Performance Prediction for the Fan of the CF6-50 Turbofan Engine at the Off-Design Conditions

Abstract

In the present study, the off-design performance of an axial transonic flow fan is predicted. The fan is 2.18 m in diameter, highly twisted, and has a number of 38 tapered blades with a long span and law aspect ratio. This fan is installed in the high bypass ratio CF6-50 turbofan engine. The three dimensional (3-D) flow field is solved in the fan and its intake at different flight conditions. A periodic sector of a central angle of (360/38) is generated to represent the required computational domain. Results show that, at the fan blade inlet, the average relative Mach number reaches unity at 54% and 40% of the blade inlet span for takeoff and cruise conditions, respectively. At the blade tip the relative Mach number reaches 1.38 at takeoff and 1.5 at cruise. Furthermore, the fan map is plotted over a range of speed lines varying from 60% to 110% of the design value. In addition, the surge line and the operating line at cruise conditions are also plotted on the fan map. The efficiency curves for each speed are plotted as well for the same relative speeds. Moreover, computations revealed that at the design speed, approximately 10.5% stall margin remained beyond design pressure ratio. In the present study, the off-design performance of an axial transonic flow fan is predicted. The fan is 2.18 m in diameter, highly twisted, and has a number of 38 tapered blades with a long span and law aspect ratio. This fan is installed in the high bypass ratio CF6-50 turbofan engine. The three dimensional (3-D) flow field is solved in the fan and its intake at different flight conditions. A periodic sector of a central angle of (360/38) is generated to represent the required computational domain. Results show that, at the fan blade inlet, the average relative Mach number reaches unity at 54% and 40% of the blade inlet span for takeoff and cruise conditions, respectively. At the blade tip the relative Mach number reaches 1.38 at takeoff and 1.5 at cruise. Furthermore, the fan map is plotted over a range of speed lines varying from 60% to 110% of the design value. In addition, the surge line and the operating line at cruise conditions are also plotted on the fan map. The efficiency curves for each speed are plotted as well for the same relative speeds. Moreover, computations revealed that at the design speed, approximately 10.5% stall margin remained beyond design pressure ratio