| In order to study the thermoacoustic instability characteristics of Rijke-type and swirl combustor under the O2/CO2 atmosphere,experimental setups have been built.A series of experimental studies were carried out and some significant conclusions were got.First we clarified the thermoacoustic phenomenon and thermoacoustic theory, and introduced the thermoacoustic instability phenomenon and its' research development.Besides,we introduced the characteristics,applications and research developments of O2/CO2 combustion Technology.After we summarized the study of the predecessor,a Rijke and swirl combustion thermoacoustic instability experimental setup were designed and built,including the Rijke combustor,swirl combustor,fuel import system,temperature measurement system and pressure measurement system.We studied the thermoacoustic characteristics of a Rijke-type combustor with the heat source located at the tube's cross section,one-fourth downstream of bottom, under the O2/CO2 atmosphere,and find that the temperature of the Rijke combustor was greatly related to the combustion power and equivalence ratios,the un-burn-off rate of methane decreases with equivalence ratios,showing a good linearity.We studied the thermoacoustic characteristics of a Rijke-type combustor with the heat source located at the tube's cross section,half downstream of bottom,under the O2/CO2 atmosphere,and find that the lower limit value of oxygen concentration to sustain combustion inside the 1/2 heat source Rijke-type combustor was found to be 25%,the unburn-off rate of methane in all studied cases was found to be larger than 5%;the excitation of thermoacoustic oscillation was found to be a multi-variant function with variants such as combustion power,oxygen concentration,average inlet velocity,and so on.The influences of the equivalence ratios,combustion power and oxygen concentrations on the swirl combustor under the O2/CO2 atmosphere were explored. The results show that the combustion delay is affected significantly by oxygen content in the oxidant stream,and that equivalence ratio has a slight effect on the combustion delay,whereas no impact was detected by combustion power.Carbon monoxide was found to be produced vastly when OF＞35%or EQ＞0.95 in oxy-fuel flames. Pressure pictures of O2/CO2/CH4 combustions are greatly different from those of O2/N2/CH4 combustions with similar oxygen content.O2/CO2/CH4 combustions excite strong oscillations in all cases studied(OF=25%-45%),however,no pressure fluctuations were detected in the reference cases when OF＞28.6%,accomplished by heavily sooting flames which were not found in O2/CO2/CH4 combustions.
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