Experimental analysis of thermo-acoustic combustion instability

Thermo-acoustic instabilities are dynamic phenomena that represent a major threat for most modern combustion systems. Many studies, mainly undertaking a linear analysis of experimental data, have been carried out to provide a deeper understanding of the underlying phenomena. However, linear analysis may lead to an oversimplified view of the problem, which involves many com plex non-linear interactions, and a more detailed non-linear analysis may b e necessary. This paper presents both linear and non-linear analyses of exp erimental measurements observed in a methane-fuelled laboratory combustor. The linear analysis aims to verify the existence of thermo-acoustic instabi lities and consists of the elaboration of both power-spectral density distr ibution and Rayleigh Index of the experimental time series. Nonlinear analy sis aims to investigate dynamic behaviours by means of the deterministic ch aos theory. Results of the analyses show that combustion instabilities occu r in all the experimental operating conditions. Moreover, the existence of a chaotic source in the combustion system under study is demonstrated. (C) 2001 Elsevier Science Ltd. All rights reserved.