Correlation analysis of lift fan lip feature geometry and aerodynamic performance

In hover, the lip of a lift fan plays a crucial role, contributing to nearly half of the lift for the VTOL aircraft power plant. Thus, investigating the geometric parameters that influence lip performance is of significant importance. In this study, four types of lift fan lips were designed, tailored to meet specific application requirements. Numerical analysis, validated through experimental data, was employed to examine the flow field and the geometric factors that lead to variations in lip performance. Based on the findings, the relationship between lip geometric parameters and aerodynamic performance was thoroughly investigated and confirmed. The results demonstrate that, at a rotational speed of 10 000 r/min, the non-dimensional lift and non-dimensional mass flow of the lemniscate lip exhibit improvements of 33% and 9.5%, respectively, compared to lips designed based on NACA65. Among the various lip configurations, it is found that the performance parameters of the lip are optimal when the slope of the inner surface equaled twice the slope of the lemniscate. On the other hand, when the slope deviated from this optimal value, whether greater or lesser, a reduction in lip performance was observed. Specifically, at a rotational speed of 10 000 r/min, the lip designed based on a lemniscate slope could increase the total lift of the lift fan by 5.6% when compared to the lemniscate lip. 悬停状态下, 唇口可为升力风扇提供接近一半的升力, 是垂直起降飞行器动力装置的重要气动部件。以挖掘影响升力风扇唇口性能的几何参数为目标, 针对某升力风扇应用需求设计了4种唇口, 采用经过试验验证的数值分析方法研究了造成唇口性能差异的流场及几何因素, 在此基础上研究了唇口几何参数与气动性能的关联关系并进行了验证。结果表明: 10 000 r/min的风扇转速下, 双纽线唇口比基于NACA65设计唇口的无量纲升力和无量纲流量分别提高33%与9.5%;对于文中研究对象, 当唇口内表面斜率等于2倍双纽线斜率时, 唇口的性能参数最优, 大于或小于2倍双纽线斜率时, 唇口性能均会降低; 10 000 r/min的风扇转速下, 与双纽线唇口相比, 基于2倍双纽线斜率设计的唇口可使升力风扇的总升力提高5.6%。