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A measurement technique is described which permits quantitative, multi-point, in-cylinder fluid composition measurements in an internal combustion engine. The technique is based on spontaneous Raman scattering with broadband signal collection, and provides simultaneous determination of the mole fractions of H2O, CO2, N2, O2, and fuel (C3H8). Calibration and data reduction procedures which largely eliminate interference between the signals from the various species are discussed. Mean mole fractions obtained in an optical access engine from the beginning of the intake stroke to the end of the compression stroke are reported. The mean mole fractions of the individual species are used to obtain independent estimates of the mean mole fraction of burnt residual gases, which, in turn, are used to evaluate the accuracy and consistency of the data. An over-prediction of the CO2 mole fraction in hot exhaust gases is found to be the most significant shortcoming of the technique.

The in-cylinder flow field of a Schnürle (loop) scavenged two-stroke engine has been examined under conditions simulating both blower and crankcase driven scavenging. Measurements of the radial component of velocity were obtained along the cylinder centerline during fired operation at delivery ratios of 0.4, 0.6, and 0.8. Both mean velocity profiles and root mean square velocity fluctuations near top center show a strong dependence on the scavenging method. Complementary in-cylinder pressure measurements indicate that combustion performance is better under blower driven scavenging for the engine geometry studied. IN THE PAST TEN YEARS the engine research and development community has demonstrated a renewed interest in two-stroke engine technology. Many manufacturers have new engine designs operating on test stands and in prototype vehicles being road tested.