Prediction of combustion instability limit cycle oscillations by combining flame describing function simulations with a thermoacoustic network model

Prediction of Limit Cycle Pressure Oscillations in Gas Turbine Combustion Systems Using the Flame Describing Function

Combining a Helmholtz solver with the flame describing function to assess combustion instability in a premixed swirled combustor

Limit cycles of combustion instabilities can be estimated by studying the nonlinear behavior of flame dynamics. In the present study the flame describing function (FDF) framework is combined with a linear acoustic Helmholtz solver in order to estimate the growth rate of the acoustic perturbations in a swirled combustor. It is assumed that when this growth rate equals the inherent dissipation of...

Limitations of the describing function for limit cycle prediction

We consider comparator-based nonlinear feedback systems, and use Tsypkin’s method to develop a strategy with which to find systems with low-pass linear part for which the describing function technique erroneously predicts limit cycles. We produce an infinite set of examples of systems with very low-pass linear parts for which the describing function technique predicts spurious limit cycles, and...

Passive Control of Limit Cycle Oscillations in a Thermoacoustic System using Asymmetry

In this paper we investigate oscillations of a dynamical system containing passive dynamics driven by a positive feedback and how spatial characteristics (i.e. symmetry) affect the amplitude and stability of its nominal limit cycling response. The physical motivation of this problem is thermoacoustic dynamics in a gas turbine combustor. The spatial domain is periodic (passive annular acoustics)...

Physics-Based Flame Dynamics Modeling and Thermoacoustic Instability Mitigation

The objectives of this work are (i) to investigate the coupled unsteady heat release mechanisms responsible for thermoacoustic instabilities under di erent ame anchoring con gurations, (ii) to develop reduced-order models to predict the dynamic ame response, and (iii) to develop passive instability mitigation strategies by modifying the dynamics of the ame anchoring zone. The two di erent ancho...