Spatial and Temporal Distribution of Secondary Fuel for Suppression of Combustion Dynamics

The effect of the spatial and temporal distribution of modulated secondary fuel on suppressing unstable combustion is evaluated in a laboratory-scale, lean premixed combustor. Two unstable operating conditions are established by varying the main fuel distribution and are characterized using high-frequency response-pressure measurements and phase-synchronized chemiluminescence imaging. The effectiveness of active combustion control employing phase-delayed subharmonic injection of secondary fuel is determined for two different secondary-fuel injection locations for each of the unstable operating conditions. Secondary fuel injection is characterized in terms of a flame-response function, which represents the temporal modulation of heat release due to the secondary fuel. The flame-response function for each injection location is used to calculate the flame-response Rayleigh index for each instability. It is found that the flame-response Rayleigh index can be used to predict the phase delay required for maximum damping. It is also shown that the most effective control for a given instability is achieved when the secondary fuel is injected into the damping region shown in the local Rayleigh index distribution for that instability.

[1]  J. H. Whitelaw,et al.  Control of Combustion Oscillations by Forced Oscillation of Part of the Fuel Supply , 1995 .

[2]  G. Billoud,et al.  Adaptive Active Control of Combustion Instabilities , 1992 .

[3]  Ann P. Dowling,et al.  PRACTICAL ACTIVE CONTROL-SYSTEM FOR COMBUSTION OSCILLATIONS , 1990 .

[4]  Kenneth J. Wilson,et al.  Liquid-fueled active instability suppression , 1998 .

[5]  Joerg R. Seume,et al.  Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine , 1998 .

[6]  Ephraim Gutmark,et al.  Active combustion control in a coaxial dump combustor , 1990 .

[7]  Jeffrey M. Cohen,et al.  The effect of fuel/air mixing on actuation authority in an active combustion instability control system , 2001 .

[8]  Yedidia Neumeier,et al.  Experimental demonstration of active control of combustion instabilities using real-time modes observation and secondary fuel injection , 1996 .

[9]  J. Lee,et al.  Effect of injection location on the effectiveness of an active control system using secondary fuel injection , 2000 .

[10]  C. M. Jones,et al.  Closed-Loop Active Control of Combustion Instabilities Using Subharmonic Secondary Fuel Injection , 1999 .

[11]  Jeffrey M. Cohen,et al.  Active Control of Combustion Instability in a Liquid–Fueled Low–NOx Combustor , 1998 .

[12]  C. Dasch,et al.  One-dimensional tomography: a comparison of Abel, onion-peeling, and filtered backprojection methods. , 1992, Applied optics.

[13]  J. Lee,et al.  Experimental Diagnostics for the Study of Combustion Instabilities in Lean Premixed Combustors , 2003 .

[14]  Luke H. Cowell,et al.  Combustion Oscillation Control by Cyclic Fuel Injection , 1997 .