This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Development of a New Measurement Technique for the Investigation of End-Gas Autoignition and Engine Knock
Annotation ability available
Sector:
Language:
English
Abstract
A newly developed measurement technique was employed to investigate flame propagation before and during knocking combustion. Two intensified CCD cameras were used in sequence to record the natural flame light during knocking combustion via a fused silica window, which was fitted to the cylinder head of a one-cylinder four-stroke SI-engine. This arrangement enabled acquisition of two images per cycle. While the first camera was triggered by the rapid rise of the cylinder pressure at the beginning of engine knock, the second camera was activated at a prescribed time of delay.
Due to the high sensitivity of the intensified CCD cameras, extremly short exposure times of 100 to 250 ns proved to be sufficient. Consequently, acquisition rates of 200 kHz and more - which are substantially higher than those of conventional natural light photography - could be realized. Acquisition rates of 100 kHz (Δtacq. = 10 μs) seem adequate to trace the rapid propagation of reaction fronts immediately after the onset of knock. By triggering the first camera through the “knock generated pressure” pulse, we evaded the problems associated with the random occurrence of engine knock.
Extensive measurements for two different combustion chamber configurations were made at different engine speeds. The octane rating was varied by mixing the primary reference fuels i-octane and n-heptane in different proportions.
The experiments clearly show that engine knock was locally induced by spontaneous ignition in the end-gas region rather than acceleration of the primary flame. The location and mode of the ensuing “secondary” propagation wave varied over a wide range, depending among other factors on octane rating and thermodynamic conditions.
Flame velocities measured directly after the onset of knock indicate that the propagation mode of the reaction wave is somewhere between deflagration and developing detonation.
Recommended Content
Authors
Citation
Stiebels, B., Schreiber, M., and Sakak, A., "Development of a New Measurement Technique for the Investigation of End-Gas Autoignition and Engine Knock," SAE Technical Paper 960827, 1996, https://doi.org/10.4271/960827.Also In
References
- Pan J. Sheppard C.G.W. “A Theoretical and Experimental Study of the Modes of end-gas Autoignition Leading to Knock in a SI Engine” SAE paper 942060 1994
- König G. Sheppard C.G.W. “End-Gas Autoignition and Knock in a Spark Ignition Engine” SAE paper 902135 1990
- König G. Maly R.R. Bradley D. Lau A.K.C. Sheppard C.G.W “Role of Exothermic Centres on Knock Initiation and Knock Damage” SAE paper 902136 1990
- Filipe D.J. Li H.L. Miller D.L. Cernansky N.P. “The reactivity behaviour of n-heptane and iso-octane blends in a motored knock research engine” SAE paper 920807 1992
- Green R.M. Cernansky N.P. Pitz W.J. Westbrook C.K. “The role of low temperature chemistry in the autoignition o n-butane” SAE Paper 881606 1988
- Griffiths J.F. Rose D.J. Schreiber M. Meyer J. Knoche K.F. “Novel features of end-gas autoignition revealed by computational fluid dynamics” Combustion and Flame 91 209 212 1992
- Schreiber M. Sakak A. Sadat Poppe C. Griffiths J.F. Rose D.J. “Spatial structure in end-gas autoignition” SAE paper 932758 1993
- Miller C.D. Olsen H.L. Logan W.O. Osterstrom G.E. “Analysis of Spark-Ignition Engine Knock as seen in Photographs taken at 200000 Frames per Second” NACA Report 857 1946
- Spicher U. Kröger H. Ganser J. “Detection of Knocking Combustion Using Simultaneously High-Speed Schlieren Cinematography and Multi Optical Fiber Technique” SAE Paper 912312 1991
- Withrow L. Rassweiler G.M. “Slow Motion Shows Knocking and Non-Knocking Explosions” SAE Journal Jan.-Dec. 1936
- Brüggemann D. Wies B. Zhang X.X. Heinze T. Knoche K.F. “CARS Spectroscopy for Temperature and Concentration Measurements in a Spark Ignition Engine” Combustion Flow Diagnostics Durao D.F. et al. 495 1992
- Br#ggemann D. Wies B. Zhang X.X. “Measurements in a Knocking Spark-Ignition Engine by CARS Spectroscopy” Joint Meeting of the German and Italian Sections of the Combustion Institute 1989
- Ganser J. “Untersuchungen zum Einflub der Brennraumströmung auf die klopfende Verbrennung” Oktober 1994
- Schreiber M. Sakak A. Sadat Lingens A. Griffiths J.F. “A Reduced Thermokinetic Model for the Autoignition of Fuels with Variable Octane Ratings” Twenty-Fith Symposium (International) on Combustion/The Combustion Institute 1994 933 940
- Hayashi T. Taki M. Kojima S. Kondo T. “Photographic Observation of Knock with a Rapid Compression and Expansion Machine” SAE paper 841336 1984
- Cuttler D.H. Girgis N.S. “Photography of Combustion During Knocking Cycles in Disc and Compact Chambers” SAE Paper 880195 1988
- Curry S. “A Three-Dimensional Study of Flame Propagation in a Spark Ignition Engine” SAE TRANS. 71 1963
- Miller C.D. “Relation between Spark Ignition Engine Knock, Detonation Waves and Autoignition as shown by High-Speed Photography” NACA Report 855 1946
- Maly R. Ziegler G. “Thermal Combustion Modeling - Theoretical and Experimental Investigation of the Knocking Process” SAE paper 820759 1982
- Zel'dovich Y.B. Librovich V.B. Makhviladze G. M. Sivashinsky G. I. “Development of detonation in a non-uniformly preheated gas” 15 313 321 Pergamon Press 1970
- Zel'dovich Y. B. “Regime classification of an Exothermic Reaction with Nonuniform Initial Conditions” Combustion and Flame 39 211 214 1980
- Hicks R.A. Lawes M. Sheppard C.G.W. Whitaker B.J. “Multiple Laser Sheet Imaging Investigation of Turbulent Flame Structure in a Spark Ignition Engine” SAE paper 941992 1994