Journal
FUEL
Volume 81, Issue 17, Pages 2219-2225Publisher
ELSEVIER SCI LTD
DOI: 10.1016/S0016-2361(02)00134-5
Keywords
controlled autoignition; homogeneous charge compression ignition; rapid compression machine
Categories
Ask authors/readers for more resources
Experiments have been performed in a rapid compression machine (RCM), to investigate the conditions for and the origins of 'knock' in controlled autoignition (CAI), or homogeneous charge compression ignition (HCCI). Ignition in an RCM is the closest approach to that in a CAI engine without engendering the full complexity of reciprocating motion and fuel + air charge induction. As a representative fuel of intermediate reactivity, the combustion of n-pentane in air was studied at the compositions phi = 1.0, 0.75 and 0.6 at end-of-compression pressures of 0.80-0.86 MPa (7.9-8.4 bar) and 1.4-1.5 MPa (13.8-14.8 bar), respectively, over the compressed gas temperature range 690820 K. Autoignition is characterised by a two-stage development in these ranges of conditions, a 'cool flame' being followed by hot stage combustion. Filtered Rayleigh scattering from a planar laser sheet was used to characterise the temperature field that developed in the combustion chamber following rapid compression. High resolution pressure records, combined with image intensified, natural light output originating from chemiluminescence, were used to characterise the transition from non-knocking to knocking reaction and the evolution of the spatial development of chemical activity in this temperature field. It appears that knock originates from a localised development of the incandescent hot stage of ignition. Even though non-homogeneities prevail in the non-knocking reaction, it is associated with a relatively benign development, in which the cool flame is followed by a second stage, blue flame rather than the normal incandescent hot flame. The kinetics that may contribute to this distinction are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available