涡扇发动机加减速特性显式与隐式计算方法

Explicit and Implicit Methods to Calculate Acceleration and Deceleration Performance of Turbofan Engines

关键词:  涡扇发动机  过渡态特性  显式格式  隐式格式  加速率控制

Key words:  Turbofan engine  Transient performance  Explicit  Implicit  n-dot control

摘要:

为了探索一种便于进行涡扇发动机过渡态控制规律设计的性能计算模型，提出了基于部件法的涡扇发动机加减速的显式格式和隐式格式计算方法，该方法通过在发动机计算模型中直接给定喘振裕度限制值、燃烧室油气比限制值和涡轮进口总温的限制值，计算出最优的加减速特性，进而获得发动机的最优加减速控制规律。计算模型针对不同的给定值，选择了不同的燃烧室容积效应模型。证明了对一般的涡扇发动机，隐式格式计算模型中，给定压气机喘振裕度算法的解是唯一的。以某涡扇发动机在地面的加减速过程为例，按最优加减速控制规律计算，显式格式算法和隐式格式算法的结果误差<1.3%。对给定高压转子转速加速率的加速特性也进行了验算，计算结果与最优加速过程的结果误差<1.7%。本文提出的加减速特性计算方法可为涡扇发动机的过渡态开环和闭环控制规律设计提供便捷的手段。

Abstract:

To find a performance calculation model which is suitable for turbofan engine transient control schedule design， the explicit and implicit methods for turbofan engine acceleration and deceleration performance calculation is proposed based on the component-level engine performance model. With the surge margin limit， the combustor fuel-air ratio limit or the turbine inlet total temperature limit being given as input， this method is able to calculate the optimal transient performance and control schedule. The calculation models use different combustor volume effect model for different given limits. The uniqueness of the solution of fixed compressor surge margin model in the implicit method is proved regarding to a turbofan engine. An example of the optimal acceleration and deceleration control schedule of a turbofan engine is calculated using the explicit and implicit method and the deviation is within 1.3%. The acceleration performance by n-dot control schedule of the high-pressure rotor is also checked， and the deviation between the result of the n-dot control schedule and the optimal acceleration process is less than 1.7%. The calculation method proposed in this paper can provide a convenient means for the design of open-loop and closed-loop transient control schedule of turbofan engines.