Propagation of premixed flames in confined channels

closed tube;premixed flames;Lewis number;numerical solution;hydrodynamic model

Navaneetha, Arjun ; Matalon ; Moshe

关键词: closed tube;    premixed flames;    Lewis number;    numerical solution;    hydrodynamic model;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/44403/Arjun_Navaneetha.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The propagation of premixed flamesin confined channels is investigated. In the unconfined case, the structure of the flame and the flame speed for the adiabatic planar flame have been numerically obtained and confirmed with the existing theory. It is seen that in the unconfined case, the flame propagates in nearly isobaric conditions with a constant flame speed whereas in the confined case there is pressure buildup which affects the flame speed. In the confined case, the time evolution of the flame is solved to obtain properties like the mass burning rate, pressure and flame location as a function of time, velocity field in the channel and propagation speed. Also the temperature and concentration profiles are obtained which give an insight in to the thickness of the flame region as the flame propagates through the entire channel. Effect of the Lewis number on the time taken for the flame to propagate the channel is examined. A non-linear analytical model that treats the flame as a discontinuity is also used to compare with the obtained numerical solution. This model requires only solving the hydrodynamic equations along with the Hugoniot jump relations across the flame front. The main difference between the numerical and the analytical solution is that the numerical solution takes into consideration a finite rate chemistry whereas in the analytical solution the reaction rate modeled as a delta function. Differences between the analytical and the numerical solution are compared.