The spray vaporization characteristics of gasoline/diethyl ether blends at sub-and super-critical conditions

[Display omitted] •Visualization of vapor and liquid fuel is actualized at identical operating conditions.•Spray vaporization behaviors of gasoline/ diethyl ether at sub-and super-critical conditions are investigated.•Vaporization process is accelerated with diethyl ether addition at subcritical condition.•Diethyl ether addition effect on vaporization is opposite at supercritical condition. The multi-hole spray vaporization characteristics of gasoline, diethyl ether (DEE) and their blends were investigated at two pressures and elevated temperatures by using high speed schlieren photography and laser sheet patternation. Results show that the effects of DEE addition on spray behaviors depend on the ambient conditions that may lead to sub- and supercritical vapor generation mechanisms: (a) for 0.5 MPa ambient pressure at sub-critical state, spray plumes from different nozzle holes are separated. DEE addition results in higher vapor tip penetration, higher spray angle and decreased liquid cross-sectional area, indicating that DEE addition enhances vaporization. However, this effect becomes weaker at higher temperature due to accelerated gasoline vaporization. (b) for 3.8 MPa ambient pressure, spray plumes coalesce as a single plume-like structure due to stronger aerodynamic resistance to the axial penetration of each plume. In addition, opposite from the 0.5 MPa ambient pressure case, DEE addition results in an inhibited vaporization because the fuel blends are more easily heated to supercritical state with the addition of DEE. The thickened interface and reduced mean free path at supercritical state lead to restricted vapor phase generation. This phenomenon is also evidenced by the absence of large liquid blob on the patternation images.