Analysis and optimization study on mode transition performance of Ma0-4 parallel TBCC combined engine

Abstract In addressing the “thrust matching” issue during the mode transition process of the Ma 0–4 parallel TBCC combined engine, an integrated analysis of flight performance and engine performance was conducted, in alignment with the mission requirements of hypersonic aircraft. Thrust matching refers to the thrust transition smoothly during the mode transition between turbine and ramjet. This analysis determined the TBCC combined engine scheme and performance indicators that meet the mission requirements. Computational models for mode transition of the TBCC combined engine and performance calculation of high Mach number turbine engines were established, delving into the mode transition characteristics of the TBCC combined engine and proposing corresponding transition strategies and control laws. The control laws were optimized using the Hooke-Jeeves Direct Search Method within the Isight optimization software. Prior to optimization, the maximum relative error between total thrust and the desired value during the mode transition process of the combined engine was 0.6 %. After optimization, the maximum relative error decreased to 0.35 %. During the mode transition process, the most significant total thrust fluctuation occurs as the turbine transitions from windmill state to idled state.