04122672 is referenced by 33 patents and cites 5 patents.

When fan-blade tips in a turbofan aero engine reach a velocity of greater than about mach 1.1, the regular shock-wave pattern near the blade tips degenerates into an irregular pattern as it moves upstream, thus causing "buzz-saw" noise. An anit-buzz acoustic liner of the spaced-cell type forms part of the fan duct wall near the blade tips and combats the degeneration by reinforcing the regular shock-wave pattern at the expense of the irregular one. This is achieved by making the depth of the cells equal to half the wavelength of the blade passing frequency at the supersonic condition of interest.

Title
Duct linings
Application Number
5/784637
Publication Number
4122672
Application Date
April 4, 1977
Publication Date
October 31, 1978
Inventor
Brian W Lowrie
Allestree
GB
Agent
Cushman Darby & Cushman
Assignee
Rolls Royce
GB
IPC
F02K 1/26
F02K 3/06
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