Simulation of a Transonic Axial Flow Fan of a High Bypass Ratio Turbofan Engine During Flight Conditions

Abstract

In the present work, the three dimensional (3-D) flow field through the transonic axial flow fan and the intake of the CF6-50 high bypass ratio turbofan engine is investigated under the flight cruise conditions (11000 meter altitude and 0.85 Mach number). The fan in concern has a large diameter, about 2.18 m. The fan blade is tapered, highly twisted, and has a long span, about 0.65 m, with a low hub to tip ratio, about 0.4. The actual dimensions of both the fan and its intake are used in the present simulation. Moreover, the steady, compressible, turbulent, and viscous 3-D air flow field in both the intake and fan is solved and investigated. The computational domain is a periodic sector of an angle (360/38) through both the fan and the intake zones. At the design speed and pressure ratio, slight deviations of the efficiency, about 1.27%, and mass flow rate, about 1%, compared with those listed in the engine manual are obtained by the simulation. Furthermore, results of simulation show shock waves formed in the passage at the trailing edge of the suction side and propagate towards the opposite blade pressure side for the outer third of blade span.