GB1259125A - - Google Patents

Abstract

1,259,125. Variable-area nozzle. HALLTHERMOTANK INTERNATIONAL Ltd. 8 Dec., 1969 [7 Dec., 1968], No. 58248/68. Heading B2F. [Also in Division F2] A variable area nozzle comprises a plurality of flexible diaphragm devices arranged in sideby-side contiguous relationship and positionable in the line of fluid flow and each diaphragm has an annular series of leaves, which are flexible, to define a central aperture of variable area dependent upon the fluid flow through the nozzle; the pitching of the leaves of each diaphragm device being staggered relative to the pitching of the leaves of the next adjacent diaphragm device, and the flexibility of the leaves of each diaphragm device varying from that of the leaves of the next adjacent diaphragm device to damp any oscillations occuring in the diaphragm devices. The nozzle 5 preferably consists of three flexible diaphragms, 8, 9, 10, which have thicknesses between 1/8-7/16 inch. Each diaphragm has a plurality, preferably ten, of leaves 12, made by providing a number of slits 13 in the material, and which are arranged so that the slits of one diaphragm are intermediate with those of an adjacent diaphragm, the diaphragms defining a central aperture 14. The outer diaphragms have a Shore hardness of 95‹ compared with the 80‹ of the central diaphragm to provide the damping mechanism for oscillations in the nozzle. The diaphragms may be made from neoprene, a urethane elstomer 'Polyvon' (Trade Mark) or a flurocarbon. A second embodiment where the diaphragms are inclined upwardly, while being supported on a wire frame, is also disclosed (Fig. 4, not reproduced). The diaphragms are sufficiently stiff to extend freely in the radial direction without drooping when no fluid flow is present, and flexible so that when a fluid flow is present, the leaves 12 fold upwards to increase the area of the throat of nozzle 5.