GB885093A - Improvements in or relating to jet propulsion nozzles - Google Patents

Abstract

885,093. Jet propulsion nozzles. YOUNG, A. D. April 26, 1960 [May 1, 1959], No. 15038/59. Class 110 (3). A jet propulsion nozzle has mounted substantially radially thereon, in the region only of the exit, a plurality of vanes which in an operative or noise suppressing position are inclined over a major portion of their length and in non- stalled relationship to the general fluid flow through the nozzle. In cases where the vanes are mounted for oscillation, the maximum angle the vanes make with the general fluid flow direction is such that the vanes are in non- stalled relationship to the fluid flow. The jet pipe nozzle 2, Fig. 1, has vanes 1 which project into the jet flow and are inclined along the whole of their length to the general direction of this flow. In a modification the nozzle also has vanes on its outer periphery inclined in a different sense from those on the inner periphery. The inner and outer vanes may be in line or displaced circumferentially relative to one another. In a further modification the angle of inclination of the inner and outer vanes is adjustable. In another modification the outer vanes are provided with a perforated shroud. The inner and outer vanes may also be twisted in opposite directions. In a still further modification, Fig. 9, the vanes 1 are pivoted on pins 7 and a coil spring is attached to the lugs 8 and pins 7. The vanes can oscillate between inclined angles on either side of the mid-position shown in full lines. The oscillation of the vanes induces corresponding oscillations in the flow direction of the jet gas and this prohibits the formation of regular annular vortices which cause noise. The vanes may extend downstream of the jet pipe nozzle.