Flexible Circumferential Seal for Gas Turbine Diffuser Gap

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Solution Overview

Problem

Existing sealing arrangements in gas turbines, such as baffle plates and metal finger plate seals, tend to crack due to thermal cycling and engine vibrations, leading to inefficiencies and high replacement costs.

Innovation Solution

A sealing arrangement featuring a flexible circumferential seal with forward and aft loop portions and retention rods, allowing for circumferential movement to accommodate thermal expansion, and a clamp system with grooves and spacers to maintain the seal across the diffuser gap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If stiff metal baffle plates are used to seal the diffuser gap, then the seal integrity is maintained, but the component is susceptible to cracking due to thermal cycling and vibrations

Engineering Contradiction:

Improveseal integrityVSAvoidresistance to thermal cycling and vibration

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces stiff metal baffle plates with a flexible circumferential seal that can bend and deform. This flexible seal accommodates thermal expansion and vibration-induced movements without cracking, while still maintaining seal integrity across the diffuser gap.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The sealing arrangement transitions from a static rigid structure to a dynamic flexible system. The flexible seal can move and adapt its shape in response to thermal and vibrational conditions, allowing the seal to maintain contact and integrity under varying operating conditions.

Inventive Principle:

Principle #15Dynamics

2Temperature

If the diffusers are spaced apart to form a circumferential gap, then thermal expansion is accommodated, but hot gas recirculation into the cavity occurs

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidhot gas recirculation

Core Design Contradiction:

TemperatureVSObject-generated harmful factors

Solution Approach 1:

A flexible circumferential seal is installed across the circumferential gap between the exhaust and manifold diffusers. This flexible seal prevents hot gas recirculation into the cavity while still allowing the diffusers to expand thermally, as the seal can deform to accommodate the dimensional changes.

Inventive Principle:

Principle #30Flexible shells and thin films

3Object-generated harmful factors

If metal finger plate seals are used across the diffuser gap, then hot gas flow is prevented, but the seal cracks under thermal cycling and vibration

Engineering Contradiction:

Improvehot gas flow preventionVSAvoidresistance to thermal cycling and vibration

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent replaces metal finger plate seals with a flexible circumferential seal that spans the diffuser gap. This flexible seal effectively blocks hot gas flow into the cavity while its flexibility allows it to withstand thermal cycling and vibration without cracking, significantly improving reliability.

Inventive Principle:

Principle #30Flexible shells and thin films

4Ease of manufacture

If rigid seal segments are used, then manufacturing and installation are simplified, but the seal cannot accommodate thermal expansion without cracking

Engineering Contradiction:

Improveseal installation simplicityVSAvoidaccommodation of thermal expansion

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent employs a flexible circumferential seal that can be manufactured as a continuous element and installed relatively simply. The flexibility of the seal allows it to expand and contract with thermal changes, preventing cracking while maintaining ease of manufacture and installation.

Inventive Principle:

Principle #30Flexible shells and thin films

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 flexible seal effectively prevents hot gas recirculation, reducing the risk of heat-induced damage and extending the lifespan of gas turbine components by accommodating thermal expansion without cracking.

Implementation Method 1

the circumferential seal is moveable in a circumferential direction to accommodate thermal expansion of the exhaust and manifold diffusers

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9650919B2Moveable sealing arrangement for a gas turbine diffuser gap

Publication Date: 2017.05.16 SIEMENS ENERGY INC

AI summary

A sealing arrangement for a gas turbine including exhaust and manifold diffusers separated by a circumferential diffuser gap. The sealing arrangement includes a forward clamp arrangement attached to the exhaust diffuser wherein the forward clamp arrangement includes a forward groove. The sealing arrangement also includes an aft clamp arrangement attached to manifold diffuser wherein the aft clamp arrangement includes an aft groove. Further, the sealing arrangement includes a flexible circumferential seal including forward and aft loop portions. The forward loop portion is located in the forward groove and the aft loop portion is located in the aft groove wherein the circumferential seal extends across the circumferential diffuser gap to seal the circumferential diffuser gap. The forward and aft loop portions are moveable in the forward and aft grooves to enable movement of the circumferential seal in a circumferential direction to accommodate thermal expansion of the exhaust and manifold diffusers.