TY - JOUR

T1 - Double flame and multiple solution computations for a wetted porous sphere vaporizing in reactive flows

AU - Jiang, T. L.

AU - Chen, W. S.

AU - Tsai, M. J.

AU - Chiu, H. H.

N1 - Funding Information:
This work was supported by the National Science Council, Taiwan, ROC, under contract NSC 82-0401-E·OO6-199.

PY - 1994/12/1

Y1 - 1994/12/1

N2 - The flame and vaporization characteristics of an n-octane droplet burning in reactive flows are investigated through numerical analyses of a convective, reactive flow over a wetted porous sphere under various flow temperatures, Reynolds numbers, and ambient equivalence ratios. The liquid fuel is assumed to come through the porous sphere and vaporize at the sphere's surface. The gas flow field is predicted by solving the quasi-steady conservation equations of mass, momentum, and energy, in which gas-phase combustion is modeled by a one-step global finite-rate chemical reaction. Numerical results reveal that multiple solutions for flame configurations and vaporization rates exist under certain flow conditions for both r., rely oxidizing and reactive flows. Reactive flows increase the vaporization rate slightly at low ambient temperatures, while significantly at high ambient temperatures. Double flames occur in both the upper and lower branch solutions. In the upper branch situation, both the premixed and nonpremixed flames merge at relatively low ambient temperatures, low ambient equivalence ratios, or high Reynolds numbers. In the lower branch solution, however, double flames do not exist at sufficiently low ambient temperatures or high Reynolds numbers where the envelope flame does not appear.

AB - The flame and vaporization characteristics of an n-octane droplet burning in reactive flows are investigated through numerical analyses of a convective, reactive flow over a wetted porous sphere under various flow temperatures, Reynolds numbers, and ambient equivalence ratios. The liquid fuel is assumed to come through the porous sphere and vaporize at the sphere's surface. The gas flow field is predicted by solving the quasi-steady conservation equations of mass, momentum, and energy, in which gas-phase combustion is modeled by a one-step global finite-rate chemical reaction. Numerical results reveal that multiple solutions for flame configurations and vaporization rates exist under certain flow conditions for both r., rely oxidizing and reactive flows. Reactive flows increase the vaporization rate slightly at low ambient temperatures, while significantly at high ambient temperatures. Double flames occur in both the upper and lower branch solutions. In the upper branch situation, both the premixed and nonpremixed flames merge at relatively low ambient temperatures, low ambient equivalence ratios, or high Reynolds numbers. In the lower branch solution, however, double flames do not exist at sufficiently low ambient temperatures or high Reynolds numbers where the envelope flame does not appear.

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U2 - 10.1080/00102209408935472

DO - 10.1080/00102209408935472

M3 - Article

AN - SCOPUS:0000894191

VL - 102

SP - 115

EP - 143

JO - Combustion Science and Technology

JF - Combustion Science and Technology

SN - 0010-2202

IS - 1-6

ER -