Multi-tube injectors have been emerging as a component that has potential to mitigate flame stability (flashback and blowout) and emission issues (NOx) associated with quick-start and fuel-flexible operations in lean premixed applications. Although several designs currently exist in literature, there currently does not exist a large source of information on the design parameters and exact dimensional configurations for these existing injectors. One cause of this may be due to the proprietary nature of this component. Furthermore, most multiport injector designs involve complex tubing and typically significant pressure drops across the exit face. In the present study a fuel injector component was designed keeping in mind simple injector geometry, possible operability limits of the flame, and turbulence intensity expected at the exit of the injector. This work presents the final design and the flame stability results from a multi-tube fuel-air injector. The injector operates on simulated syngas mixtures of hydrogen and carbon monoxide including 20–80, 30–70, and 40–60% representing the variation in the hydrogen found in syngas mixtures. Tests were completed for lean conditions ranging from equivalence ratios between 0.6 and 0.9. The experimental results showed that for the current injector design at an equivalence ratio of 0.6 a stable flame was not achieved for any of the fuel mixtures tested. It was also observed that the stability region of the syngas flame increased as equivalence ratios above 0.7 and the hydrogen concentration in syngas fuel increases with the 40–60% hydrogen-carbon monoxide mixture demonstrating the greatest stability region which can accommodate more than three times the stability range of other conditions. Results from this study may benefit others who are currently designing such fuel injectors for lean premixed combustion applications.
