EFFECT OF VARYING TURBULENCE INTENSITY ON THERMOACOUSTIC INSTABILITY IN A PARTIALLY PREMIXED COMBUSTOR

An experimental study on a turbulent combustor with a swirl stabilized flame was conducted to understand the effect of the turbulence intensity on the dynamics of the combustor as it transitions from a low amplitude aperiodic (stable) state to high amplitude thermoacoustic instability. High speed imaging of the flame (representative of the field of heat release rate fluctuations) and simultaneous unsteady pressure measurements were performed. We observe that as the turbulence intensity at the inlet is increased, there is a decrease in the acoustic power generated by the interaction between the heat release rate fluctuations and the acoustic field. This is observed from the time averaged field of Rayleigh Index. Further, we also observe that the onset of the thermoacoustic instability is advanced as the turbulence intensity is increased. We also perform the study with a bluff body stabilized flame and observe that increase in turbulence intensities causes a different response compared to swirl stabilized flame. Increased turbulence intensities produce varied results across different flame stabilizing mechanisms.