Investigations of Premixed Flames Driven Acoustic in a Combustor

• Main Authors: Hsin-Cherng Lee, 李新成
• Other Authors: Tseng-Yuan Chen
• Format: Others
• Language: zh-TW
• Published: 1993
• Online Access: http://ndltd.ncl.edu.tw/handle/38058232672643980412

碩士 === 淡江大學 === 機械工程研究所 === 81 === The research is concerned with the theoretical and experi- mental investigations of sound generation by premixed flames located on the sidewall of a long rectangular duct. The experi- mental studies were conducted by using microphone probes and photomultiplier tube. These studies reveal that the self- excited oscillatory flame radiation and the induced pressure oscillation were observed only at certain equivalence ratios which are between 0.64 and 0.81 for the mixture(LPG + air) flow velocity in the vicinity of 8 cm/sec. In addition, the flame oscillates with several frequencies and the main frequencies of the flame oscillations decrease as the equivalence ratio decrease. However, the acoustic oscillations could be enhanced when the frequencies of the flame oscillations are close to the harmo- nics of the experimental duct. From the theoretical analysis and experimenatal observations, it was shown that the flame induced acoustic oscillations depend on the flame location with respect to the standing wave pattern within the duct. Driving of acoustic oscillations occurred when the flame was located close to the pressure antinode. On the other hand, the acoustic oscillations were damped when the flame was located near the pressure node. Finally, the results of this research reveal that the predicted pressure spectra are in good agreement with the experimental observations.