Gas Turbine Rotor Seal Hub-Mounted Design

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Solution Overview

Problem

Gas turbine engine rotor disks experience low cycle fatigue and creep due to exposure to high temperatures and pressures, leading to structural damage and requiring frequent maintenance of disk-mounted knife edge seals, which is costly and time-consuming.

Innovation Solution

A rotary seal is mounted on the rotor hub with a sealing element supported by a radially outer edge portion, a radially inner mounting portion, and a medial flexible web portion, which is fixed to the hub using a lock ring and circumferential groove, reducing exposure to extreme temperatures and pressures and allowing for easier maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If knife edge seals are mounted on rotor disks, then sealing function is achieved, but thermal mechanical fatigue and structural damage occur due to discontinuities and stress concentrations

Engineering Contradiction:

Improveseal reliabilityVSAvoidthermal mechanical fatigue

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The seal is extracted from the rotor disk and mounted on the rotor hub instead. This relocation removes the seal from the high-stress, high-temperature environment of the disk, eliminating the thermal mechanical fatigue and stress concentration problems while maintaining the sealing function.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

A flexible web portion is introduced as an intermediary element between the seal and the rotor hub. This flexible web allows the seal to accommodate thermal expansion and mechanical deformation without creating stress concentrations, thereby protecting the seal from thermal mechanical fatigue.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of repair

If knife edge seals are mounted on rotor disks, then sealing function is achieved, but maintenance becomes expensive and time-consuming due to disk disassembly requirements

Engineering Contradiction:

Improveseal maintenance easeVSAvoidmaintenance time

Core Design Contradiction:

Ease of repairVSLoss of time

Solution Approach 1:

The seal assembly is segmented into independent components: the seal element, the flexible web portion, and the mounting portion. This segmentation allows the seal to be removed and replaced independently from the rotor hub without disassembling the rotor disks, significantly reducing maintenance time and cost.

Inventive Principle:

Principle #1Segmentation

3Reliability

If seals are mounted on rotor disks, then sealing is achieved, but mechanical stress concentrations intensify damage from thermal mechanical fatigue

Engineering Contradiction:

Improveseal durabilityVSAvoidseal strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The flexible web portion is designed with specific local properties including flexibility and stress distribution characteristics. This local quality allows the web to accommodate thermal and mechanical stresses without creating stress concentrations at the seal mounting location, thereby enhancing seal durability.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9169737B2Gas turbine engine rotor seal

Publication Date: 2015.10.27 RTX CORP

AI summary

A rotary seal for sealing a bladed rotor of a gas turbine engine to a stator thereof comprises a sealing element and a sealing element support comprising a radially outer edge portion on which the sealing element is fixed, a radially inner mounting portion adapted to be attached to a supported rotor hub, and a flexible, medial web portion extending between the radially outer edge portion and the radially inner mounting portion.