Investigation into Air-Fuel Ratio Measurement of a High Performance Two-Stroke Engine by an Optical Method

Close control of air-fuel ratio is vital to attaining optimum performance from internal combustion engines. To ensure that air-fuel ratio is maintained at the correct value, an accurate measurement of the real-time air-fuel ratio is required.

This paper investigates the use of an optical method to measure air-fuel ratio of a high performance two-stroke engine.

The technique measures the light emission from the combustion process at two wavelengths, corresponding to the CH and C₂ radicals. A relationship between characteristics of this light emission and air-fuel ratio has been developed over a range of engine operating conditions. Other factors that affect this relationship have also been quantified.