Abstract: Method for cetane number determination was studied by air flow control with FCD-Ⅱ cetane number tester. The principle for air flow control was introduced. The relations between air flow and cetane number were tested, the repeatability of the method was investigated for 8 samples having different cetane number were conducted, and the results were compared with that by compression ratio. The results show that the air flow has a nonlinear relationship with the cetane value. The cetane number can be calculated by interpolation method. Repeatability bias of cetane numbers measured is less than 1.0 in the range of 25 to 75, which is in good agreement with the compression ratio method.

Key words: cetane number, air flow control, compression ratio, diesel