Streamwise Vortex Generators for Premixer Flame-Holding Resistance
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Solution Overview
Problem
Existing gas turbine combustion systems face challenges in optimizing air/fuel mixing and flame-holding resistance, leading to potential overheating and hardware damage due to premature combustion, despite advancements in premixing techniques such as air passages, swirl-stabilized premixers, and cratered fuel injection holes.
Innovation Solution
The implementation of streamwise vortex generators within the premixer to passively redirect high-velocity air into wake and vortex regions, enhancing mixing and increasing resistance to flame-holding while minimizing momentum deficits and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If premixing capabilities are increased to enhance air/fuel mixing, then mixing capability is improved, but flame-holding resistance deteriorates due to increased risk of premature combustion
Solution Approach 1:
The premixer outlet is segmented into multiple injection holes arranged in a circular array, with each hole having a specific diameter and spacing optimized to create discrete jet streams that enhance mixing while controlling flame propagation. This segmentation allows independent optimization of each jet's contribution to mixing versus flame-holding resistance.
Solution Approach 2:
Different regions of the premixer outlet are given different qualities through varying hole diameters and spacing. The circular array configuration creates localized high-velocity jets at specific positions, providing enhanced mixing capability in the core region while maintaining flame-holding resistance in the peripheral regions through controlled jet placement and spacing.
2Productivity
If premixing capabilities are increased to enhance air/fuel mixing, then mixing capability is improved, but combustion dynamics issues increase leading to hardware damage
Solution Approach 1:
The segmented circular array of injection holes creates multiple discrete jet streams rather than a single large jet, which breaks up large-scale combustion dynamics and reduces the intensity of individual combustion events that could cause hardware damage. Each segment contributes to mixing while limiting the propagation of harmful combustion waves.
Solution Approach 2:
The design converts the potentially harmful effect of high-velocity jets (which could cause combustion dynamics issues) into a beneficial mixing mechanism. By carefully controlling jet diameter, spacing, and arrangement, the high-velocity jets are harnessed to enhance air/fuel mixing while their distributed nature prevents them from causing harmful combustion dynamics.
3Productivity
If conventional premixer techniques are used to increase premixing capability, then mixing is improved, but flame-holding resistance remains insufficient
Solution Approach 1:
The circular array configuration creates a dynamic flow pattern where jets from multiple holes interact and merge in a controlled manner. The spacing and arrangement of holes are optimized to create a self-regulating flow structure that adapts to operating conditions, providing both enhanced mixing and improved flame-holding resistance through dynamic flow management.
Solution Approach 2:
The design uses multiple identical injection holes arranged in a circular array, where each hole is a copy of the others but positioned to create complementary flow patterns. This replication strategy allows the system to achieve enhanced mixing through collective jet action while maintaining flame-holding resistance through the distributed, symmetric arrangement that prevents localized hot spots.
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 approach effectively increases flame-holding resistance and air/fuel mixing capabilities, reducing the risk of hardware damage and NOx emissions, while also minimizing turbulent flow structures and combustion dynamics.
Implementation Method 1
one or more streamwise vortex generators configured to passively redirect surrounding high velocity air to fill in wake and vortex regions within a fuel nozzle
Implementation Method 2
streamwise vortex generators configured to passively redirect surrounding high velocity air
Implementation Method 3
enhancing mixing and increasing resistance to flame-holding while minimizing momentum deficits and noise
Data Source
AI summary
A combustion system premixer includes one or more streamwise vortex generators configured to passively redirect surrounding high velocity air into at least one of wake and vortex regions within a combustion system fuel nozzle in response to air passing through the premixer. The streamwise vortex generators operate to minimize turbulent flow structures, thus improving air/fuel mixing, and enhancing resistance to flame-holding and flash-back within the premixer.