بررسی تاثیر الگوی پاشش اسپری سوخت بر تبخیر قطرات در لوله پیش مخلوط توربین گاز

Abstract

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 to occur in the non-premix mode and the emission of NOx increases as a result. To avoid the emission of this pollutant, it is necessary that the droplets are evaporated completely in a limited space. Herein, a mechanism is proposed for spraying the droplets, in which, fuel droplets are injected to form a hollow-cone spray pattern in the opposite of the gas flow direction. 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 this matter, various patterns of injected n-heptane droplets into nitrogen gas passing through a premix tube have been simulated at the temperature of 800 K and the pressure of 20 bar using the Eulerian-Lagrangian approach. The validation of heat and mass transfer models, as well as the influence of gas molecules penetration into fuel droplets, has been evaluated. The results showed that using this type of injection, in addition to full evaporation of droplets in the limited space, the distribution of the temperature and the fuel vapor mass fraction in the tube outlet are more evenly distributed