Spray characteristics of supercritical DME

Ryuhei TAKADA, Rio WAKABAYASHI, Shinsuke KIKUCHI, Yuta MITSUGI, Satoshi SAKAIDA, Kotaro TANAKA, Mitsuru KONNO
2020 Transactions of the JSME (in Japanese)  
The penetration of DME spray is shorter than that of diesel fuel when the same injection system is used because DME cannot be injected at high pressure like diesel fuel due to its high compressibility. Chris reported that supercritical gasoline spray has a wider spray angle and has increased penetration. Therefore, there is possibility that supercritical DME spray has increased penetration. However, there is no observation on the shape, development process, combustion of supercritical DME
more » ... In this study, the spray and combustion characteristics of supercritical DME in an optically accessible constant volume vessel were observed under turbo charged engine-like ambient condition. Parallel light shadow graph and diffused light shadow graph method were applied to image the liquid and vapor phase behavior. Moreover, the spray angle of supercritical spray was compared with that of subcritical one under the same ambient condition to confirm the influence of fuel temperature. The results show that there is no significant difference in spray shape between supercritical and subcritical spray under turbo charged engine-like ambient condition. Moreover, the spray angle of supercritical spray was bigger than that of subcritical one under relatively low pressure ambient conditions. These can be explained by p -v diagram. The reasons are as follows the difference in specific volume between liquid and vapor is small at ambient pressure near critical pressure. The ignition timing of the supercritical spray was slightly earlier than the subcritical spray.
doi:10.1299/transjsme.19-00050 fatcat:mh2mqz6mvnbptnlqmbsti4yyr4