A zero-Mach solver and reduced order acoustic representations for modeling and control of combustion instabilities

Abstract

Thermoacoustic instabilities are a serious problem for lean premixed combustion systems. Due to different time and length scales associated with the flow field, combustion, and acoustics, numerical computations of thermoacoustic phenomena are conceptually challenging. Using these methods to successfully design active control strategies is therefore difficult. This work presents a coupled method for the simulation of thermoacoustic instabilities in low Mach number reacting flows. The acoustics are represented by an experimentally identified reduced order model. A zero-Mach solver is used for the flame dynamics on the hydrodynamic scale. Two control schemes are employed to suppress thermoacoustic oscillations, equivalence ratio modulation and control of the acoustic boundary conditions. Both methods are shown to be capable of effectively diminishing the instability.