0
RESEARCH PAPERS

Spray and Flame Structure in Diesel Combustion

[+] Author and Article Information
E. N. Balles

Arthur D. Little, Inc., Cambridge, MA 02140

J. B. Heywood

Sloan Automotive Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139

J. Eng. Gas Turbines Power 111(3), 451-457 (Jul 01, 1989) (7 pages) doi:10.1115/1.3240275 History: Received August 01, 1988; Online October 15, 2009

Abstract

The diesel combustion process in direct-injection diesel engines consists of four distinct stages: an ignition delay, a premixed phase, a mixing-controlled phase, and a late combustion phase. This paper uses geometric information from high-speed direct and shadowgraph movies and corresponding combustion chamber pressure histories, taken in a rapid compression machine study of direct-injection diesel combustion, for a coupled analysis of the diesel flame geometry and energy or heat release to develop our understanding of the diesel spray and flame structure during the ignition delay period and premixed combustion phase. It is shown that each fuel spray from a multihole fuel-injector nozzle consists of a narrow liquid-containing core centered within a much larger fuel-vapor air region, which has a distinct boundary. The liquid core does not penetrate to the chamber periphery, while the vapor containing spray interacts strongly with the boundary. Ignition occurs part way along each growing spray. Once combustion starts, the outer boundary of the fuel-vapor-containing region expands more rapidly due to the combustion energy release. Very high initial spreading rates of the luminous region boundary are observed. A comparison of enflamed areas and volumes, and burned gas volumes, indicates that the luminous region during the early stages of combustion (assumed stoichiometric) is around 1 cm thick and does not fill the full height of the chamber. During the premixed combustion phase, the burned gas volume is one-half the enflamed volume, indicating the presence of a substantial unburned (rich) fuel-vapor/air core within the luminous region of each fuel spray. A close correspondence of flame geometry to spray geometry is evident throughout the combustion process.

Copyright © 1989 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In