KHOOMEI is a traditional throat-singing art created by the Mongolian ethnic group and is regarded as one of the oldest forms of this low rumbling vocal technique in the world.In 2006,Khoomei was included in China’s f...KHOOMEI is a traditional throat-singing art created by the Mongolian ethnic group and is regarded as one of the oldest forms of this low rumbling vocal technique in the world.In 2006,Khoomei was included in China’s first national list of intangible cultural heritage items,followed in 2009 by its inclusion on UNESCO’s Representative List of the Intangible Cultural Heritage of Humanity.展开更多
Lean-burn combustor is particularly susceptible to combustion instability and the unsteady heat release is usually considered as the excitation of the self-maintained thermoacoustic oscillations. The transverse coolan...Lean-burn combustor is particularly susceptible to combustion instability and the unsteady heat release is usually considered as the excitation of the self-maintained thermoacoustic oscillations. The transverse coolant injection is widely used to reduce the temperature of burnt gas, but on the other hand, it will introduce temperature fluctuation inside the combustor.Therefore, it is necessary to consider the influence of the coolant injection on combustion instability, and evaluate its dynamic feature. In this paper, Large-Eddy Simulation（LES） of the self-excited pressure oscillations in a model combustor with coolant injection is carried out. The analysis of transient flow characteristics and the identification of the pressure modes confirm that one of the low frequency pressure oscillations is related to entropy fluctuations, which is known as rumble combustion instability. The LES results show that transient coolant injection is another excitation of temperature fluctuation other than unsteady combustion. The amplitude of the entropy mode oscillation increases with increasing coolant air mass whereas the change of its frequency is insignificant. According to the major feature of entropy wave oscillation caused by coolant injection, a compact coolant injection model is proposed and applied in the One Dimensional（1 D） Acoustic Network Method（ANM）. Key correlations used in the model match well with LES data in low frequency range. This means that the coolant injection model is a complex one reflecting the interaction of the fluctuating coolant mass, pressure and temperature. Finally, the combustion instability frequencies and modes predicted by acoustic network method are also in good agreement with LES results.展开更多
文摘KHOOMEI is a traditional throat-singing art created by the Mongolian ethnic group and is regarded as one of the oldest forms of this low rumbling vocal technique in the world.In 2006,Khoomei was included in China’s first national list of intangible cultural heritage items,followed in 2009 by its inclusion on UNESCO’s Representative List of the Intangible Cultural Heritage of Humanity.
基金The funding of the National Natural Science Foundation of China (No. 51776191)
文摘Lean-burn combustor is particularly susceptible to combustion instability and the unsteady heat release is usually considered as the excitation of the self-maintained thermoacoustic oscillations. The transverse coolant injection is widely used to reduce the temperature of burnt gas, but on the other hand, it will introduce temperature fluctuation inside the combustor.Therefore, it is necessary to consider the influence of the coolant injection on combustion instability, and evaluate its dynamic feature. In this paper, Large-Eddy Simulation（LES） of the self-excited pressure oscillations in a model combustor with coolant injection is carried out. The analysis of transient flow characteristics and the identification of the pressure modes confirm that one of the low frequency pressure oscillations is related to entropy fluctuations, which is known as rumble combustion instability. The LES results show that transient coolant injection is another excitation of temperature fluctuation other than unsteady combustion. The amplitude of the entropy mode oscillation increases with increasing coolant air mass whereas the change of its frequency is insignificant. According to the major feature of entropy wave oscillation caused by coolant injection, a compact coolant injection model is proposed and applied in the One Dimensional（1 D） Acoustic Network Method（ANM）. Key correlations used in the model match well with LES data in low frequency range. This means that the coolant injection model is a complex one reflecting the interaction of the fluctuating coolant mass, pressure and temperature. Finally, the combustion instability frequencies and modes predicted by acoustic network method are also in good agreement with LES results.
