Combustion regime identification on a bluff-body burner by using experimental PLIF-OH images and RANS numerical simulations

Nattan Roberto Caetano (1) , Americo Cunha Jr (1) , André Reinaldo Novgorodcev Jr (1) , Luís Fernando Figueira da Silva (1)

1 PUC-Rio

The aim of this work is to determine the different combustion regimes in a classical turbulent combustion diagram (Reynolds vs Damköhler), in order to qualify the turbulent flames that are obtained at the bluff-body experimental apparatus of the Combustion and Turbulence Laboratory at PUC–Rio. Additionally, the purpose is to estimate the influence of different fuel types (e.g. natural gas and hydrogen) on the combustion regimes. The velocity of the fuel (oxidizer) stream was varied between 0.4 and 50.0 m/s (1.2 and 11.7 m/s) in order to get representative experimental results for each flame regime within the diagram. Instantaneous and time-averaged flames thickness were obtained from the images captured via Planar Laser induced Fluorescence of the Hydroxyl Radical (PLIF-OH). Reynolds Averaged Navier Stokes (RANS) models were employed to determine the turbulence characteristics of the flow field, in terms of the dimensionless Reynolds and Damköhler numbers. The determination of the Damköhler number also required the construction of specific flamelets libraries. The experiment allowed to investigate several combustion regimes, including the laminar flame regime, the flamelet regime and the unsteady effects regime, each of which was obtained for a large range of Reynolds and Damköhler numbers. The comparison of the combustion regimes actually obtained experimentally with those estimated by using the classical regime diagram evidences the shortcomings of such a simplified approach.

Mots clés: turbulent combustion; bluff-body burner; PLIF-OH images; CFD; nonpremixed combustion

Domaines: Mécanique des fluides [physics.class-ph]; Statistiques [math.ST]; Génie mécanique [physics.class-ph]

Nattan Roberto Caetano, Americo Cunha Jr, André Reinaldo Novgorodcev Jr, Luís Fernando Figueira da Silva. Combustion regime identification on a bluff-body burner by using experimental PLIF-OH images and RANS numerical simulations. 20th International Congress of Mechanical Engineering (COBEM 2009), Nov 2009, Gramado, Brazil. ⟨hal-01487371⟩