Design method and analysis of differential planetary gear mechanism for contra-rotating propellers/propfans

A design and analysis method of the differential planetary gear decelerating mechanism for driving the type of loading of aerodynamic turbo-machinery, especially the co-axial contra-rotating propellers or propfans, was put forward. Differing from the ordinary path, this integral performance method considered the kinetic parameters first and solved the speed ratios, radii, steady exerting forces last, then the correlations among those parameters of the transmission mechanism were established by equations. The conceivable design principles, utilizing types, suitable prime mover aero-engines of the mechanism were discussed. An analytical case of modern turboprop was provided for obtaining the variable intervals of the propfan and mechanism, the features and the importance of those design parameters. Result shows that this method can reveal the domains of feasible solution and the optimal designs of all stable parameters of the mechanism and serve as a theoretical model in the overall simulation of the off-design characteristic of a propulsion system.