Abstract
It is desired to increase the core engine speed of the turbofan, to get the best efficiency for the next leap of the engine technology. The conventional mechanism in which the front fan is directly connected to the output shaft of the core engine has a limit of increasing the spool speed because the fan diameter is very large. The authors have proposed a new driving system in which the front fan is driven through the aerodynamic torque converter. The front fan can work at the conventional speed while the core engine runs more efficiently at higher speed. Continuously, in this paper, the flow through the converter is simulated numerically by CFX-5 with the k-epsilon turbulence model of the commercial CFD code. The secondary flow occurred on the hub wall affects markedly the flow condition on the blade surfaces, and the flow along the suction surface of the driver blade separates near the trailing edge, which is deviated to the blade tip by the centrifugal force due to the wheel rotation.