Transient 3D simulations of turbulent premixed flames of gas-to-liquid (GTL) fuel in a fan-stirred combustion vessel

Abstract

This work aims to conduct turbulent flame studies of GTL fuel and 50/50 diesel-GTLblend and compare them to diesel under a wide range of equivalence ratio (0.7 < Ф < 1.3) and turbulence intensities (0.5 m/s < u′ < 3.0 m/s). For this purpose, Zimont Turbulent Flame Speed Closure (Zimont TFC) model is adapted and implemented into ANSYS Fluent to study the influence of turbulence on premixed combustion. The model is verified against the experimental results of the turbulent flame speeds for methane-air mixture using a cylindrical fan-stirred combustion vessel. Results show that (i) rich diesel and lean GTL fuels are characterized by a faster flame development and higher turbulent flame speeds; (ii) at the same elapsed time, ReT and Da are found to be greater for stoichiometric GTL fuel compared to diesel and 50/50 diesel GTL blend, which indicates that the flame propagates towards the vessel’s wall at a faster rate and the chemistry has dominated turbulence in a shorter time, and (iii) at low turbulence intensity level (u′=0.5 m/s), the flame morphology is defined by a wrinkled flamelet regime in Borghi diagram. However, at moderate and higher turbulence levels (u′=1.5 m/s and u′=3.0 m/s, respectively), the flame structure is defined by the corrugated flamelets regime. Furthermore, the turbulence homogeneity and isotropy have been investigated throughout the combustion vessel by conducting a study for the turbulent kinetic energy balance.