Wavy Annular Dilution Slots for Lower-NOx Combustor Liners
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Solution Overview
Problem
Conventional gas turbine engines experience high NOx formation due to high temperature regions behind circular dilution jets, which do not spread laterally, leading to localized high temperatures and increased NOx emissions.
Innovation Solution
Implementing a combustor liner with curved or wavy dilution openings and deflector walls that introduce dilution air at different axial locations around the circumference, enhancing mixing and quenching of combustion gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If circular dilution holes are used, then the structure is simple and easy to manufacture, but high temperature regions form behind the dilution jet causing high NOx emissions
Solution Approach 1:
The patent applies curvature by replacing circular dilution holes with wavy or curved dilution slots. The wavy geometry creates lateral spreading of the dilution jet, which eliminates high temperature regions between jets and reduces NOx formation. This curved/wavy configuration maintains manufacturing feasibility while solving the emissions problem.
Solution Approach 2:
The invention transitions from circular (1D radial flow) to wavy/curved slots that introduce dilution air at multiple axial locations around the circumference. This dimensional change creates a more three-dimensional mixing pattern, enhancing lateral spread and reducing localized high temperatures that cause NOx emissions.
2Device complexity
If circular dilution holes are used, then the structure is simple, but the dilution air jet does not spread laterally creating high temperatures in-between jets
Solution Approach 1:
The wavy or curved geometry of the dilution slots inherently promotes lateral spreading of the dilution air jet. The undulating shape creates multiple injection angles around the circumference, ensuring better coverage and reducing high temperature regions between adjacent jets while maintaining a relatively simple single-piece liner structure.
Solution Approach 2:
The wavy slot configuration provides different local injection characteristics around the circumference. Each section of the wavy slot injects dilution air at slightly different angles and locations, creating localized mixing zones that collectively cover the entire combustion chamber cross-section, eliminating hot spots between jets.
3Object-generated harmful factors
If wavy or curved dilution slots are used, then lateral spreading and mixing are enhanced reducing NOx emissions, but the manufacturing complexity increases
Solution Approach 1:
The wavy or curved slot geometry can be manufactured using modern additive manufacturing or precision machining techniques. The continuous wavy pattern, while more complex than circular holes, can be produced as a single integrated feature in the combustor liner, avoiding the need for multiple separate components and reducing assembly complexity.
Solution Approach 2:
The invention integrates the wavy dilution slot geometry directly into the combustor liner structure as a single unified component. This merging of the complex wavy geometry with the liner body eliminates the need for separate inserts or assemblies, making the overall manufacturing process more efficient despite the increased geometric complexity.
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
Reduces NOx emissions by improving the dilution quenching of hot combustion gases, minimizing high-temperature regions, and enhancing mixing efficiency.
Implementation Method 1
a flow of dilution air into a combustion chamber downstream of a primary combustion zone
Implementation Method 2
The flow of air through the circular dilution holes in the conventional combustor mixes with combustion gases within the combustion chamber
Implementation Method 3
High temperature regions seen behind the dilution jet (i.e., in the wake region of dilution jet) are associated with high NOx formation
Data Source
AI summary
A combustor liner for a combustor of a gas turbine includes an outer liner having a plurality of outer liner segments, and an inner liner having a plurality of inner liner segments. Each segment of the inner liner and the outer liner includes at least one slotted dilution opening therethrough extending in a circumferential direction, and each slotted dilution opening includes a deflector wall extending radially from the respective liner into a dilution zone of a combustion chamber between the outer liner and the inner liner. The at least one slotted dilution opening may be a curved slot (either concave or convex) dilution opening, and the curved slot dilution openings for each segment of the outer liner and the inner liner may be connected so as to provide a wavy slotted dilution opening extending annularly through the outer liner and the inner liner.