Macroscopic and Ignition Characteristics of High-Pressure Sprays of Single-Component Fuels

Using a combination of imaging techniques, we have produced a database of the macroscopic properties of sprays produced by a common-rail injection system in a diesel simulation cell. The parameters of the data base include injection pressure (40, 80 and 150 MPa), gas-side temperature (387, 800 and 1100 K), gas density (12, 25 and 30 kg/m³), injector nozzle hole size (0.17 and 0.20 mm) and injection programs (with and without pilot injection). Single component fuels (heptane and dodecane) were used in order to simplify data interpretation and modeling.

The spray characteristics which were measured include the initial “dispersion” angle of the nozzle, initial spray tip speeds, and spray tip penetration vs. time for both the liquid and vapor parts of the spray. The sites of initial self ignition and combustion propagation within the sprays were visualized, and a luminous delay was measured for several of the operating conditions.