Optical study on spray, combustion and flame characteristics of n-hexanol/diesel blends under various diesel engine-like conditions

•Spray combustion process of n-hexanol/diesel blends were tested via optical methods.•Blending n-hexanol into diesel is able to improve the spray evaporation noticeably.•The flame lift-off length prolongs obviously when n-hexanol is blended into diesel.•Fuel blends always exhibit a much lower natural luminosity than that of pure diesel.