PERFORMANCE OF A GAS BURNING RIJKE PULSE COMBUSTOR WITH TANGENTIAL REACTANTS INJECTION

This paper describes an investigation of the dependence of the performance of a propane burning Rijke pulse combustor upon the design of a recently developed tangential injection system. Two injection systems were investigated. In one the fuel and air were rapidly premixed before injection into a duct where most of the combustion occurred. In the second air and fuel were injected separately into the duct. In both cases the pulse combustor could be operated for air/fuel ratios alpha between 0.5 and 1.8. However, when the reactants were premixed, the combustor pulsations were dominated by the fundamental acoustic mode when alpha was low, and by its first harmonic when 1.1 < alpha < 1.6. In contrast, the fundamental acoustic made dominated for all alpha when the reactants were injected separately. This suggests that this pulse combustor does not behave like a true Rijke tube, at least while operated in the premixed mode. In addition, exhaust flow analyses revealed that the combustor's combustion efficiency practically equals 100 percent when alpha is slightly above 1.0 and that NOx emissions equal several ppm for both rich and lean operation.