M.Sc Thesis

M.Sc StudentRabinovich Daniel
SubjectFlameless Oxidation in Gas Turbine Combustors for
Reduction of NOx Emissions
DepartmentDepartment of Aerospace Engineering
Supervisor PROFESSOR EMERITUS Yeshayahou Levy


Flameless Oxidation (Mild Combustion) is a mode of combustion which comprises a novel solution to NOX reduction. In this mode combustion takes place in an environment containing a significant amount of hot reaction products. The effect of the hot reaction products is similar to preheat of the mixture, causing stabilization of the flame, which, in turn, allows operation at leaner mixtures and lower combustion temperatures, thus reducing NOX emissions. Dilution with products is achieved by enforcing strong internal recirculation of the products inside the combustor, and causes the mixture to burn at a slower rate, creating a continuous reaction zone rather than separate thin flames.

Two models are used to investigate the performance of a mild combustion combustor: a pseudo one-dimensional model and a CFD model. In the pseudo one-dimensional model the combustor is modeled as a recycle reactor, the stability limits of the reactor are found, providing an operational map for the combustor. It was found that the dominant kinetic pathway in this case is the "N2O-intermediate" pathway, and that the NO emissions that may be achieved are lower than the corresponding lean-premixed case. The recycling achievable according to the CFD model tested was a value feasible for mild combustion according to the pseudo-one dimensional model, demonstrating that construction of a combustor operating in the flameless mode is possible.