垂直/短矩起降飞机机翼内埋式风扇布局气动特性分析

Analysis on aerodynamic characteristics of fan-in-wing configuration of V/STOL aircrafts

以垂直/短距起降飞机过渡飞行状态为背景,针对机翼内埋式风扇布局的自由来流/风扇喷流混合型流动,基于结构/非结构混合网格使用CFD方法进行了非定常数值模拟和分析.首先使用滑移网格技术对NASA涵道螺旋桨进行算例验证,其时均计算结果与实验值的误差为5.3%,证明了计算方法的可靠性和准确性,然后数值模拟了机翼内埋式风扇布局在不同迎角下的气动性能.结果表明:风扇喷流在机翼上产生了特有的"抽吸"和"堵塞"效应,引起了机翼总升阻力的显著增加,升力最大增量达到干净机翼升力的2.6倍,阻力最大增量为干净机翼阻力的3.2倍,混合流场在机翼后缘引起了升力损失并卷起对涡.

The complex flow caused by the interaction of the fan jets with the freestream was numerically simulated and compared using computational fluid dynamics （CFD） method based on structured/unstructured mixed grids in order to investigate aerodynamic character- istie of a fan-in-wing configuration about vertical/short takeoff and landing （V/STOL） un- der transition. The ducted propeller of NASA was simulated firstly using sliding mesh technique. Time-averaged results showed a good agreement with experiments and the relative er- ror was 5.3~, proving the CFD methods using above was reliable and accurate. And then, the aerodynamics of fan-in-wing configuration with different attack angles was calculated. Results indicate that the special effects of suckdown and blocking caused by the fan iets lead to notable lift and drag increments, the max lift increment is 2.6 times the closed-wing＇s lift and the max drag increment is 3.2 times the closed-wing＇s drag. The mixed flow field located at the rear of the wing results in a little of lift loss and rolls up in a pair of vortices.