发动机入口粒子分离器设计要求在一定清除流量比情况下,分离效率高而流动损失小.本文针对不同入口雷诺数(2×105至9×105)、不同清除流量比(10%到20%)的入口粒子分离器进行了数值模拟与实验研究.通过细致分析不同截面上的速度场和总压损失系数Cp,显示在分离通道内存在明显的低速区域和涡结构,同时在该区域内的出现了大的流动分离.这一结果与实验测得的结构吻合.分析结果显示该分离区域导致了流动通道内部总压损失的增加,由此根据流线分布情况对该分离区域进行结构改进.改进后流动通道内的原分离位置的涡结构强度和空间尺度均大大减小,使在高雷诺数下分离器两个出口的总压损失都降低了30%以上,且通道主出口流动更均匀,同时给出了不同雷诺数下的总压损失,建立了Cp与入口雷诺数的函数关系.数值计算结果显示本文使用的流道改进方法使分离器形状获得改善,获得了更优的流动性能.根据数值模拟结果提出了入口粒子分离器的改进方案.%The separation of micro-particles such as dust or ashes mixed in a gas flow for turbine engines is an important matter in the aeronautics industry. By performing gas flow field numerical simulations, the present study has proposed to improve the shape of an inlet particle separator (IPS). The method is based on the streamlines' profile along the passage of the duct. The influence of micro-particles on the gas flow can be neglected since their mass is insignificant compared to Reynolds number at stake in the study. The analysis of the original shape model of the IPS illustrated a vacuum region near the separation area. The improved shape has been designed in order to suit smoothly to those streamlines in this region. An adjacent objective of the study is to lower pressure losses of the IPS. In order to deduce if the improved shape model represents an improvement of the initial shape, several parameters were investigated: pressure coefficient Cp, and the Reynolds number distribution in longitudinal and transverse sections of the bypass outlet. The improved shape confirmed some considerable improvements compared to the original shape. The significant vortices which appeared in the original shape, were no more critical for separation efficiency of particles; and pressure losses were greatly decreased. Furthermore the results of numerical calculations demonstrated the method applied in this study has succeeded to design a shape which enhances flow behavior. However further work is needed to check the behavior of the gas flow in presence of micro-particles in order to confirm the improvements encountered in this study.
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