Experimental and numerical study of combustion characteristics in a liquid fuel CAN micro-combustor

Abstract

In the present study, combustion characteristics of a CAN type combustor of a micro gas turbine working with liquid fuel are evaluated. First, an experimental work is conducted to measure the combustion chamber temperature values. The goal of the experimental study is to determine the experimental behavior of the chamber at one of its operating points. Then, numerical simulation is done to investigate the details of combustion phenomenon in the combustor. The measured temperature distribution by experiment is well predicted by the results of numerical calculation. However, there are points making a difference between experimental and numerical results in few regions due to the two-dimensional axisymmetric simulation error. The results show that the IRZ (Inner Recirculation Zone) and recirculation zones around the liner walls increase forces applying to the droplets and promote breakup and droplet evaporation rates, due to the instability and high turbulence kinetic energy. These zones play an influential role in the evaporating liquid fuel droplets, creating a homogeneous mixture of fuel and air and forming and stabilizing the flame, by providing high residence time for the mixture of vaporized fuel droplets and air. Zones where the fuel-air mixing is such that the mixture fraction is equal to the stoichiometric amount, in addition to forming and stabilizing flame, the species of complete combustion such as CO2 and the species of incomplete combustion such as CO have the highest and lowest values, respectively. Finally, the chamber performance in the operating point is found to be at an acceptable level, by investigating the chamber's performance parameters such as evaporation efficiency, combustion efficiency, pattern factor and the entropy generation.