Design, Evaluation and Performance Analysis of Staged Low Emission Combustors

The most uncertain and challenging part in the design of a gas turbine has long been the combustion chamber. There has been a large number of experimentations in industry and universities alike to better understand the dynamic and complex processes that occur inside a combustion chamber. This study concentrates on gas turbine combustors, as a whole, and formulates a theoretical design procedure for staged combustors, in particular. Not much of the literature currently available in the public domain provides intensive study on designing staged combustors. The work covers an extensive study of the design methods applied in conventional combustor designs, which includes the reverse flow combustor and the axial flow annular combustors. The knowledge acquired from this study is then applied to develop a theoretical design methodology for double staged (radial and axial) low emission annular combustors. Additionally, a model combustor is designed for each type, radial and axial, of staging using the developed methodology. A prediction of the performance of the model combustors is executed. The main conclusion is that the dimensions of the model combustors obtained from the developed design methodology are within the feasibility limits. The comparison between the radially staged and the axially staged combustor has yielded the predicted results such as a lower NO_x prediction for the latter and a shorter combustor length for the former. The NO_x emission results of the new combustor models are found to be in the range of 50–60 ppm. However, the predicted NO_x results are only very crude and need further detailed study.