GB799504A - An improved air intake duct for a jet propulsion plant - Google Patents

Abstract

799,504. Jet propulsion plant. POWER JETS (RESEARCH & DEVELOPMENT), Ltd. March 1, 1956 [March 11, 1955], No. 7194/55. Class 110 (3). The area of the air intake of a ram jet or gas turbine jet propulsion plant is varied by a vane or vanes, having a portion inclined towards one of the walls or the axis of the intake to divide the flow into a number of parallel paths, which are movable along the general path of the air flow relative to the walls of the intake or adjacent vanes to vary the spacing between the vanes or between the vanes and the walls. The ram jet or gas turbine air intake comprises a duct wall 1 which supports through a spider 6 a centre tubular vane 4. Three coaxial openended tubular vanes 5 are arranged around the vane 4 and supported therefrom by spiders 7 slidable in slots 8 in the wall of the vane. The larger spiders may be strengthened by support rings 9. The vanes 5 are movable from a retracted position in which the leading edges of the vanes lie in the plane of the orifice to the extended position shown by means of three hydraulic or pneumatic jacks. The jacks may be connected in series to co-ordinate the movement of the vanes or in parallel for independent movement of each vane. Other means such as a rack and pinion, lazy-tongs screw-threaded rod or other mechanical means may be used to move the vanes. In an alternative embodiment, the vane 4 is mounted on a telescopic tube supported on the axis of the duct. The rearward end of the vanes have flanges which abut in the extended position spiders supporting the next adjacent vane. The arrangement is such that when operating fluid is supplied to an actuating piston, the vane 4 moves forward and by means of its rearward flanges moves the next adjacent vane 5 which in turn moves the following vane 5. The invention is also described with reference to an air intake of rectangular crosssection. In one of these arrangements the vanes are arranged at a common inclination to an axial plane lying along the general direction of air flow. If a centre vane is employed, the vanes may be inclined towards the centre vane. The vanes may have a major portion parallel to the direction of air flow and only its leading portion inclined as described. The inclined portion may be curved.