Application of flamelet/progress-variable approach to the large eddy simulation of a turbulent jet flame of pulverized coals

Numerical Analysis of a Turbulent Pulverized Coal Flame Using a Flamelet/Progress Variable Approach and Modeling Experimental Artifacts

“…To avoid an intractable dimensionality of the chemistry table, the impact of the char surface reactions on the gas phase has been neglected in this work. The recent FPV simulation of the original flame configuration by Akaotsu et al 29 showed that the char off-gas mixture fraction is on the order of 10 −2 , indicating that the influence of char combustion is negligible, which is confirmed by earlier studies. 3,4,14,25 The flamelet model is thus based on the mixture fraction for volatiles Z vol , the mixture fraction for the hydrogen pilot Z pil , a progress variable Y PV , and the absolute enthalpy h to account for the strong interphase heat transfer between the solid and gas phase during combustion.…”

“…For example, Rieth et al, 14 Stein et al, 3 and Khan et al 24 predicted that O 2 is consumed (and CO 2 is formed) further upstream than in the DNS of Hara et al 27 The axial temperature distributions matched with the species distributions but predicted different maximum temperatures and overshoots of different magnitudes. 3,4,14,24,27 Wen et al 28 and Akaotsu et al 29 tested the FPV approach on the original flame configuration by LES. Wen et al found that the EBU model performed less well than the flamelet model.…”

“…28 Akaotsu et al stated that premixed and diffusion combustion modes co-exist even in the downstream region of the flame and that char combustion is negligible in the region of interest. 29 Both studies used two mixture fractions for char off-gases and volatiles and replaced the pilot stream with volatile gas. Recently, the experimentalists at CRIEPI have introduced a new test case, which uses hydrogen as pilot gas instead of methane and aims to minimize the relative heat input by the pilot to set a stronger focus on coal combustion.…”

“…In the present work, we apply the FPV approach to simulate the latest experiments of a coaxial burner with a hydrogen-supported PCC flame, experimentally investigated by CRIEPI. ,− The flame is a target flame of the biennial workshop on measurement and simulation of coal and biomass conversion (CBC) and serves as a reference flame for model development with its large experimental database. ,− The original flame configuration with methane as pilot gas has been widely studied by RANS simulations, LES, and even DNS. ,,,,− Direct comparison of the various numerical data sets and the experiments have been conducted within the CBC workshop series, but potential measurement difficulties (volume averaging of the gas sampling probe and limited accuracy of pyrometry experiments) and different modeling strategies (in terms of grid, modeling, model parameters, inflow settings, etc.) made it difficult to clearly highlight an advanced modeling strategy over others.…”

“…Wen et al and Akaotsu et al tested the FPV approach on the original flame configuration by LES. Wen et al found that the EBU model performed less well than the flamelet model .…”