Session: 04-21: Combustion Dynamics - Flame Transfer Functions

Paper Number: 82871

82871 - Dynamic Response of Stratified Flames to Acoustic Excitation in a Multi-Swirler Model Combustor 

Flame response is a key element in predicting thermoacoustic instabilities in gas turbine combustors. Flame dynamic response of single swirling flames to acoustic excitation was well studied in the past decades, while the unsteady dynamic of multi-swirling flames, such as stratified flames, is not fully reported. This paper presents dynamic response of stratified flames in a multi-swirler combustor which includes a main stage and a pilot stage. The stratified flame contains an outer main flame and an inner pilot flame. The overall Flame Transfer Function (FTF) of the stratified flame is extracted during the experiment. OH Planar Laser Induced Fluorescence (OH-PLIF) and Particle Image Velocimetry (PIV) are used to captured the evolution of the flame structure and flowfield. Experimental results show the overall flame transfer function of the stratified flame is very different with the combination of the pilot and main flame. The interaction between the pilot flame and main flame determines the overall flame dynamic behaviors of the stratified flame. The first peak of overall FTF of the stratified flame is induced by the pilot flame while the secondary peak is caused by the main flame. Phase-averaged OH-PLIF reveals the main flame oscillates back and forth while the pilot flame flaps around the burner axis which indicates different flame behaviors between the pilot flame and main flame. Proper Orthogonal Decomposition (POD) of the high-speed PIV data reveals coherent structures are formed in the pilot flame. The dynamic motion of pilot flame modulates the main flame, eventually leads to the overall dynamic behavior of the stratified flame.

Presenting Author: Weijie Liu Aero-Engine Academy of China

Presenting Author Biography: Weijie Liu recieved his Ph D. degrees in Power Machinery and Engineering from Shanghai Jiao Tong University, China, in 2017. He is currently an senior engineerer at Aero-Engine Academy of China. His research interests include lean premixed combustion, multi-nozzle combustion and theromacoustic instabilities.

Authors:

Weijie Liu Aero-Engine Academy of China
Ming Jin Shanghai Jiao Tong University
Bing Ge Shanghai Jiao Tong University
Ranran Xue Aero-Engine Academy of China
He Su Aero-Engine Academy of China
Shusheng Zang Shanghai Jiao Tong University