Determination of the Conditions for Stabilizing the Flame Height During Burning in Narrow Long Capacities by Natural and Numerical Methods

The paper experimentally studies the combustion of combustible liquids (acetone, nonane) in rectangular cuvets in which one linear dimension (length) significantly exceeds the other (width). It was found that when the length of the container exceeds a certain critical value, the height of the flame stops growing and stabilizes at a constant level that is determined only by the width of the cuvette and the properties of the liquid. For each fixed width, the critical lengths at which stabilization occurs were determined. The criterion for transition to a stabilized regime is the length-to-width ratio b/a, and the threshold value depends on the width of the container: for narrow cuvets (a=0.7 cm), stabilization occurs when b/a≥15, and for wider cuvets (a=1.7 cm), it occurs when b/a≥5. For practical calculations, it is proposed to use the universal condition b/a≥3 (the container is narrow and long) with an additional check for reaching the maximum flame height. The results are verified by numerical modeling in the Fire package.