Large eddy simulation of turbulent premixed combustion flow around bluff body

Abstract

Large eddy simulation (LES) of turbulent premixed flame stabilized by the bluff body is developed by using sub-grid scale combustion model based on the G-equation describing the flame front propagation. The basic idea of LES modeling is to evaluate the filtered-front speed, which should be enhanced in the grid scale by the scale fluctuations. The dynamic sub-grid scale models newly introduced into the G-equation are validated by the premixed combustion flow behind the triangle flame holder. The objective of this study is to investigate the validity of the dynamic sub-grid G-equation model to a complex turbulent premixed combustion such as bluff body stabilized turbulent premixed flames for realistic engineering application. A new turbulent flame speed model, introduced by the sub-grid turbulent diffusivity and the flame thickness, is also proposed and is compared with the usual model using sub-grid turbulent intensity and with the experimental data. The calculated results can predict the velocity and temperature of the combustion flow in good agreement with the experiment data.

Large Eddy Simulation of Bluff Body Stabilized Turbulent Premixed Flame

“…These figures show the flow structure in the (x, y) cut at the center of the channel. As in Park's discussion (Park and Ko 2011), the chemical reaction has a stabilizing effect on the vortex shedding. Figure 19.…”

“…A number of investigators have used LES to simulate reactive flows with bluff body flame holders. Porumbel and Menon (2006), Akula, Sadiki, and Janicka (2006), Ge et al (2007), Park and Ko (2011) and Manickam et al (2012) simulated the Volvo experiment (Sjunnesson, Olovsson and Sjoblom, 1991). Porumbel and Menon (2006) have simulated bluff body flows with the Linear Eddy Mixing (LEM) LES based on the model proposed by Kerstein (1989) and developed into a sub-grid model by Menon et al (1993) for premixed combustion.…”

“…These models are intended to better represent the flame characteristics. Park and Ko (2011) present comparisons between non-reacting and reacting flows and discuss the effect of chemical reaction on the development of the wake behind the triangular bluff body. They show that their model is able to capture the stabilization of the Karman vortex street behind the obstacle due to combustion.…”

Application of a Central Composite Design for the Study of NOx Emission Performance of a Low NOx Burner

“…When bluff body is used as a flame holder, the incoming fuel and oxidizer mixture is ignited by the hot combustion products recirculating in a wake structure formed behind the bluff body. This stabilization mechanism has been investigated extensively by many researchers [6][7][8][9][10][11][12]. Many studies associated with bluff body stabilization mechanism focus on premixed combustion systems, where premixed fuel and oxidizer are provided to the combustion zone and thus complex physics that controls mixing process can be neglected.…”

A Numerical Study on Premixed Bluff Body Flame of Different Bluff Apex Angle

“…Erickson and Soteriou [16] carried out numerical study on reactant temperature effect of a twodimensional triangular bluff body flame. Park and Ko [17] introduced a G equation to Les subgrid scale combustion model for turbulent premixed flame stabilized by the bluff body.…”