Double bipod fitting to mitigate thermal loading of engine exhaust structures
AssigneeThe Boeing Company
InventorsMichael D. Nevinsky, David T. Misciagna, Joseph Orso, Robert A. DiChiara, Jr, Marc Daniel Spiccia Karasek
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Abstract
A system and method for mitigating thermal loading between engine exhaust structures having different coefficients of thermal expansion. The engine exhaust structure comprises a metallic duct portion, a ceramic duct portion, and a double bipod fitting joining the metallic duct portion to the ceramic duct portion. The double bipod fitting is capable of flexing and taking up the thermal expansion differences between the joined metallic and ceramic ducts across the full temperature spectrum that an engine exhaust structure will experience in service.
Claims20
An engine exhaust structure comprising:
- a metallic duct portion configured to be attached to an aft end of an aircraft engine;
- a ceramic duct portion;
- and
- a set of double bipod fittings equally spaced around the circumferences of both the metallic duct portion and the ceramic duct portion, wherein a gap exists laterally between each double bipod fitting such that each double bipod fitting does not contact an adjacent double bipod fitting;
- wherein each double bipod fitting of the set of double bipod fittings comprises a base flange formed in an arc shape and attached to the metallic duct portion, the arc shape conformal to a curvature of the metallic duct portion;
- wherein each bipod of each double bipod fitting comprises:
- leg members extending from and integrally formed with the base flange and converging at a head, the head attached to the ceramic duct portion;
- and
- a spring loaded fastener configured to attach the head to the ceramic duct portion.
A set of double bipod fittings configured to mitigate thermal loading of a structure having a high coefficient of thermal expansion (CTE) connected to a structure having a low CTE by the set of double bipod fittings, comprising:
- a gap laterally between each double bipod fitting of the set of double bipod fittings such that each double bipod fitting does not contact an adjacent double bipod fitting;
- wherein each double bipod fitting of the set of double bipod fittings comprises:
- a first bipod mounted on a base flange, the base flange formed in an arc shape and connected to a flange of the structure having the high CTE, the arc shape conformal to a curvature of the structure having the high CTE;
- a second bipod mounted on the base flange;
- the first bipod comprising a first pair of leg members extending from the base flange and converging at a first head, wherein a first spring loaded fastener connects the first head to the structure having the low CTE;
- and
- the second bipod comprising a second pair of leg members extending from the base flange and converging at a second head, wherein a second spring loaded fastener connects the second head to the structure having the low CTE;
- wherein the first pair of leg members extend from and are integrally formed with the base flange and the second pair of leg members extend from and are integrally formed with the base flange.
A method for mitigating thermal loading between engine exhaust structures having different coefficients of thermal expansion (CTE) connected by a set of double bipod fittings, wherein the engine exhaust structures comprise an engine exhaust structure having a high CTE and an engine exhaust structure having a low CTE, the method comprising:
- attaching an arc shaped base flange of each double bipod fitting of the set of double bipod fittings to the engine exhaust structure having the high CTE, the arc shape conformal to a curvature of the engine exhaust structure having the high CTE, wherein each double bipod fitting has a CTE similar to the CTE of the engine exhaust structure having the high CTE and wherein a gap exists laterally between each double bipod fitting equally spaced around both engine exhaust structures having different CTE such that each double bipod fitting does not contact an adjacent one of the double bipod fittings;
- and
- attaching a head of each bipod of each double bipod fitting to the engine exhaust structure having the low CTE with a respective spring loaded fastener, wherein each bipod of each double bipod fitting comprises leg members extending from and integrally formed with a respective one of the arc shaped base flanges and converging at the respective head.
Dependencies are inferred from the claim text.