Scale Model Design of a Turboshaft Engine with Mid Turbine Frame

The object of this work is to develop a method which can control the adverse effect caused by the manual adjustments during the scale model design work, in order to design a better dynamic-similar test rig for a turboshaft engine. The test bed's driving system which is a hollow shaft motor requires a larger length difference between the two rotors, which means different similarity scales on two rotors in the dual-rotor scale model should be used. In addition, the influence of the manual distortion on the dual rotor system is unpredictable. This paper makes some improvements on the traditional rotor dynamic theory, makes it can be apply on dual rotor system with different geometry similarity scale. Then, raises up a method which use genetic algorithm to optimize the scale model's mode shape and critical speed. Finally, use the finite element method compare the critical speed, mode shape and unbalance response of the scale model and the origin rotor system in order to validate the theory and the method.