Turbine Mid-Seal Segmentation for Leakage Reduction

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Solution Overview

Problem

Conventional gas turbine engines experience increased leakage across the mid-seal due to its positioning further away from the engine axis, leading to potential leaks and a larger rotating seal circumference, necessitating a mid-seal structure closer to the engine axis.

Innovation Solution

The implementation of a turbine interstage structure featuring two mid-seals and a central plenum, with a forward mid-seal and an aft mid-seal positioned closer to the engine axis, utilizing a solid annular inner boundary and configured as labyrinth seals to reduce leakage, and a central plenum that maintains a positive purge flow rate to prevent hot gases from entering the forward and aft chambers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mid-seal is positioned further away from the engine axis, then the sealing circumference is larger, but the potential leakage increases

Engineering Contradiction:

Improvesealing performanceVSAvoidleakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent divides the single mid-seal into two separate mid-seals (first mid-seal and second mid-seal) positioned at different radial locations. This segmentation allows each seal to operate at a smaller radius where leakage is reduced, while collectively providing the necessary sealing coverage. The first mid-seal is positioned at a first radial location and the second mid-seal at a second radial location, both closer to the axis than a conventional single seal would be.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a radial dimension variation by positioning seals at multiple different radial distances from the axis rather than using a single seal at one radius. This multi-dimensional approach to sealing allows the system to achieve effective sealing at smaller radii where leakage is minimized, while still providing comprehensive coverage through the distributed seal locations.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-generated harmful factors

If the mid-seal is positioned closer to the engine axis, then the leakage is reduced, but the sealing circumference is smaller

Engineering Contradiction:

ImproveleakageVSAvoidsealing performance

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent compensates for the reduced circumference at smaller radii by using multiple segmented seals distributed at different radial positions. The first and second mid-seals work together to provide cumulative sealing effectiveness that matches or exceeds a single large-diameter seal, while each individual seal operates at a smaller radius where leakage is reduced.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent merges the sealing functions of multiple smaller seals to achieve the performance of a single larger seal. By combining the sealing action of the first mid-seal and second mid-seal positioned at different radial locations, the system achieves comprehensive sealing coverage while maintaining the leakage benefits of smaller seal diameters.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If a single mid-seal is used, then the structure is simpler, but the leakage potential increases with seal radius

Engineering Contradiction:

Improveseal structureVSAvoidleakage

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the sealing function into multiple independent mid-seals positioned at different radial locations. This segmentation allows each seal to be simpler in design (smaller diameter) while the collective arrangement provides comprehensive sealing coverage. The first and second mid-seals can be implemented as standard seal components, maintaining simplicity while reducing leakage.

Inventive Principle:

Principle #1Segmentation

4Reliability

If the mid-seal diameter is increased, then the sealing coverage is improved, but the leakage area increases

Engineering Contradiction:

Improvesealing coverageVSAvoidleakage area

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces a single large-diameter seal with multiple smaller seals positioned at different radial locations. This segmentation maintains comprehensive sealing coverage through the distributed arrangement while significantly reducing the leakage area at each individual seal location, since leakage increases with the square of the radius.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10815805B2Apparatus for supplying cooling air to a turbine

Publication Date: 2020.10.27 GENERAL ELECTRIC CO

AI summary

A turbine interstage structure for a gas turbine engine that includes a first stage disk and a second stage disk. A central plenum is defined by a an inner band for supporting nozzle vanes, a forward stator plate and an aft stator plate wherein the forward stator plate is spaced-apart from the aft stator plate, and an inner boundary. A forward mid-seal positioned between the inner boundary and the forward stator plate. An aft mid-seal positioned between the inner boundary and the aft stator plate; and wherein the inner boundary is a solid annular component.