Using the hydrogen

ethylene and kerosene (chemically surrogated by a mixture of n-decane 0.8 and 1

2

4-trimethylbenzene 0.2 by mass fraction) as fuels

the characteristic scales in supersonic combustion and the related influence factors were analyzed

and the operating range of scramjet under the typical flight conditions was calculated.At last

the applicability of flamelet model for the numerical simulation of supersonic combustion was explored.The results show that the operating range of scramjet for these fuels decreases successively and Damkohler number(Da) varies boardly in the order of magnitude

and flamelet in eddies regime is usually the main part

where Taylor micro-scale plays an important role.At the same time

it is found that the flamelet model needs to be considered carefully in numerical simulation of supersonic combustion compared with subsonic combustion.