Finite Volume Time-Domain Solver to Estimate Combustion Instabilities

Abstract

Modeling tools used to estimate thermoacoustic combustion instabilities include classic network models, three-dimensional frequency-domain acoustic solvers, and computational fluid dynamics. Motivated by the large gap in both computational cost and predictive capability between the first two tools and computational fluid dynamics, the present work discusses and tests an approach that bridges this gap: a three-dimensional finite volume, acoustic solver in the time domain. Distinguishing features of the newly developed solver include the ability to capture both linear and nonlinear acoustics, the use of a solution algorithm based on an approximate Riemann solver, and the ability to handle complex geometries with unstructured meshes. This new solver produces results that agree well with analytical solutions for a two-dimensional isothermal cavity and a one-dimensional Rijke tube, as well as with the experimental data of a reheat buzz. For this last problem, a limit cycle is produced with a physical model that bounds heat-release fluctuations. In addition, results from the new acoustic solver for an annular combustor compare well with those of a three-dimensional frequency-domain acoustic solver, demonstrating the capabilities of the new solver to capture multidimensional acoustics.