Variable Spacing Combustor Liner Cooling Holes

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Solution Overview

Problem

Existing combustor liners in gas turbine engines face challenges in achieving uniform cooling due to fixed hole spacing and size, leading to overcooling and undercooling in areas with varying temperatures, which complicates the application of thermal-barrier coatings and increases material distress.

Innovation Solution

The combustor liner features a plurality of cooling holes arranged in circumferentially extending rows with variable axial spacing, allowing for tailored cooling airflow distribution by using a smoothing function to optimize hole spacing and reduce interference, enabling preferential cooling with a single hole size and minimizing manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If cooling holes are spaced equidistantly in the axial direction, then manufacturing is simplified, but cooling effectiveness becomes non-uniform due to varying circumferential spacing on contours with changing slopes

Engineering Contradiction:

Improvecooling hole spacingVSAvoidcooling uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies local quality by varying the axial spacing between circumferential rows of cooling holes based on the local thermal conditions and contour geometry. Instead of uniform spacing, the spacing is adjusted locally to account for changing slopes and heat flux distributions, ensuring optimal cooling effectiveness at each location while maintaining manufacturability.

Inventive Principle:

Principle #3Local quality

2Temperature

If cooling holes are spaced closer together, then cooling effectiveness is improved, but thermal-barrier coating application becomes difficult

Engineering Contradiction:

Improvecooling effectivenessVSAvoidcoating application

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The patent applies parameter changes by systematically varying the axial spacing parameter of cooling holes along the combustor liner length. The spacing is reduced in high-heat-flux regions to enhance cooling effectiveness, while maintaining sufficient spacing in other regions to allow proper thermal-barrier coating application and avoid manufacturing difficulties.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If variable circumferential spacing is used to achieve preferential cooling, then cooling effectiveness in high-temperature areas is improved, but fabrication complexity increases due to interference among multihole rows

Engineering Contradiction:

Improvepreferential cooling effectivenessVSAvoidfabrication complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the cooling hole arrangement into multiple circumferential rows with controlled axial spacing. This segmentation allows preferential cooling to be achieved through axial spacing variation rather than complex circumferential spacing, thereby reducing fabrication complexity and avoiding interference among multihole rows while still providing targeted cooling to high-temperature areas.

Inventive Principle:

Principle #1Segmentation

4Temperature

If varying hole sizes are used for circumferential preferential cooling, then cooling effectiveness is improved, but maintaining axial and circumferential distances within design limitations becomes difficult and cost increases

Engineering Contradiction:

Improvecooling effectivenessVSAvoidhole spacing control

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by using axial spacing variation as the primary control parameter for achieving preferential cooling, rather than varying hole sizes. This approach maintains consistent hole dimensions and spacing control requirements, avoiding the manufacturing precision challenges and cost increases associated with varying hole sizes while still providing effective preferential cooling.

Inventive Principle:

Principle #35Parameter changes

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 approach enhances cooling effectiveness by directing increased airflow to high-temperature areas, reducing temperature gradients and hot spots, and preventing material failures like oxidation and corrosion, while simplifying the design and manufacturing process.

Implementation Method 1

Multi-hole film cooling reduces the overall thermal load on the liners because the mass flow through the cooling holes dilutes the hot combustion gas next to the liner surfaces, and the flow through the holes provides convective cooling of the liner walls.

Methodology Applied

Scientific EffectFilm cooling: Convection

Implementation Method 2

the flow through the holes provides convective cooling of the liner walls

Methodology Applied

Scientific EffectConvective cooling: Convection

Implementation Method 3

the mass flow through the cooling holes dilutes the hot combustion gas next to the liner surfaces

Methodology Applied

Scientific EffectDilution: Diffusion

Data Source

PatentUS7669422B2Combustor liner and method of fabricating same

Publication Date: 2010.03.02 GENERAL ELECTRIC CO

AI summary

A combustor liner includes a liner having an upstream end and a downstream end having a longitudinal axis extending therethrough, and a plurality of cooling holes formed in the liner, the cooling holes are arranged along the longitudinal axis into a plurality of circumferentially extending rows that are variably spaced apart along the longitudinal axis.