Simultaneous capture of liquid length of spray and flame lift-off length for second-generation biodiesel/diesel blended fuel in a constant volume combustion chamber

•Simultaneous capture of the liquid length of spray and flame lift off length.•First time to visualization research the interaction between flame and liquid phase.•Combustion of second-generation biodiesel/diesel blended fuel was studied via OH∗.•Ambient oxygen concentration has little impact on the LL under reacting condition.

Simultaneous imaging of OH∗ chemiluminescence and Mie scattering of fuel spray have been performed under reacting conditions in a constant volume combustion chamber aimed for a second-generation biodiesel/diesel blended fuel. Mie scattering of 532 nm laser light technique was used for the liquid fuel measurement. In order to remove the interference signal from soot radial, filtered Mie scattered light from the fuel droplet was recorded with a charge coupled device (CCD) camera. The spray liquid length and the flame lift-off length for this high cetane-number fuel were investigated under different ambient gas conditions (temperature, density, oxygen concentration) and injection pressure. Experiments showed that the spray liquid length under the reacting condition was shorter than that under non-reacting condition. The flame lift-off length was significantly influenced by the ambient gas temperature, density, oxygen concentration and injection pressure, while the spray liquid length was slightly affected by the injection pressure and oxygen concentration. The overlap between liquid fuel and combustion flame easily happened at high temperature, high oxygen concentration, and low injection pressure conditions.