The Temperature and Pressure Dependencies of Propagation Characteris-tics for Premixed Laminar Ethanol-Air Flames

Laminar burning velocity is strongly dependent on mixture characteristics, e.g. initial temperature, pressure and equivalence ratio. In this work, spherically expanding laminar premixed flames, freely propagating from a spark ignition source in initially quiescent ethanol-air mixtures, have been imaged and then the laminar burning velocities were obtained at initial temperatures of 358 K to 500K, pressure of 0.1 to 0.2 MPa and equivalence ratio of 0.7 to 1.4. The measured re-sults and literature data on ethanol laminar burning velocities were accumulated, to analyze the effects of initial tempera-ture and pressure on the propagation characteristics of laminar ethanol-air flames.Acorrelation in the form ofu_l=u_lo(T_u/T_u0)^α_T(P_u/P_u0)^β_P, and validated over much wide temperature, pressure and equivalence ratio ranges. The global activation temperatures were determined in terms of the laminar burning mass flux for ethanol-air flames. And the Zel'dovich numbers were estimated as well. The dependencies of global activation temperature and Zel'dovich number on initial mixture pressure, temperature and equivalence ratio were explored. Additionally, an alterna-tive correlation of laminar burning velocities, from the view of theoretical arguments, was proposed on the basis of the de-termined ethanol-air laminar mass burning flux. Good agreements were obtained in its comparison with the literature data.

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