초록 ▼

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 she

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.

대표청구항 ▼

1. A gas turbine engine comprising: a propulsor including a fan; anda 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

1. A gas turbine engine comprising: a propulsor including a fan; anda 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⁢⁢DBwhere B is the number of fan blades in said fan and D is a fan diameter measured in inches; anda depth to the blade gap ratio is in a range of 0.035 to 0.08. 2. The gas turbine engine as set forth in claim 1, wherein said depth to blade gap ratio is reached by selecting a desired reactance. 3. The gas turbine engine as set forth in claim 2, wherein said desired ratio of the depth relative to the blade gap is selected by identifying a reactance associated with a desired level of noise attenuation. 4. The gas turbine engine as set forth in claim 3, wherein the depth to blade gap ratio is calculated as: dτ=tan-1⁡(1-X)2⁢π⁢⁢Mtipwherein X is the desired reactance, and Mtip is a tip rotational mach number for a tip of said fan. 5. The gas turbine engine as set forth in claim 4, wherein Mtip equals Mtip=π720⁢c⁢DN1wherein N1 is a fan rotational speed, and c is the local speed of sound at the fan leading edge. 6. The gas turbine engine as set forth in claim 4, wherein the tip rotational Mach number for the tip of said fan is greater than or equal to 0.8, and less than or equal to 1.2.