Analysis of Component Matching Phenomena in a Double Bypass Compression System

Multiple bypasses and variable area valves perplex the aerodynamic connections between the compression components, i.e. fan, core-driven fan stage (CDFS) and high pressure compressor (HPC), of a double bypass engine (DBE). Reasonably matching the components lays on the foundation of the design of a DBE compression system. To explore the design rules of DBE compression systems, the component matching principles of a custom-designed DBE compression system was analyzed in the present study by employing a versatile integrated compressor throughflow procedure. The baseline matching state and two throttling schemes, i.e. first bypass throttling and second bypass throttling, were investigated. For the DBE compression system considered in this paper, the throughflow calculation results show that the total pressure ratio of the compression system is reduced by 2% and the efficiency decreased by 0.002 for the spanwise mismatches in CDFS and HPC at baseline matching state. First bypass throttling remarkably affects the matching state of HPC first stage while having little effects on the spanwise matching state of subsequent stages and CDFS. Second bypass throttling substantially changes the inlet flow profiles of CDFS and cuts down the stable work range of CDFS while having little impacts on the matching state of HPC.