民用飞机尾吊发动机安装效应对推力影响研究

Numerical Study of Engine Installed Effect on a Tail-Mounted Civil Aircraft Thrust Characteristic

关键词:  民用飞机  发动机  安装效应  推力损失  数值模拟

Key words:  Civil Aircraft  Engine  Install effect  Thrust loss  Numerical simulation

摘要:

为准确分析并确定飞机气动力从而获取飞机气动特性，根据民用飞机研制和性能飞行试验的研究需求，采用数值模拟方法对飞机和发动机带动力三维流场进行了计算，分析了安装和非安装状态下发动机附近流场和其推力参数的变化，初步获得了发动机安装效应对尾吊式民机推力预测的影响。结果表明:本文采用的基于流管假设的推阻力划分方法和数值模拟分析方法，可以获得发动机安装前后的总推力、净推力、安装推力和各推力分量，其结果与发动机性能模型预测基本一致；在带动力条件下，对飞机可用推力的预测需仔细分析安装效应对发动机安装推力的影响，和非安装状态不同，安装状态下喷管气流易受机体/机翼/吊挂流场干扰，其上产生较为明显的压缩-膨胀-再压缩过程；对发动机安装和非安装状态内外涵喷管流动分析表明，出口气流的压力损失和摩阻差异可能是导致推力分量产生变化的主要原因。

Abstract:

In order to determine the aerodynamic force of aircraft and obtain the performance accurately，the numerical simulation is used to calculate the aircraft and engine three-dimensional powered flow field according to the requirements of civil aircraft research and performance flight test. The flow field and its thrust characteristics near the engine are analyzed under the installation and isolated configuration，the effects of engine installation effect on aerodynamic characteristics and thrust prediction are preliminarily obtained. The results suggest that the thrust/drag bookkeeping based on the assumption of flow tube of engine nacelle and numerical simulation method in this paper can obtain the engine gross thrust，net thrust and installed net thrust plus different thrust component in installed and isolated configuration. The numerical results are in good agreement with the predicted results of the relevant engine theoretical performance model. The prediction of aircraft installed thrust needs to carefully analyze the installation effect of the engine with power，which is obviously different from the isolated configuration. The flow field at fan and core nozzle exit in installed state is affected by the installation and the difference of thrust characteristic of engine is mainly driven by compression-expansion-recompression process in installed and isolated configuration，which is affected by the installation of fuselage/wing/pylon. The main reason for the change of thrust components is the difference between the pressure loss and the friction resistances on the outer wall of the fan and core nozzle in the engine installed and isolated configuration.