Reduced order models applied to laminar diffusion flames

Abstract

Computational model of combustion chambers is a major topic of research on the past decades. The modelling of such physical systems enables the analysis of several flame properties, such as velocity, species mass fraction and temperature. However, there is a high computational burden associated with the parametric exploration and the complexity of such systems. To overcome this problem, reduced order models (ROM) have been used to predict the behavior of those systems, decreasing the cost associated to the computational modeling. Accordingly, this work presents modeling of non premixed laminar flames stabilized in the Gülder burner, using a skeletal kinetic mechanism. The computational fluid dynamics flame model has been developed using Fluent 2019 R3 for the isothermal and reactive cases, for different prescribed fuel inlet velocities. The analysis of the flow and flame structures are respectively by means of the axial and radial velocity components and the mass fraction of CH 4 fields in the isothermal case; and the temperature, mass fraction of OH and CO for the reactive case. Then, the ROM is construct with StaticROM from Twin Builder based on the CFD results. The results of the ROM have a maximum absolute error of 0.0025 m/s for the velocity ROM, 0.0737 for the mass fraction of CH 4 , 98.91 K for the temperature, 1.47 10 −3 for the mass fraction of OH and 0.018 for the mass fraction of CO. These errors are acceptable for the isothermal case and for the temperature, however, for the mass fractions of OH and CO it shows a significant difference since the concentration of these species is small.