Spray characteristics of DME in common rail injection system were investigated within the high-pressure chamber by using the particle motion analysis system. The injectors used in this study have single hole with the different orifice diameter of 0.2, 0.3 and 0.4mm. The injection pressure was fixed at 35MPa and the ambient pressures were varied from 0.6 to 1.5MPa.
Spray characteristics such as spray angle, spray penetration and SMD were measured. The measured spray angle increased with an increase in ambient pressure and nozzle orifice diameter. An increase of ambient pressure results in a decrease of spray penetration and an increase of nozzle orifice diameter leads to an increase of spray penetration.
The experimental results of spray penetration were compared with the predicted one by various theoretical models. For modeling the spray penetration of DME, Wakuri et al's and Sazhin et al's models show satisfactory agreement with experimental data. The spray angle at a distance 30do downstream of the nozzle is recommended for Wakuri et al's model and one at a distance 45do downstream of the nozzle for Sazhin et al's model.
An increase in the ambient pressure and nozzle diameter results an increase of SMD at a distance 30, 45 and 60do downstream of the nozzle, respectively.