The controlling factors in the design of a high speed Diesel engine are the ignition lag, the time lapse between fuel injection and the start of combustion, and the rate of burning. To obtain a better understanding of the effects of fuel composition and engine design on these two factors a long range research project was initiated for the fundamental study of combustion phenomena in internal combustion engines.
A commercial single-cylinder Diesel engine was equipped with electronic instruments to measure and record instantaneous and continuous flame temperature and engine pressure as functions of the engine crank rotation. In addition complete equipment was provided for simultaneously obtaining all conventional test data.
The electro-optical pyrometer used to measure flame temperatures is a new development which indicate and records true flame temperature, independent of flame emissivity and the transmissivity of the window through which it is sighted. Radiation from a quartz window placed in the combustion chamber is dispersed and focused on a barrier with two slits located in the red and near infra-red portion of the spectrum. The light through each slit falls on a phototube which develops a current proportional to the intensity of the light. The output of each phototube is amplified and impressed on the vertical plates of a cathode-ray tube. The horizontal plates carry the voltage developed by a sweep circuit so designed that the position of the cathode-ray is a measure of hte position of hte engine crank. In this manner diagrams are obtained on the cathode ray tube screens showing the variation of apparent temperature with crank rotation. From the two apparent temperatures corresponding to two different wavelengths of radiation the true flame temperature is calculated.
Results are presented showing the effects on combustion phenomena of varying engine speed, time of injection, jacket-water temperature and engine load while other operating variables were maintained constant.
It is hoped when similar data are obtained for other fuels it will be possible to correlate fuel composition with combustion characteristics, and develop the fundamental kinetic of combustion process.
Copyright 1945
Engine Research Center
University of Wisconsin-Madison