Swirl Combustor for Gas Turbine Flame Stability
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Solution Overview
Problem
Gas turbine engines face issues such as flame-out due to unstable flame fronts and high NOx emissions, particularly in aircraft and stationary power generating systems, where high primary aeration improves efficiency but reduces flame stability and increases CO production.
Innovation Solution
A combustor design that imparts centrifugal force to a pre-mixed air-fuel mixture using fluid directing structures within concentric tubes, ensuring thorough mixing and stability, thereby reducing the likelihood of flame-out and NOx emissions while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high primary aeration is used to improve combustion efficiency and reduce NOx emissions, then combustion efficiency is improved, but flame stability deteriorates and CO production increases
Solution Approach 1:
The patent applies mechanical vibration through the introduction of a swirl generator that creates rotational motion in the air-fuel mixture. This rotational flow pattern stabilizes the flame front by continuously renewing the mixture supply to the combustion zone, preventing flame-out while maintaining efficient combustion even at high primary aeration levels.
Solution Approach 2:
The patent changes the flow parameters of the air-fuel mixture by introducing swirl flow and controlling the rotational speed through the swirl generator. This modifies the combustion dynamics to allow stable combustion at high excess air ratios, thereby reducing NOx emissions while maintaining flame stability and reducing CO production.
2Object-generated harmful factors
If high primary aeration is used to reduce NOx emissions, then NOx production is reduced, but flame stability deteriorates
Solution Approach 1:
The swirl generator creates continuous rotational motion that stabilizes the flame front by maintaining a consistent flow pattern. This mechanical stabilization allows the system to operate at high primary aeration levels for NOx reduction while preventing flame-out through the persistent swirl-induced mixing and heat transfer.
Solution Approach 2:
The swirl generator acts as an intermediary device between the air-fuel mixture and the combustion zone. It conditions the flow by introducing rotational motion that enhances mixing and stabilizes the flame, enabling high aeration operation without compromising flame stability.
3Reliability
If pre-mixed air-fuel mixture is used to improve combustion stability, then flame stability is improved, but mixing thoroughness deteriorates
Solution Approach 1:
The swirl generator introduces continuous rotational motion that dynamically mixes the air-fuel mixture throughout the combustion chamber. This mechanical mixing action ensures thorough mixing even when the mixture is pre-mixed, preventing local rich or poor zones and maintaining stable combustion.
Solution Approach 2:
The patent transitions from static pre-mixing to dynamic mixing by introducing swirl flow. The rotational motion continuously renews and redistributes the mixture, ensuring thorough mixing throughout the combustion process while maintaining flame stability through the persistent swirl pattern.
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 design enhances combustion stability, reduces NOx production, and allows for operation at low excess air levels, improving overall efficiency and reducing the risk of flame-out in gas turbine engines.
Implementation Method 1
The tube includes fluid directing structure for directing the pre-mixed mixture radially outward from the central passage to an exterior of the tube such that the pre-mixed mixture rotates radially about the central axis along the exterior of the tube
Data Source
AI summary
A fuel burner includes a tube extending from a first end to a second end and having an outer surface and an inner surface defining a central passage. The central passage is supplied at the first end with a mixture of air and combustible fuel pre-mixed upstream of the tube. The second end is closed by an end wall in a fluid-tight manner. The tube includes fluid directing structure for directing the pre-mixed mixture radially outward from the central passage to an exterior of the tube such that the pre-mixed mixture rotates radially about the central axis along the exterior of the tube.