Based on a novel high bypass ratio turbofan propulsion system with additional tip-driving fan

the flow characteristics and working mechanism of the core components tip-turbine were investigated using numerical simulation

which laid a theoretical foundation for the further development of high bypass ratio propulsion. Research results indicated that tip-turbine was essentially the axial flow turbine with low solidity and low aspect ratio characteristic

solidity can be as low as 0.6

aspect ratio as low as 0.4. The reduction of solidity caused the migration of throat position

which led to a substantial decrease in the flow deflection and the acceleration of the expansion; the gap leakage loss caused by the low aspect ratio was 2 times larger than the original one

and the influence of leakage vortex was gradually extended to the vicinity of the root of the blade

which reduced the effective extraction of energy area and the energy extraction rate greatly; for the novel power system

effective extraction of energy region and energy extraction rate were proposed to measure the specific work of tip-turbine qualitatively and quantitatively.