Numerical Analysis on the Effect of Fuel Injection Location on Combustion Characteristics in a Trapped Vortex Combustor

The present work focuses on the numerical simulations of non-reactive and reactive cases in a trapped vortex combustor. Numerical simulations are carried out in ANSYS FLUENT to analyze the effects of fuel injection locations on mixing and combustion characteristics in a model trapped vortex combustor. Three different combinations of fuel injection viz (i) injection in cavity alone, (ii) injection in both main stream and cavity, and (iii) injection in mainstream alone were analyzed using steady, 2D RANS Non-premixed combustion model for mainstream air velocities of 10 and 30 m/s. From the simulations, it has been observed that fuel injection location plays a vital role in mixing and complete combustion both inside the cavity and mainstream. The species concentration contours for the 3 different cases indicate that fuel injection on top of the cavity enhances combustion and also improves the strength of the locked vortex by helping in shear layer entrainment. Static temperature plots obtained for the different cases show that fuel injection in both cavity and mainstream is the optimum one with minimum partial combustion and highest lean burn rates.