GB781661A - Improvements in variable area jet propulsion nozzles - Google Patents

Abstract

781,661. Jet propulsion nozzles. SOC. D'EXPLOITATION DES MATERIELS HISPANO SUIZA. April 6, 1955 [April 8, 1954], No. 10103/55. Class 110 (3). In a variable area jet propulsion nozzle including a movable flap arranged to guide exclusively the gaseous stream flowing inside the nozzle and adapted to project more or less into the nozzle, the flap forms one of the walls of a variable volume chamber, the other walls of which are fixed with respect to the nozzle and means are provided to vary the pressure in the variable volume chamber so as to position the flap with respect to the nozzle. The nozzle 1 has one or more variable volume chambers C formed by fixed walls carried by the nozzle and a movable wall 2 which forms the shutter. The movable wall 2 is formed by a box member having two side walls 2s, an inner wall 2i, an outer wall 2o and an end wall 2e, which is pivoted about an axis 4. The inner and outer walls 2i, 2o have extensions 5a, 5b, preferably flexible, which abut against the nozzle walls in the limit positions of the shutter. Sealing means is provided between the nozzle walls and the walls of the shutter. The seal may be constituted by a corrugated flexible sheet attached to the nozzle wall in frictional contact with the shutter walls or by packing which is spring- loaded against the shutter walls. A number of shutters may be provided and they may be operated as shown in Fig. 6. When the control lever 12 is in the position I shown in Fig. 1, the chambers C are connected to a source of gas pressure greater than the pressure of the exhaust gases in the nozzle through a conduit 10 and control valve 11. The four shutters 2 are then caused to project into the nozzle. When the lever 12 is moved to the position II the conduit 13 is connected to atmosphere through the valve 11 and conduit 9. Two of the shutters are then retracted. In the position III of the lever 12 all the shutters are retracted. The minimum area of the nozzle may be predetermined. by changing partitions 15, which are slipped into channel-shaped members 16, by other partitions having a different central curved portion. The valve 11 may be controlled automatically by compressor intake or discharge pressure, the turbine exhaust pressure, the rotational speed of the turbine, the turbine exhaust temperature or by a pressure in the final circuit.