Variable Immersion Lobe Mixer for Gas Turbine Exhaust
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Solution Overview
Problem
Existing mixers for gas turbine engine exhaust systems incur pressure losses that diminish the performance benefits of mixing core and bypass flows, leading to suboptimal engine performance.
Innovation Solution
A mixer with an annularly undulating contour featuring varying bypass and core immersion lobes, where the crown contour lines of the lobes have different slopes, allowing some lobes to extend radially further than others, optimizing mixing while minimizing pressure losses by varying lobe immersion and scalloping the trailing edges to enhance vortex placement and mixing effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a mixer is used to mix core flow with bypass flow in the exhaust system, then mixing efficiency is improved, but pressure losses increase
Solution Approach 1:
The mixer employs lobes with varying immersion depths where different portions of the mixer structure have different properties. Specifically, some lobes extend further into the core flow than others, creating localized variations in mixing intensity. This allows the mixer to optimize mixing efficiency in specific regions while minimizing overall pressure losses by not uniformly disrupting the flow throughout the entire structure.
Solution Approach 2:
The mixer design features asymmetric lobe configurations where the lobes are not uniform in shape or immersion depth. The crown contour lines of adjacent lobes have different slopes, creating an asymmetric pattern that enhances mixing effectiveness while reducing pressure losses compared to symmetric designs. This asymmetry allows for optimized vortex placement and flow interaction.
2Productivity
If lobes are extended radially further to enhance mixing, then mixing efficiency is improved, but pressure losses increase
Solution Approach 1:
Different lobes have different radial extension lengths, with some lobes extending further into the core flow than others. This localized variation allows the mixer to achieve effective mixing in critical regions while maintaining lower pressure losses in other regions, optimizing the overall performance by not uniformly maximizing lobe extension throughout the structure.
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 solution reduces overall pressure losses and improves mixing efficiency, resulting in better thrust and specific fuel consumption (SFC) by balancing the radial extension of lobes and optimizing vortex placement within the exhaust system, thereby enhancing the uniformity of temperature and noise attenuation.
Implementation Method 1
optimizing vortex placement and mixing effectiveness
Implementation Method 2
annularly undulating contour that defines a plurality of core immersion lobes and a plurality of bypass immersion lobes
Implementation Method 3
the first crown contour line is different than the second crown contour line... whereby one of the first or second bypass immersion lobes extends radially further than the other
Data Source
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AI summary
A method of fabricating a mixer for a gas turbine engine is provided. The method includes forming a forward end and an aft end of the mixer, and forming an annularly undulating contour that defines a plurality of core immersion lobes and a plurality of bypass immersion lobes between the forward end and the aft end. The plurality of bypass immersion lobes includes a first bypass immersion lobe and a second bypass immersion lobe. The first bypass immersion lobe has a first crown contour line extending from the forward end to the aft end of the mixer, and the second bypass immersion lobe has a second crown contour line extending from the forward end to the aft end of the mixer. The first crown contour line is different than the second crown contour line.