Experimental Study on Thermoacoustic Instability of an Axially Staged Combustor
In order to investigate the influence of the secondary fuel ratio on thermoacoustic char-acteristics,an experimental study on an axially staged combustor under high temperature and high pressure condition was carried out.Based on the dynamic pressure signals obtained under different operating conditions and different secondary fuel ratios during the experiment,the methods of time-frequency analysis and phase-space reconstruction analysis were used to investigate the change of the combustor's thermoacoustic characteristics.The results showed that there were low frequencies of 30 Hz,90 Hz and high frequency of 1500 Hz.With the increase of the secondary fuel ratio,the air-fuel ratio in primary zone increased,the amplitude of low frequencies increased rapidly after a certain ratio,and the amplitude of high frequency decreased.The reconstructed phase plots showed that the impact of combustion noise was critical under high temperature and high pressure condition.Although the limit cycle structure could be observed,the trajectory was not smooth.As the load increased,the secondary fuel ratio increased to maintain the air-fuel ratio in primary zone in the stable region,and then stabilized the thermoacoustic state.
axially staged combustorsecondary fuelthermoacoustic stabilityphase space ana-lysis
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