分开式与混合式排气喷管气动特性对比研究

通过内外流场的3维数值模拟,考察多种结构形式的V形齿和波瓣混合器分别对分开式和混合式排气喷管气动特性的影响,此外,比较了涵道比为7一级的分开式和混合式2种喷管在起飞和巡航状态下的推力性能,以期为大涵道比涡扇发动机排气系统的方案选择和气动设计提供参考和指导.计算结果表明：内外交错型V形尾缘十分显著地加强了分开排气喷管尾喷流的掺混,并且造成的推力损失不大;内窄外宽型尾缘的波瓣混合器有利于混合排气喷管气动性能的提高;在7一级的涵道比下,混合排气喷管的推力性能要优于分开排气喷管的.

Comparison Investigation on Aerodynamic Characteristics of Separate-Flow and Mixed-Flow Exhaust Nozzles

Three-dimensional numerical simulation of internal and external flow fields was conducted to identify the influence of a variety of chevrons and lobed mixers on the aerodynamic characteristics of separate-flow and mixed-flow exhaust nozzles respectively. Moreover, a thrust efficiency comparison between separate-flow and mixed-flow exhaust nozzles with the equal bypass ratio of 7 was presented under both take-off and cruise conditions. The objective of the research reported here is to provide reference and guideline for the scheme selection or aerodynamic design of high bypass ratio turbofan engine exhaust system. The calculation results show the chevrons which alternately deflect inward and outward significantly enhance the jets mixing of separate-flow exhaust nozzle. The lobed mixer with the trailing edge of narrow inner wall and broad outer wall contributes to improve aerodynamic performance of the mixed-flow exhaust nozzle. The thrust coefficient of mixed-flow exhaust nozzle is higher than that of separate-flow exhaust nozzle at a bypass ratio of 7.