GB896982A - Improvements in jet propulsion power plants for aircraft - Google Patents

Abstract

896,982. Jet propulsion plant. BRISTOL SIDDELEY ENGINES Ltd. July 17, 1959 [July 18, 1958; Dec. 24, 1958], Nos. 23205/58 and 41778/58. Class 110 (3). [Also in Group XXIX] An aircraft jet propulsion power plant comprises four walls enclosing a main duct having an air intake at one end and a rectangular section outlet at the other end, at least one gas turbine jet engine and at least one combustion duct engine mounted side by side in the main duct, at least one further wall dividing the main duct into separate rectangular outlet nozzles, one for each engine. Each combustion duct nozzle is defined in part by a main wall part which divides that nozzle from the atmosphere outside the plant and is of articulated construction so as to allow that nozzle to be at least partially closed while producing a tapered external configuration, and by a wall part which is opposite the said main wall part and which is humped towards the said main wall part so as to form a throat in that nozzle. The plant shown is bounded by two pairs of flat walls 11, 12 and 13, 14. The upstream portion of the duct bounded by the four walls comprises a diffuser consisting of upper and lower divergent channels 15, 16, the adjacent walls of which are defined by the opposite surfaces of a central wedge member 19. At the downstream portion of the duct is disposed a gas turbine jet engine 23 and on either side thereof a ram jet unit 24, 25, all of which receive air from the common outlet end 22 of the divergent diffuser channels 15, 16. The gas turbine jet engine comprises a compressor 26, combustion equipment 29, turbine 28 and propulsion nozzle 34. The ram jet units 24, 25 each comprise combustion equipment having a flame tube 31, pilot combustion zone 32 and fuel sprayers 33, and propulsion nozzles 38, 39, respectively. The propulsion nozzle 34 comprises upper and lower flaps 35 pivotally mounted at 36 and adjustable by means of actuators 37, the forward ends 35a of the flaps being flexible in order that they may slide on the casing of the engine. Adjustment of the flaps varies the divergence of the nozzle outlet and simultaneously varies the area of the nozzle throat. The propulsion nozzles 38, 39 each have a flat top wall 40, flat side walls 41 and an adjustable bottom wall consisting of a forward portion 42 hinged at 43 to the bottom wall of the duct and a rearward portion 44 hinged at its rearward end 45 to a short divergent bottom wall part 46. The forward part 42 has a curved rear end 47 which forms the throat of the nozzle. The parts are adjusted by means of an actuator 48, the adjacent ends keeping together in sliding relationship. Before the ram jet units are brought into operation, their nozzles 38, 39 are closed completely by means of their upper walls 40 which are pivotally mounted at their forward ends, the walls being moved by means of actuators 48a, the closed position of the walls being shown by chain-dotted line. During this phase of operation of the plant, the gas turbine jet engine nozzle members 35 are adjusted to a convergent position as shown by chain-dotted lines. The area of the intake throat is varied by means of an actuator 50 which causes the sides of the wedge 19 to move inwards to the position shown in chain-dotted lines. The adjacent parts 51 of the inner walls of the diffuser channels 15, 16 are pivotally mounted at 52 and move simultaneously with the sides of the wedge. In Fig. 4, the diffuser comprises a single channel 53 formed by wedgeshaped walls 54, which are pivotally mounted at 56 so that the area of the throat may be varied. The portions 59 of the diffuser wall are pivoted at 60. The plant shown in Figs. 9, 10, 11 comprises a gas turbine jet engine 110 having a propulsion nozzle 112 and ram jet units 111a, 111b, each having a propulsion nozzle 114a, 114b, disposed on either side thereof. The nozzles 112, 114a, 114b have at their lower sides humped members 116, 116a, which produce constrictions 117, 117a, respectively. The upper sides of the nozzles comprise a fixed wall portion 118 and hinged flaps 119, 121, 119a, 121a and 119b, 121b which are pivoted at their upstream edges 120, 122, 120a, 122a and 120b, 122b. The humped members of the ram jet nozzles such as 116a are made in two parts 123, 124 which are pivoted at 125, 126 to the fixed lower wall 127 so that they may be adjusted so as to vary the width of the throat 117a. Alternatively the humped members 116a may be non-adjustable like the humped member 116 of the gas turbine jet nozzle. In Fig. 13, each gas turbine jet engine has twin nozzle passages 212 and 312 above and below a central horizontal plane, and each ram jet unit has similar nozzle passages 214 and 314. The humped members 216, 316 are disposed adjacent the central plane. The actuators for the flaps and humped members are housed in the space 140 within the humped members. In another arrangement the turbine jet engines are disposed one above another in pairs and the ram jet units are similarly disposed. The adjustable flaps of the gas turbine jet engine nozzle, also the flaps and humped members of the ram jet nozzles are controlled by a Mach number sensing device. The humped members of the ram jet nozzles are also controlled by means of an intake shock-wave position sensing device. The variable area intake is also controlled by means of a Mach number sensing device.