Wedge Nozzle Leaf Seal for Gas Turbine Leakage
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Solution Overview
Problem
Gas turbine combustors face challenges in sealing between adjacent wedge-shaped sector nozzles due to the use of hula seals on the center nozzle and combustor liner, leading to cooling air leakage.
Innovation Solution
A wedge-shaped sector nozzle with a radially-oriented leaf seal assembly comprising convex metal spring fingers and rigid end plates, which engage flat surfaces of adjacent nozzles to enhance sealing, and optional seal wedges for rounded corners to eliminate leakage paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hula seals are used on the center nozzle and combustor liner, then sealing is provided in those areas, but cooling air leakage occurs between adjacent sector nozzles
Solution Approach 1:
The sealing solution is segmented by providing individual leaf seal assemblies on each sector nozzle rather than using a continuous hula seal. Each leaf seal assembly includes multiple spring fingers that can independently engage with adjacent nozzles, allowing customized sealing for each gap between sector nozzles while maintaining overall sealing effectiveness.
Solution Approach 2:
The leaf seal assemblies incorporate spring fingers that provide dynamic, resilient engagement between adjacent sector nozzles. The spring fingers can flex and adapt to thermal expansion, manufacturing tolerances, and operational vibrations, maintaining continuous sealing contact without rigid constraints that could cause leakage or damage.
2Loss of energy
If leaf seal assemblies are added to sector nozzles to seal between adjacent nozzles, then cooling air leakage is reduced, but device complexity increases
Solution Approach 1:
The leaf seal assemblies use thin, flexible spring fingers made of resilient material that can bend and conform to the mating surfaces of adjacent sector nozzles. This flexible membrane approach provides effective sealing without requiring complex rigid structures, multiple components, or intricate assembly procedures.
Solution Approach 2:
The spring fingers in the leaf seal assemblies are self-adjusting and self-aligning during installation and operation. They automatically conform to the geometry of adjacent nozzles and maintain sealing contact through their inherent elasticity, reducing the need for precision adjustment mechanisms or complex mounting hardware.
3Reliability
If radially-oriented leaf seals are mounted on diverging side surfaces, then sealing engagement is achieved against flat surfaces of adjacent nozzles, but manufacturing precision requirements increase
Solution Approach 1:
The leaf seal assemblies incorporate spring fingers with controlled elastic properties that allow them to flex and adapt to variations in surface flatness and alignment. By changing the physical parameters of the sealing element (resilience, flexibility, spring rate), the system tolerates broader manufacturing tolerances on the rigid nozzle surfaces while maintaining reliable sealing engagement.
Solution Approach 2:
The spring fingers provide a cushioning effect that compensates for manufacturing imperfections and surface irregularities before they can cause sealing failure. The elastic deformation of the spring fingers absorbs dimensional variations and misalignments, ensuring continuous sealing contact even when flatness tolerances are not perfectly achieved.
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 solution effectively reduces cooling air leakage between adjacent sector nozzles by providing a resilient, sealing engagement that minimizes potential leakage paths and ensures a flush fit with adjacent nozzle surfaces, improving the sealing effectiveness.
Implementation Method 1
a radially-oriented leaf seal assembly (24) attached to one of the diverging, radially-oriented side plates (16, 18) such that the seal assembly (24) will engage a substantially flat, radially-oriented side plate of an adjacent sector nozzle
Implementation Method 2
spring-loaded leaf seals are used to seal between two concentric surfaces
Data Source
AI summary
A substantially wedge-shaped sector nozzle includes a nozzle body having inner and outer arcuate segments connected by diverging radial side plates and a nozzle plate at an aft end of the nozzle body formed with an array of fuel orifices. One of the diverging radial side plates supports a radially-oriented leaf seal assembly adapted to seal against a flat plate of an adjacent similarly-shaped sector nozzle.