Session: 04-37: Combustion dynamics - experiments II

Paper Number: 125993

125993 - Experimental Investigation on the Effect of Inlet Temperature on Thermoacoustic Oscillation in a Centrally-Staged Combustor 

Self-excited thermoacoustic instabilities are frequently observed in Lean Premixed Prevaporized (LPP) centrally-staged combustors, typically affecting the dynamic characteristics of flames and causing damage to the combustor components. As thermoacoustic instabilities are susceptible to external factors, this study explores mechanisms by which combustor inlet air temperature and swirl intensity impact thermoacoustic oscillations. Differing from the previous studies, starting from the combustion instabilities of the system at 400K, as the inlet temperature increases, the oscillation amplitude of the system gradually decreases, while the frequency initially rises and then declines, reaching its peak at 550K. Additionally, the stronger the swirl intensity of the swirlers, the larger the amplitude and frequency of the system. The axial length and heat release of the flame are obtained through the time-averaged and Abel-inverted transformation. Dynamic mode decomposition (DMD) is used to analyze the flame dynamic characteristics. Combining the local Rayleigh map, it is found that the thermoacoustic oscillation originates from the inner/out shear layer and the region where the main and pilot flame intersect. A stronger thermoacoustic oscillation in a region indicates the more pronounced coupling between pressure and heat release fluctuations. Researching the thermoacoustic oscillation mechanism affecting the centrally-staged combustor is helpful for the design and optimization of the combustor.

Presenting Author: Jinglong Ma Beihang University

Presenting Author Biography: The author's primary research focus is on thermoacoustic oscillations and combustion instability.

Authors:

Jinglong Ma Beihang University
Xiao Han Beihang University
Zhipeng Yang Beihang University
Xin Hui Beihang University