科研之友
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摘要
A computational fluid dynamics model for high-temperature oxynatural gas combustion is developed and exercised. The model features detailed gas-phase chemistry and radiation treatments (a photon Monte Carlo method with line-by-line spectral resolution for gas and wall radiation PMC/LBL) and a transported probability density PDF) method to account for turbulent fluctuations in composition and temperature. The model is first validated for a 0.8MW oxynatural gas furnace, and the level of agreement between model and experiment is found to be at least as good as any that has been published earlier. Next, simulations are performed with systematic model variations to provide insight into the roles of individual physical processes and their interplay in high-temperature oxyfuel combustion. This includes variations in the chemical mechanism and the radiation model, and comparisons of results obtained with versus without the PDF method to isolate and quantify the effects of turbulencechemistry interactions and turbulenceradiation interactions. In this combustion environment, it is found to be important to account for the interconversion of CO and CO2, and radiation plays a dominant role. The PMC/LBL model allows the effects of molecular gas radiation and wall radiation to be clearly separated and quantified. Radiation and chemistry are tightly coupled through the temperature, and correct temperature prediction is required for correct prediction of the CO/CO2 ratio. Turbulencechemistry interactions influence the computed flame structure and mean CO levels. Strong local effects of turbulenceradiation interactions are found in the flame, but the net influence of TRI on computed mean temperature and species profiles is small. The ultimate goal of this research is to simulate high-temperature oxycoal combustion, where accurate treatments of chemistry, radiation and turbulencechemistryparticleradiation interactions will be even more important.
- 出版日期2013-4-1
