Analyses and in-cylinder measurements of local and hemispherical particulate radiant emissions and temperatures in a direct injection diesel engine

Local and hemispherical radiation probes using the two-color theory were developed to measure the radiation intensities at three different wavelengths, 0.55, 0.70 and 0.85 {dollar}mu{dollar}m, respectively, in an Cummins single cylinder NH diesel engine. Data were processed to determine both local and hemispherical instantaneous in-cylinder flame temperatures and particulate concentrations. These resulting data were used to evaluate the potential radiation fluxes. Heat release and exhaust emission data for NO, NO{dollar}sb{lcub}rm x{rcub}{dollar}, and CO are presented along with these radiant emission data.; The radiation probes consist of a specially designed trifurcated fiber optical bundle and a sapphire rod window for the narrow field of view (14 degree cone) and a Lucalox rod window for the hemispherical view. A self-cleaning window for the local measurement was designed, which stays clean under steady state full load conditions. The hemispherical radiation probe with a special configuration of the sensor had a nearly cosine normalized directional response.; The engine was operated at both standard cooled and simulated mini-cooled configurations. The simulated mini-cooled condition was accomplished by increasing the coolant temperature and inlet air temperature levels. The tests were made for various intake pressures, intake temperatures, equivalence ratios, engine speeds and spray tip rotations. The local peak flame temperature was found to be as high as 2500 K. In-Cylinder particulate increased very drastically near the start of diffusion burning and started to be oxidized rapidly around the end of injection. Changing the intake air temperature did not affect the soot production. The peak flame temperature increased with the coolant temperature. Increasing the coolant temperature gave slightly more exhaust smoke as well as in-cylinder soot production, because more late burning occurred at the higher coolant temperature. This increased late burning was caused by a delayed end-of-injection and lower injection rate caused by thermal expansion effects in the injector. The peak effective temperature for the entire hemisphere was observed to be as high as 2340 K. The peak radiation flux ranged from 1.05 to 1.2 MW/m{dollar}sp2{dollar} and increased with load. The ratio of the average radiation flux to the average total flux was approximately 12% from light to medium loads.