Experimental study of droplet temperature in a two-phase heptane/air V-flame

摘要

An understanding of the complex phenomena involved in droplet combustion, such as two-phase flows and heat/mass transfer, is a necessary step towards improving combustion efficiency and reducing pollutant emissions. This paper is focused on an analysis of the droplet temperature evolution across the flame front in two-phase flow systems. In this experiment, the flame was stabilized on a rod at atmospheric pressure and the fuel was liquid at injection, which implies the presence of fuel droplets close to the flame front. However the flame was partially premixed because part of the fuel vaporized quickly and contributed to the stabilization of the flame. The configuration was two-dimensional and so called "V-shape" flame. Two different flow conditions were investigated: a pseudo-laminar flow as the reference case (R) and a low-turbulence level flow (LT). The evolution of the mean fuel droplet temperature across the flame brush was quantified. The shape of the fuel droplet temperatures histogram became clearly bimodal for high values of the mean progress variable c, indicating the presence of droplets in the measurement volume that were heated up by the burnt gases and the flame. The temperature evolution and the statistics across the flame front can be used to compare the numerical and the physical models applied to two-phase combustion.