Performance of Prototype High Pressure Swirl Injector Nozzles for Gasoline Direct Injection

Prototype intermittent swirl-generating nozzles for gasoline direct injection application were fabricated by modifying MPI injector nozzles. Design parameters include geometric configuration of nozzle internal flow passage such as orifice diameter and length, needle geometry and swirler passage designs. Operating parameters are considered such as injection pressure, ambient pressure, injected fuel mass and duration of injector opening.

Performances of the nozzles have been characterized in terms of static and transient flow rate, initial and overall spray angle, penetration, mean droplet diameter and drop size distribution. Computational fluid dynamic modeling of internal flow for the nozzles provided additional insight in addition to the experimental measurements.

Sprays from the prototype nozzle used for measurement in this study exhibited the general features of swirl injection sprays. The spray drop size varied from 20μm to 28μm in Sauter mean diameter under wide range experimental conditions. Computation of internal flow of prototype nozzles was validated with the measurements in terms of flow rate and initial spray angle. After validation, the influence of various design factors on these two performance parameters was examined. The most significant factor was found to be the orifice diameter.