Influence of fuel temperature on atomization parameters in a pressure-swirl atomizer from a port fuel injector by Shadowgraphy technique

Abstract

The atomization process that occurs in fuel injectors has a strong relation with the subsequent combustion reaction and thus with the engine thermal efficiency. Experiments were performed to investigate the fuel temperature effect on atomization parameters in a pressure-swirl atomizer. The experimental apparatus consisted of a flow control rig connected with a heat control system. The flow rig was built specifically for that purpose and the heat system goal was to vary the fuel temperature. The atomization parameters were evaluated by means of Shadowgraphy technique. Gasoline and ethanol in different temperatures, from 16 to 55 $^{\circ }$C, were used to provide variation in liquid properties and the same injection pressure (0.3 MPa) was used for both fuels. The results for drop sizing were expressed in terms of Sauter mean diameter (SMD) and the velocity field as well as the particle size distribution measurements were taken into two different axial distances from the nozzle exit. SMD and velocity field were also evaluated as function of injection pressure (from 0.1 to 0.5 MPa) as an additional test. At both distances, 25 and 100 mm, SMD and velocity seemed to be insensitive to the range of temperature used because it provided low variation in fuel properties. On the other hand, particle size distribution allowed the visualization of temperature effect on drop diameters, showing that increasing temperatures decrease droplet sizes, and the comparison between two axial distances allowed seeing the effects of first and second atomization on the spray.