The broadband component of fan noise has grown in relevance with the increase in bypass ratio and incorporation of advanced fan designs. Therefore, while the attenuation of fan tones remains a major factor in engine nacelle acoustic liner design, the simultaneous reduction of broadband fan noise levels has become more important. Advanced Mutli-Degree-of-Freedom liners have been developed to address the broadband component This paper reports the results of the attenuation achieved from a Mutli-Degree-of-Freedom liner installed in the bypass section of a scale model highspeed fan. Attenuations relative to the hardwall configuration and to a traditional Single-Degree-of-Freedom liner are presented.
展开▼
