Interlocking Combustor Tiles for Laser Drilling Access

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Solution Overview

Problem

The manufacturing of tiles with impingement effusion cooling arrangements in gas turbine engines faces difficulties due to clashes between laser heads and protruding studs, leading to inefficient cooling and increased manufacturing time, and conventional securing arrangements can compromise the efficiency of air flow and heat transfer.

Innovation Solution

A double-walled combustor design featuring interlocking and interengaging members on tiles, with an annular outer wall having apertures and blind apertures for alignment and secure attachment, reducing the need for conventional fasteners and allowing for efficient alignment and assembly of tiles, enabling precise placement of effusion cooling holes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional tiles with studs and pedestals are used, then the tiles can be securely attached to the outer wall, but the laser head clashes with the protruding studs during manufacturing of effusion cooling holes

Engineering Contradiction:
Improvemanufacturing of effusion cooling holesVSAvoidtile structure with studs and pedestals
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent removes the protruding studs from the tile structure and replaces them with recesses that receive fasteners from the opposite side. This extraction of the problematic protruding elements eliminates the laser head clash during effusion cooling hole manufacturing while maintaining secure attachment capability through the recess-mounted fasteners.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If threaded receptacles with multiple thread turns are used to secure tiles, then the attachment is secure, but the air flow channel depth becomes too great, reducing cooling efficiency

Engineering Contradiction:
Improvetile attachment securityVSAvoidcooling efficiency and air flow
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

Instead of having threaded receptacles protruding into the air flow channel from the inner wall, the patent inverts the approach by having recesses in the tile that receive fasteners from the outer wall side. This inversion positions the fastening mechanism outside the critical air flow path, maintaining secure attachment while preserving optimal air flow channel dimensions for cooling efficiency.

Inventive Principle:
Principle #13The other way round (Inversion)

3Ease of manufacture

If alternative approach vectors are used for laser drilling to avoid stud clashes, then manufacturing can proceed, but the positioning precision of effusion cooling holes is compromised

Engineering Contradiction:
Improvelaser drilling processVSAvoidpositioning of effusion cooling holes
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

By removing the protruding studs that cause laser head clashes, the patent eliminates the need for alternative approach vectors. The laser can now drill effusion cooling holes along the optimal perpendicular approach vector, maintaining both manufacturing feasibility and high positioning precision for the cooling holes.

Inventive Principle:
Principle #2Taking out (Extraction)

4Productivity

If more air is used for cooling through larger flow area, then cooling efficiency improves, but less air is available for diluting combustion

Engineering Contradiction:
Improvecooling efficiencyVSAvoidair availability for combustion dilution
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent inverts the fastening approach to eliminate protruding elements that create turbulence and flow resistance in the air flow channel. By using recess-mounted fasteners instead of protruding studs, the air flow path is smoothed and optimized, allowing efficient cooling with minimal air consumption, thereby preserving more air for combustion dilution.

Inventive Principle:
Principle #13The other way round (Inversion)

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

This design reduces the number of fasteners required, lowers assembly time, minimizes interference during manufacturing, and allows for precise placement of effusion cooling holes, enhancing cooling efficiency and reducing overall assembly complexity and weight.

Implementation Method 1

each interlocking member extending through a corresponding one of the circumferentially spaced apertures in the annular outer wall

Methodology Applied
Scientific EffectMechanical Fastening: Mechanical Fastener

Implementation Method 2

the at least one interengaging member extending circumferentially from a second wall at the second circumferential end of the tile and the interengaging member at the second circumferential end of the tile engaging with the first circumferential end of an adjacent tile

Methodology Applied
Scientific EffectMechanical Engagement: Mechanical Fastener

Implementation Method 3

Tiles with an impingement effusion cooling arrangement have an array of effusion cooling holes

Methodology Applied
Scientific EffectHeat Transfer: Heat Exchanger

Data Source

PatentEP2886962B1A combustion chamber
Publication Date: 2019.10.23 ROLLS ROYCE PLC
  • EP2886962B1 patent drawingFigure 1~2
  • EP2886962B1 patent drawingFigure 3~4
  • EP2886962B1 patent drawingFigure 5~7

AI summary

A double wall structured combustor having an outer wall 36 having an inner surface 42 and an outer surface 44 and an inner wall comprising a plurality of tiles. Each tile 38a has at least one interlocking member 52 at a first wall 50a and at least one interengaging member 56 at a second wall 50b. The interlocking member 52 extending through an aperture in the outer wall 36, and the interengaging member 56 at the second wall 50b engaging with a cutaway section 54 in the first wall 50a of an adjacent tile 38b. On assembly of the combustion chamber, the interlocking members 52 and interengaging members 56 of the tiles ensure lower profile fixings and an overall reduction in number of conventional fasteners used.