Flow Structure and Heat and Mass Transfer Near the Leading Edge of Ethanol Flame Evaporating in the Boundary Layer Behind the Rib and Behind the Step
B. F. Boyarshinov
Kutateladze Institute of Thermal Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: flame stabilization, behind the edge, behind the backward-facing step, heat transfer, momentum, turbulence, heat release rate, thermal expansion
Abstract
In order to study the combustion stabilization mechanisms, the gas parameters near the flame leading edge behind the rib and behind the step in the boundary layer with ethanol evaporation and combustion were compared. It was shown that at an air flow velocity of ≈11 m/s, an attached flame is formed behind the step, and the ethanol evaporation intensity is lower than behind the rib with a detached flame. At the flame leading edge behind the barriers, a zone is localized where the maximum heat release is located at the mixture ignition temperature, and the static and dynamic pressures are equal. It was shown that under conditions of gas motion with combustion and separation behind the rib, the maximum contribution of turbulent momentum transfer reaches ≈30 ÷ 40% of the averaged convective, and the share of molecular transfer is 2 ÷ 3%.
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