GB1288379A - - Google Patents

Abstract

1288379 Ship jet propulsion apparatus H A KERSHAW 13 Oct 1969 [3 Dec 1968] 57211/68 Heading B7V [Also in Division F1] A jet propulsion, gas turbine or gas generator unit comprising several stages each of which consists of a Venturi tube or similarly shaped chamber through the walls of which heat is conducted as described in Specification 1,100,903 includes cooling means for at least one of the tubes or chambers wherein air is induced thereover and then fed into the main working fluid entering the tube or chamber. In one arrangement the unit comprises a casing 1 having an inlet with shutters 2 past which air is drawn by a gas jet issuing from nozzle 4 into a convergent duct portion 5. The thus compressed mixture flows to Venturi tubes 6, 6a in series for further compression before issuing into the atmosphere as a jet for propulsion or other purposes. A device may be provided for inducing into the jet ambient air for silencing, or water when the unit is used for ship propulsion. The exterior surface of the convergent portion of Venturi 6 is finned and is cooled by air drawn through a surrounding cowling 10, the air then being mixed with the mainflow entering the Venturi. A flow of cooling air is also drawn through inlets 7, over the finned exterior of duct portion 5 and thence through pipe 9 to the interior of cowling 10. A liquid, e.g. water, liquid air or oxygen may be injected into the cooling air. Venturis 6, 6a are heated, at least at starting, by feeding gas from a gas generator 15 to nozzles 4, 4a, the nozzles subsequently receiving gas tapped from the mainflow through pipes 11, 11a respectively. The tapped flow in pipes 11, 11a may be heated by a surrounding water jacket. Each stage may comprise several Venturis in series. The unit may include a turbine (38, Fig. 7, not shown) with repeated action of the working fluid on the same blade ring. The turbine may drive a variable pitch fan or airscrew through a gear-box or hydraulic coupling. Additional heat may be applied to the working fluid in casing 1 by electric heating elements which may include a plasma system consisting of a rod and ring electrode in tail pipe 13. These heating systems may be energized by a dynamo driven by a turbine in casing 1. Fuel may be burnt in the working fluid. The Venturis may be surrounded by chambers containing sodium to improve heat conductivity. All surfaces in contact with working fluid may be coated with fluorine to reduce friction. Several units may be mounted together as in Figs. 4, 5 (not shown).