Discrete phase method (DPM) model was used to analyse rotary drum systems for segregation behavior. DPM simulations were performed for comparison with a dynamic segregation experimental measurement from the literature. This included dynamic segregation and time-averaged particle velocity field, which were validated with experimental data. In addition, a direct DPM and parcel scaled DPM simulation study was performed to analyse the effect of drum and particle parcel size scaling. The segregation dynamics was evaluated using the Lacey mixing index. This work shows segregation dynamics decreases with increasing drum size while keeping the same particle size. It further shows that for a given drum size the segregation dynamics deviate after a certain particle parcel scaling limit. The parcel scaling limit also increases with increasing drum size.
Blends of H2 with CH4 and/or CO have become of interest with hydrogen as sustainable fuel. In the past, numerical models were derived to simulate combustion of H2-CO (syngas) mixtures. This paper compares the performance of a newly implemented Flamelet Generated Manifold (FGM) combustion model to an earlier model by Correa and Pope and experimental data in the bluff-body stabilized syngas flame by Correa and Gulati. The FGM in the presented model consists of premixed flamelets stretching the flammable region, parametrized by mixture fraction and Computational Singular Perturbation-based reaction progress variable. RANS simulations are performed in Fluent with k-ε, k-ω SST and Reynolds Stress Model turbulence modelling. Radial and axial profile plots of temperature and major species concentrations showed generally improved results with the FGM model, although locally deviations occur. Causes for these deviations are scrutinized: the use of premixed opposed to diffusion flamelets and the unity Lewis number assumption.
Numerical simulations are performed on a combustor setup which represents the recirculating behaviour of a combustor in the flameless combustion regime. Previous experimental and numerical studies showed that heat loss is prominent for this setup. Here, the amount of heat loss through the combustor walls is quantified and its effect analysed. For this a non-adiabatic Flamelet Generated Manifold (FGM) model is employed. This model uses tabulated chemistry in combination with governing equations for a small set of control variables to accurately describe a turbulent flame. In the current implementation, equations for enthalpy and the mean and variance of the reaction progress variable are solved. Turbulence-chemistry interactions are incorporated through a presumed-PDF approach. In contrast to earlier work, the model is applied in the commercial solver Ansys CFX, coupled to a low-mach, compressible, steady-state Reynolds-Averaged Navier-Stokes (RANS) turbulence model. Results from the simulations show that heat loss consumes over 30% of the combustor’s thermal power. Despite this large heat loss, its effect on the combustion chemistry is small. The inclusion of heat loss in the chemistry tabulation does improve the prediction of the velocity and temperature field in the primary reaction zone. However, the effect of including heat loss is limited in the prediction of species concentrations.
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