涡扇发动机整机环境下压缩部件稳定工作边界计算方法

Numerically Assessing Aerodynamic Stability of Compression Component Running in Turbofan Engine

基于部件匹配技术的涡扇发动机非设计点性能计算模型和基于李亚普诺夫稳定性理论的压缩部件气动稳定性评定模型有机的耦合,实现了发动机整机环境下的压缩部件气动稳定性评定,使得该模型成为一种实用的涡扇发动机压缩部件气动稳定性分析模型。以某型涡扇发动机为例,计算比较了均匀进气时发动机整机环境和单独部件评定时压缩部件稳定工作边界的异同,从计算结果可以看到,均匀进气条件下,无论是风扇部件,还是压气机部件,在发动机环境下和单独部件环境下所得到的稳定工作边界基本相同,即发动机进口气流如果均匀,则风扇或压气机的稳定工作边界与稳定性评定环境无关。

After a decade or so of research, we have come to the point at which we are confident that we can assess by calculation the aerodynamic stability of compression component running in turbofan engine. Such assessment, though highly desirable, was generally avoided because of its complexity. The occurrence of surge of aero-engine is disastrous for fighter aircraft, so ensuring its stability margin to be sufficient is important. Traditional method for aerodynamic stability assessment of compression component is not in engine environment. For accurately analyzing effect of other components of turbofan engine on aerodynamic stability of compression component, a new model is presented for predicting aerodynamic stability limit of compression component in turbofan engine. Firstly, according to the actuator-lag-volume model and parallel compressor model, a quasi one-dimensional and time dependent compression system model is given to model the dynamic flow in compressor. Secondly, Lyapunov stability theory is used to identify the aerodynamic stability of compression component. Finally, this aerodynamic stability numerical model is coupled with steady state thermodynamic-cycle model of turbofan for predicting aerodynamic stability limit of compression component in turbofan engine environment. A turbofan engine with 3 stage fan and 5 stage compressor as an example was simulated. Fig. 5 in the full paper gives fan surge lines for clean inflow in different stability assessment environments and similarly, Table 1 in the full paper gives fan surge lines for distortion inflow. The analysis of Fig. 5 shows that for clean inflow, the effect of different stability assessment environments on surge line is negligible. For distortion inflow, the effect of different stability assessment environments on surge line is considerable; for example, at 100% speed and 8% distortion index, in turbofan engine environment, the loss of surge margin is 6. 67%, but in isolated component environment, under the same conditions, the loss of surge margin is 11.13%, or 4. 46% higher.