Variable impedance liners for aero-engines
Jingwen Guo and Ryu Fattah
Last updated on April 5, 2022
The high bypass ratio of modern turbofan engine results in that the tonal noise decrease while the broadband noise is becoming a more and more important contributor in engine noise. Thus improved acoustic liners should be develop to: 1. Improve the maximum noise attenuation induced by acoustic liners. 2. Broaden the attenuation frequency range by using non-uniform acoustic liners.
Engine intake noise radiation: In the m24n1 case study with no acoustic liner treatment, the bulk of the acoustic energy is concentrated towards the upper wall. As the wave propagates across the inlet there is no change in the acoustic wavelength. However, the wave is diffracted by duct lip.
Non-uniform liner distribution: The possibility of reducing radiated noise by varying the liner properties along the duct in both axial and circumferential directions was investigated. A serrated joint liner distribution was proposed
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Mr. Jingwen Guo is supported by a PhD fellowship from HKUST. Part of the study was supported by the Hong Kong Innovation and Technology Commission (Ref. ITS/038/FP15).