Validation of leading point concept in RANS simulations of highly turbulent lean syngas-air flames with well-pronounced diffusional-thermal effects
| Autor: | Salman Verma, Florian Monnier, Andrei Lipatnikov |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Materials science
Laminar flame speed Hydrogen Renewable Energy Sustainability and the Environment Turbulence Energy Engineering and Power Technology chemistry.chemical_element Laminar flow 02 engineering and technology Mechanics 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Combustion 01 natural sciences 0104 chemical sciences Fuel Technology Closure (computer programming) chemistry Thermal 0210 nano-technology Reynolds-averaged Navier–Stokes equations |
| Zdroj: | International Journal of Hydrogen Energy. 46:9222-9233 |
| ISSN: | 0360-3199 |
| Popis: | While significant increase in turbulent burning rate in lean premixed flames of hydrogen or hydrogen-containing fuel blends is well documented in various experiments and can be explained by highlighting local diffusional-thermal effects, capabilities of the vast majority of available models of turbulent combustion for predicting this increase have not yet been documented in numerical simulations. To fill this knowledge gap, a well-validated Turbulent Flame Closure (TFC) model of the influence of turbulence on premixed combustion, which, however, does not address the diffusional-thermal effects, is combined with the leading point concept, which highlights strongly perturbed leading flame kernels whose local structure and burning rate are significantly affected by the diffusional-thermal effects. More specifically, within the framework of the leading point concept, local con sumption velocity is computed in extremely strained laminar flames by adopting detailed combustion chemistry and, subsequently, the computed velocity is used as an input parameter of the TFC model. The combined model is tested in RANS simulations of highly turbulent, lean syngas-air flames that were experimentally investigated at Georgia Tech. The tests are performed for four different values of the inlet rms turbulent velocities, different turbulence length scales, normal and elevated (up to 10 atm) pressures, various H2/CO ratios ranging from 30/70 to 90/10, and various equivalence ratios ranging from 0.40 to 0.80. All in all, the performed 33 tests indicate that the studied combination of the leading point concept and the TFC model can predict well-pronounced diffusional-thermal effects in lean highly turbulent syngas-air flames, with these results being obtained using the same value of a single constant of the combined model in all cases. In particular, the model well predicts a significant increase in the bulk turbulent consumption velocity when increasing the H2/CO ratio but retaining the same value of the laminar flame speed. |
| Databáze: | OpenAIRE |
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