| 摘要 |
In one aspect, the fluid dynamic device (such as an aircraft 100) comprises a shroud 130,140 disposed about a central axis 210, and has an upstream fluid intake region 215 and a downstream fluid exit region 222. The shroud 130, 140 directs fluid flow between the upstream fluid intake region 215 and the downstream fluid exit region 222 and is configured so that, at least during some operating conditions of the fluid dynamic device 100, at least a portion of fluid exiting the fluid exit region 222 is directed towards the central axis 210. A rotor 120 may be provided to draw air in through the intake region 215 and direct it into the shroud, and the shroud may comprise a flexible skirt 130 and a rim 140, which may be moved to vector thrust. In another aspect, the fluid dynamic device comprises first and second drum rotor fans which rotate in different directions, a shroud being provided which directs radially outward flow from the first fan to a region beneath the first fan. The shroud may direct the flow radially inward onto the second drum rotor fan. |
