Trapped Vortex Cavity Pilot for Gas Turbine Augmentor Flame Stability
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Solution Overview
Problem
Existing afterburners and augmentors in gas turbine engines suffer from flow losses and reduced efficiency due to flameholders, which cause flame instability and shorten the useful life of V-gutter flameholders, and are affected by thermal stress and aerodynamic performance issues.
Innovation Solution
An annular trapped vortex cavity pilot is introduced, featuring radial flameholders with integral spraybars and circumferential film cooling apertures, creating rotating vortices to stabilize flames and improve combustion efficiency, while eliminating the need for V-gutter flameholders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If flameholders are used to stabilize combustion in high velocity core gases, then flame stability is improved, but flow losses increase and engine efficiency decreases
Solution Approach 1:
The patent extracts the flameholding function from traditional V-gutter flameholders and relocates it to the exhaust liner wall through trapped vortex cavities. This removes the intrusive flameholder structures from the combustion zone, eliminating their negative impact on flow while maintaining flame stabilization through the vortex-induced recirculation zones formed in the cavities.
Solution Approach 2:
The trapped vortex cavities act as intermediaries between the high velocity core gases and the fuel injection system. They create controlled recirculation zones that stabilize flames without requiring physical flameholder structures in the flow path, thus mediating between the need for flame stability and the need to minimize flow losses.
2Stability of the object's composition
If V-gutter flameholders are suspended in core gases for flame stabilization, then combustion is maintained, but thermal stress and aerodynamic performance issues reduce the useful life of flameholders
Solution Approach 1:
The patent removes V-gutter flameholders from the combustion zone and replaces them with trapped vortex cavities formed in the exhaust liner wall. This extraction eliminates the flameholders from direct exposure to high thermal stress and aerodynamic loads, thereby extending their service life while maintaining combustion stability through the vortex-induced recirculation zones.
Solution Approach 2:
The patent replaces the mechanical flameholder structures (V-gutters) with a fluid dynamic solution (trapped vortex cavities). The cavities utilize the existing high velocity core gas flow to create stable recirculation zones that hold flames, substituting mechanical flameholding structures with a flow-based mechanism that has no moving parts and is inherently more durable.
3Stability of the object's composition
If radial spraybars are integrated with radial flameholders to improve flame stability, then combustion efficiency increases, but device complexity increases
Solution Approach 1:
The patent extracts the spraybar integration from the flameholder structure, placing spraybars in the exhaust flowpath without integrating them with flameholders. This separation simplifies the overall device by eliminating the complex integrated flameholder-spraybar assemblies while maintaining effective fuel delivery and flame stability through the trapped vortex cavity mechanism.
Solution Approach 2:
The trapped vortex cavities serve multiple functions: they stabilize flames, mix fuel and air, and eliminate the need for complex integrated flameholder-spraybar assemblies. This multi-functionality reduces device complexity while maintaining or improving combustion efficiency compared to traditional integrated designs.
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 enhances flame stability and reduces flow losses, extending the life of flameholders and improving engine performance by maintaining stable combustion across varying flight conditions.
Implementation Method 1
An annular trapped vortex cavity pilot is introduced, featuring radial flameholders with integral spraybars and circumferential film cooling apertures, creating rotating vortices to stabilize flames
Implementation Method 2
circumferential film cooling apertures
Data Source
AI summary
A gas turbine engine augmentor includes an annular trapped vortex cavity pilot having a cavity forward wall, a cavity radially outer wall, and a cavity aft wall, an annular cavity therebetween, and cavity fuel injector tubes operably disposed through the outer wall into the cavity. Circumferentially spaced apart radial flameholders with integral spraybars and/or radial spraybars interdigitated with the radial flameholders radially inwardly into an exhaust flowpath of the augmentor just forward and upstream of the trapped vortex cavity pilot at a radially outer portion of a combustion zone of the exhaust flowpath. An annular trapped dual vortex cavity pilot version is operable for producing trapped dual counter-rotating inner and outer vortices of fuel and air mixtures.