GB1044243A - Jet propulsion engines - Google Patents

Abstract

1,044,243. Jet propulsion nozzles; combustion chambers. ROLLS-ROYCE Ltd. April 20, 1965, No. 16678/65. Headings F1J and F1L. A gas turbine jet propulsion engine has a propulsion nozzle which is defined between a cylindrical nozzle casing and a plug member mounted therein, the casing and the plug member being relatively movable so as to constitute a variable area nozzle, at least the upstream face or faces of the plug member being provided with a layer or layers of metal shingles. In the engine shown the jet nozzle comprises an outer casing 14 and a plug member 19 mounted therein for axial movement, axial movement being effected by an air motor 37 acting through gearing 38 and a ball screw arrangement 39, 40. The upstream face of the plug member 19 is is covered by a layer of metal shingles which afford a passage for the flow of cooling air, the air discharging through the spaces between the overlapping shingles. The annular space 13 may constitute a combustion section and the inner and outer walls thereof are formed by double walls with annular spaces therebetween for the flow of cooling air. The inner wall of the outer casing may be provided with a layer of overlapping shingles 16 similar to the upstream surface of the nozzle plug. The wall thickness of the nozzle plug at the region of greatest diameter is greater than that of the other parts of the plug, and the wall of the plug in this region is coated with a layer of anti-radiation, anti-oxidation material such as silicon carbide. The reversible air motor 37 is actuated by air tapped from the intake through duct 36 and the air after expansion in the motor is utilised for cooling the ball screw device. Rotation of the screw 39 causes axial movement of the nut 40 and sleeve 41 and hence of the nozzle plug 19 which is mounted for axial movement by means of rollers 34 which engage longitudinallyextending rails 33 secured to fixed structure.