Segmented Combustion Chamber Cooling via Film Formation
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Solution Overview
Problem
Current gas turbine engine combustion chambers require excessive coolant air, which limits heat removal due to short residence time, necessitating a more efficient cooling mechanism to enhance heat extraction and reduce emissions.
Innovation Solution
The combustion chamber assembly features a novel design with annular walls divided into regions, utilizing a network of apertures and passages to form coolant films on inner and outer surfaces, along with dilution ports for additional mixing air, optimizing coolant flow and residence time for enhanced heat extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant flows through the combustion chamber walls to remove heat, then heat removal is achieved, but the residence time is short and heat removal amount is limited
Solution Approach 1:
The combustion chamber wall is divided into multiple segments or zones with separate cooling channels. Each segment can be cooled independently, allowing optimized coolant flow paths that extend residence time in high-heat areas without requiring excessive overall coolant flow through the entire chamber.
Solution Approach 2:
Cooling channels are nested within the combustion chamber wall structure, with inner and outer walls containing multiple layers of cooling passages. This nested arrangement maximizes the cooling surface area and extends coolant residence time within the limited wall thickness, enhancing heat removal efficiency.
2Loss of energy
If more coolant air is used in the combustion chamber, then heat removal increases, but coolant is wasted that could be used elsewhere for nozzle guide vane cooling
Solution Approach 1:
Different regions of the combustion chamber wall are provided with different cooling characteristics. High-heat areas receive intensified cooling with extended residence time, while lower-heat areas use less coolant. This localized optimization reduces total coolant consumption while maintaining effective heat removal where most needed.
Solution Approach 2:
The cooling system adjusts coolant flow parameters (flow rate, pressure, temperature) dynamically based on local heat generation. By varying these parameters across different chamber sections and over time, the system achieves efficient heat removal with minimized coolant consumption, allowing the same coolant to be effectively reused for nozzle guide vane cooling.
3Productivity
If coolant flow rate is increased to improve heat removal, then combustion efficiency improves, but emissions of NOx and smoke increase due to excessive cooling air
Solution Approach 1:
The cooling system maintains continuous, optimized coolant flow through the combustion chamber walls, ensuring consistent heat removal that stabilizes combustion temperatures. This continuous cooling prevents thermal conditions that lead to NOx formation while maintaining combustion efficiency, and the optimized flow rate reduces excess air that would contribute to smoke emissions.
Solution Approach 2:
The combustion chamber employs composite wall structures with different material properties in different layers. These composite constructions provide thermal management that enhances combustion efficiency while controlling peak temperatures to reduce NOx emissions, and the integrated design optimizes coolant usage to minimize harmful 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 reduces coolant mass flow requirements while effectively maintaining combustion chamber wall temperatures, allowing coolant to be reused for nozzle guide vane cooling, reducing NOx and smoke emissions, and improving combustion efficiency.
Implementation Method 1
coolant, e.g. air, flows through the combustion chamber walls and removes heat from the combustion chamber walls by passing through impingement apertures in the outer wall and then by flowing through effusion apertures in the tiles to form a film of coolant on the inner surface of the tiles of the inner wall
Implementation Method 2
coolant flows through the combustion chamber walls and removes heat from the combustion chamber walls
Implementation Method 3
supply coolant from a first upstream region of the interior of the box like structure and onto an inner surface of the inner wall to form a film of coolant
Implementation Method 4
The downstream end of the at least one box like structure having a plurality of apertures to supply dilution air from a second downstream region of the interior of the box like structure into the combustion chamber
Data Source
AI summary
A combustion chamber assembly comprises a combustion chamber and a plurality of nozzle guide vanes. Each nozzle guide vane comprises an inner platform, an outer platform and an aerofoil. The combustion chamber comprises an annular wall which includes at least one box like structure. An outer wall of each box has a plurality of apertures for the supply of coolant into the box and the interior of the box is divided into at least two regions. The upstream end of each box has apertures to supply coolant from a first region of its interior onto an inner surface of the inner wall to form a film of coolant. The downstream end of each box has apertures to supply coolant from a second region of its interior onto a surface of the inner or outer platform of the nozzle guide vanes to form a film of coolant.