Potential of combined adjustment of primary stream and secondary air system on adaptive cycle engine

The adaptive cycle engine (ACE) meets complex mission requirements through flexible variable-geometry regulation, however, this also presents significant challenges for the design of its secondary air system (SAS). Specifically, it remains difficult to ensure that the SAS meets all functional requirements under complex operating conditions while simultaneously preventing excessive bleed during low-load conditions, which lead to efficiency losses. Current research on ACE primarily focuses on primary-stream component modulation, with limited attention given to its SAS. This study proposes a modulated secondary air system and develops a coupled model integrating ACE overall performance with the modulated secondary air system. The effects of combined adjustment of the primary stream and SAS on the function of SAS and engine performance are investigated. The results demonstrate that combined adjustment of the primary stream and SAS reduces specific fuel consumption by 3.03 % during subsonic cruise and increases engine thrust by 2.03 % during supersonic cruise. This study highlights the significant potential of the modulated secondary air for ACEs and provides valuable insights and references for the design of their secondary air systems.