Divergent Nozzle Seals with Bridge Brackets
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Solution Overview
Problem
Convergent/divergent nozzle systems face limitations in achieving a significant area ratio range due to restrictions at the interfaces between flaps and seals, which hinder the flexibility needed for efficient engine performance and thrust optimization.
Innovation Solution
A flap and seal arrangement is implemented, where convergent and divergent seals are pivotably connected with bridge brackets providing axial and radial support, allowing for increased area ratio range without axial sliding of the divergent seal relative to the divergent flap, and featuring radiused surfaces to reduce radar cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flaps and seals slide relative to each other to accommodate flexibility, then the nozzle can change orifice area, but the interface between flaps and seals restricts the area ratio range
Solution Approach 1:
The patent extracts the sealing function from the sliding interface between flaps and seals. By providing seals that extend beyond the gaps between adjacent flaps and contact the opposite flap, the sealing function is separated from the sliding mechanism, allowing the sliding interface to be simplified and the area ratio range to be increased without compromising sealing effectiveness.
Solution Approach 2:
The seals are positioned to contact the opposite flap before the flaps reach their maximum relative displacement. This preliminary contact prevents gas leakage at the interfaces during the entire range of motion, enabling the flaps to slide freely over a larger area ratio range without worrying about sealing failures at the extremes of motion.
2Productivity
If the area ratio range is increased for better engine performance, then thrust efficiency improves, but the interface restrictions between flaps and seals must be overcome
Solution Approach 1:
By extracting the sealing function from the sliding interface and providing seals that contact the opposite flap, the patent removes the interface restriction that previously limited the area ratio range. This allows the nozzle to achieve a significantly larger area ratio range, directly improving engine thrust efficiency across all operating conditions.
3Reliability
If seals are positioned to prevent gas leakage at sliding interfaces, then sealing effectiveness improves, but the sliding capability and flexibility are reduced
Solution Approach 1:
The patent extracts the sealing function from the sliding interface by providing seals that extend beyond the gaps and contact the opposite flap. This separation allows the sliding interface to be simple and flexible while the seals independently provide reliable sealing throughout the entire range of motion, preventing gas leakage without restricting sliding capability.
Solution Approach 2:
The seals act as intermediaries between the flaps, contacting the opposite flap to prevent gas leakage while allowing the primary flaps to slide freely relative to each other. This intermediary sealing approach maintains sliding flexibility while ensuring sealing effectiveness, as the seals accommodate the relative motion between flaps.
Data Source
AI summary
A nozzle system includes a multitude of circumferentially distributed divergent seals that circumscribe an engine centerline. Each divergent seal includes an interface between a forward seal bridge bracket and an aft seal bridge bracket with a forward bridge support and an aft bridge support which provides axial and radial support for the divergent seals between adjacent divergent flaps. A divergent-convergent seal joint structure includes a horn and a fork. By having the forward bridge bracket retain the divergent seal in the axial direction, there is no need for axial sliding of the divergent seal relative to the divergent flap. The joint structure provides circumferential support as the axial and radial support are provided by the bridge-bracket interface. The joint interface permits the forward end section of the divergent seal and the forward end section of the divergent flap to include a radiused surface which provides a smooth interior interface between the convergent section and the divergent sections.