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

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 characteristic of a fan-in-wing configuration about vertical/short takeoff and landing(V/STOL) under 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 error 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 jets 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.