Gas Turbine Combustor Cooling Structure with Guide
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Solution Overview
Problem
Gas turbine combustors face challenges in effectively cooling the wall surfaces and reducing NOx emissions, as existing cooling structures are inefficient and contribute to environmental pollution.
Innovation Solution
The proposed gas turbine combustor design includes a guide that directs coolant downstream from a nozzle to a tail tube, with main and auxiliary coolant supply openings arranged radially and downstream, respectively, and spacers to maintain gap width, along with a cavity to reduce coolant flow rate, enhancing film cooling and preventing flashback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling passages are formed between inner and outer wall surfaces, then wall surface cooling is improved, but device complexity increases
Solution Approach 1:
The cooling structure is divided into multiple cooling passages arranged in parallel between the inner and outer wall surfaces. Each cooling passage independently channels coolant to specific regions, allowing segmented cooling control that reduces overall system complexity while effectively managing wall surface temperatures.
Solution Approach 2:
Coolant supply openings are strategically positioned at specific locations along the cooling passages to provide localized cooling where heat flux is highest. This selective cooling approach optimizes thermal management without requiring complex cooling structures throughout the entire combustor wall.
2Temperature
If coolant supply openings are provided at multiple locations, then cooling efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The coolant supply openings are asymmetrically distributed along the cooling passages, with higher density openings positioned in regions experiencing greater heat flux. This asymmetric arrangement optimizes cooling effectiveness while accommodating manufacturing tolerances, as not all openings require identical precision.
Solution Approach 2:
Multiple coolant supply openings are provided along each cooling passage to ensure adequate cooling coverage. The number and distribution of openings are designed to provide sufficient cooling margin, allowing some variation in position without compromising overall cooling performance.
3Temperature
If cooling air is supplied along the inner wall surface, then film cooling is improved, but NOx emissions increase
Solution Approach 1:
Coolant is supplied through openings along the inner wall surface to create a protective film before the hot combustion gases can directly contact the wall. This preliminary cooling action reduces wall temperature while the film thickness and velocity are controlled to minimize interference with combustion, thereby reducing NOx formation.
Solution Approach 2:
The cooling system parameters including coolant flow rate, opening diameter, and opening distribution are optimized to achieve the minimum coolant flow necessary for effective wall cooling. By precisely controlling these parameters, the film cooling effectiveness is maximized while minimizing the impact on combustion temperature and NOx emissions.
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 design efficiently cools the tube wall, reduces NOx emissions by optimizing coolant distribution, and prevents oil residue on the inner surface, improving the reliability and environmental performance of the combustor.
Implementation Method 1
a plurality of cooling passages 22 through which a coolant flows are formed between an inner wall surface 23 facing a combustion zone 8 and an outer wall surface 20
Implementation Method 2
Cooling air is supplied along the inner wall surface in that it is introduced through coolant supply openings in the outer wall surface into the cooling passages and the cooling air is subsequently ejected from the cooling passages through coolant supply openings located at the inner wall surface
Implementation Method 3
a plurality of cooling passages 22 through which a coolant flows are formed between an inner wall surface 23 facing a combustion zone 8 and an outer wall surface 20
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
It is required for a gas turbine combustor to exhaust low NOx. The gas turbine combustor is provided with a combustion tube which has a cooling passage through which cooling air flows in a double wall structure. The cooling passage has a main cooling air supply opening opened to a side of a combustion zone. The cooling air supplied from the main cooling air supply opening is guided to a direction along an inner wall surface of the combustion tube by a guide. The cooling air flows through the cooling passage inside the combustion tube, and then is reused for film cooling along the inner wall surface. Thus, it is possible to save cooling air. Therefore, a more part of the air supplied from a compressor can be used as air for combustion and it becomes possible to exhaust low NOx.