Hot gas intake scroll case assembly for aircraft engine
A scroll case configured for directing combustion gases to a turbine section of an aircraft engine, comprises an outer shell extending around a central axis and having an inlet for receiving the combustion gases, and an inner casting received inside the outer shell and defining therewith a conduit extending around the central axis from the inlet to an axially oriented outlet for directing the combustion gases to the turbine section of the aircraft engine. The inner casting has vanes circumferentially distributed around the central axis and projecting axially across the conduit from a front axially facing surface of the inner casting to a rear axially facing surface of the outer shell. The vanes are fastened to the rear axially facing surface of the outer shell around the axially oriented outlet.
1 . A scroll case assembly for directing combustion gases to a turbine section of an aircraft engine, the scroll case assembly comprising:
an outer shell extending around a central axis and having an inlet for receiving the combustion gases;
an inner casting received inside the outer shell and defining therewith a conduit extending around the central axis from the inlet to an axially oriented outlet for directing the combustion gases to the turbine section of the aircraft engine, the inner casting having vanes circumferentially distributed around the central axis and projecting axially across the conduit from a front axially facing surface of the inner casting to a rear axially facing surface of the outer shell, the vanes fastened to the rear axially facing surface of the outer shell around the axially oriented outlet;
wherein the front axially facing surface of the inner casting includes a front annular bolting flange the vanes spaced radially inwardly from the front annular bolting flange, and wherein the outer shell has a corresponding front annular bolting flange at a front end thereof opposite to the axially oriented outlet of the conduit, the front annular bolting flange of the outer shell bolted to the front annular bolting flange of the inner casting.
2 . The scroll case assembly according to claim 1 , wherein the rear axially facing surface of the outer shell includes a rear annular bolting flange spaced radially inwardly from the front annular bolting flange of the outer shell and disposed radially outwardly from the axially oriented outlet of the conduit, wherein the vanes extend axially from the front axially facing surface of the inner casting to respective distal ends, and wherein the respective distal ends of the vanes are individually bolted to the rear annular bolting flange of the outer shell.
3 . The scroll case assembly according to claim 2 , wherein each of the vanes is fastened to the rear annular bolting flange of the outer shell by two or more bolts threadedly engaged in corresponding threaded holes extending axially through the respective distal ends of the vanes.
4 . The scroll case assembly according to claim 2 , further comprising spacers received in corresponding recesses defined in the respective distal ends of the vanes, the spacers axially trapped between the respective distal ends of the vanes and the rear annular bolting flange of the outer shell.
5 . The scroll case assembly according to claim 4 , wherein each spacer has a pair of holes in registry with corresponding holes defined in an associated one of the vanes for receiving a corresponding pair of bolts used for individually bolting each of the vanes to the outer shell.
6 . The scroll case assembly according to claim 2 , wherein the rear annular bolting flange of the outer shell is located in an axially facing recess defined in a flow boundary side of the rear axially facing surface of the outer shell.
7 . The scroll case assembly according to claim 1 , wherein the outer shell is a casting.
8 . An aircraft engine comprising:
a combustion engine having an exhaust, the combustion engine drivingly engaged to a load rotatable relative to a central axis;
a turbine section in driving engagement with the load to compound power with the combustion engine; and
a scroll case assembly fluidly interconnecting the exhaust of the combustion engine to the turbine section, the scroll case assembly comprising:
an outer casting in the form of a shell extending in a non-axisymmetric fashion around the central axis and defining an inlet fluidly connected to the exhaust of the combustion engine;
an inner casting axially inserted inside the outer casting to define therewith a conduit extending around the central axis from the inlet to an outlet fluidly connected to the turbine section of the aircraft engine, the inner casting having vanes circumferentially distributed around the central axis and projecting axially across the conduit from a front axially facing surface of the inner casting to a rear axially facing surface of the outer casting, the inner casting fastened to the outer casting via a first bolted joint interface at a front end of the scroll case assembly and a second bolted joint interface at a rear end of the scroll case assembly, the first bolted joint interface and the second bolted joint interface spaced radially from one another;
wherein the second bolted joint interface includes a rear annular flange provided at a rear axially facing surface of the outer casting and respective distal ends of the vanes, the vanes individually bolted to the rear annular flange of the outer casting around the outlet of the conduit.
9 . The aircraft engine according to claim 8 , wherein the second bolted joint interface further comprises individual spacers axially trapped between the respective distal ends of the vanes and the rear annular flange of the outer casting.
10 . The aircraft engine according to claim 9 , wherein the individual spacers are received in corresponding recesses defined in the respective distal ends of the vanes.
11 . The aircraft engine according to claim 8 , wherein the rear annular flange is provided in an axially recessed annular portion of the rear axially facing surface of the outer casting.
12 . The aircraft engine according to claim 8 , wherein the second bolted joint interface comprises two or more bolts per vane.
13 . The aircraft engine according to claim 8 , wherein the first bolted joint interface comprises a front annular flange projecting radially outwardly from an outer diameter surface of a front projection at a front end of the outer casting, and a corresponding front annular flange projecting radially outwardly front an outer diameter surface at a front end of the inner casting, the outer diameter surface at the front end of the inner casting sized to fit inside the front projection of the outer casting.
14 . The aircraft engine according to claim 8 , wherein the first bolted joint interface is disposed radially outwardly from the second bolted joint interface, the second bolted joint assembly being radially aligned with the vanes relative to the central axis.
15 . An aircraft engine comprising:
a combustion engine having an exhaust, the combustion engine drivingly engaged to a load rotatable relative to a central axis;
a turbine section in driving engagement with the load to compound power with the combustion engine; and
a scroll case assembly fluidly interconnecting the exhaust of the combustion engine to the turbine section, the scroll case assembly comprising:
an outer casting in the form of a shell extending in a non-axisymmetric fashion around the central axis and defining an inlet fluidly connected to the exhaust of the combustion engine;
an inner casting axially inserted inside the outer casting to define therewith a conduit extending around the central axis from the inlet to an outlet fluidly connected to the turbine section of the aircraft engine, the inner casting having vanes circumferentially distributed around the central axis and projecting axially across the conduit from a front axially facing surface of the inner casting to a rear axially facing surface of the outer casting, the inner casting fastened to the outer casting via a first bolted joint interface at a front end of the scroll case assembly and a second bolted joint interface at a rear end of the scroll case assembly, the first bolted joint interface and the second bolted joint interface spaced radially from one another;
wherein the first bolted joint interface comprises a front annular flange projecting radially outwardly from an outer diameter surface of a front projection at a front end of the outer casting, and a corresponding front annular flange projecting radially outwardly front an outer diameter surface at a front end of the inner casting, the outer diameter surface at the front end of the inner casting sized to fit inside the front projection of the outer casting.
16 . The aircraft engine according to claim 15 , wherein the first bolted joint interface is disposed radially outwardly from the second bolted joint interface, the second bolted joint assembly being radially aligned with the vanes relative to the central axis.