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Experimental results are presented from an investigation of the effects of large transverse accelerations on flame propagation and blowout limits in premixed step-stabilized flames. The accelerations, which exceed ±10,000 g in the present study, induce large body forces on the high-density reactants and low-density products. These body forces can substantially alter the flame propagation mechanisms and dramatically increase the flame blowout limits. Sustained centripetal accelerations a c ≡ U 2 / R are created by flowing a premixed propane–air reactant stream with equivalence ratios 0.7 ⩽ Φ ⩽ 1.9 at various speeds U through a semicircular channel with radius R . A backward-facing step of height h on the radially outer ( a c > 0) or inner ( a c a c > 0 the acceleration acts to force high-density reactants into the recirculation zone and low-density products into the reactant stream, while a c a c = 0) results for comparison. The flow speed U , equivalence ratio Φ , and step height h are systematically varied for a c = 0, a c > 0, and a c a c → +∞ the propagation of the flame across the channel becomes independent of the flame burning velocity and instead is primarily due to large-scale “centrifugal pumping” driven by the induced body forces. For a c → −∞ the body forces effectively segregate reactants and products to produce a nearly flat flame. In both cases, for large | a c | values the resulting blowout limits can be substantially higher than those at a c = 0. |
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