Lewis number effect on the flame height of circulation-controlled firewhirls

Abstract

A theoretical analysis was carried out on the circulation-controlled firewhirls, considering multiple physical effects, including the previously investigated variable physical properties and strong vortex, and with emphasis on the effect of non-unity Lewis number. By means of perturbation method, an analytical expression of the flame height, with all effects presented in explicit forms, was derived in the situation of both fuel and of oxidizer Lewis numbers being near unity. In leading order approximation, the non-unity Lewis number effect tends to change the flame height by a factor of 𝐿𝑒ₒ⁄𝐿𝑒բ.