CMC Liner Baffles for Gas Turbine Cooling
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Solution Overview
Problem
Traditional cooling methods for ceramic matrix composite (CMC) liners in gas turbine combustors are inefficient due to large hole-to-hole spacing in effusion hole film cooling, leading to hot streaks and increased air requirements, and interruptions by combustor and seal housing supports cause aerodynamic wakes and efficiency losses.
Innovation Solution
Integration of baffles into the CMC liner system to optimize cooling air usage, reduce pressure drop, and eliminate aerodynamic losses, with baffles incorporated into support structures to enhance cooling patterns and heat transfer, and provide radiation shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional effusion hole film cooling is used, then cooling is provided, but hole-to-hole spacing becomes too large resulting in hot streaks and more air is required for cooling
Solution Approach 1:
The cooling system is segmented into multiple functional zones: effusion holes for film cooling, impingement cooling holes for direct cooling, and baffles for flow control. This segmentation allows different cooling mechanisms to work together, achieving better temperature control with reduced air consumption by distributing cooling functions across multiple elements rather than relying solely on dense effusion holes
Solution Approach 2:
Baffles are introduced as intermediary elements between the cooling air supply and the CMC liner surface. These baffles redirect and optimize the flow of cooling air, ensuring it reaches critical hot spots effectively. The impingement cooling holes also act as intermediaries, directing high-velocity cooling jets to specific areas, thereby improving cooling efficiency without increasing overall air consumption
2Strength
If combustor support and seal housing support are present on liner ends, then structural support is provided, but air flow is interrupted twice causing aerodynamic wakes and efficiency losses
Solution Approach 1:
The combustor support and seal housing support are merged into a single integrated support structure at the liner end. This consolidation reduces the number of flow interruptions from two to one, minimizing aerodynamic wakes and efficiency losses while maintaining all necessary structural support functions. The integrated design allows cooling air to flow more continuously through the liner passages
Solution Approach 2:
The integrated support structure performs multiple functions simultaneously: it provides structural support for both the combustor and seal housing, serves as a flow management element to minimize aerodynamic losses, and acts as a mounting platform for cooling system components. This multi-functionality eliminates the need for separate support elements that would interrupt flow
3Temperature
If densely populated cooling hole pattern is used, then cooling effectiveness is improved, but significantly more cooling air is required
Solution Approach 1:
Cooling is applied with local quality by directing impingement cooling jets to specific high-heat-flux areas on the liner surface rather than distributing cooling uniformly. The baffles also create localized cooling zones by redirecting film cooling air to critical regions. This targeted approach achieves effective temperature control in hot spots without requiring the high air consumption needed for uniform dense hole cooling across the entire surface
Solution Approach 2:
The cooling system changes parameters by using impingement cooling with high-velocity jets at specific locations rather than relying on low-velocity film cooling through dense holes. The baffles modify flow parameters by redirecting air streams to create optimal cooling conditions in critical areas. This parameter change from uniform film cooling to localized impingement cooling reduces air consumption while maintaining effectiveness
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 baffle system enables a more densely populated cooling pattern, reducing gas surface temperatures, increasing CMC liner durability, and lowering operating temperatures, while reducing weight, costs, and specific fuel consumption, and improving turbine component design efficiency.
Implementation Method 1
effusion hole film cooling has been utilized in efforts to reduce the amount of air required for cooling
Implementation Method 2
baffles for enhanced cooling of CMC combustor liners... providing enhanced durability for associated turbine component designs
Implementation Method 3
baffles provide radiation heat shielding to surrounding structures, thereby allowing those structures to experience cooler temperatures in operation
Data Source
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AI summary
A system of integrating baffles 500, 800 for enhanced cooling of CMC liners 300, 700 is comprised of a combustor assembly having a dome mount assembly, outer liner (300) and inner liner (700). Liners include those manufactured from and in a process for CMC (Ceramic Matrix Composite). One or more liner baffles such as outer baffle (500) and inner baffle (800), are provided to reduce the pressure drop across the liner 300, 700, allowing the addition of more cooling holes and thereby reducing the cooling hole spacing while not increasing the required amount of cooling air. CMC liners 300, 700 are incorporated, as desired, to take advantage of shapes and hole dispositions made possible by use of CMC over past designs.