Split Hoop Seal Assembly with Integral Springs for Gas Turbine Exhaust
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Solution Overview
Problem
Gas turbine engine exhaust duct seal assemblies face challenges in accommodating wide temperature ranges and significant radial and axial movements, particularly in STOVL applications, requiring complex designs to manage thermal growth and pressure deflections effectively.
Innovation Solution
A seal assembly featuring a split hoop with multiple springs that interface with both exhaust ducts, allowing for axial displacement and rotation, and incorporating a pre-load mechanism to maintain contact between seal surfaces, reducing complexity and weight by minimizing retention features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a seal assembly is designed to accommodate wide temperature ranges and significant radial and axial movements, then the seal assembly can effectively manage thermal growth and pressure deflections, but the design complexity increases
Solution Approach 1:
The seal assembly is divided into multiple functional components: a seal ring, a back-up ring, and multiple springs arranged in series. Each component performs a specific function - the seal ring provides the sealing interface, the back-up ring supports the seal ring, and the springs provide progressive force to accommodate movements. This segmentation allows the complex adaptation requirements to be distributed across simpler individual components.
Solution Approach 2:
The seal assembly incorporates multiple springs that can compress and extend to dynamically accommodate axial and radial movements of the exhaust duct. The springs allow the seal assembly to adapt its configuration in real-time as the duct expands thermally or deflects under pressure, maintaining the seal without requiring a rigid fixed design.
2Reliability
If a seal assembly incorporates multiple springs and pre-load mechanisms to maintain seal contact, then the seal effectiveness is improved, but the weight and complexity of retention features increase
Solution Approach 1:
The seal ring and back-up ring are integrated into a single assembled unit with the springs positioned between them. The springs serve dual functions: they apply pre-load to maintain seal contact pressure for reliability, and they provide the necessary compliance to accommodate movements. This merging of functions into a compact assembly reduces the need for separate heavy retention features.
Solution Approach 2:
The use of multiple springs in series allows for progressive compression, where each spring can be designed with optimized spring rates. This enables the seal assembly to maintain adequate contact pressure (pre-load) across a range of positions, ensuring seal effectiveness without requiring excessive force or heavy-duty retention mechanisms.
3Adaptability or versatility
If the seal assembly is designed to accommodate axial displacement and rotation, then the adaptability to exhaust duct movements is improved, but the device complexity increases
Solution Approach 1:
The spring-loaded seal assembly design provides multi-functionality: the springs simultaneously accommodate axial displacement, radial expansion, and rotational movement of the exhaust duct. The same spring mechanism that maintains pre-load contact also provides the compliance needed for all three types of movement, eliminating the need for separate mechanisms for each degree of freedom.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The seal assembly effectively manages axial and rotational movements while maintaining a fluid seal, accommodating thermal growth and pressure variations, thus simplifying the design and reducing weight compared to previous complex solutions.
Implementation Method 1
a multiple of springs that axially extend from the split hoop opposite the seal surface
Data Source
AI summary
A seal assembly for an exhaust duct section of a gas turbine engine includes a multiple of springs that axially extend from a split hoop opposite a seal surface.