| A single cylinder Cummins NH Diesel engine was instrumented and run to acquire radiation data at two wavelengths, simultaneously at three locations, along with cylinder pressure data and injection data. The injector was indexed to acquire data, at three other radial locations, at different angles from the spray axis. The locations on the radial direction were at approximate distances of 23, 35, and 47 mm from the central injector tip while the spray plume was a maximum of 50 mm long. The angles from the spray axis were 0{dollar}spcirc{dollar}, 11{dollar}spcirc{dollar}, and at 22.5{dollar}spcirc{dollar} while the angle between two sprays is 45{dollar}spcirc{dollar}. 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 engine ran at different intake temperatures and different oxygen ratios with intake pressure adjusted to keep the oxygen partial pressure constant. These 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. The values were highest at the 11{dollar}spcirc{dollar} locations which are near the spray edge, except at the 23 mm location where the highest values were at 0{dollar}spcirc{dollar}. Oxygen enrichment also increased the flame temperature; the temperature stayed higher during the main combustion period for all locations. The peak soot concentration was highest for the intermediate oxygen ratio; however, during the expansion stroke, the concentrations crossed over giving the lowest concentration for the highest oxygen ratio. The effect of changing the intake temperature between 313 and 348 K was insignificant. The ensemble average flame temperature and soot concentration were quite low at locations far from the fuel spray indicating a sparsity of flame clouds there.; Data also showed that the flame started at the spray tip while it was almost halfway distant from the bowl walls, and that the spray slowed down as it moved radially outward. The flame appeared earlier at all locations as the oxygen ratio was increased, indicating faster chemical reactions and spray penetration. |
