Investigating Lean Blowout of an Alternative Jet Fuel in a Gas Turbine Combustor

In the global effort to reduce the climate impact of combustion emissions, sustainable aviation fuels offer the ease and reliability of conventional petroleum-derived jet fuels without the significant pollutant effects. Ongoing research efforts include experimental testing of alternative jet fuels to identify fuel candidates that produce less pollutant combustion products and are cheaper and environmentally cleaner to source than conventional jet fuels. Fuel lean combustion already reduces the emissions of jet engines and increases fuel efficiency, but lean blowout (LBO) can occur at reduced throttle and minimum power scenarios such as descent. Lean blowout (LBO) has been identified as a critical figure of merit to ensure the stability of alternative jet fuels in the place of conventional fuels. This work aimed to further understand the LBO phenomenon, leveraging computational studies of the alternative fuel designated C-5 by the National Jet Fuel Combustion Program (NJFCP). The fuel sensitivity of LBO has been established by the NJFCP’s participants recently. In this thesis, the chemical kinetics for C-5 is first verified using zerodimensional (0-D) and one-dimensional (1-D) studies and then this is followed by three dimensional (3D) large-eddy simulations (LES). In LES to observe LBO, a direct-step and gradual equivalence ratio reduction were separately employed to assess fuel sensitivity of LBO against available experimental data. The time histories of pressure, temperature, and composition were analyzed for precursor signatures of LBO both inside and outside the flame. Localized extinction, a reduction in the vortex breakdown bubble size and magnitude, and a reduction in the exhaust velocity were all observed to occur during the LBO event.M.S