SUMMARY

Military jet aircraft engines generally employ augmentors to supply additional thrust when needed, for example, during takeoff or combat. Augmentor designers face several challenges in producing a practical design. Primarily, the high velocity and low oxygen content of the bulk flow through the augmentor make it difficult to burn all the augmentor fuel in a compact space. Further challenges such as detrimental acoustic instabilities and flame blowout plague these devices during functional operation as well. Traditionally, maintaining stable operation was accomplished by the use of bluff body flame holders to stabilize the combustion process. Unfortunately, bluff body flame holders present significant design challenges that can reduce engine thrust during dry operation, reduce engine life, increase aircraft visibility, and other detrimental effects. The work presented here proposes a method in maintaining stable combustion in a practical augmentor without the use of bluff body flame holders. Stabilization is accomplished through a concept called the “prime and trigger” method where the augmentor fuel is injected into the bulk flow upstream of the engine’s turbine section to atomize, vaporize and mix as much as possible (priming) prior to entering the augmentor section. The fuel and vitiated air mixture is then ignited in the augmentor section (triggering) by injecting a highly reactive mixture which is produced by partial oxidation of the engine’s fuel in a separate combustor. The work presented will attempt to determine what composition of partial oxidation mixtures (POx) can be achieved within practical constraints, what effectiveness the POx may have in triggering stable combustion and what would be the optimal method of injection of the POx to achieve stabilization.