Numerical Prediction Of Thermoacoustic Instabilities With A V-Flame

In this paper, results from a numerical solver for the Helmholtz equation using the Finite Element Method (FEM) for predicting thermoacoustic instabilities are presented. The one-dimensional n-tau flame model, which is governed by an interaction index n and a time-delay tau as well as a Flame transfer function (FTF) is used for flame source term.We show results for the validation of the numerical solver for the Rijke tube benchmark case with the variation of n and tau in the one-dimensional n-tau model. Thereafter, thermoacoustic instabilities for a V-flame are predicted, for a typical configuration of a dump combustor - a tube with an area expansion. This is a more realistic test case, since a bluff-body flame holder is often used in combustors, where a V-flame will be generated and anchored to the rod. Usually, the V-flame is more susceptible to thermoacoustic instabilities. In the paper, the eigenfrequencies, as well as the acoustic pressure perturbations are presented as numerical results.