Patent GB-656090-A (GB)
Title: Improvements in and relating to liquid fuel atomizing systems
IPC: F23D11/26
Filed: 1946-10-16
Abstract: 656,090. Gas turbine plant. BRITISH THOMSON-HOUSTON CO., Ltd. Oct. 16, 1946, No. 30843. Convention date, Oct. 16, 1945. [Class 110(iii)] [Also in Groups XI, XXII and XXIX]. A liquid fuel atomizing system applicable to the combustion apparatus of gas turbine plant for aircraft includes duplex-type nozzles wherein each nozzle has a whirl chamber supplied through primary and secondary ducts, the primary ducts being supplied at a pressure determined by the control throttle and the secondary ducts being supplied through a valve regulating the flow in accordance with the displacement of the valve against a spring-closing bias under the pressure of the throttled supply, and wherein the outlet from the whirl chamber is smoothly flared up to its termination at a sharp annular cut-off edge; an atomized spray in the shape of a hollow cone stable over a wide range of flow is thus given. In the apparatus shown in Fig. 1 one or more duplex-type nozzles 2 discharging into a combustion chamber 1 are fed by a positive displacement pump 6 the pressure in the main supply conduit 17 being controlled by a byepass valve 11 operated by a governor 9 driven from the power plant, by a byepass valve 14 operated by a barometric device according to the altitude &c.. and by a throttling and stop valve 15 which is controlled in accordance with the fuel flow desired. The fuel substantially at this pressure is supplied to a chamber 21 in the nozzle body through a manifold 18 and filter 19 while fuel is supplied to a further chamber 33 in the nozzle body through a valve device 3, manifold 30, and filter 31. The chambers 21, 33 communicate through arcuate slots or circularly arranged holes 54, 55 respectively in a plate 53, Fig. 11, with annular grooves 65, 67 in a nozzle tip 59, Fig. 12, and the grooves 65, 67 communicate respectively through slots 40 substantially inclined to the radial direction and tangentially opening holes 39, with a whirl chamber 37 having a conical end surface 62 leading to a cylindrical bore 63 formed with a flared discharge 64 terminating at a sharp annular cut-off edge 72. The plate 53 is positioned by dowels 57 in the nozzle body 49 and, with the nozzle tip 59, is held in place by a threaded cap 60. The two faces of the plate 53, the associated end face 52 of the nozzle body, the plane and conical surfaces of the nozzle tip 59, and the conical inner surface of the cap 60, are polished or lapped to give fluid tight joints. The slots 40 are preferably formed by impressing the top surface of the land 66 with a coining die to a greater depth than desired and then lapping the rear surface of the tip member to reduce the slots to the required depth The inlet ends of the slots are rounded to give the optimum flow. The whirl chamber should have a diameter of 2 to 3 times that of the throat 63. The arc 64 of the discharge orifice may form part of a circle, ellipse, parabola or hyperbola and is of a radius of the order one to one and a half times the throat diameter and the tangent to the surface at the sharp edge 72 should be at an angle of between 2 and 15 degrees to a plane at right angles to the orifice axis to obtain a wide angled hollow spray cone 22. The valve device 3 (see Group XXIX) may comprise a spring-pressed contoured pin 27 raised or lowered in the orifice plate 28 by a bellows 26 which may be sealed either evacuated or with a certain amount of contained gas or be subjected to the ambient atmosphere pressure or be connected by a conduit 35 to the combustion chamber. Specifications 590,422, 637,223 and 638,494 are referred to. Reference has been directed by the Comptroller to Specification 579,417, [Group XI].