We carry out a series of experimental investigations in a model combustor to detect a precursor of thermoacoustic combustion oscillations based on permutation entropy,which can amplify the subtle changes effected in t...We carry out a series of experimental investigations in a model combustor to detect a precursor of thermoacoustic combustion oscillations based on permutation entropy,which can amplify the subtle changes effected in the time sequence to identify the anomaly.By changing the flame’s location or the fuel flow to a value,an abrupt switch from aperiodic small-amplitude oscillations to periodic large-amplitude oscillations would occur in pressure fluctuations.The characteristic frequency of combustion oscillation is obtained by spectral analysis,with which a modified algorithm of the permutation entropy is proposed.The impact evaluation on key parameters such as moving step sizes and window sizes reveals that the moving data permutation entropy has strong robustness,and can accurately detect the onset of thermoacoustic oscillations.Further nonlinear analysis exhibits peculiar dynamics of the combustion system,which result in specific patterns in the time series and provide a theoretical basis for anomaly detection.Our results suggest that the permutation entropy has a certain potential in early warning and detection of combustion oscillations.展开更多
Flameless combustion is a new technology with the following advantages:1)Ultra-low emissions of both NOX and CO;2)fuel flexibility,from liquid fuels,natural gas to hydrogen-rich syngas;3)lower possibility of flashback...Flameless combustion is a new technology with the following advantages:1)Ultra-low emissions of both NOX and CO;2)fuel flexibility,from liquid fuels,natural gas to hydrogen-rich syngas;3)lower possibility of flashback and thermoacoustic oscillations.In this paper,we focus on the dynamic characteristics of a flameless model combustor.Experimental results show that flameless combustion can lower emissions while maintaining combustion stability.However,combining a pilot flame with flameless combustion may excite thermoacoustic instability.展开更多
基金funding from National Science and Technology Major Project (J2019-Ⅲ-0020-0064, J2019-Ⅲ-0002-0045)the National Defense Basic Research Program (JCKY2020130C025)
文摘We carry out a series of experimental investigations in a model combustor to detect a precursor of thermoacoustic combustion oscillations based on permutation entropy,which can amplify the subtle changes effected in the time sequence to identify the anomaly.By changing the flame’s location or the fuel flow to a value,an abrupt switch from aperiodic small-amplitude oscillations to periodic large-amplitude oscillations would occur in pressure fluctuations.The characteristic frequency of combustion oscillation is obtained by spectral analysis,with which a modified algorithm of the permutation entropy is proposed.The impact evaluation on key parameters such as moving step sizes and window sizes reveals that the moving data permutation entropy has strong robustness,and can accurately detect the onset of thermoacoustic oscillations.Further nonlinear analysis exhibits peculiar dynamics of the combustion system,which result in specific patterns in the time series and provide a theoretical basis for anomaly detection.Our results suggest that the permutation entropy has a certain potential in early warning and detection of combustion oscillations.
基金supported by the National Natural Science Foundation of China(Grant No.50706054)
文摘Flameless combustion is a new technology with the following advantages:1)Ultra-low emissions of both NOX and CO;2)fuel flexibility,from liquid fuels,natural gas to hydrogen-rich syngas;3)lower possibility of flashback and thermoacoustic oscillations.In this paper,we focus on the dynamic characteristics of a flameless model combustor.Experimental results show that flameless combustion can lower emissions while maintaining combustion stability.However,combining a pilot flame with flameless combustion may excite thermoacoustic instability.
