ACOUSTIC TREATMENT TO MITIGATE FAN NOISE

摘要

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.