Numerical simulations of spontaneous ignition of mono-disperse fuel spray in lean premixed gas

O. Moriue, Y. Kawaida, H. Kato, E. Murase

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Spontaneous ignition of mono-disperse fuel spray with uniform droplet distribution in hot fuel/air premixed gas was simulated through one-dimensional numerical model of an isolated fuel droplet in a closed constant-volume cell. Namely, the inter-droplet interaction in a spray was expressed through the interference of the outer boundary of the cell. Equivalence ratio calculated from initial amounts of fuel in the liquid phase and oxygen in the gas phase was defined as liquid-phase equivalence ratio φl. Since the premixed gas was fuel-lean, the existence of the droplet might either promote the ignition through a role as fuel source or hinder the ignition through a role as heat sink, which could depend on initial droplet diameter d0, φl, initial gas-phase temperature Tg0, initial liquid-phase temperature Tl0, gas-phase equivalence ratio φg and initial pressure P0. The effects of the first three conditions were examined. d0 was less than 200 μm and typically around 30 μm. Tl0, φg and P0 were 300 K, 0.4 and 3 MPa, respectively. Fuel was nheptane. Detailed chemical kinetics including the low-temperature oxidation reactions were employed, and therefore cool-flame ignition delay τcf and hot-flame ignition delay τig were evaluated. First, only d0 was varied. When d0 was relatively large, both τcf and τig were not different from those of only premixed gas with the same φg. It means that such large droplet required relatively long time for vaporization compared with chemical characteristic time, and the ignition occurred at the outer boundary of the cell that the fuel vapor from the droplet did not reach. However, as d0 decreased, τcf and τig increased and decreased, respectively, first. Thus interaction between spray and premixed gas was recognized. Next, only φl was varied. With increasing φl, τig either increased monotonically or had minimal value depending on Tg0

Original languageEnglish
Title of host publication11th International Annual Conference on Liquid Atomization and Spray Systems 2009, ICLASS 2009
PublisherILASS Americas/Professor Scott Samuelsen UCI Combustion Laboratory University of California Irvine, CA 92697-3550
ISBN (Electronic)9781617826535
Publication statusPublished - 2009
Event11th International Annual Conference on Liquid Atomization and Spray Systems, ICLASS 2009 - Vail, United States
Duration: Jul 26 2009Jul 30 2009

Publication series

Name11th International Annual Conference on Liquid Atomization and Spray Systems 2009, ICLASS 2009

Conference

Conference11th International Annual Conference on Liquid Atomization and Spray Systems, ICLASS 2009
CountryUnited States
CityVail
Period7/26/097/30/09

All Science Journal Classification (ASJC) codes

  • Surfaces, Coatings and Films

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