An experimental study of the knock initiation and development period was conducted in a single-cylinder research engine. Cylinder pressure was recorded at two locations in the combustion chamber using a high sampling frequency, thus allowing the identification of spatial and temporal pressure characteristics introduced by knock. It was found that substantial local pressure differences exist inside the chamber during the initiation of autoignition. In most cases, knock-induced pressure waves are of acoustic nature, but they can become weak shock waves in heavily knocking cycles. Waves appear first in the pressure trace of the transducer closer to the site of autoignition, and are subsequently detected by the other transducer. The results show evidence of multiple sites of autoignition, and indicate changes in the nature and the direction of propagation of pressure waves. Cylinder pressure signals sampled at locations closer to the center of the chamber show significantly smaller amplitude of pressure fluctuation, making them more suitable for further mathematical processing.

Issue Section:
Spark Ignition Engine Combustion
Keywords:
internal combustion engines, ignition, combustion, pressure measurement, pressure transducers
Topics:
Cycles, Cylinders, Pressure, Signals, Transducers, Waves, Combustion chambers
1.
Drapper
,
C. S.
,
1938
, “
Pressure Waves Accompanying Detonation in the Internal Combustion Engine
,”
J. Aeronaut. Sci.
,
5
(
6
), pp.
219
–
226
.
2.
Zucrow, M. J., and Hoffman, J. D., 1976, Gas Dynamics, 2, John Wiley and Sons, New York, pp. 69–111.
3.
Lee, W., and Schaefer, H. J., 1983, “Analysis of Local Pressures, Surface Temperatures and Engine Damages under Knock Conditions,” SAE Paper No. 830508.
4.
Konig, G., and Sheppard, C. G. W., 1990, “End Gas Autoignition and Knock in a Spark Ignition Engine,” SAE Paper No. 902135.
5.
Konig, G., Maly, R. R., Bradley, D., Lau, A. K. C., and Sheppard, C. W., 1990, “Role of Exothermic Centers on Knock Initiation and Damage,” SAE Paper No. 902136.
6.
Stiebels, B., Schreiber, M., and Sadat Sakak, A., 1996, “Development of a New Measurement Technique for the Investigation of End-Gas Autoignition and Engine Knock,” SAE Paper No. 960827.
7.
Brunt, M. F. J., Pond, C. R., and Biundo, J., 1998, “Gasoline Engine Knock Analysis Using Cylinder Pressure Data,” SAE Paper No. 980896.
8.
Puzinauskas, 1992, “Examination of Methods Used to Characterize Engine Knock,” SAE Paper No. 920808.
9.
Syrimis, M., Shigahara, K., and Assanis, D. N., 1996, “Correlation Between Knock Intensity and Heat Transfer Under Light and Heavy Knocking Conditions,” SAE Paper No. 960495.
10.
Bendat, J. S., and Piersol, A. G., 1986, Random Data Analysis and Measurement Procedures, 2nd Ed., John Wiley and Sons, New York.
11.
Checkel, M., and Dale, J., 1986, “Computerized Knock Detection from Engine Pressure Records,” SAE Paper No. 860028.
12.
Ando, H., Takemura, J., and Koujina, E., 1989, “A Knock Anticipating Strategy Based on the Real-Time Combustion Mode Analysis,” SAE Paper No. 890882.
13.
Meirovitch, L., 1976, Elements of Vibration Analysis, McGraw-Hill, New York.
Copyright © 2003
 by ASME
You do not currently have access to this content.