Active Control of Combustion for Optimal Performance”,

Combustion-zone stoichiometry and fuel-air premixing were actively controlled to optimize the combustor performance over a range of operating conditions. The objective was to maximize the combustion temperature, while maintaining NO x Introduction With increasing concerns for air quality improvement, the combustion systems are undergoing major design changes to reduce the harmful by-products. In particular, emphasis has been placed on reducing emissions of nitrogen oxides (NOJ coincident with high combustion efficiency to decrease carbon monoxide (CO), unburnt hydrocarbons (UHC), and soot etc. Techniques to reduce NO, formed by the thermal mechanism usually involve lowering the combustion temperature, for example, by lean-premixed combustion. Although low-emission combustion systems are designed to operate efficiently at specified conditions, a particular challenge lies in achieving optimal performance at off-design operations. The operating conditions differ from the design point because of the part-load operation or changes in the inlet conditions due to ambient, fuel composition etc. Furthermore, a combustor design will not be optimal as new emission standards are introduced. Active control provides the means to adapt the combustor design to changes in the operating conditions. The most common application of active techniques in combustion has been the control of pressure oscillations by continuously perturbing certain parameters in response to filtered outputs from sensors placed in the combusto