In order to study the influence of air compressibility upon the time-averaged quantities in flow field of turbulent boundary layer

a numerical simulation and calculation of 2D flow field in steady turbulent boundary layer with inlet Mach number of 0.058

0.233

0.446

0.872

and 1.457 respectively has been carried out.The results show that the compressibility of air has little influence upon the velocity and temperature distribution in the viscous sublayer zone of the velocity boundary layer and temperature boundary layer

but it can make the velocity and velocity gradient

as well as the temperature and temperature gradient

to be enlarged;the influence of air compressibility upon molecules' diffusion process is utmost small

but has larger influence upon the diffusion process of turbulent flow.When the local Reynolds number is greater than 1×106

and the inlet Mach unmber is larger than 0.466

the local frictional resistance coefficient on the plate will be smaller than that in non-compressible state.Whereas the