Combustion characteristics of small isolated methanol droplets

Inkant Awasthi, George Gogos, Thirumalachari Sundararajan

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

Abstract

The paper presents a transient, axisymmetric numerical simulation of combustion of methanol droplets in a nearly quiescent environment (with ambient temperature of 1200 K, ambient pressure of 1 atm., and Reynolds number of 10-2). The focus is on the combustion process of droplet sizes applicable in a practical spray. A gradual transition from kinetically controlled combustion to diffusion controlled combustion is found with the increase in droplet sizes. Droplets smaller than ≈ 60 μm are influenced more by chemical kinetics due to the reaction zone broadening and a concomitant reduction in flame temperatures. In this kinetically controlled regime, the burning rate of an individual droplet first increases to a maximum, and then decreases. In this regime, the average of droplet burning rate over its life time is bounded by an upper bound of thin flame-sheet burning rate (large Damk̈ohler number limit), and a lower bound of pure evaporation rate (small Damk̈ohler number limit). The actual average burning rate lies between the two values, determined by the droplet size. For droplets smaller than ≈ 60 μm, the flame stand-off ratio varies throughout their lifetime. The analysis underlines the importance of accurate chemical kinetics modelling for small droplets.

Original languageEnglish (US)
Title of host publicationASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012
Pages405-415
Number of pages11
EditionPARTS A, B, C, D
DOIs
StatePublished - 2012
EventASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012 - Houston, TX, United States
Duration: Nov 9 2012Nov 15 2012

Publication series

NameASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE)
NumberPARTS A, B, C, D
Volume7

Conference

ConferenceASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012
CountryUnited States
CityHouston, TX
Period11/9/1211/15/12

ASJC Scopus subject areas

  • Mechanical Engineering

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    Awasthi, I., Gogos, G., & Sundararajan, T. (2012). Combustion characteristics of small isolated methanol droplets. In ASME 2012 International Mechanical Engineering Congress and Exposition, IMECE 2012 (PARTS A, B, C, D ed., pp. 405-415). (ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE); Vol. 7, No. PARTS A, B, C, D). https://doi.org/10.1115/IMECE2012-86165