SUDIPTO SUR |
Interaction of heat-release with the gas/fluid-dynamics causes instabilities in a combustor. This degrades combustor performance and limits the range of opeeration. Further, certain types of instabilities cause combustors to be run at operating points where they cause more pollution (NOX emission). Active control seeks to control these instabilities by using feedback information from the combustor. Good models for better understanding of the operation of combustors and possible control ideas are required to effectively tackle this problem. The system itself is defined by nonlinear partial differential equations which must be reduced to low-order models for analysis and controller synthesis with available tools.
I was developing low-order models for the operation of combustion chambers from combustor data using a technique called time delay embedding. These low order models were to be used for control.
Pressure Trace of Combustion Instability in Rijke Tube
Pressure instabilities initially exhibit linear system behavior (exponential rise) till the nonlinearities cause limit cycle behavior. The goal of control is to minimize the amplitude of the limit cycles.