Measurement of temperature, fuel concentration and equivalence ratio fields using tracer LIF in IC engine combustion

A technique based on planar laser-induced fluorescence of 3-pentanone, for measurements of absolute concentration, temperature and fuel/air equivalenc e ratios in turbulent, high-pressure combustion systems such as an internal combustion engine is presented. Quasi-simultaneous excitation with 248 nm and 308 nm of 3-pentanone that is used as a fluorescence tracer doped to is o-octane, yields pairs of strongly temperature-dependent fluorescence image s. Previous investigations have resulted in information on temperature and pressure dependence of absorption cross-sections and fluorescence quantum y ields. Using these data the ratio of corresponding fluorescence images can be converted to temperature images. Instantaneous temperature distribution fields in the compression stroke and in the unburned end-gas of an SI engin e were measured. The temperature fields obtained from the two-line techniqu e are used to correct the original tracer-LIF images in order to evaluate q uantitative fuel distributions in terms of number densities and fuel/air eq uivalence ratio.