Nested Seal Assembly for Turbine Duct Thermal Growth
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Solution Overview
Problem
The existing seal assemblies in gas turbine engines face challenges in minimizing leakage between transition ducts and turbine inlet structures due to thermal growth, leading to radial, circumferential, and axial movements, which current technologies do not adequately address.
Innovation Solution
A seal assembly with inner and outer seal members arranged in a shiplap configuration, featuring L or V-shaped legs and notches, and anti-rotation pins, which are received in slots defined by transition and vane seal structures, providing radial and axial restraints while accommodating thermal expansion and preventing circumferential movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seal assemblies are used between transition ducts and turbine inlet structure, then leakage between working gases and cooling air is minimized, but thermal growth causes radial, circumferential, and axial movements that compromise sealing effectiveness
Solution Approach 1:
The seal assembly incorporates movable components including a radially movable outer seal member and axially movable inner seal members that can dynamically adjust their positions to accommodate thermal growth movements between the transition duct and turbine inlet structure, maintaining sealing effectiveness despite relative position changes
Solution Approach 2:
The seal assembly utilizes components with different thermal expansion characteristics and allows position parameters (radial, axial, circumferential) to change in response to thermal growth, enabling the seal to adapt to temperature-induced dimensional changes while maintaining sealing function
2Reliability
If rigid seal structures are used to prevent leakage, then sealing effectiveness is improved, but thermal expansion is restricted causing increased stress on components
Solution Approach 1:
The seal assembly employs dynamically movable seal members that can shift radially and axially to accommodate thermal expansion, preventing stress buildup by allowing controlled movement rather than restricting thermal growth with rigid constraints
Solution Approach 2:
The design explicitly accounts for thermal expansion by providing clearance and movement capability for the seal members, allowing them to expand and move with temperature changes without generating excessive stress on connected components
3Reliability
If multiple seal members are added to accommodate thermal growth movements, then sealing effectiveness under thermal conditions is improved, but device complexity increases
Solution Approach 1:
The seal assembly is divided into distinct functional segments including outer seal members for radial movement and inner seal members for axial movement, with each segment handling specific thermal growth directions, making the complex thermal compensation function manageable through modular design
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 limits fluid leakage between hot gas and cooling fluid paths, enhances sealing efficiency, and accommodates thermal expansion, thereby improving part life and reducing stress on components.
Implementation Method 1
Because the transition ducts and the turbine inlet structure are formed from different materials, they experience different amounts of thermal growth. That is, both the transition ducts and the turbine inlet structure may move radially, circumferentially, and/or axially relative to one another as a result of thermal growth of the respective components.
Data Source
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AI summary
A seal assembly (12) between a transition seal structure (14) associated with a downstream end (16) of a transition duct (10) and a vane seal structure (18) associated with an upstream end (20) of a vane structure (22) in a first row vane assembly (24) of a gas turbine engine includes a seal structure (30). The seal structure (30) includes inner and outer seal members (34, 36), each having a radially extending first leg (34A, 36A) and an axially extending second leg (34B, 36B) that provide each seal member with an L or V-shape. The seal members are arranged in a nested relationship with one of the seal members being positioned between the first and second legs of the other seal member. The first and/or second legs of the inner and outer seal members is/are received in a corresponding slot (40, 50) defined at least in part by one of the transition seal structure and the vane seal structure.