustion chamber liner design. Here, this concept was enhanced by combining a single cavity ZML liner with a honeycomb-structured SDOF liner yielding a hybrid ZML liner concept. Within this work, this concept was investigated in detail focusing on different parameters like the cavity excitation amplitude, the face sheet porosity and the grazing flow in uence. In conclusion, the hybrid ZML concept reveals a signiffcant potential for increased broadband dissipation behavior due to an additional damping effect based on the periodically excited flow through the liner facesheet.