Abstract: The thin layer N S equations and Baldwin Lomax algebraic turbulence model are used to calculate the transonic turbulent flow in a forward nozzle. The numerical algorithm is based on the implicit finite volume form of Van Leer flux vector splitting schemes in generalized coordinates. A line Gauss Seidel relaxation is used to invert the coefficient matrix by alternating sweep, and the local time stepping is implemented to accelerate the convergence rate of steady problems. A flow field with the Reynolds number of 1 66×10 6 is simulated, and the results are consistent with the experimental data.