Study on the Dimethyl Ether Spray Characteristics According to the Diesel Blending Ratio and the Variations in the Ambient Pressure, Energizing Duration, and Fuel Temperature

The purpose of this study was to investigate the effects of the energizing duration, ambient gas pressure, fuel temperature, and diesel−dimethyl ether (DME) blending ratio on DME spray characteristics. The DME spray characteristics were analyzed using the spray images obtained from the spray visualization system. The experimental results for the DME spray were compared to the numerical results calculated using KIVA code. DME fuel had a shorter spray tip penetration and a wider spray cone angle compared to those of conventional diesel fuel atomization. DME spray became blurry at the outer region of the spray, and its evaporation was more active than that of diesel fuel. The droplet sizes of DME were much smaller than those of diesel fuel because of the low kinematic viscosity and evaporation of DME. In the results of calculations, the increased ambient gas pressure caused restraint in spray development and entrainment of the surrounding air. On the other hand, the short energizing duration induced short spray tip penetration; however, the variation in the energizing duration had little effect on the spray cone angle. The elevated ambient gas pressure retrained the DME spray development, which increased the spray cone angle of DME.