A single cylinder diesel engine with simulated turbocharging was instrumented and run to acquire radiation data at two wavelengths, simultaneously at three locations, along with cylinder pressure data and injection data. The 8 hole injector was indexed to acquire data, at three angles of 0°, 11° and 22.5° from the spray axis. The engine speed was 1500 rpm, the equivalence ratio (based on fuel to oxygen ratio) was 0.47, and the partial pressure of oxygen was 58 kPa for all runs. The radiation data were processed to produce the flame temperature and soot concentration using the two-color theory. The soot concentration and temperature increased in the outward radial direction, with the highest values at the 11° locations except for near the injector where the highest values were on the axis.
The flame appeared to start at the spray tip when it was almost half-way distant from the bowl walls. The spray slowed down as it moved radially outward. The flame appeared earlier at all locations as the oxygen concentration was increased, indicating faster chemical reactions and spray penetration.
The peak soot concentration was highest for the intermediate oxygen ratio (25%), however, during the expansion stroke, the concentrations crossed over giving the lowest concentration for the highest oxygen ratio (27%).