TECHNICAL FIELD

The present disclosure relates generally to fixed-variable vane shrouds, and specifically to a radially fastened fixed-variable vane inner shroud.

BACKGROUND

Gas powered turbines typically include a compressor section, a combustor section, and a turbine section that operate in conjunction to drive rotation of a shaft. Each of the compressor section, the combustor section and the turbine section are fluidly connected by a flow path that allows a fluid, such as air, to flow axially through the gas powered turbine. In order to ensure that proper flow characteristics are maintained within the flow path, multiple static and variable vanes are positioned within the flow path and impart desirable flow characteristics on the fluid flowing through the flow path.

In some example engines, a combination of fixed and variable vanes, referred to as a fixed-variable vane system is incorporated. In typical split shroud manufacturing processes, the two stems resulting from the combination of the fixed-variable vane system cannot be installed simultaneously without significant modification to the fixed-variable vane fastening design.

SUMMARY OF THE INVENTION

In one exemplary embodiment, a gas turbine engine includes a compressor section, a combustor section fluidly connected to the compressor section by a flow path, a turbine section fluidly connected to the combustor section by the flow path, a fixed-variable vane system disposed within the flow path, wherein the fixed-variable vane system includes a plurality of fixed vanes disposed circumferentially about, and radially spanning, the flow path, a plurality of variable vanes, aft of the plurality of fixed vanes, wherein the plurality of variable vanes comprise at least a blade and a button, and wherein the plurality of variable vanes are disposed circumferentially about and radially spanning the flow path, a plurality of inner diameter boxes radially inward of the plurality of fixed vanes and the plurality of variable vanes, each inner diameter box in the plurality of inner diameter boxes including at least one inner diameter box clearance hole receiving a connection feature of at least one corresponding fixed vane, a plurality of inner diameter shoes disposed radially between the plurality of inner diameter boxes and the plurality of fixed vanes and the plurality of variable vanes, each of the inner diameter shoes including at least one inner diameter shoe clearance hole for receiving the connection feature, and at least one button hole for receiving the button of the variable vane.

In another exemplary embodiment of the above described gas turbine engine, each variable vane in the plurality of variable vanes is interfaced with one fixed vane in the plurality of fixed vanes.

In another exemplary embodiment of any of the above described gas turbine engines, the inner diameter box at least partially defines an inner diameter of the flow path.

In another exemplary embodiment of any of the above described gas turbine engines, the connection feature is a trunnion.

Another exemplary embodiment of any of the above gas turbine engines includes a bushing disposed in the inner diameter box clearance hole and the inner diameter shoe clearance hole, wherein the bushing is between a trunnion of a fixed vane and an outer diameter of the inner diameter box clearance hole and the inner diameter shoe clearance hole.

In another exemplary embodiment of any of the above described gas turbine engines, the button holes in the inner diameter shoe comprise a first hole having an upstream edge with a radial depth of zero and a downstream edge with a radial depth larger than zero, and wherein a nesting hole protrudes radially inward from the button hole and receives a connection feature of a variable vane.

In another exemplary embodiment of any of the above described gas turbine engines, a plurality of inner diameter shoes comprises circumferentially adjacent inner diameter shoes, and wherein each of the inner diameter shoes is disposed radially between at least one of the fixed vanes in the plurality of fixed vanes and one of the inner diameter boxes in the plurality of inner diameter boxes.

In another exemplary embodiment of any of the above described gas turbine engines, each inner diameter box in the plurality of inner diameter boxes is interfaced with at least one circumferentially adjacent inner diameter box in the plurality of inner diameter boxes.

An exemplary embodiment for a split case assembly for a gas turbine engine includes an outer diameter case defining a partial case structure for a gas turbine engine, a plurality of fixed-variable vanes attached to an inner diameter surface of the outer diameter case each of the fixed-variable vanes protruding radially inward from the outer diameter case, each of the fixed-variable vanes in the plurality of fixed-variable vanes being interfaced with one of a plurality of inner diameter boxes at a radially inward end of the fixed-variable vane, such that the inner diameter boxes define an inner diameter of a flow path and the outer diameter case defines an outer diameter flow path, and wherein each of the fixed-variable vanes are interfaced with the one of the plurality of inner diameter boxes through at least one inner diameter shoe in a plurality of inner diameter shoes.

In another exemplary embodiment for the split case assembly described above, each of the fixed-variable vanes comprises a fixed vane portion interfaced with a variable vane portion, and wherein an orientation of the fixed vane portion is constant relative to the flow path.

In another exemplary embodiment for any of the split case assemblies described above, each of the fixed-variable vanes includes a fixed vane stem, and wherein each of the fixed vane stems protrudes through a clearance hole in one of the plurality of inner diameter boxes and a clearance hole in one of the plurality of inner diameter shoes.

Another exemplary embodiment for any of the split case assemblies described above includes a bushing disposed between the fixed vane stem and an outer diameter of the clearance hole in one of the plurality of inner diameter boxes and the clearance hole in one of the plurality of inner diameter shoes.

In another exemplary embodiment for any of the split case assemblies described above, the plurality of inner diameter boxes includes a starter inner diameter box and at least one additional inner diameter box, and wherein the clearance holes in the starter inner diameter box are clocked, and wherein the clearance holes in the at least one additional inner diameter box are keyed.

In another exemplary embodiment for any of the split case assemblies described above, each inner diameter box in the plurality of inner diameter boxes is interfaced with an adjacent inner diameter box, each inner diameter box includes a radially aligned edge having a reduced circumference, and wherein the radially aligned edge is received in an adjacent inner diameter box.

In another exemplary embodiment for any of the split case assemblies described above, each of the inner diameter shoes comprises a plurality of clearance holes and a plurality of button holes, wherein the number of clearance holes and the number of button holes is the same.

In another exemplary embodiment for any of the split case assemblies described above, each of the button holes comprises an upstream edge having a first depth and a downstream edge having a second depth, and wherein the second depth is greater than the first depth.

In another exemplary embodiment for any of the split case assemblies described above, the first depth is zero.

An exemplary method for assembling any of the split engine cases described above includes radially installing a plurality of fixed-variable vanes in an outer diameter fan case, sliding at least one inner diameter shoe axially, relative to an axis defined by the outer diameter fan case, such that a connection feature of each fixed vane portion of the fixed-variable vanes is received in a clearance hole, and such that a button portion of each variable vane portion of the fixed-variable vanes is received in a button hole in the inner diameter shoe, interfacing the at least one inner diameter shoe with a plurality of inner diameter boxes, such that each of the inner diameter boxes receives at least one of the connection features in a corresponding clearance hole, such that the inner diameter boxes define an engine flow path inner diameter, and securing each of the inner diameter boxes in place using a fastener connected to the connection feature.

Another exemplary embodiment of the exemplary method for assembling any of the split engine cases described above includes interfacing each inner diameter box with at least one adjacent inner diameter box by shifting one of the inner diameter boxes circumferentially after the connection feature is received in the inner diameter box clearance holes.

In another exemplary embodiment of the exemplary method for assembling any of the split engine cases, interfacing the at least one inner diameter shoe with the plurality of inner diameter boxes comprises ensuring that each joint between one of the inner diameter boxes and an adjacent of the inner diameter boxes is overlapped by at least one of the inner diameter shoes.

These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.

