Multi-Walled Gas Turbine Combustor Cooling
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Solution Overview
Problem
Existing gas turbine engine combustors with dual-walled structures face challenges in achieving improved cooling characteristics and reducing foreign matter accumulation on the heat shield, particularly as combustion gas temperatures increase and due to the susceptibility of the backside of the heat shield to dirt and sand accumulation.
Innovation Solution
A multi-walled structure is designed with specific aperture configurations, including impingement and effusion apertures, where the cold wall pressure drop is between 5% and 45% of the total pressure drop, and the hot wall pressure drop is between 55% and 95%, with hot wall apertures having a tortuous trajectory and larger longitudinal length compared to the hot wall thickness, to enhance cooling efficiency and reduce foreign matter accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a dual-walled structure with impingement apertures and effusion apertures is used, then cooling of the heat shield is achieved, but foreign matter accumulation occurs on the backside of the heat shield
Solution Approach 1:
The patent divides the cooling system into two separate wall structures (cold wall and hot wall) with distinct aperture configurations. The cold wall contains impingement apertures that direct cooling air toward the hot wall, while the hot wall contains effusion apertures that distribute cooling air along its exterior surface. This segmentation allows each wall to be optimized for its specific cooling function while minimizing foreign matter accumulation on the hot wall backside.
Solution Approach 2:
The patent applies different aperture types and configurations to different locations within the dual-walled structure. The cold wall uses impingement apertures positioned to direct cooling flow, while the hot wall uses effusion apertures positioned to distribute cooling air along its surface. This local differentiation of aperture qualities enables optimized cooling performance and reduced foreign matter accumulation at each location.
2Power
If combustion gas temperatures are increased, then power output is improved, but cooling requirements become more difficult to meet
Solution Approach 1:
The dual-walled structure segments the cooling function across two walls with different aperture configurations. The cold wall's impingement apertures and the hot wall's effusion apertures work together to provide comprehensive cooling coverage, enabling the system to handle higher combustion gas temperatures while maintaining adequate cooling performance.
Solution Approach 2:
The patent optimizes parameters such as aperture size, aperture distribution, and wall thickness ratios to enhance cooling effectiveness. By carefully controlling these parameters, the structure can accommodate increased combustion temperatures while maintaining reliable cooling performance.
3Temperature
If the pressure drop across the shell is made greater than across the heat shield, then cooling flow is improved, but the overall pressure loss increases
Solution Approach 1:
The patent creates different pressure drop characteristics in different locations by using distinct aperture configurations. The cold wall impingement apertures are designed to create a higher pressure drop to drive cooling flow toward the hot wall, while the hot wall effusion apertures are designed to distribute flow with lower resistance. This local differentiation optimizes cooling flow while managing overall pressure loss.
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 multi-walled structure effectively increases cooling efficiency of the hot wall, reduces foreign matter accumulation, and maintains a higher hot wall pressure drop, enabling more complex aperture configurations and improved convection, thus addressing the limitations of existing dual-walled structures.
Implementation Method 1
The cold wall apertures may include an impingement aperture configured to direct a jet of cooling fluid to impinge against the hot wall
Implementation Method 2
The hot wall apertures may include an effusion aperture configured to direct cooling fluid out of the cooling cavity into a plenum and along an exterior surface of the hot wall
Implementation Method 3
The effusion apertures are also provided to cool the heat shield by facilitating convection within the heat shield (e.g., as cooling air passes through the effusion apertures)
Data Source
Figure 1
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Figure 4
AI summary
An assembly (30) is provided for a gas turbine engine. This assembly (30) includes a multi-walled structure (32) including a cold wall (34), a hot wall (36) and a cooling cavity (38) vertically between the cold wall (34) and the hot wall (36). The cold wall (34) includes a plurality of cold wall apertures (80) fluidly coupled with the cooling cavity (38). The cold wall apertures (80) are configured to subject the cold wall (34) to a cold wall pressure drop vertically across the cold wall (34). The hot wall (36) includes a plurality of hot wall apertures (82) fluidly coupled with the cooling cavity (38). The hot wall apertures (82) are configured to subject the hot wall (36) to a hot wall pressure drop vertically across the hot wall (36) that is greater than or equal to the cold wall pressure drop.