DISI Fuel Spray Effects During Simulated Injection Timing

The instantaneous structure of sprays from two Direct Injection, Spark Ignition (DISI) injectors were studied within a non-motored research cylinder. In-cylinder conditions simulating injection up to 27° before top dead center (BTDC) were utilized in the characterizations. Comparisons between the two injectors highlight the impact of nozzle design on spray performance. Experiments include axial and horizontal flow visualization and PIV, illustrating the effect of in-cylinder density (with in-cylinder pressure used to control in-cylinder density) on instantaneous fuel spray structure. Fuel spray imaging experiments illustrate the effect of in-cylinder density on the initial clump of fluid and other spray development phases. In-cylinder density increases hollow cone narrowing and decreases spray penetration. PIV results show that the initial clump of fluid travels with extremely high velocities for all injection strategies. These results will aid in the selection of injection strategies during DISI engine design