Additive Manufacturing Gas Turbine Casing with Integrated Cooling
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Solution Overview
Problem
Existing abradable honeycomb lands in gas turbine engines are difficult to machine, costly, and hard to cool actively, leading to wear, over-tip leakage, and performance degradation due to oxidation, with no adjustable cooling to maintain performance.
Innovation Solution
A method of manufacturing a component with a metallic body using additive layer processes, creating an enclosed pocket of lower density particles within a fused body, allowing for an abradable liner and integrated cooling passages to reduce wear and oxidation, achieved through Direct Laser Deposition (DLD) with post-build heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional EDM and sinter powder filling is used to create abradable lands, then the abradable surface is achieved, but machining difficulty and manufacturing cost increase significantly
Solution Approach 1:
The patent combines the abradable land creation and cooling passage formation into a single additive manufacturing process. The lattice structure with unfused powder pockets is built directly with integrated cooling channels, eliminating the need for separate EDM machining and sintering operations. This merging of operations reduces manufacturing complexity while maintaining abradable surface quality.
Solution Approach 2:
The patent changes the manufacturing approach from subtractive (EDM) to additive (selective laser sintering), fundamentally altering how the abradable land is created. By controlling laser parameters (power, speed, hatch spacing) and powder characteristics, the process directly creates the desired porosity and abradability without complex machining operations.
2Reliability
If sinter powder is used to create lower density abradable regions, then abradability is improved, but oxidation resistance deteriorates
Solution Approach 1:
The patent applies local quality by creating regions of different density within the same component. The unfused powder pockets provide localized low-density abradable regions, while the surrounding fused lattice structure maintains higher density and oxidation resistance. This spatial variation in material properties allows both abradability and oxidation resistance to coexist in different locations of the same component.
3Reliability
If honeycomb structure is used for abradable lands, then abradability is achieved, but active cooling becomes extremely difficult
Solution Approach 1:
The patent merges the abradable land structure with the cooling system by integrating cooling passages directly into the lattice structure during additive manufacturing. The unfused powder pockets are positioned to facilitate cooling airflow, combining the abradable function with thermal management in a single integrated design, eliminating the difficulty of post-manufacturing cooling system integration.
4Manufacturing precision
If deep blade rubs occur on abradable surface, then close tolerant fit is achieved, but oxidation attack increases and performance degrades
Solution Approach 1:
The patent implements a feedback mechanism where cooling air flow is monitored and adjusted based on operational conditions. The integrated cooling passages allow dynamic control of cooling airflow to the abradable surface, providing feedback-based temperature management that prevents oxidation attack during deep blade rub conditions, thereby extending service life while maintaining precision clearance.
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 reduces blade fin tip wear, lowers manufacturing and replacement costs, and allows for adjustable cooling to maintain performance by directing air to areas of concern, thereby extending the component's lifecycle and reducing over-tip leakage.
Implementation Method 1
depositing successive layers of a metal powder on a bed; progressively forming the shape of the metallic body within the layers of powder by selectively fusing particles of the metal powder after each layer has been deposited
Implementation Method 2
exposing the body to a heat treatment to fuse the particles of the powder within the pocket together
Data Source
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AI summary
The present invention provides a method of manufacturing an abradable section to be formed on the interior of the casing of a gas turbine engine. The abradable section is formed by an additive manufacturing process to be of a lower density than the surrounding portions of the casing, but integrally formed with those portions. The method including the step of forming a metallic body of a component by: depositing successive layers of a metal powder on a bed; progressively forming the shape of the metallic body within the layers of powder by selectively fusing particles of the metal powder after each layer has been deposited, wherein forming the shape of the metallic body includes creating an enclosed pocket of unfused particles within the successive layers, the pocket being defined by walls of fused particles so that the metallic body has a first density outside of the pocket and a second density which is lower than the first density within the pocket. The abradable section thus formed can result in reduced blade fin tip wear, and may also have an improved performance. It may also have lower manufacturing costs. Formation of cooling passages in the abradable section is also easier and a wider range of designs of cooling passages can be provided. A gas turbine engine included such a casing is also provided.