Heat release rate responses in self-excited thermoacoustic instabilities of tangential swirling non-premixed flames

This paper investigates the thermoacoustic stability of non-premixed flames in a tangential swirler combustion chamber. Thermoacoustic instabilities, characterized by intense pressure oscillations, pose significant challenges in the design and operation of combustion devices such as gas turbines and rocket engines. This study focuses on understanding the dynamics of flame heat release rate (HRR) and its interaction with acoustic waves under varying operating conditions. The experimental setup involves a single-injector tangential swirler non-premixed flame with detailed measurements of pressure fluctuations, HRR, and flame dynamics using high-speed imaging and chemiluminescence techniques. The results reveal distinct thermoacoustic instability modes, influenced by factors such as inlet velocity and equivalence ratio. This paper highlights the complex interplay between flame structure, HRR fluctuations, and acoustic coupling, providing insight into the mechanisms that govern thermoacoustic stability in non-premixed combustion systems. This research contributes to the development of strategies for mitigating thermoacoustic instabilities in practical combustion applications.