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Author
Green, R. M. | Smith, J. R.
Title
Experimental Study of Engine Knock.
Coporate
Sandia Labs., Livermore, CA
Report
WSS/CI Paper 84-46, 1984, 14 p.
Book or Conf
Combustion Institute/Western States Section. Spring Meeting, 1984. April 2-3, 1984, Boulder, CO, 1984
Keywords
engines | engine knock | radicals
Abstract
Raman and emission spectroscopy, laser induced fluorescence, schlieren photography, and gas sampling have been used in a single cylinder, spark ignition engine to study preflame conditions and reactions that lead to knock. The intake manifold temperature and pressure were used control the fraction of fuel autoigniting in a 5.1 compression ratio engine. N-butane and isobutane were studied, and both were found to knock within the range of achievable inlet conditions. In the present experiment, knock is the result of a dramatic increase in the rate of heat release caused by the nearly homogeneous autoignition of the compression-heated end gas. Detonation waves could not be detected and do not appear to be necessary for the occurrence of knock. Preflame reactions involving OH and CH radicals producing carbon monoxide, formaldehyde and faint blue light were observed.