By using the skeletal reaction mechanism

the combustion in an opposed methane jet in coaxial narrow air stream tubes is studied. The temperature

species distribution

heat flux

flame stretch rate and flame curvature are calculated. When the fuel flow rate (QF)=120 ml·min-1

with increasing QA

the flame changes from flat-disk shape to curved one and covers the inner tube exit

and the flame is forced to move toward the exit of inner pipe. The flame is compressed and the distributions of temperature and species are compact. When equivalence ratio (ER)>1.00

with increasing QA

the peak temperature and the flame length along the flame surface rise and reach the maximum

while when ER≤1.00

the peak temperature and the flame length decrease. The after burning gas preheats the inlet methane through the inner pipe and the total heat flux is influenced by the flame temperature and gas flow. With the increase of QA

the heat flux is much stronger and the preheating increases

reaching the maximum when QA=2450 ml·min-1. When QA>2450 ml·min-1

the preheating goes down. When ER>1.00

the stretch rate of flame κ is small and changes slowly at the beginning

and then it rises sharply along the flame surface but finally it is no more than 65 s-1. When ER≤1.00

along the flame surface

κ increases first and then decreases

and finally become negative with the minimum value of -262 s-1. The increase of QA makes κ change seriously. The maximum of κ is 638 s-1.