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

Abstract

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.

Mitigating combustion instability and NOx emissions with annular oxyfuel jets into the flame shear layer region

“…The inlet part of the bluff body was connected to Teflon pipes that delivering CO 2 /O 2 gas. According to the geometric parameters, the cut‐off frequency of this combustor can be calculated as f = 1510 Hz 8,48–51 . This value is larger than the self‐excitation frequency of the combustor (268 Hz).…”

“…Figure 1a shows the geometrical system of the model lean premixed gas turbine combustor of our laboratory 48–51 . The detailed structure of the pivotal section is presented and dimensioned.…”

“…(a) The geometrical structure of the model lean premixed gas turbine combustor. The detailed structure of the swirling part is presented and dimensioned 48–51 . (b) The sectional view of the combustor.…”

“…c indicates the speed of sound, c = 344 m/s. d means the inner diameter of the burner, d = 0.114 mm 8,50,51 …”

“…Besides, the CO 2 /O 2 atmosphere could damp the flame combustion instability and NO x emissions at the same time 8,48,49 . Last but not least, the flame temperature is one of the main factors affecting flame soot formation, 50 which will be changed under gas dilution 51 . For better understanding the soot evolution with fuel under different flame temperatures, Liu et al 52–54 studied the surrogate of diesel fuel consisting of the blends of n ‐heptane and toluene.…”