A new heterogeneous burning velocity formula for the propagation of a laminar flame front through a polydisperse spray of droplets
- Technion-Israel Inst. of Tech., Haifa (Israel). Faculty of Aerospace Engineering
A new burning velocity formula for the heterogeneous mode of laminar combustion of a premixed polydisperse spray of droplets is derived, using activation energy asymptotics and the method of multiple scales. For a mass fractional flux of fuel vapor, G{sub F}, of O(1) at the homogeneous reaction zone the homogeneous burning velocity formula obtained by Silverman et al is applicable. Here, it is shown that for G{sub F} of O({theta}{sup {minus}1}) (where {theta} the nondimensional activation energy) heterogeneous combustion is predominant, whence the new formula is developed. The spray of droplets is modeled with the sectional approach, so that an arbitrary initial multisize distribution of droplets may be considered. Calculated results show that the behavior of the heterogeneous burning velocity as a function of the Sauter mean diameter is in qualitative accord with experimental data from the literature. For a polydisperse tetralin spray of low volatility the theory produces evidence suggesting a critical initial SMD at which a switchover from the homogeneous to the heterogeneous mode of flame propagation occurs that is in agreement with independent experimental and theoretical predictions for monodisperse sprays.
- OSTI ID:
- 215655
- Journal Information:
- Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 3 Vol. 104; ISSN CBFMAO; ISSN 0010-2180
- Country of Publication:
- United States
- Language:
- English
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