Low swirl

High momentum jet-stabilised combustion systems offer great versatility in a diverse fuel market, ranging from pure hydrogen to extra light heating oil while maintain low emissions (i.e. NOx and particulates). The combustion process offers short mixture residence time that addresses issues like premature auto-ignition or flashback while ensuring homogenous temperature distribution throughout the combustion process, regardless of fuel composition. One drawback is the elongated flame length and, for liquid fuel operated systems, the scalability to compact designs.

Characteristic features of low-swirl combustion are the absence of an internal recirculation zone, which transports large amounts of exhaust gas to the flame root for stabilization, and a diverging flow with shorter residence times for hot combustion products, which minimizes NOx formation in the flame burnout. Low-swirl concepts are typically investigated in premixed moderate to high swirl flames.

In this work we have integrated a newly developed additive manufactured (AM) low-swirl injector into a high momentum jet-stabilised combustion framework, successfully addressing both concerns: (i) improved robustness of injection systems to enhance scalability and mixture formation, and (ii) reduced flame length to realize compact combustors. Furthermore, the circumferential flow amplifies radial fuel placement with enhanced turbulence kinetic energy, leading to rapid mixture homogenization and reduced soot propensity.

The developed injection system can be considered a key technology for integrating liquid fuel-powered high momentum jet-stabilized combustion into compact systems, such as micro gas turbines and hybrid aero-engines.

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