Abradable Material Fluid Pockets for Heat Dissipation
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Solution Overview
Problem
In gas turbine engines, the use of abradable materials to prevent damage from blade excursions generates heat, which can adversely affect the fan blades and abradable material, and existing solutions compromise engine performance by increasing clearance between fan blades and the fan case.
Innovation Solution
An abradable material with a matrix defining pockets of fluid, an outer surface configured to be coupled to the fan case, and an inner surface featuring a circumferential ridge and groove, designed to manage heat dissipation and minimize material exfoliation, with the groove structure allowing for efficient ejection of exfoliated material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clearance between fan blades and fan case is increased to reduce damage from blade excursions, then reliability is improved, but engine performance is degraded
Solution Approach 1:
The abradable material is designed with a porous structure containing pockets of fluid. This porous structure allows the material to be softer and more compliant than traditional solid materials, enabling it to absorb blade excursions through controlled deformation and material removal without requiring increased clearance. The fluid pockets provide additional compliance and energy absorption capacity, allowing tight clearances to be maintained while preserving reliability.
Solution Approach 2:
The abradable material functions as a composite system combining a matrix material with embedded fluid pockets. This composite structure provides both the softness needed for blade excursion absorption and the controlled material removal characteristics necessary for maintaining tight clearances. The combination of solid matrix and fluid components creates a material that behaves differently from traditional solid abradables, enabling simultaneous achievement of reliability and performance.
2Reliability
If abradable material is used to absorb blade excursions, then reliability is improved, but heat generation increases which adversely affects fan blades and abradable material
Solution Approach 1:
The fluid pockets within the abradable material undergo phase transitions or thermal transformations that facilitate heat absorption and dissipation. The fluid can change phase (e.g., from liquid to vapor) or undergo thermal expansion/contraction cycles that absorb and redistribute heat energy generated during blade-abradable material contact. This phase change mechanism provides a powerful heat sink effect, reducing the temperature at the blade interface while maintaining the material's ability to absorb blade excursions.
Solution Approach 2:
The fluid pockets create a pneumatic or hydraulic cushioning effect during blade excursions. The fluid can compress, expand, or flow in response to mechanical contact, providing a mechanism for energy absorption that generates less heat than direct solid-to-solid friction. The fluid's ability to move and redistribute under pressure reduces the intensity and duration of thermal contact, thereby reducing peak temperatures at the blade-abradable material interface.
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 solution maintains tight blade tip clearances, reduces heat generation, and effectively dissipates friction heat, minimizing damage and maintaining engine performance by efficiently ejecting exfoliated material, thus addressing the heat-related issues and performance compromises of prior systems.
Implementation Method 1
a matrix material defining pockets of fluid
Implementation Method 2
These rub events, however, generate heat which may increase the temperature of the interface of the fan blades and the abradable material
Implementation Method 3
The use of an abradable material is desirable as it can absorb intermittent blade excursions by locally exfoliating material associated with the rub event
Data Source
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AI summary
An abradable material (300) includes a matrix material (350) defining pockets of fluid (352). The abradable material (300) also includes an outer surface (301) configured to be coupled to an interior surface (322) of a fan case (200) such that in response to the outer surface (302) being coupled to the fan case (200), the abradable material (300) is positioned circumferentially about an axis. The abradable material (300) also includes an inner surface (302) defining a circumferential ridge (307,309,311;603) and a circumferential groove (303,305).