Numerical study of bluff-body non-premixed flame structures using laminar flamelet model

Abstract

• This is an article from the journal, Proceedings of the IMechE, Part DOI: 10.1243/095765005X28616Abstract: A laminar flamelet model is applied for bluff-body stabilized flames to study the flow field, mixing pattern, and the flame structure at two different velocities. The k À 1 turbulence model is applied for accounting the turbulence fluctuations. It is found that the recirculation zone dominates the near field, while the far field structure is similar to the jet flow. The intermediate neck zone is the intense mixing region. The computation shows that the fuel jet velocity has significant effect on the structure of the flow field, which in turn has significant effect on the combustion characteristics. The laminar flamelet model is found to be adequate for simulating the temperature and the flame composition inside the recirculation zone. The flamelet model has, however, failed to account for the local extinction in the neck zone. Possible limitation of the laminar flamelet model to predict the local extinction is discussed.

Effects of hydrogen addition on the structure and pollutant emissions of a turbulent unconfined swirling flame

“…They concluded that among studied models only laminar flamelet model predicted temperature and mass fraction of major and minor species with acceptable accuracy. A similar flame was modeled by Hossain and Malalasekera in [12,13] using flamelet model and by Hossain et al [14] with a coupled radiation/flamelet combustion model, yielding reasonably good predictions at upstream locations.…”

Large-Eddy Simulation of Bluff-Body Flame Using the Equilibrium Combustion Model

“…A detailed account of the experiments can be found on the Web site of the International Workshop on Measurement and Computation of Turbulent NonPremixed Flames (TNF workshop) [18]. The experimental dataset with a jet velocity of 118 m∕s and a coflow air velocity of 40 m∕s was designated as a standard test case for the validating combustion models by the TNF workshop [12]. The same dataset was used for the validation of our simulation.…”

“…Therefore, in addition to their practical importance, bluff-body flames also provide a challenging computational test case for turbulence and chemistry interaction due to the presence of recirculation zones and their effects on the evolving flow. Several studies [8,[11][12][13][14][15] have been carried out in the past using different turbulence and chemistry models. Dally et al [11] studied a bluff-body flame using both the standard and modified k-ϵ models, as well as a Reynolds stress model.…”

“…By adjusting the coefficient C ϵ1 in standard and modified k-ϵ models, they found a better prediction of the recirculation. Hossain and Malalasekra [12] also used the k-ϵ turbulence model with a laminar flamelet chemistry model and found that the model failed to account for local extinction effects.…”

Development and application of the drop number size moment modelling to spray combustion simulations

“…Successful use of flamelet model in a spray combustion have been reported in [27,28]. Traditionally, engine combustion studies have preferred to use some simplified models for the mean reaction rate closure.…”