Experimental investigation of the two-stage ignition delay and flame structure of pentanol/n-dodecane binary fuel

High thermal efficiency and low emissions are achievable with pentanol direct injection compression ignition, but there are issues of difficulty and unstable combustion at low loads. To solve the above problem, a binary fuel is obtained by blending high-activity n-dodecane with pentanol. In a constant-volume combustion chamber, the natural flame luminosity, schlieren, formaldehyde planar laser-induced fluorescence, and the OH* chemiluminescence methods were used to investigate the combustion characteristics of the two-stage ignition delay, the formaldehyde, and the flame liftoff length. The results show that, compared with n-dodecane, the two-stage ignition delay of pentanol/n-dodecane binary fuel is longer; and the initial time of the formaldehyde signal of pentanol/n-dodecane binary fuel is delayed by about 100 μs? Additionally, under all operating conditions, the initial position of formaldehyde varies concurrently with changes in the flame lift-off position, and the formaldehyde signals of the pentanol/n-dodecane binary fuel and n-dodecane gradually decrease downstream from the flame liftoff position. The pentanol/n-dodecane combustion model was built with experimental data, and it can be helpful in further numerical simulation.