Numerical Simulation of a Model Spray Flame under MILD conditions using Stochastic Upstream Flow and Temperature Forcing

Numerical simulations of the Delft Spray in Hot Co-flow (DSHC) flame are presented, in order to aid the understanding of reacting multiphase flows under moderate or low-oxygen dilution (MILD) conditions. The test case consists of a single swirled pressure atomizer installed in the center of a cylindrical hot co-flow, operated with ethanol fuel. A large variety of experimental data is available for the burner’s MILD combustion configuration. Here, the particular H-II case is studied. Three different modelling approaches are employed, an unsteady RANS simulation and two scale-resolving methods, namely LES (Large Eddy Simulation) and SAS-SST (Scale Adaptive Simulation) in combination with a Shear Stress Transport turbulence model. Here, for the scale resolving SAS and LES, transient inflow boundary conditions are necessary in order to propagate turbulent flow and temperature structures into the computational domain, supporting the evolution of a full turbulent energy cascade. However, preliminary simulations have shown that due to the low Reynolds number of the co-flow, artificially imposed spatial and temporal turbulent fluctuations of temperature and velocity field are subject to strong artificial decay, prior to reaching the actual combustion zone. Therefore, a simplified stochastic forcing approach based on a first order Langevin model is adopted, reducing the boundary condition to a time dependent function which generates time-coherent structures featuring turbulent decay in time. The accurate implementation of the methodology is verified by means of analytical solutions and validated with the Delft Spray flame test case

Entrained flow gasification. Part 3: Insight into the injector near-field by Large Eddy Simulation with detailed chemistry

Entrained flow gasification is a promising process for the conversion of low-grade feedstock, e.g. highly viscous slurries and suspensions with a significant content of solid particles, to high quality fuels. A major scientific challenge is the prediction of the physical and chemical phenomena occurring in such high-temperature and high-pressure multiphase flow systems. In this context, this article is the sequel to “Entrained flow gasification. Part 1: Gasification of glycol in an atmospheric-pressure experimental rig” and “Entrained flow gasification. Part 2: Mathematical modeling of the gasifier using RANS method”. The same strategy as in the first two parts was followed. In order to reduce complexity, this study focused on a two-phase (gas and liquid) flow system with a model fuel (mono-ethylene glycol) under the simplified conditions provided by the atmospheric lab-scale gasifier REGA. Using the experimental data set provided in Part 1 of the coordinated papers for validation purposes, the main focus of this study was on the detailed understanding of the near injector region of the entrained flow gasifier REGA. The unsteady flow and the chemical conversion in the gasifier were investigated by means of Large Eddy Simulations with a detailed chemistry solver including 44 individual species and a direct calculation of 329 chemical reactions. The dispersed phase was solved by Lagrangian Particle Tracking. Downstream comparisons with experimental data showed a reasonable agreement concerning temperature and species profiles. The analysis of the injector near-field revealed that the high temperature reaction zone close to the injector could not be explained by a direct reaction of the fuel with the oxidizer. Instead, carbon monoxide and hydrogen mainly formed on the axis were transported upstream by the recirculation zone. The reaction of CO and H2 with the oxygen stabilized the flame. The heat release from this reactions supported the vaporization and decomposition of fuel as well as the downstream gasification reactions

Co-expression patterns of cancer associated fibroblast markers reveal distinct subgroups related to patient survival in oropharyngeal squamous cell carcinoma

Background: The incidence of oropharyngeal squamous cell carcinoma (OPSCC) is rapidly increasing in high income countries due to its association with persistent high-risk human papilloma virus (HPV) infection. Recent scientific advances have highlighted the importance of the tumor microenvironment in OPSCC. In this study, including 216 OPSCC patients, we analyze the composition of four established markers of cancer associated fibroblasts (CAFs) in the context of intratumoral CD8 T-cell infiltration.Methods: Immunohistochemical staining for fibroblast activation protein (FAP), platelet-derived growth factor receptor beta (PDGFRb), periostin, alpha smooth muscle actin (α-SMA) and CD8 were analyzed digitally and their association with survival, tumor- and patient characteristics was assessed.Results: Co-expression of CAF markers was frequent but not associated with HPV status. FAPhigh and PDGFRbhigh expression were associated with increased CD8 T-cell infiltration. Low expression of PDGFRb improved patient survival in female patients but not in male patients. We identified PDGFRblow periostinlow α-SMAlow status as an independent predictor of improved survival (hazard ratio 0.377, p = 0.006).Conclusion: These findings elucidate the co-expression of four established CAF markers in OPSCC and underscore their association with T-cell infiltration and patient survival. Future analyses of CAF subgroups in OPSCC may enable the development of individualized therapies