Annular Combustion Chamber Flame Propagation
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Solution Overview
Problem
In annular combustion chambers for turbine engines, particularly in converging configurations with fewer injection systems, the circumferential propagation of the combustion flame is hindered due to increased circumferential pitch, leading to reduced performance without viable solutions like increasing the number of injectors or aperture angle, which would result in hot points and weight gain.
Innovation Solution
The combustion chamber design modifies the distribution and dimensioning of air injection orifices in the mixer bowls to create local enlargements in the air/fuel mixture sheets, ensuring they intersect adjacent sheets upstream from primary dilution orifices, maintaining the same angular aperture while enhancing flame propagation without additional injectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the number of injection systems is reduced in converging combustion chambers, then the device complexity is reduced, but the circumferential propagation of combustion flame deteriorates
Solution Approach 1:
The invention applies local quality by creating asymmetric orifice configurations in specific bowls. Certain bowls have orifices of smaller diameter than others, creating local variations in the air/fuel mixture sheet characteristics. This local modification enables circumferential intersection with adjacent sheets without requiring additional injection systems, thus maintaining reliability while reducing device complexity.
Solution Approach 2:
The invention changes the parameter of orifice diameter in specific bowls to achieve the desired effect. By reducing the diameter of orifices in certain bowls, the air flow rate through those orifices is reduced, which increases the aperture angle of the resulting air/fuel mixture sheet. This parameter change allows the sheet to intersect adjacent sheets circumferentially, ensuring proper flame propagation with fewer injection systems.
2Reliability
If the aperture angle of fuel sheets is increased to ensure circumferential intersection, then the flame propagation is improved, but hot points are formed on the inner and outer coaxial walls
Solution Approach 1:
The invention applies local quality by selectively modifying orifice diameters in specific bowls rather than uniformly increasing the aperture angle of all fuel sheets. This localized approach allows certain sheets to intersect circumferentially for proper flame propagation while maintaining normal aperture angles in other areas, preventing excessive fuel projection onto the walls and avoiding hot point formation.
Solution Approach 2:
The invention changes the orifice diameter parameter in specific bowls to increase the aperture angle only where needed for circumferential intersection. This selective parameter change ensures flame propagation reliability while limiting the increase in aperture angle in other areas, thereby preventing the formation of hot points on the inner and outer coaxial walls.
3Reliability
If additional injection systems are added to ensure circumferential intersection, then the flame propagation is improved, but the weight of the engine increases
Solution Approach 1:
The invention changes the orifice diameter parameter in existing bowls to achieve circumferential intersection of air/fuel mixture sheets. This parameter modification allows the existing injection systems to produce sheets with increased aperture angles that intersect circumferentially, ensuring proper flame propagation without the need for additional injection systems and avoiding the weight penalty that would result from adding more injectors.
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 ensures circumferential continuity and effective propagation of the combustion flame, preventing hot points and weight increase, by locally modifying the orifice diameters and distribution to intersect adjacent fuel sheets, thus improving engine performance.
Implementation Method 1
a bowl having a substantially frustoconical wall downstream from the swirler and formed with an annular row of air injection orifices for producing a substantially frustoconical and rotating sheet of a mixture of air and of fuel
Implementation Method 2
at least one swirler that is arranged downstream from the head of the injector, on the same axis, and that delivers a rotating stream of air downstream from the injection of fuel
Implementation Method 3
delivers downstream a stream of hot gas for driving the rotors of high-pressure and low-pressure turbines
Data Source
AI summary
An annular combustion chamber including inner and outer walls forming surfaces of revolution that are connected together upstream by an annular chamber end wall having injection systems passing therethrough. Each injection system includes at least one swirler for producing a rotating stream of air downstream from a fuel injector, and a frustoconical bowl downstream from the swirler and formed with an annular row of air injection orifices, the outer wall having an annular row of primary dilution orifices. The orifices of the bowls are distributed and dimensioned such that sheets of air/fuel mixture present a local enlargement circumferentially intersecting an adjacent sheet of fuel upstream from the primary dilution orifices.