Abstract: The inner flow field characteristic of the Model K100 autocycle engine is analyzed. The flow pattern of flow field is investigated. A method of structure improve and performance amelioration is studied in complex machine product. The three-dimensional numerical simulation model is constructed in engine inner flow field for transient flow calculation. The method of time difference and finite volume to conjugate explicitness and implicitness is adopted to disperse the equa-tions. The terms of diffuse and pressure and convection are calculated. According to the simulation results, modified sche-me of engine structure is put forward. The calculation results show that expectation streamline pattern is improved in the inner flow field of engine and its general performance is ame-liorated. Three-dimensional transient numerical simulation is a credibility and application technique to treat structure improve and performance amelioration of some complex machine prod-uct.

Key words: Complex machine Structure improve Performance amelioration, Flow field dynamics, Numerical simulation