Finite volume method and second order Roe's scheme are employed to discretize the three-dimensional N-Sequation.Lower-upper symmetric Gauss-Seidel(LUSGS) implicit time stepping method and multigrid technique are employed to accelerate convergent rate.Different turbulence models and wall function are applied to 3Dnumerical simulation of internal-external flow field of axisymmetric nozzle.The comparison with experimental data shows that the most accurate results can be obtained by the means of RNGmodel coupled with eddy viscosity formula

and by using enhanced wall functions for inner wall treatment and standard wall functions for outer wall treatment.The final calculation data are summarized

the pressure distribution of nozzle's outer wall at different NPR(nozzle pressure ratio) and Mach numbers are compared under transonic and supersonic conditions.