| 摘要 |
946,917. Air cushion vehicles. HOVERCRAFT DEVELOPMENT Ltd. March 21, 1960 [March 26, 1959], No. 10543/59. Heading B7K. A vehicle for travelling over a surface and which in operation is supported above the surface by at least one cushion of pressurized gas formed and contained beneath the vehicle, the cushion being contained for at least part of its periphery by a curtain of moving fluid issuing from the lower part of the vehicle includes means distributed along said part of the periphery for supplying further fluid to the region of the cushion immediately inboard of and adjacent to the position from which the curtain of moving fluid issues. The vehicle comprises a main body 1 and a base portion 2 and air is drawn through an intake 3 by an engine-driven propeller 4 and delivered via a duct 7 to a chamber 8 formed in base 2, from which it passes through ducts 9 and 10 to two annular ports 11 and 12 formed in the bottom of the vehicle. Once a supporting cushion has been formed, the cushion pressure will deflect the air curtains from ports 11 and 12 so that they follow a curved path outwards. The flow of air from the ports causes a flow of entrained air along the surface of each air curtain and in particular at regions A, thus causing a reduction of pressure in those regions. Air therefore flows in the direction BC and is carried round, if the system is operating correctly, to form vortices 15 and 16. Under normal conditions of operation the system of flow shown in Fig. 1 is stable so long as the pressure at A is greater than the pressure outside the relevant curtain. If, however, the pressure at A falls sufficiently due to an undesirable alteration in trim or other reason, the curtain jets, instead of being deflected outwards, maintain their inward flow by clinging to the undersurface of the vehicle by a Coarda effect, thus resulting in a loss of cushion pressure. To prevent the reduction in pressure at A a nozzle 22, Fig. 3, is provided directed towards the region at which the loss may occur, through which air is discharged at a pressure higher than the cushion pressure. Nozzles 22 may be single or continuous and an arrangement is described for blowing air into one of a plurality of annular shaped cavities to promote the generation of vortices to maintain the cushion pressure. In a further embodiment (Fig. 4, not shown), air is drawn from the cushion by a compressor and discharged from a nozzle just inboard of the curtain-forming nozzle or air may be caused to flow from the cushion as the result of differential pressures (Fig. 6, not shown). Specifications 854,211, 893,715 and 944,502 are referred to. |
