Gas Turbine Sealing Segment Land Relocation for TMF Reduction

Solution Overview

Problem

Turbine blade outer air seal (BOAS) segments are susceptible to thermal mechanical fatigue (TMF) due to the presence of lands from ceramic cores, which preclude trip strips, leading to cracking and reduced lifespan.

Innovation Solution

Relocating the push-pin lands from the middle portion of the BOAS segment to the end portions, where they are less susceptible to thermal gradients and curling/uncurling effects, allowing for the inclusion of trip strips to enhance cooling and reduce TMF risk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If ceramic cores with lands are used to form cooling passages, then the cores can be easily ejected from dies, but trip strips cannot be formed at the land location, leading to thermal mechanical fatigue

Engineering Contradiction:

Improvecore ejection from dieVSAvoidresistance to thermal mechanical fatigue

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The cooling passage is divided into multiple sections with trip strips at different locations. The land is positioned to affect only a limited portion of the cooling passage, while other sections maintain full trip strip functionality, thereby segmenting the impact of the manufacturing constraint.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Trip strips are provided at specific locations within the cooling passage rather than uniformly throughout. The land is strategically positioned to minimize its impact on cooling performance by affecting only a localized region, while other regions maintain optimal trip strip coverage for heat transfer.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If lands are located in the middle portion of the BOAS segment, then core ejection is facilitated, but the absence of trip strips at this location makes the segment susceptible to thermal mechanical fatigue

Engineering Contradiction:

Improvecore ejection from dieVSAvoidresistance to cracking

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The cooling passage is divided into multiple sections with trip strips at different locations. The land is positioned to affect only a limited portion of the cooling passage, while other sections maintain full trip strip functionality, thereby segmenting the impact of the manufacturing constraint.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Trip strips are provided at specific locations within the cooling passage rather than uniformly throughout. The land is strategically positioned to minimize its impact on cooling performance by affecting only a localized region, while other regions maintain optimal trip strip coverage for heat transfer.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If trip strips are removed to allow land formation, then core ejection is enabled, but cooling performance and heat transfer rate are reduced

Engineering Contradiction:

Improvecore ejection from dieVSAvoidheat transfer rate

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

Trip strips are provided at specific locations within the cooling passage rather than uniformly throughout. The land is strategically positioned to minimize its impact on cooling performance by affecting only a localized region, while other regions maintain optimal trip strip coverage for heat transfer.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cooling passage is divided into multiple sections with trip strips at different locations. The land is positioned to affect only a limited portion of the cooling passage, while other sections maintain full trip strip functionality, thereby segmenting the impact of the manufacturing constraint.

Inventive Principle:

Principle #1Segmentation

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 relocation of lands reduces the likelihood of thermal mechanical fatigue, thereby extending the lifespan and improving the durability of the BOAS segment by maintaining effective cooling and heat transfer.

Implementation Method 1

cooling air flow is passed often in a circumferential direction

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

improves the heat transfer rate and its cooling performance

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 3

turbulators, known as trip strips, that create ripples within the cooling passages so as to promote turbulent airflow through the passage, which improves the heat transfer rate and its cooling performance

Methodology Applied

Scientific EffectTurbulence: Turbulence

Data Source

PatentEP2060745B1Gas turbine sealing segment

Publication Date: 2013.09.18 UNITED TECH CORP

Figure 1~2
Figure 3~4
Figure 5~6

AI summary

A turbine blade outer air seal segment assembly has a first turbine blade outer air seal segment (14) with a first end portion (18), a middle portion (22) and a second end portion (26). The first turbine blade outer air seal segment (14) is for connection with a second turbine blade outer air seal segment (30) to form at least a part of a shroud of a turbine rotor. A first cooling passage (82) is disposed within the first turbine blade outer air seal segment (14). The cooling passage (82) extends from the first end portion (18) to the second end portion (26) and a land (50) is disposed in at least one of the first or second end portions (18, 26). The land (50) represents a portion for receiving a mold ejection pin for a core forming the cooling passage (82).