Compressor variable vane assembly
AssigneePratt & Whitney Canada Corp.
InventorAndrew R. Marshall
Life of this patent
Estimating the term…
Abstract
A variable vane assembly for a gas turbine engine compressor with a plurality of pivoting variable vanes extending between inner and outer shrouds and having an overhang portion that protrudes from a button at opposed ends of the vane. A plurality of projections, disposed on at least one of the inner and outer shrouds, protrude into the gas path relative to a nominal gas path boundary of the shrouds. The projections are disposed adjacent the overhang portion and have an angled planar surface that is substantially parallel to a plane swept by a terminal edge of the overhang portion when the variable vane is rotated through its vane pivot arc, so that a radial clearance gap between the shroud and the overhang portion remains substantially constant through a substantial portion of the vane pivot arc.
Claims20
A variable vane assembly for a compressor of a gas turbine engine, the variable vane assembly comprising:
- an inner shroud and an outer shroud radially spaced apart from each other and defining therebetween an annular compressor gas path, the inner shroud and the outer shroud each having an annular boundary surface facing the gas path, the boundary surface defining a nominal gas path boundary;
- a plurality of variable vanes radially extending between the inner and outer shrouds, each of the variable vanes being pivotable through a vane pivot arc about a respective span-wise vane axis, the variable vanes having a button disposed on each of the radially inner and outer opposed ends, the buttons being respectively pivotably mounted in corresponding openings formed in the inner shroud and the outer shroud, the variable vanes having an airfoil extending between the buttons on said opposed ends and having a chord between a leading edge and a trailing edge, the airfoil having an overhang portion disposed at at least said opposed ends and protruding beyond each of the buttons to overhang the shroud, and a radial clearance gap being defined between a terminal edge of the overhang portion and the respective inner and outer adjacent shrouds, the terminal edge of the overhang portion defining a plane swept by the terminal edge when the variable vane is pivoted through said vane pivot arc;
- and
- wherein at least one of the inner and outer shrouds has a plurality of projections protruding into the gas path relative to said nominal gas path boundary, the projections disposed adjacent the overhang portion and having at least one angled planar surface that is substantially parallel to said plane, an that said radial clearance gap remains substantially constant through a substantial portion of said vane pivot arc.
A compressor for a gas turbine engine, the compressor comprising:
- an annular inner shroud and an annular outer shroud radially spaced apart and defining therebetween an annular compressor gas flow path;
- at least one rotor having an array of blades mounted on a rotatable shaft, the blades extending across the gas flow path;
- and
- a plurality of circumferentially spaced apart variable vanes located upstream of the rotor and extending across the gas flow path from the inner shroud to the outer shroud, each of the variable vanes being rotatable through a range of rotation about a respective span-wise vane axis, each of the variable vanes defining an airfoil portion with leading and trailing edges, and opposed ends of the variable vane being pivotably mounted to the inner and outer shrouds, the airfoil portion defining a cord length between the leading edge and the trailing edge and having a downstream overhang portion at each of said opposed ends terminating at said trailing edge, a radial clearance gap being defined between a terminal edge of the overhang portion at each of said opposed ends and the respective inner and outer adjacent shrouds, the terminal edge of the overhang portion defining a plane when the variable vane is rotated through said range of rotation;
- and
- wherein a portion of the boundary surfaces of each of the inner and outer shrouds defines a nominal gas path boundary, and at least one of the inner and outer shrouds having an irregular surface profile thereon relative to the nominal gas path boundary, the irregular surface profile comprising a plurality of projections that protrude into the gas path relative to said nominal gas path boundary, said projections having at least one angled planar surface that is substantially parallel to said plane defined by the terminal edge of the overhang portion of said variable vane when pivoted through said vane pivot arc, the radial clearance gap between said angled planar surface and the terminal edge being substantially constant throughout said range of rotation of the variable vane.
A method of reducing compressor vane tip leakage losses in a variable vane assembly of a gas turbine engine compressor, the variable vane assembly having a plurality of pivoting variable vanes extending through a gas path defined between radially spaced apart inner and outer shrouds, the method comprising:
- minimizing a radial tip clearance gap between opposed ends of the variable vanes and the adjacent inner and outer shrouds by providing an irregular surface profile on a portion of a boundary surface of each of the inner and outer shrouds, the irregular surface profile including a plurality of projections that protrude into the gas path relative to a nominal gas path boundary of said boundary surface, and forming said projections having a gap-controlling surface thereon configured such that the radial clearance gap remains substantially constant throughout a pivoting travel of the variable vanes.
Dependencies are inferred from the claim text.