The Influence of Air/Fuel Ratio and Swirl Number on the Combustion Characteristics of a Model Combustor

Abstract

Combustion characteristics of a model can-type combustor are reported for air/fuel ratios encompassing take-off and ground-idle conditions and for two swirlers with gaseous fuel and at atmospheric pressure. Temperatures were obtained with fine-wire thermocouples, and concentrations of UHC, H2, CO, CO2, O2 sampled through a water-cooled probe with a flame ionization detector, a gas chromotograph and infrared and paramagnetic analyzers. The results indicate combustion efficiencies greater than 97%. For the air/fuel ratio corresponding to that of take-off, 45% of the mass flow of the primary jets turned upstream after impingement, combustion occurred in the wakes of the swirler and of the primary jets resulting in a pattern factor of 0.46. At ground-idle condition, 58% of the primary jet flow turned upstream reducing the pattern factor to 0.43. An 18% reduction in the swirl number at the ground-idle condition led to a pattern factor to 0.35 and, for takeoff, to a pattern factor of around 0.37 with combustion occurred mainly in the intermediate zone.