GB1520783A - Hot venturi tube jet propulsion units - Google Patents

Abstract

1520783 Gas turbine plant; jet propulsion plant; generating combustion products under pressure; ejectors H A KERSHAW 4 Aug 1975 32599/75 Headings F1E F1G F1J and F1L A jet propulsion unit has a jet pipe 1 fed with compressed air by five rings of Venturi tube ducts, the last ring of which actually exhausts into the pipe 1. The Venturi tube ducts are the channels lying between struts 2 of aerofoil shape mounted in rings in the inlet end of the pipe 1 between two coaxial tapered tubes 3, 4. The struts 2 are of radial formation and form the main part of the walls of the Venturi tubes, tubes 3, 4 forming the remaining part of these walls. Heat is conveyed through the struts 2, which are of hollow construction, by an air-flow, induced through inlets 5 and exhausted from outlets 6. Small vents 7 provided in both tubes 3 and 4 admit additional air to the Venturi tubes of the last four rings. Instead of a plurality of rings of Venturi tubes, a single ring of such tubes may be used. In operation, air which is drawn through an inlet 9 is forced through the first ring of Venturi tubes by the action of jets of compressed air or, in some cases, compressed combustion gases, discharged from slotted nozzles 10 into the inlet ends of the tubes and is alternately compressed and expanded isothermally in this and the remaining four rings of Venturi tubes before being exhausted, together with the additional air induced through air inlets 7 and the air discharged from outlets 6, through pipe 1 to produce a thrust reaction. The nozzles 10 are fed with compressed fluid by conduits 11, led from pipe 1 through scoops 11a. Heat is passed from the air under compression, by the heat conveying air directed through the hollow struts 2 and by conduction through their walls, to the expanding air flowing through the outlet sections of the Venturi tube ducts. Fuel is injected through atomizers 12 into pipe 1 from an annular, encircling duct 1a, and is burnt in the air passing through the pipe to produce extra thrust. A turbine driven by the working fluid could be incorporated in the pipe 1, the struts 2 then being placed at an angle to exhaust in the direction of rotation of the turbine rotor. Alternatively, the unit may be adapted as an air or gas compressor, generator, or ejector. A small scoop tube 1b leads compressed air from pipe 1 to a storage bottle (not shown) for use in starting the working cycle of this unit. The struts 2, in a further embodiment, have hollow walls either filled with sodium or through which air is passed. The sodium would melt at the operating temperature and convey heat by convection.