外形参数对涡扇发动机冠状喷口气动性能影响

Effects of Configuration Parameters on Aerodynamic Performance for Chevron Nozzle in Turbofan Engine

为准确评估涡扇发动机冠状喷口的气动性能,提出了一种基于流量守恒的出口定义方式,并验证该出口定义方式与物理出口的一致性,对冠状喷口在设计点和非设计点工况下的气动性能进行了系统性评估与考察。结果表明:在设计点工况下,冠状喷口外形参数中,内切角对推力性能影响最大、齿数影响次之、齿长影响最小;冠状喷口下游流向涡对是导致剪切层增厚、湍动能衰减、核心区长度减小的主要原因;在非设计点工况下,冠状喷口可有效降低出口附近的激波强度,使其堵塞状态压比远高于基础构型喷管。

In order to evaluate aerodynamic performance of chevron nozzle accurately,one definition of its outlet based on flow conservation was firstly proposed. And the consistency between outlet definition method and physical outlet was verified. Then aerodynamic performance of chevron nozzle was assessed and investigated systematically at the design point and off-design point. The results show that among chevron parameters bend angle has the greatest influence on thrust performance,chevron number has less influence and length has the least influence at the design point. Streamwise vortices introduced by chevrons result in thicker shear layer,faster turbulent energy decay and shorter potential core. Chevron nozzle can efficiently decrease shock wave intensity downstream the exit at the off-design point. Larger pressure ratio is needed for chevron nozzle to reach to blockade condition accordingly.