Numerical study of the characteristics of a variable cycle core compressor

Throttling characteristics of a variable cycle core compressor under design rotation speed were investigated by use of a sophisticated CFD tool. Two different throttling schemes, primary ow throttling and bypass ow throttling, were considered. The operational features of each component, i.e. core-driven fan stage (CDFS), high pressure compressor (HPC) and secondary bypass, during throttling were analyzed and the matching relationships between them were interpreted. The critical limit factors for cycle adapting were discussed. The results show that bypass ow throttling can realize a large range (0.243~0.062) of bypass ratio adjustment, while primary ow throttling can realize a large range (0.81~1.13) of total pressure ratio adjustment. Secondary bypass OGV's stall and CDFS' chock are the limiting factors of bypass ratio's adjustment and HPC's stall and chock are that of total pressure ratio's adjustment.