Influence of Adjustment Modes with Reducing Bypass Ratio on VCE Fan Flow Characteristics

The influence law of bypass ratio adjustment modes of variable cycle engine (VCE) fan was discovered by a three-dimensional numerical simulation for the first stage fan of VCE. The results show that there are many ways to reduce the bypass ratio of VCE fan, according to the characteristic curve of coupling affected in bypass ratio and throttling strength for VCE fan. It is found that reducing the bypass ratio of VCE fan only by throttling the outer bypass will decrease the aerodynamic performance and stability margin for VCE fan, while changing the throttling strength in both bypasses at the same time will make VCE fan maintain good comprehensive performance when reducing the bypass ratio, by further analyzing the characteristics of VCE fan with different adjustment modes.