Numerical simulation of unsteady combustion at elevated pressure and initial temperature of the mixture for the model combustion chamber

Abstract

The paper presents the results of investigation of combustion features of a fuel-lean methane-air swirling flame in a model combustion chamber using numerical simulation at an elevated pressure and initial temperature of the mixture. The equivalence ratio is 0.7, the initial temperatures of the mixture are 300 and 500 K, and the overpressure corresponds to 2 and 4 bars. Setting the increased pressure as the output boundary conditions in the numerical simulation of combustion in a model combustion chamber is shown to be efficient. It is found that a change in the initial temperature of the mixture from 300 to 500 K (at a fixed Reynolds number equal to 30000) leads to a significant change in the combustion regime. So, in the case of the initial temperature of the mixture equal to 300 K, the recirculation zone is formed only near the walls of the combustion chamber, and the flame has a compact shape, and is stabilized inside the premixer. With elevated initial temperatures of the mixture, a stagnation region is formed on the jet axis, and the flame displacement downstream relative to the premixer exists.