Session: 04-41 Combustion dynamics - hydrogen flames I

Paper Number: 127424

127424 - Experimental Investigation on the Effect of Nozzle Bluntness Thickness on the Combustion Characteristics of a High-Speed Parallel Jet Mild Combustor 

The safe, stable, and low-emission combustion of high-content hydrogen and pure hydrogen fuels is a crucial aspect of the gas turbine combustion system for achieving carbon-neutral and ultimately carbon-free combustion. However, employing high hydrogen content and even hydrogen as a fuel in combustors presents unique challenges due to distinct fuel characteristics compared to natural gas. The rapid flame propagation speed, strong reactivity, and elevated flame temperature of hydrogen impose novel requirements on the design of gas turbine combustion engines. This study parametrically investigates the impact of three different nozzle bluntness thicknesses on the combustion stability and NO_x emission characteristics of the high-speed parallel jet MILD combustor. The self-excited instability and nitrogen oxide emissions were measured for methane fuel mixed with varying hydrogen contents ranging from 60% to 100% under different bluntness thicknesses. OH* images captured by an image-enhanced high-speed camera were utilized to characterize reaction zone features. The dynamic response characteristics of flames and combustion behavior in the MILD combustor were examined during high hydrogen concentration and pure hydrogen combustion. The findings demonstrate that the effect of bluntness thickness variation on the reaction zone morphology can be classified into two distinctive stages, including reaction zone morphology, which is dominated by the flow field at relatively low hydrogen content and equivalency ratios and by the chemical reactivity of the reactants at higher hydrogen content and equivalence ratios. Under different hydrogen concentration levels, altering the bluntness thickness leads to energy transfer shifts in pulsating pressure peaks within the combustion chamber. Despite significant differences in thermoacoustic characteristics among different bluntness thicknesses, total nitrogen oxide emissions remain relatively unchanged. Additionally, in the high-speed jet MILD combustor, nitrogen oxides exhibit little variation at different hydrogen concentrations.

Presenting Author: Ningjing Yang Key Laboratory of Advanced Energy and Power, Institute of Engineering Thermophysics, Chinese Academy of Sciences

Presenting Author Biography: Ningjing Yang is a student of Institute of Engineering Thermophysics (Chinese Academy of Sciences).The objectives of her research are (i) to investigate the low emission combustion technology for gas turbine, including flameless combustion, (ii) to analyze the influence of hydrogen content on pollutant emission and stability of combustion. If you are interested in her research topics, please feel free to contact her via email: yangningjing@iet.cn.

Authors:

Ningjing Yang Key Laboratory of Advanced Energy and Power, Institute of Engineering Thermophysics, Chinese Academy of Sciences
Yan Xiong Key Laboratory of Advanced Energy and Power, Institute of Engineering Thermophysics, Chinese Academy of Sciences
Zhigang Liu Key Laboratory of Advanced Energy and Power, Institute of Engineering Thermophysics, Chinese Academy of Sciences
Xiang Xu Key Laboratory of Advanced Energy and Power, Institute of Engineering Thermophysics, Chinese Academy of Sciences