Multi-splice acoustic liner
A liner assembly for an aircraft engine housing includes a noise attenuation structure that is covered by a face sheet. The face sheet covering the noise attenuation structure includes a surface having a plurality of circumferentially spaced apart acoustic energy absorption areas that are interspersed between a corresponding plurality of acoustic energy reflective areas. The acoustic energy reflective areas scatter higher order acoustic modes into a plurality of lower order modes. The difficult to attenuate lower order acoustic modes produced by the various acoustic energy cancel each other out to provide significant improvement in liner noise reduction efficiency.
1. A method of attenuating noise within an aircraft engine housing comprising the steps of:
a) absorbing a portion of generated acoustic energy in an acoustic energy absorption area, where the acoustic energy absorption area comprises a noise attenuation structure disposed under a face sheet portion including a plurality of openings, wherein a width of the plurality of energy absorption areas varies to provide a uniformly orientated repeating pattern within the aircraft engine housing; and
b) scattering higher order acoustic energy at a plurality of locations into a corresponding plurality of lower orders that cancel a portion of the generated lower order acoustic energy scattered from the higher orders.
2. The method as recited in claim 1 , including the step of alternating acoustic energy absorption areas with acoustic energy reflective areas about an inner surface of the engine housing, wherein each of the acoustic energy reflective areas includes a width greater than a width of the energy absorption areas.
3. The method as recited in claim 1 , including the step of determining a number of acoustic energy reflective areas required for attenuating a desired frequency of acoustic energy.
4. The method as recited in claim 3 , including the step of determining the number of acoustic energy reflective areas in relation to a number of fan blades rotating within the housing.