CMC Blade Pressurized Cavity Erosion Control
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Solution Overview
Problem
Ceramic matrix composite (CMC) blades in gas turbine engines are vulnerable to foreign object damage, which can lead to catastrophic failures due to the inability of existing thermal barrier coatings to prevent breaches and subsequent degradation from water vapor exposure.
Innovation Solution
The implementation of CMC blades with integral interior cavities that are pressurized with cool, dry air, maintaining structural integrity even after initial penetration, using a system with fluid passageways and a compressor to ensure continuous air flow and prevent hot gas path degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If CMC blades are used to improve temperature capability and reduce weight, then engine efficiency and thrust-to-weight ratio are improved, but the blades become vulnerable to foreign object damage and erosion
Solution Approach 1:
The patent applies beforehand cushioning by introducing a pressurized inert gas (such as nitrogen) into the internal cavity of the CMC blade before foreign object impact occurs. This pre-established protective pressure cushion prevents hot gas and water vapor from penetrating into the blade interior through impact breaches, thereby cushioning against the harmful effects of foreign object damage while maintaining the lightweight CMC structure
Solution Approach 2:
The patent implements an inert atmosphere by filling the internal cavity of the CMC blade with an inert gas (such as nitrogen) at a pressure higher than the surrounding hot gas environment. This inert pressurized atmosphere prevents oxidative degradation and water vapor penetration into the blade through impact breaches, creating a protective inert environment that enhances blade reliability without adding significant weight
2Temperature
If thermal barrier coatings are applied to protect blades from high temperatures, then thermal protection is improved, but the coatings cannot prevent breaches from foreign objects and subsequent water vapor degradation
Solution Approach 1:
The patent applies beforehand cushioning by pre-pressurizing the internal cavity with inert gas before any impact breach occurs. This pre-established pressure cushion prevents hot gas and water vapor from penetrating into the blade interior through impact breaches, thereby cushioning against the harmful effects of foreign object damage while maintaining the lightweight CMC structure
Solution Approach 2:
The patent introduces an intermediary pressurized inert gas atmosphere between the external hot gas environment and the blade interior. This intermediary pressurized inert atmosphere acts as a barrier that prevents water vapor and hot gas penetration through impact breaches, supplementing the thermal barrier coating's protective function and enhancing reliability against water vapor degradation
3Reliability
If leading edge protection strips are added to prevent catastrophic failure, then some erosion protection is provided, but impact energy transmission causes blade oscillation and matrix strain exceeding material limits
Solution Approach 1:
The patent applies beforehand cushioning by introducing a pressurized inert gas (such as nitrogen) into the internal cavity of the CMC blade before foreign object impact occurs. This pre-established protective pressure cushion prevents hot gas and water vapor from penetrating into the blade interior through impact breaches, thereby cushioning against the harmful effects of foreign object damage while maintaining the lightweight CMC structure
Solution Approach 2:
The patent introduces an intermediary pressurized inert gas atmosphere between the external hot gas environment and the blade interior. This intermediary pressurized inert atmosphere acts as a barrier that prevents water vapor and hot gas penetration through impact breaches, supplementing the thermal barrier coating's protective function and enhancing reliability against water vapor degradation
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 solution extends the life of critical engine components by preventing catastrophic failures and reducing degradation, maintaining structural integrity and engine performance despite foreign object impacts.
Implementation Method 1
providing a source of pressurized fluid to each one of the interior fluid cavities in each airfoil
Implementation Method 2
using dry, cool air to protect the structural integrity of the blade
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A ceramic matrix composite blade (30) for use in a gas turbine engine having an airfoil (23) with leading (11) and trailing edges (12) and pressure and suction side surfaces, a blade shank (15) secured to the lower end of each airfoil (23), one or more interior fluid cavities (13,24) within the airfoil (23) having inlet flow passages (17,18) at the lower end which are in fluid communication with the blade shank (15), one or more passageways in the blade shank corresponding to each one of the interior fluid cavities (13,24) and a fluid pump (or compressor) that provides pressurized fluid (nominally cool, dry air) to each one of the interior fluid cavities (13,24) in each airfoil (23). The fluid (e.g., air) is sufficient in pressure and volume to maintain a minimum fluid flow to each of the interior fluid cavities (13,24) in the event of a breach due to foreign object damage. A corresponding method is also provided.