Investigation of a methodology for core driven fan stage matching in the off-design mode

The core driven fan stage (CDFS) is one of the key components for the double bypass variable cycle engine. A methodology called CDFS matching map for the CDFS matching in the off-design operating mode, the double bypass mode, was established using velocity triangle. The matching map describes the operating characteristics and the variations of the main aerodynamic parameters of the CDFS in the double bypass mode. For a given mass flow rate and reduced pressure ratio of the CDFS in the double bypass mode, the rotation speed needs to be reduced to keep the rotor inlet relative flow angles unchanged. Given the mass flow rate and pressure ratio in the double bypass mode, the rotor inlet relative flow angles decrease if the rotation speed increases in the double bypass mode.