Non-linear system identi®cation using closed-loop data with no external excitation: the case of a lean combustion chamber

This paper deals with the analysis of a set of measurements collected on a lean premixed combustion process operating in a limit cycle. Due to the fact that the data are collected in closed-loop and the system has no external excitation, the identi®cation task is particularly challenging. This work mainly focuses on the issue of the feasibility of the identi®cation task. It will be shown that, despite the paucity of information available, a grey-box non-linear model can be estimated. The model provides an explanation both of the limit-cycle fundamental oscillation and of a non-harmonic high-frequency signal a€ ecting the pressure of the combustion chamber.