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US 9,957,840 B2Granted
Acoustic treatment to mitigate fan noise
AssigneeUnited Technologies Corporation
InventorsDavid A. Topol, Bruce L. Morin, Dilip Prasad, Thomas J. Ouellette
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Abstract
A gas turbine engine has a propulsor including a fan and a liner positioned upstream of the fan. The liner has a backing plate, a cellular structure with cells extending from the backing plate, and a perforated sheet with a depth defined as a distance between the perforated sheet and the backing sheet. The depth is selected to achieve a desired ratio of the depth relative to a gap?. A depth to gap ratio is substantially in a range of 0.035 to 0.08. A method is also disclosed.
Claims6
A gas turbine engine comprising:
- a propulsor including a fan;
- and
- a liner positioned radially outwardly and upstream of said fan, said liner having a backing sheet, a cellular structure having cells extending from said backing sheet, and a perforated outer sheet facing radially inward with a depth ‘d’ of said cells being defined as a distance between said perforated outer sheet, and said backing sheet;
- said depth in inches is selected to achieve a desired ratio of the depth relative to a blade gap, the blade gap τ being defined by the equation:
- τ
- =
- π
-
-
- D
- B
- where B is the number of fan blades in said fan and D is a fan diameter measured in inches;
- and
- a depth to the blade gap ratio is in a range of 0.035 to 0.08.
11 more elements
Dependencies are inferred from the claim text.