Effects of Inlet Flow on Combustion Characteristics of n-Heptane in a Micro-Combustor

In order to improve flame stability by changing inlet flow condition, following experiments were performed by using n-heptane as fuel in a micro-combustor of 4mm internal diameter to study effects of fuel flowrate and oxygen concentration on n-heptane droplet combustion in micro-tube. It was found that, when equivalence ratio is fixed at 0.9 and heptane flow rate increases from 10μL/min to 30μL/min, ignition time decreases and droplet drips. Then the film was formed, which was beneficial for ignition and flame stability. At a fixed inlet flow velocity of 0.33m/s, instantaneous jet flame appeared when pure oxygen was added to air and the flame didn't quench. Increasing oxygen concentration can reduce ignition time and improve flame stability. With increasing of oxygen concentration, flame length first increased and then decreased on the whole. Combustion sound-vibration exhibited low frequency characteristics and became most intense when oxygen concentration is 0.46.