Study the Effect of Acoustical Fuel Enhancement on the Flame Characteristics

Abstract

This work presents a 2D numerical simulation of the nonpremixed combustion of natural gas in an axisymmetric cylindrical chamber, focusing on the effect of adding acoustical excitation to inlet fuel velocity on temperature, exhaust pollutants, and combustion products velocity. Pulsation combustion generates vortices and enhances mixing, which in turn increases combustion efficiency and reduces emissions so it is used in many industrial applications like dryers and boilers. The turbulence is solved using detached eddy simulation model, which is a hybrid modeling between large eddy simulation and realizable k–e model. The chemical reactions are described by the eddy dissipation model. The radiative intensity transport equations are solved using P-1 radiation model. The numerical model achieved a great agreement with experimental data on temperature and species mass fraction. The main outcome of the work is the demonstration of a significant decrease in a volume of pulsed flame compared to a nonpulsed flame with 18% reduction in the flame length. Increasing the Strouhal number enhances the temperature homogenization along the combustion chamber and the flame does not concentrate in the chamber core and toward the chamber exhaust. Changing the fuel velocity from the stoichiometric ratio due to the fuel pulsation cools the chamber and reduces the average temperature from 2000 to 1750 K. There was a reduction in the mass fraction of carbon monoxide, nitrogen monoxide and soot by 50, 28, and 285%, respectively. Increasing fuel frequency increases maximum velocity by 66% axially and 14% radially.