Abstract: In response to the trend of shrinking aspect ratio of nacelle of the next generation’s civil turbofan engines, the effects of the key geometric parameters of the inlet lip on flow characteristics of the nacelle inlet were carried out in order to improve the uniform of the airflow parameters at the fan face and the flow field structure of the inlet, thus improve the aerodynamic performance of the nacelle inlet. The effects of contraction ratio, lip super-ellipse index, and lip super-ellipse long-short axis ratio on nacelle inlet performance parameters were studied by CFD numerical simulation. The results show that the three key design parameters all have a direct impact on the performance of the inlet, with the most obvious impact on the distortion index. Among them, the contraction ratio has the greatest effect. When the contraction ratio changes by 0.025, the rate of the change of distortion index can reach a maximum of 50%. The change of the contraction ratio affects the flow of throat, the change of the super-ellipse index affects the curvature of the inlet leading edge, and the change of the super-ellipse long-short axis ratio affects the curvature of the inner surface of lip. As the contraction ratio increases, the super-ellipse long-short axis ratio increases and the index of the super-ellipse decreases, the initial pressure loss and the wall friction loss increase. As a result, the total pressure recovery coefficient of the inlet decreases, and the distortion index increases.

Key words: Turbofan engine;Nacelle inlet;Lip;Key geometric parameters;Inlet performance

摘要： 针对下一代民用涡扇发动机短舱长径比不断缩小的发展趋势，为改善发动机进口气流参数分布不均、改善进气道的流场结构、提高其气动性能，开展了进气道唇口关键几何参数对短舱进气道流动特性影响的研究。通过CFD数值模拟方法研究了进气道收缩比、唇口超椭圆指数以及唇口超椭圆长短轴比对短舱进气道性能的影响。研究发现，这三个设计参数改变时，均会对进气道性能产生直接的影响，对畸变指数的影响最明显，其中收缩比改变的影响最大，当收缩比每改变0.025，畸变指数的变化率最大可达到50%。进口收缩比的改变影响喉道截面的流动，超椭圆指数变化影响了进口前缘曲率的变化，而超椭圆长短轴比变化影响了进气道唇口内型面的曲率；超椭圆长短轴比越大，超椭圆指数越小，收缩比越大，唇口初始压力损失越大，壁面摩擦损失越大，进气道总压恢复系数越低，畸变程度越高。

关键词: 涡扇发动机;短舱进气道;唇口;关键几何参数;进气道性能