Variable geometry inlet system
A variable geometry inlet system of an aircraft engine includes an inlet duct. The inlet duct includes at least first and second sections moveable between extended and retracted positions such that the inlet duct defines a variable axial length of an inlet passage for selective flight conditions. The inclusion of acoustic treatment may assist in controlling noise.
1. A turbofan aeroengine comprising
a fan and compressor section, a combustion section, a turbine section and a nacelle surrounding at least the fan and compressor section,
the nacelle including a main portion in a stationary relationship with the aeroengine,
the main portion having an annular outer skin and an inner barrel radially spaced apart from each other relative to a main engine axis,
the nacelle including an inlet cowl disposed upstream of the main portion with respect to an air flow entering the nacelle through a front opening defined by an annular lip portion of the inlet cowl,
the lip portion being affixed to an annular outer skin of the inlet cowl, and
each of a plurality of circumferentially distributed plates being pivotally connected at a respective front edge thereof to the lip portion to form an annular inner wall radially spaced apart from the outer skin of the inlet cowl relative to the main engine axis, each of the plurality of circumferentially distributed plates comprising a rear edge opposite to the respective front edge of the respective plate,
the annular inner wall being in a variable truncated conical profile having a fixed diameter at the front edges of the plurality of circumferentially distributed plates and a variable diameter at the rear edges of the plurality of circumferentially distributed plates,
the inlet cowl being operatively connected to the main portion and being axially translatable between a retracted position in which the outer skins of the respective inlet cowl and main portion of the nacelle are immediately axially adjacent each other with the inner barrel of the main portion being partially inserted radially inward of the annular inner wall of the inlet cowl relative to the main engine axis, and
an extended position in which the outer skins of the respective inlet cowl and the main portion of the nacelle are positioned axially spaced apart from each other with the inner barrel of the main portion being partially inserted radially inward of the annular inner wall of the inlet cowl less than the insertion in the retracted position,
the annular inner wall of the inlet cowl and the inner barrel of the main portion thereby forming a length-variable inlet duct for directing the air flow.
2. The aeroengine as defined in claim 1 wherein adjacent plates of said plurality of circumferentially distributed plates overlap or interweave at adjacent side edges thereof to define the annular inner wall of the inlet cowl substantially free of gaps between adjacent plates.
3. The aeroengine as defined in claim 1 wherein the inner barrel of the main portion comprises an annular front edge in contact with the plurality of circumferentially distributed plates, thereby preventing formation of an abrupt step normal to the air flow entering the nacelle, regardless of the position of the inlet cowl.
4. The aeroengine as defined in claim 1 wherein the plurality of circumferentially distributed plates each comprise an acoustic treatment area.