Sound suppression means for rotating machinery

Claim 2

Means for reducing the noise propagated by an appurtenance disposed in a duct of an air propulsor where one member of said appurtenance extends in the air path of the duct forming a wake downstream thereof and being disposed upstream of another member of said appurtenance also extending in the air path of the duct, said one member being enclosed defining a cellular structure each cell being an acoustic chamber and having at least one surface over which the air passes, means for inducing a portion of the air in said duct to flow continuously in a given direction through openings formed in said surface and through said acoustic chambers so as to remove strata of boundary layer adjacent said surface and reduce the size of said wake for minimizing the generation of and for absorbing a portion of the generated noise.

Claim 3

Means as claimed in claim 1 wherein said means for inducing a portion of the air is a suction pump.

Claim 4

Means as claimed in claim 1 wherein said one member is inlet guide vanes having an airfoil section, slots in the airfoil section permitting boundary layer air adjacent said airfoil section to pass internally of said inlet guide vane.

Claim 5

Means as claimed in claim 3 wherein said other member is a rotating fan rotatable about an axis of rotation, a discharge passage in coincidence with said axis of rotation and connection means interconnecting said slots and said discharge passage.

Claim 6

In combination, means for reducing noise propagated by an appurtenance disposed in a duct of an air propulsor where one member of said appurtenance extends in the air path of the duct forming a wake downstream thereof and being disposed upstream of another member of said appurtenance also extending in the air path of the duct, and means for suppressing noise of said members, said one member being enclosed and having at least one surface over which the air passes, means for inducing a portion of the air in said duct to flow continuously in a given direction through openings formed in said surface so as to remove strata of boundary layer adjacent said surface and through acoustic chambers and reduce the size of said wake, sound suppression means adjacent said surface such that the air induced by said inducing means passes through said sound suppression means.

Claim 7

In combination, means for reducing noise propagated by an appurtenance disposed in a duct of an air propulsor where one member of said appurtenance extends in the air path of the duct forming a wake downstream thereof and being disposed upstream of another member of said appurtenance also extending in the air path of the duct, and means for suppressing noise of said members, said one member being enclosed and having at least one surface over which the air passes, means for inducing a portion of the air in said duct to flow continuously in a given direction through openings formed in said surface so as to remove strata of boundary layer adjacent said surface and through acoustic chambers and reduce the size of said wake, sound suppression means adjacent said surface such that the air induced by said inducing means passes through said sound suppression means.

Claim 8

The combination as claimed in claim 5 wherein said one member includes a bottom and top surface defining an airfoil, a core formed by a plurality of cells each defining an acoustic chamber, each of said cells having an opening communicating internally thereof for leading boundary layer air adjacent said airfoil through openings formed in said bottom and top surfaces through said cells and into said air inducing means.