The experimental investigation on the response of the Burke–Schumann flame to acoustic excitation

Abstract

This paper presents experiments showing the response of a diffusion jet flame to acoustic forcing. The experimental results from the Burke–Schumann flame, which is a special case of the diffusion flame, are compared with the analytical results. The flame response is described by comparing the flame surface, flame length, and heat release oscillation measurements with those from reference papers that have calculated the analytical solution. The flame shape depends on both the forcing frequency and the mean input velocity. The flame shape is divided into three types depending on the forcing frequency. The local stagnation point of the flame propagation and the cutting phenomenon are shown with a low-frequency forcing of the test condition. The flame consists of an undulation form when a high forcing frequency is used as the test condition. At a specific frequency, no flame oscillation is seen, even with acoustic forcing. The forcing frequency also affects the flame length. The mean input velocity affects the magnitude of flame surface oscillations. The heat release ratio oscillation shows that both a premixed flame and a diffusion flame act like low-pass filters. The Peclet number's dependence on the flame surface and the response of the heat release both fit well with the analytical results, whereas the Strouhal number's dependence on the flame surface varies slightly from the analytical solution. The heat release rate oscillation is closely connected to the flame surface oscillations.