Research on the principle configuration and performance of a wide-speed-range, high-throughflow "dual-variable" cycle engine

To extend the operating speed range of turbine engines, bridge the "thrust gap" with ramjet engines, and meet the requirement for subsonic cruise fuel economy, this paper proposes a "dual-variable" cycle principle characterized by a "full-speed-range, high-throughflow aerodynamic-thermal layout" as its core essence and regulated by the "wide-range adaptive adjustment of pressure ratio and bypass ratio" as its key mechanism. Based on this principle, a high-throughflow "dual-variable" cycle engine configuration is developed. The cycle principles and parameter characteristics under different operating modes are introduced. A set of common working equations for the dual-variable cycle engine is established based on the component-based method, and a corresponding overall performance simulation model is developed using an object-oriented programming language. Performance simulation results show that in turbofan mode at Mach 4, the relative corrected mass flow remains at 48%, and in turbojet mode at Mach 5, the corrected mass flow can still maintain 35%. Compared with a typical small-bypass-ratio military turbofan engine, the corrected mass flow in subsonic cruise is increased by approximately 30%, and the fuel consumption rate is reduced by 15%. This study demonstrates that the dual-variable cycle engine exhibits significant advantages and potential in wide-speed-range flow retention capability and fuel economy, providing a new technological pathway for the design of future hypersonic vehicle propulsion systems.