GB800871A - Jet reaction units - Google Patents

Abstract

800,871. Jet propulsion plant. BERGER, M., and BOURCART, E. A. Oct. 17, 1955 [Oct. 22, 1954; Feb. 11, 1955], No. 29592/55. Class 110 (3). [Also in Group XII] A jet propulsion unit comprises a body the interior shape of which is constituted by a convergentdivergent inlet portion 3 followed by a cylindrical combustion chamber portion 4, a slightly convergent portion 5 and finally a cylindrical discharge portion 6. A venturi tube 18 is disposed within the convergent portion 13, the venturi discharging into the throat 14 of the convergent-divergent inlet 3 and a fuel supply conduit 20 opening into the throat of the venturi. Ignition means 33 are provided in the combustion chamber 4. The divergent portion 16 is formed by generators in the form of an involute of a circle followed by a parabolic curve. The body of the unit is formed of ceramic material reinforced by rings 2, and the body is surrounded by a casing 7 so as to provide an annular passage for flow of cooling air; a cowling 11 surrounds the casing 7 and heat-insulating material is disposed therebetween. The minimum area of the convergent portion 5 is greater than the area of the annular inlet between the convergent portion of the inlet portion 3 and the venturi tube mounted therein. A conical member 22 is mounted centrally within the divergent portion 16 and carries on its downstream face fuel injectors 24 which are connected by a duct 25 to a supply of liquid ammonia. The conduit 20 is connected to a supply of fuel such as petrol or kerosene. At the inlet of the unit an annular member 27 of parabolic section is mounted on axial rods 28 so that it may move axially, the member 27 being urged by springs 31 to the forward position shown in full lines, and being moved to the rearward position shown in chaindotted lines against the action of the springs by ram pressure when the unit is moving forward at a certain speed. The annular inlet opening is closed by the member 27 when in the rearward position. Movement of the rods 28 operates fuel control valves 21, 26 in the ducts 20, 25 respectively, the valve 26 being fully open when the member 27 is in the forward position, i.e. the starting position, whereby ammonia which is the starting fuel is admitted through the injectors 24. The ammonia is mixed with air supplied in the direction of the arrow f, and the mixture is ignited in the combustion chamber 4 and the gases discharge through the outlet 6; escape of gases in the forward direction is prevented by the member 27, and a pulsating combustion ensues. The member' 27 moves rearwardly with increasing speed of the unit and the valve 26 is gradually opened. Fuel is then admitted to the venturi tube 18 which with air admitted in the direction of the arrows f1 forms a mixture which burns in the combustion chamber 4, the unit then operating as a ram-jet propulsion unit. A jet propulsion unit A in accordance with the invention is shown combined with a convergent-divergent ram-jet unit 34 in Fig. 5, the unit A discharging into the throat of the ram-jet, and secondary fuel is admitted through injectors 39.