Investigation of the effect of spray fuel injection pattern on evaporation of droplets in the gas turbine pre-mixer

In a liquefied gas turbine combustor, due to the limited length of the premix tube, the evaporation process of fuel droplets is not completely carried out inside the tube and the droplets enter the combustion chamber. The presence of droplets in the combustor causes the reactions occur in the non-premix mode and the emission of NOx increases as a result. To avoid the emission of this pollutants, it’s necessary the droplets are evaporated completely in a limited space. In here, a mechanism is proposed for spraying the droplets. In which, fuel droplets with hollow-cone spray pattern are injected in the opposite direction of the air. In this type of injection, due to the relative velocity of droplets and subsequent enhancement of the droplet break-up and evaporation processes, it is possible to achieve this goal. To verify, various patterns of injection are modeled using an Eulerian-Lagrangian approach. The validity of turbulence, heat and mass transfer models, as well as the influence of gas molecules penetration into droplets has been evaluated. The results showed that using this type of injection, in addition to full evaporation of droplets in a limited space, the fuel vapor in the tube outlet is more evenly distributed.