变循环发动机过渡态性能直接模拟方法

为了实现多变量可调的变循环发动机（VCE）过渡态性能模拟和控制规律设计，在稳态逆算法和过渡态性能隐式格式计算方法的基础上开发了变循环发动机过渡态直接模拟方法。在稳态逆算法模型中加入容积效应和转子动力学方程，实现了同时给定加速率、涡轮前温度和压缩部件工作点的条件下直接模拟计算过渡态过程中变几何参数和燃油流量的调节规律，验证了方法的精度和可行性，并将该方法用于变循环发动机转模态性能模拟和控制规律设计。计算结果表明，过渡态直接模拟方法的误差在0.58%以内，超声速巡航状态下由单外涵模态转换到双外涵模态的时间约为1 s，海平面静止状态下双外涵转单外涵的时间约为3 s，且推力、转速、涡轮前温度、喘振裕度等参数过渡平稳。该方法可简化转模态控制规律设计流程，并提高设计精度。

Direct simulation method of transient-state performance of variable cycle engines

To simulate the transient-state performance and design the control schedule of variable cycle engines (VCEs), we develop the VCE transient-state direct simulation method based on the steady-state reverse method and the transient-state implicit simulation model. Models of the volume effect and the rotor dynamics are added to the steady-state reverse method, making it possible to directly calculate the control schedule of the variable geometry parameters and the fuel mass flow with the given accelerating rate, turbine inlet total temperature and the operating points of compressors. The method is validated in terms of feasibility and accuracy and is then used to design the control schedule and simulate the performance of a VCE mode-transition process. Results show that the deviations of the transition-state direct simulation method are within 0.58%. The mode-transition time from the single-bypass mode to the double-bypass mode under the supersonic cruise condition is around 1 s, while that from double-bypass to single-bypass in the sea level steady state is 3 s. During the mode-transition, the parameters such as thrust, rotational speeds, turbine inlet total temperature and surge margins vary smoothly. The direct simulation method can simplify the design process and improve the design accuracy of the VCE mode-transition control schedule.