Design for Thermo-Acoustic Stability: Modeling of Burner and Flame Dynamics

Abstract

A design for thermo-acoustic stability (DeTAS) procedure is presented that aims at selecting the most stable burner geometry for a given combustor. It is based on the premise that a thermo-acoustic stability model of the combustor can be formulated and that a burner design exists, which has geometric design parameters that sufficiently influence the dynamics of the flame. Describing the flame dynamics in dependence of the geometrical parameters, an optimization procedure involving a linear stability model of the target combustor, maximizes the damping and thereby yields the optimal geometrical parameters. To demonstrate the procedure on an existing annular combustor a generic burner design was developed that features significant variability of dynamical flame response in dependence of two geometrical parameters. In this paper the experimentally determined complex burner acoustics and complex flame responses are described in terms of physics-based parametric models with excellent agreement between experimental and model data. It is shown that these model parameters correlate uniquely with the variation of the burner geometrical parameters, allowing interpolating the model with respect to the geometrical parameters. The interpolation is validated with experimental data.