Gas Turbine Combustor Liner with Protuberances for Efficient Cleaning
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Solution Overview
Problem
The existing methods for forming effusion holes in gas turbine combustor tiles, such as the 'coat-drill' and 'drill-coat' processes, face challenges like blockage by thermal barrier coatings, increased production costs, and reduced convective heat removal due to obstruction by attachment studs, which hinder effective cleaning and manufacturing efficiency.
Innovation Solution
The solution involves a liner element with protuberances projecting from the cooling side, allowing for a shorter profile that enables effective cleaning of effusion holes without obstruction and improved manufacturing efficiency, using a 'drill-coat-clean' process with a cleaning jet positioned close to the cooling side surface, and incorporating larger effusion holes near protuberances for better access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If effusion holes are formed by laser cutting after applying thermal barrier coating (coat-drill process), then the coating is applied first, but the laser must be operated at reduced power to avoid damage to the brittle ceramic coating, increasing cycle time and production cost
Solution Approach 1:
The effusion holes are formed by laser cutting before the thermal barrier coating is applied. This preliminary action allows the laser to operate at full power without risking damage to the coating, thereby reducing production cycle time while maintaining coating integrity through subsequent proper coating application techniques
2Productivity
If effusion holes are formed before applying thermal barrier coating (drill-coat process), then production cost is reduced, but the holes become partially or completely blocked by the coating material
Solution Approach 1:
The effusion holes are formed before coating application, allowing full-power laser operation and reduced production costs. The coating application process is then carefully controlled to minimize blockage, and any minor blockages are addressed through targeted cleaning methods that preserve the coating's protective function
Solution Approach 2:
The thermal barrier coating is applied with varying thickness characteristics - thinner at the effusion hole openings to prevent blockage, and thicker in other areas for optimal thermal protection. This local variation in coating quality maintains both hole clearance and thermal insulation effectiveness
3Strength
If attachment studs are used to secure tiles, then the tiles are firmly fixed to the combustor wall, but the studs obstruct the cleaning jet from effectively cleaning the effusion holes
Solution Approach 1:
The attachment function is segmented from the tile body into separate attachment studs, allowing the cleaning jet to access effusion holes through spaces between the studs. The studs provide secure fixation while their spaced arrangement permits cleaning fluid penetration to all effusion hole locations
4Ease of operation
If effusion holes are made larger near protuberances for better access, then cleaning effectiveness is improved, but the structural integrity of the tile may be compromised
Solution Approach 1:
Effusion holes near protuberances are made larger to facilitate cleaning jet access, while holes in other locations maintain standard dimensions. This local variation in hole size optimizes cleaning effectiveness in critical areas while preserving overall structural integrity through appropriate hole sizing elsewhere
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 ensures effective cleaning of effusion holes, reduces production costs, and enhances the thermal insulation and manufacturing efficiency of gas turbine combustor tiles by minimizing blockages and improving the quality of thermal barrier coatings.
Implementation Method 1
A jet of water or air, which may contain abrasive particles, is directed towards and through the holes to blast out any coating material therefrom
Implementation Method 2
a thermally insulating top coat which may comprise Yttria Partially Stabilised Zirconia ("PYSZ") and which is applied over the bond coat
Implementation Method 3
The cooling air which is directed into the chambers and which impinges on the cooling side surface of the tiles is thus exhausted through the effusion holes and in doing so provides convective heat removal from the tiles
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
There is disclosed a liner element (30) for a gas turbine combustor (24) having a structural wall (28) with fixing apertures (46) provided therethrough. The liner element (30) has a unitary construction defining a cooling side (37) and combustion side (38), and a plurality of effusion holes (35) extending between a cooling side surface (34) of the element and a combustion side surface (36) of the element. The liner element (30) is configured to be affixed to the structural wall (28) of a combustor (24) with its cooling side surface (34) spaced from the wall (28) to define a chamber (31) between the cooling side surface (34) and the wall (28), and the liner element further includes integrally formed and non-threaded protuberances (40) on its cooling side (37), the protuberances (40) being arranged to engage and extend through respective fixing apertures (46) in the combustor wall (28). Also disclosed is a method of thermally insulating the liner element (30).