Effect of variable inlet guide vanes on thermodynamic characteristic and flow mechanism of a core compression system for variable cycle engine

As a critical component of the variable cycle engine (VCE), the variable cycle core compression system (VCCCS) necessitates exceptional performance stability across a wide range of operating conditions. This research delves into the effects of varying the angles of variable inlet guide vanes (VIGV) on the thermodynamic characteristics and internal flow structure of the VCCCS under wide-range operational adjustments. The results reveal that modulating the VIGV significantly broadens the operating envelope of the VCCCS, extending the range of stable and efficient operation from a single curve to a surface. Moreover, adjusting the VIGV reconfigures the load distribution among VCCCS components, consequently altering the internal flow structure. The relationship between aerodynamic losses and entropy distribution in VCCCS components at different VIGV angles has been clarified. Closing the VIGV reduces the secondary flow losses and the extent of high-entropy regions within the core driven fan stage (CDFS) passage, while having a relatively minor impact on the losses in the high-pressure compressor (HPC). The evolution of the feasible domain of the bypass ratio and the mechanisms of adjustment limitation are uncovered. Notably, when the VIGV is adjusted from −20° to 50°, the sources of flow instability within the VCCCS under extreme boundary conditions exhibit three distinct changes. Additionally, a correlation has been established between the VIGV configurations and the thermodynamic characteristics of the VCCCS, thereby providing valuable insights for the design of efficient operation across a wide range of operating conditions.