桨尖间隙和双桨间距对涵道螺旋桨气动性能的影响

Influence of tip clearance and propeller separation space on aerodynamic performance of ducted propeller

采用基于非结构网格的滑移网格技术,对悬停状态下涵道螺旋桨流场进行了非定常Euler方程数值模拟,分别考查了桨尖间隙和双桨间距对涵道螺旋桨气动性能的影响.桨尖间隙比的变化范围取为0-1.37%,双桨间距变化范围取为0.25-0.65倍的桨叶半径.研究发现：随着桨尖间隙增大,涵道螺旋桨拉力降低,功率载荷减小;桨尖间隙比存在一个临界值,约为1.10%,在该值附近,桨尖泄漏涡显著增强,引起涵道和螺旋桨的拉力分配关系剧烈变化,涵道拉力占总拉力的比值下降10.27%,系统气动性能迅速恶化;大间隙下桨尖泄漏流表现出较强的非定常现象.增大双桨间距可以提高共轴双桨涵道的气动效率,但是因为涵道对螺旋桨滑流的改善作用,这种影响并不显著,气动力的相对变化量在3%以内.

The aerodynamics of flow field around the ducted propeller system in hover was simulated to investigate the influence of tip clearance and propeller separation space on aerodynamic performance individually around the unsteady Euler equations with unstructured sliding mesh technique. The tip clearance ratio varied between 0 and 1. 37%, and the propeller separation space range was 0.25-0.65 times of propeller radius. The investigation shows that increasing tip clearance leads to decrease in total trust and power loading of ducted propeller. The critical tip clearance ratio is about 1.10%. The magnitude of leakage vortices increases dramatically at the critical tip clearance, causing significant change of the thrust sharing ratio between duct and propeller; the proportion of duct thrust to total trust decreases by 10.27%, and system aerodynamic performance worsens rapidly. The unsteady characteristic of tip clearance flow appears at large tip clearance ratio. Increasing propeller separation space can improve aerodynamic efficiency of ducted coaxial propeller. However, the influence is denotable as the relative variation in aerodynamic force is within 3 %, due to the diffusion effect of duct on propeller slipstream.