In order to study the effect of viscosity and thermal conductivity coefficient on the basic flow and flow stability in the boundary layer

the calculation model of the viscosity and thermal conductivity coefficient of high temperature gases was established by comparing Sutherland formula and Gupta fitting relation. Then Sutherland formula and the established model were applied to the 7species air model for chemical equilibrium flow respectively

and these models were compared in flatplate boundary layer of Mach number 10

16 and 20 at the flight height of 30-5km. The calculation result shows that

within the high temperature range

the viscosity and thermal conductivity coefficient both affect basic flow

flow stability and transition prediction. The increase of viscosity can raise the disturbance growth rate

broaden the growth zone and advance the transition location

whereas the increase of thermal conductivity coefficient leads to opposite results.