Effect of carbon dioxide, argon, and helium jets on the synchronous control of combustion instability and NOx emission

摘要

This article experimentally studies the synchronous control of combustion instability and NOx emission in a model gas turbine combustor. The application of tabular jet in cross flow was adopted to test the effectiveness of synchronous control. The flow rate, height, direction, and relative molecular masses were studied in this research. Results suggest that the ideal damping ratio of the sound pressure amplitude can be as high as 73.7% under the carbon dioxide jet in cross flow case. The carbon dioxide jet in cross flow case can lead to a better thermoacoustic instability suppression result than the instances of argon or helium. Besides, amplitude and frequency switching of the unsteady flame emerged during the experiment. Adding minimal inert gaseous can change the local oscillation of equivalence ratio. The suppression ratio of NOx emission can reach as high as 44% under the carbon dioxide cases, which performs better than the argon or helium cases. Moreover, the flame length declines as the tabular jet in cross flow rate increases. When the flow rate increases (or the height decreases), the size of the flame front or root will decrease. The average flame length dropped from 122 to 41 mm. The macrostructure of the flame changes significantly under different injecting heights or directions. This article can serve as a specific guideline for the passive control of thermoacoustic instability in gas turbine, rocket, and industrial burners.