Shaped Dilution Openings for Gas Turbine Combustor Liners
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Solution Overview
Problem
Conventional gas turbine engines experience high NOx formation and reduced combustor liner durability due to the formation of wakes behind dilution airflow, which limits the lateral spread of dilution air and increases temperature between dilution holes.
Innovation Solution
The design incorporates a main dilution opening with secondary and tertiary openings that extend laterally and longitudinally, providing improved airflow at the trailing edge and better lateral spread within the combustion chamber, reducing wake formation and NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional dilution holes are used, then the structure is simple, but wake formation occurs behind the dilution airflow, reducing lateral spread and increasing temperature between holes
Solution Approach 1:
The dilution opening is segmented into a main body and multiple lobes (first lobe, second lobe, third lobe, fourth lobe) that extend in different directions. This segmentation allows the dilution air to spread laterally in multiple directions simultaneously, filling wake regions and reducing temperature between dilution openings while maintaining overall structural integrity.
Solution Approach 2:
The dilution opening transitions from a conventional circular or slot shape to a multi-lobed configuration that extends in radial and circumferential directions. This dimensional expansion creates additional flow paths that improve lateral spread of dilution air, reduce wake formation downstream, and lower temperatures in interstitial regions between adjacent dilution openings.
2Object-generated harmful factors
If dilution air flow is increased to reduce NOx, then NOx emissions decrease, but the lateral spread of dilution air is limited by wake formation
Solution Approach 1:
The multi-lobed configuration segments the dilution opening into multiple directional outlets (lobes extending in different radial and circumferential directions). This segmentation enables the dilution air to occupy multiple spatial zones simultaneously, expanding the effective lateral spread area and reducing NOx emissions by ensuring more comprehensive mixing with combustion gases.
Solution Approach 2:
The design converts the potentially harmful wake formation into a beneficial feature by positioning lobes to specifically target and fill wake regions downstream. The lobes extending in the downstream direction utilize the wake region to enhance mixing and further reduce temperatures, turning the wake's natural flow pattern into a useful mixing zone that reduces NOx emissions.
3Area of stationary object
If conventional circular dilution holes are used, then manufacturing is simple, but the lateral spread of dilution air is insufficient
Solution Approach 1:
The liner incorporates multiple dilution openings with multi-lobed configurations that provide enhanced lateral spread. While the shape is more complex than conventional circular holes, the manufacturing process remains feasible through standard drilling and shaping operations, achieving a balance between improved lateral spread and manufacturability.
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 configuration enhances the mixing of dilution air with combustion gases, reducing NOx emissions and improving the durability of the combustor liner by effectively spreading dilution air and cooling combustion gases.
Implementation Method 1
enhances the mixing of dilution air with combustion gases
Implementation Method 2
providing improved airflow at the trailing edge and better lateral spread within the combustion chamber
Data Source
AI summary
A combustor liner for a gas turbine includes a liner at least partially defining a combustion chamber. The liner includes a plurality of dilution openings therethrough, at least one dilution opening of the plurality of dilution openings defined by (a) a main dilution opening portion defining a main dilution opening perimeter, and (b) a plurality of secondary dilution opening portions arranged about the main dilution opening perimeter and extending outward from the main dilution opening portion.