分开式排气系统气动性能与喷流特性数值研究

CFD-Based Research on Aerodynamic Performance of Separate-Flow Exhaust System of High Bypass Ratio Turbofan Engine

为分析大涵道比涡扇发动机分开式排气系统的气动性能、喷流特性以及挂架支板对排气系统性能的影响,采用数值模拟方法对2种结构形式的分开式排气系统流场进行了2维和3维计算研究。结果表明:挂架支板主要影响外涵流动,对外涵流量、总压损失等系数的影响随外涵落压比非线性变化,外涵进入临界状态后挂架支板造成的总压损失趋于不变,挂架支板对内涵流动的影响几乎不随外涵落压比而变化;外涵喷流主要通过内涵出口处剪切层影响内涵的流动,且其影响方式与喷管结构相关;喷管内涵气动性能不仅受外涵喷流特性影响,也与自身工况相关。

In order to analyze aerodynamic performance, exhaust flow characteristics and the influence of jet-pylon on separate-flow exhaust system of high bypass ratio turbofan engine, 2D and 3D numerical simulation methods were adopted to two different configurations of separate-flow exhaust nozzles. The results show that the pylon mainly influences the bypass flow field, the mass flow and total pressure loss coefficients of bypass vary non-linearly with the bypass nozzle pressure ratio （NPR）, while the total pressure loss caused by the pylon is invariable when the bypass in the critical state. The influences of the pylon on the core flow field remain unchanged with bypass NPR. The core flow field is influenced by the bypass flow through the mixing shear layer, which varies with the core structure, and also is related to its own flow condition.