Abstract: A revisory quasi-one-dimensional compressible flow method is putted forward in calculating radial leakage across sealing dam of most faces without free groove for gas film face seal. The method can not only overcome the error between the classic theory and practices but also develop the limitation of previous method. The pressure distribution arid thickness of gas film should be known to this end. Thus Sit is necessary to establish the pressure differential equation of gas film for face seal and find its static solution by using finite element method at first.

Key words: Gas film face seal, Quasi-one-dimensional compressible flow, active design, CNC machine, interval parameter, joints, optimization