Distribution of thermal energy of child-droplets issued from an optimal micro-explosion


Tarlet D., Mura E., Josset C., Bellettre J., Allouis C. G. , Massoli P.

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, vol.77, pp.1043-1054, 2014 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 77
  • Publication Date: 2014
  • Doi Number: 10.1016/j.ijheatmasstransfer.2014.06.054
  • Title of Journal : INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
  • Page Numbers: pp.1043-1054
  • Keywords: Micro-explosion, Child-droplets, Emulsified fuel, Emulsions, WATER, COMBUSTION

Abstract

The micro-explosion phenomenon is involved in emulsified fuel droplets placed in a hot atmosphere, such as spray combustion. Droplets of water-in-sunflower oil emulsion are used, since they are representative of a class of emulsions used in practical applications of biofuels. Once the micro-explosion is triggered after a short delay, the rapid (<= 1 ms) vaporization of the inside water droplets and the subsequent disintegration of the emulsion droplet blow the fragmented droplets away. These fragmented droplets are called "child-droplets", and they are too small and fast for an on-the-fly infra-red imaging thermal characterization. The present study focuses on the thermal reaction of a thin plate when impacted by them. Thorough and detailed tests are carried out, to make sure that the plate and the acquisition system are collecting a data that is actually representative of the child-droplets thermal energy. A quantitative post-processing is applied to the transient temperature field on the plate. It leads to the thermal energy of the whole plate, and of representative samples of individual child-droplets. The results show that their thermal energy is governed by a log-normal distribution. (C) 2014 Elsevier Ltd. All rights reserved.