Quantitative 2-D Fuel Distribution Measurements in an SI Engine Using Laser-Induced Fluorescence with Suitable Combination of Fluorescence Tracer and Excitation Wavelength

This paper describes a laser-induced fluorescence (LIF) method for quantitative 2-D fuel concentration measurements in an SI engine. The combination of fluorescence tracer and excitation wavelength to lower the temperature and pressure effects on LIF intensity were evaluated. Each kind of fluorescence tracer selected from ketones, aldehydes and aromatics has been excited at 248 nm or 266 nm in a heated and pressurized constant volume vessel. For the promising candidates, further evaluation has been performed using a fired visualization engine. The results show that the optimum combination which gives the lowest effects of temperature and pressure on LIF intensity is acetone with 266 nm excitation. 3-pentanone, which is commonly used fluorescence tracer has been shown to be not suitable for the quantitative measurements, especially in a fired engine. Based on these fundamental examinations, a quantitative 2-D fuel concentration measurement technique has been applied to analyze the influence of fuel supply conditions on the mixture formation processes. The measurement accuracy of this method has also been discussed.