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عنوان انگلیسی مقاله:
Laminar flame speeds of methane/air mixtures at engine conditions: Performance of different kinetic models and power-law correlations
ترجمه فارسی عنوان مقاله:
سرعت شعله چند لایه مخلوط های متان / هوا در شرایط موتور: عملکرد مدل های مختلف جنبشی و همبستگی قدرت قانون
Sciencedirect - Elsevier - Combustion and Flame, 218 (2020) 101-108. doi:10.1016/j.combustflame.2020.05.004
Yiqing Wang a , Ashkan Movaghar b , Ziyu Wang c , Zefang Liu d , Wenting Sun d , Fokion N. Egolfopoulos b , Zheng Chen
The laminar flame speed is an important input in turbulent premixed combustion modelling of spark ignition engines. At engine-relevant temperatures and pressures, its measurement is challenging or not possible and thereby it is usually obtained from simulations based on chemical models or power-law correlations. This work aims to investigate the performance of different models and power-law correla- tions in terms of predicting laminar flame speeds of methane/air at engine conditions. The propagation of spherically expanding laminar flames in a closed chamber was simulated and laminar flame speeds were computed over a broad range of pressures (1-120 atm) and temperatures (30 0-110 0 K) for methane/air mixtures based on seven kinetic models. It was found that at engine conditions, there are notable dis- crepancies among the predictions. GRI Mech. 3.0 and USC Mech. II respectively predict the largest and smallest values at high pressure conditions. This was explained by the difference in CH 3 oxidation and recombination according to reaction pathway analysis. Additionally, laminar flame speeds of methane flames were experimentally determined under engine-relevant conditions. It was shown that the recently developed Foundational Fuel Chemistry Model Version 1.0 model predicts closely the data at high pres- sures and temperatures. Therefore, it was chosen as the reference model for the comparisons. Thirteen published power-law correlations for laminar flame speeds of CH 4 /air were implemented, and their per- formance in predicting the laminar flame speeds at engine conditions was investigated. Most of these correlations have been derived for a narrow range of temperatures and pressures, which are lower than those encountered in engines. A new power-law correlation was derived based on predictions by the Foundational Fuel Chemistry Model Version 1.0. This new correlation is expected to provide reliable pre- dictions at engine conditions for a stoichiometric methane/air mixture and thereby it is recommended to be used in modeling turbulent premixed combustion in spark-ignition engine simulations.
Keywords: Laminar flame speed | engine conditions | methane | power-law correlation | propagating spherical flame