Gas Turbine Combustor Liner Looped Feature for NOx Reduction
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Solution Overview
Problem
Conventional gas turbine combustors face challenges in achieving optimal mixing of dilution air with combustion gases, leading to inadequate reduction of NOx emissions due to discrete jets of dilution air, which result in hot spots and inefficient mixing.
Innovation Solution
The combustor design incorporates a looped feature on the liner with dilution slots that provide an annular ring of dilution air, combined with a fence to direct and increase turbulence, ensuring quicker and more uniform mixing of dilution air and combustion gases, reducing NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If discrete jets of dilution air are used, then the combustor structure is simple, but mixing with combustion gases is inadequate and hot spots occur
Solution Approach 1:
The dilution air supply is segmented into multiple discrete holes arranged in a pattern around the combustor, allowing dilution air to be introduced at multiple locations simultaneously. This segmentation enables more uniform distribution of dilution air across the combustion gases, reducing hot spots while maintaining structural simplicity.
Solution Approach 2:
The dilution holes are strategically positioned at specific locations around the combustor where they can most effectively mix with combustion gases. The local arrangement of holes creates zones of enhanced mixing at critical areas, improving overall mixing uniformity without requiring complex system-wide changes.
2Object-generated harmful factors
If dilution holes are added to improve mixing, then NOx emissions are reduced, but the liner becomes more complex and prone to thermal stress
Solution Approach 1:
The dilution holes are integrated directly into the liner structure itself, merging the dilution air supply function with the liner's structural role. This eliminates the need for separate dilution air delivery systems, reducing overall device complexity while still achieving effective mixing and NOx reduction.
Solution Approach 2:
The liner serves multiple functions: it provides structural containment, thermal insulation, and dilution air supply through integrated holes. This multi-functionality reduces the need for additional components, simplifying the overall combustor design while achieving emission reduction goals.
3Object-generated harmful factors
If more dilution air is supplied to reduce NOx, then emissions improve, but thermal expansion and stress in the liner increase
Solution Approach 1:
Cooling air is supplied to the liner before the combustion process reaches peak temperatures, pre-cooling the liner structure. This preliminary cooling action reduces the thermal gradient and stress in the liner, allowing more dilution air to be supplied for NOx reduction without exceeding thermal stress limits.
Solution Approach 2:
A cooling air pathway acts as an intermediary between the external environment and the liner, providing thermal management. This intermediary cooling air flow reduces thermal stress on the liner, enabling the liner to withstand the additional thermal load from increased dilution air supply needed for NOx reduction.
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 enhances aerodynamic performance, reduces NOx emissions, and increases the operational lifespan of the combustor by providing a more efficient combustion process and improved airflow.
Implementation Method 1
a looped feature configured to absorb deflection during thermal expansion of the liner
Implementation Method 2
The dilution holes, in turn, supply additional air to the combustion chamber to mix with the combustion products coming from the primary zone of the combustion chamber and complete the combustion process rapidly
Data Source
AI summary
A combustor for a gas turbine engine, the gas turbine engine defining a longitudinal centerline extending in a longitudinal direction, a radial direction extending orthogonally outward from the longitudinal centerline, and a circumferential direction extending concentrically around the longitudinal centerline, the combustor including: a liner at least partially defining a combustion chamber of the gas turbine engine, wherein the liner comprises a looped feature.