Annular Combustion Chamber Fuel Injector Swirl Alignment
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Solution Overview
Problem
The existing fuel injection systems in annular combustion chambers of turbomachines suffer from turbulence and recirculation of the air-fuel mixture, leading to soot and coke deposits on the venturi surfaces, which result in hot spots and increased emissions of nitrogen oxides (NOx).
Innovation Solution
The longitudinal axes of the swirl channels are inclined to match the helix angle of the injector head, and the auger channels are separated by blades with inclined orifices, allowing the air flow to shear the fuel layer and reduce recirculation, eliminating the need for bleed orifices and optimizing the air-fuel mixture delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If axial air purge ports are used in the support means, then ventilation is provided, but turbulence and recirculation of air-fuel mixture occurs causing soot and coke deposits
Solution Approach 1:
The invention removes the axial air purge ports from the support means, extracting the source of turbulence and recirculation. Instead, ventilation is achieved through the spiral channels themselves, which naturally vent air without creating disruptive flow patterns that lead to deposits.
Solution Approach 2:
The invention changes the orientation parameter of the air channels from axial (perpendicular to spiral axis) to inclined (at angle α matching the helix angle). This parameter change transforms the flow pattern from turbulent and recirculating to laminar and co-current, eliminating deposit formation while maintaining ventilation.
2Device complexity
If channels have longitudinal axes perpendicular to the spiral axis, then simple structure is maintained, but turbulence and recirculation occur
Solution Approach 1:
The invention modifies the orientation parameter of the channels from perpendicular to the spiral axis to inclined at angle α (matching the helix angle). This single parameter change simultaneously achieves flow stability and maintains structural simplicity, as the inclined channels remain straightforward rectangular passages.
3Ease of operation
If helical channels rotate fuel around injector head, then fuel spray pattern is created, but velocity vectors are not aligned with optimal airflow direction
Solution Approach 1:
The invention changes the orientation parameter of the air channels from perpendicular to the injector axis to inclined at angle α matching the helix angle. This alignment ensures that the air flow velocity vectors are parallel to the fuel droplet velocity vectors, optimizing the air-fuel mixing and combustion efficiency.
4Productivity
If recirculation of air-fuel mixture occurs, then mixing is enhanced, but hot spots and NOx emissions increase
Solution Approach 1:
Instead of relying on recirculation to enhance mixing, the invention inverts the approach by creating a unidirectional co-current flow where air and fuel move in the same direction. This eliminates recirculation and hot spots while maintaining effective mixing through the aligned velocity vectors and continuous contact between air and fuel streams.
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 minimizes turbulence, reduces coke and soot deposits, stabilizes the flame, and decreases NOx emissions by ensuring co-current or counter-current air flows with the fuel vectors, enhancing combustion efficiency and reducing production costs through simplified design.
Implementation Method 1
the air flow to shear the fuel layer and reduce recirculation
Implementation Method 2
each injector comprises one or two fuel circuits, each feeding a helical channel located in the injector head. This helical channel rotates the fuel around the head's longitudinal axis
Implementation Method 3
The air exiting the primary auger is accelerated in a venturi interposed between the two augers
Implementation Method 4
A frustoconical mixing bowl is mounted downstream of the augers to atomize the air/fuel mixture entering the combustion chamber
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
Annular combustion chamber (10) for a turbomachine, comprising an annular row of fuel injectors (28) the tips (30) of which are engaged in fuel injection systems (126) mounted in openings (24) in the chamber end wall, each injector tip comprising at least one helical channel (42, 48) for carrying fuel in order to set this fuel in rotation about the longitudinal axis (XX) of the tip, and each injection system comprising at least one swirl inducer (154) the air passage channels (100) of which have cross sections the axes of which are inclined with respect to the longitudinal axis of the swirl inducer, by an angle (ß') that is substantially equal to the helix angle (ß) of the aforementioned helical channel, give or take 10°, and which are oriented in the same direction as this channel about the longitudinal axis of the swirl inducer.