Journal
FLOW TURBULENCE AND COMBUSTION
Volume 108, Issue 4, Pages 1139-1157Publisher
SPRINGER
DOI: 10.1007/s10494-021-00309-3
Keywords
Low-swirl flame; Acoustic excitation; Flame dynamics; Proper orthogonal decomposition
Categories
Funding
- National Natural Science Foundation of China [51806204]
- Aeronautics Power Foundation of China
Ask authors/readers for more resources
This study experimentally investigates the dynamic response of a forced low-swirl methane/air premixed flame, revealing that flame response is influenced by swirl number, with time delay decreasing as swirl number increases. The flame oscillates mainly in the axial direction at low frequency and turns into radial direction at high frequency, with flame intensity fluctuation mainly controlled by the flame tail.
This paper presents an experimental study on dynamic response of a forced low-swirl methane/air premixed flame with external acoustic excitation over a wide range of driving frequency. Global flame response in terms of gain and phase delay between flame intensity and incoming velocity perturbation is determined. Local flame response is investigated in detail at three typical frequencies: 55 Hz, 105 Hz and 155 Hz. The effect of swirl number on the flame response is also discussed. Proper orthogonal decomposition is applied to identify the large coherent structures in the forced flame. Experimental results show flame response gain exhibits a successive of valleys and peaks which is dependent on swirl number. Time delay decreases as swirl number is increased. The low-swirl flame oscillates back and forth mainly in the axial direction at low excitation frequency and it turns into radially dominated direction at high frequency. Flame intensity fluctuation is mainly dominated by the tail of the flame at 55 Hz and 155 Hz while the flame response is controlled by a combined effect of the base and tail region at 105 Hz. Further POD analysis shows symmetric, anti-symmetric and helical modes in the flame. The most energetic modes (mode 1 and mode 2) feature a symmetric wave-like structure at low excitation frequency while it tends to be in antisymmetric modes at high frequency.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available