The numerical simulation of jet flow field of inner and out of Laval tube has been carried out by commercial software CFX4. 4

and the fluid flow distribution of axis symmetry turbulence jet out of tube with different stagnation pressure was analyzed to verify the k-ε turbulence model. Results showed that at environment temperature 300 K

the cross section area of jet flow was obviously influenced by the distance from cross section to jet nozzle

but with different stagnation pressure (0.596~0.996 MPa) the change of jet flow expanding along radial was minor ； and with same stagnation pressure the jet flow expanding along radial obviously increased.